□ 
 
 '# • % • \* 
 
 Qualitative 
 Chemical Analysis 
 
 A. quiz manual and laboratory guide for the use of 
 students imChemistry 3a and 3b 
 
 University of Illinois 
 
 H. S. Grindley, Sc. D. 
 
 Professor of General Chemistry 
 
 AND 
 
 S. C. Clark, S. B. and W. A. Redenbaugh, Ph: D. 
 Instructors in General Chemistry 
 
 Third Revised Edition 
 Urbana, Illinois 
 1907 
 
 m UBBMif 
 5F THE . 
 
 Kwvwarnf IB 
 

 t 
 
 
 
 
 PREFACE 
 
 This quiz manual and laboratory guide, which has ex- 
 $ isted in one form or another for several years, is a distinct 
 } product of the growth of the department of chemistry in 
 Oq the University of Illinois. It is designed for use in the 
 courses in qualitative analysis offered in the first year in 
 this University. These courses presume the completion 
 of Chemistry 1, or of one year’s work in chemistry in a good 
 high school. The quiz manual, which is intended to aid 
 and to assist the student in getting his bearings in a field 
 of activity somewhat new, contains an outline of all of the 
 work attempted in Chemistry 3a and in Chemistry 3b. The 
 laboratory guide and notebook on the other hand, con¬ 
 tains only the directions for those experimental operations, 
 which the student is expected to perform in the laboratory, 
 such questions as he must answer at the time in the course 
 of his laboratory work, and the forms for the experimental 
 records. 
 
 The authors wish to acknowledge their indebtedness to 
 many who have written on the subject of general inorganic 
 chemistry and qualitative analysis and^to those who have 
 taught in the elementary courses in chemistry in the Uni¬ 
 versity of Illinois; acknowledgments are T especially due to 
 
IV 
 
 PREFACE 
 
 Dr. G. McP. Smith, who has taken an unusual interest in this 
 revision. Dr. P. F. Trowbridge, Miss A. V. Flather, Dr. W. 
 M. Dehn, and Mr. G. T. Davis have also given valuable 
 suggestions. For any errors of fact, typography, or expres¬ 
 sion, the authors alone are responsible. They will be glad 
 to receive in writing any and all suggestions for the im¬ 
 provement of the book. 
 
 H. S. G. 
 
 S. C. C. 
 
 W. A. R. 
 
 
PART I 
 
 Chemistry 3a and 3b 
 
 A QUIZ MANUAL AND LABORATORY GUIDE 
 

 
 
CHAPTER I 
 
 INTRODUCTION 
 
 SPECIAL DIRECTIONS TO THE STUDENT 
 
 THE METHOD OF PROCEDURE IN THE LABORATORY WORK 
 
 The first experiment in the laboratory is a study of the 
 solubility of the chlorides of the metals in water and in di¬ 
 lute hydrochloric acid. Instead of using prepared metallic 
 chlorides, the student is required to prepare them for him¬ 
 self from the solutions of the salts of the metals 8 . 
 
 Researches in chemistry have demonstrated that, if a 
 solution of sodium chloride, for instance, is added to a 
 solution of potassium nitrate, potassium chloride and sod¬ 
 ium nitrate are formed in greater or less quantity. It has 
 also been proved that, if a solution of hydrochloric acid is 
 added to a solution of sodium sulphate, sodium chloride 
 and sulphuric acid are formed in greater or less quantity. 
 Since these facts are true, it is evident that the chloride of 
 any metal can be prepared by adding either hydrochloric 
 acid or the solution of any soluble metallic chloride to a so¬ 
 lution of any soluble salt of this metal. In this manner both 
 the soluble and the insoluble metallic chlorides are formed. 
 If the resulting chloride is soluble under the conditions of 
 the experiment, it is not precipitated and the solution re¬ 
 mains clear. On the other hand, if the resulting chloride is 
 
2 GENERAL DIRECTIONS FOR LABORATORY WORK 
 
 insoluble in the surrounding medium, it is precipitated and 
 the solid usually settles to the bottom of the vessel leaving 
 a clear zone of liquid above. In a like manner, any series of 
 salts that it is desired to study can be prepared by adding 
 the proper reagents to soluble salts of the metals. 
 
 Every experiment in the laboratory guide should be per¬ 
 formed exactly as directed and the results should be record¬ 
 ed while the experiment is under way. After an experi¬ 
 ment is finished, the conclusions should be reported as indi¬ 
 cated in the appendix 19-25 . Reference is made by means 
 of small index figures to specific paragraphs in the appendix 
 in connection with nearly all of the experiments. These ref¬ 
 erences are notes of general application or they contain in¬ 
 formation of especial interest to the subject in hand. 
 
 GENERAL DIRECTIONS FOR LABORATORY WORK 
 
 In the laboratory read intelligently and work carefully. 
 Be thoughtful, use your own reasoning powers, and work in¬ 
 dependently. It is essential for the best work that you 
 isolate yourself from others in the laboratory, so that you 
 can concentrate your energy and attention upon the work 
 in hand. Information gleaned from other students fre¬ 
 quently is incorrect, often seriously disturbs the one from 
 whom it is sought, and always tends to create more or less 
 confusion in the laboratory. 
 
 Refer continually to your notes on last semester’s work 
 and to the laboratory guide in Chemistry 1, in particular to 
 pages 5-8 and xiii-xxxii. Keep in mind the cautions 
 
THE PRELIMINARY RECITATION 
 
 3 
 
 there given, as many of them apply in a deeper sense in 
 qualitative analysis. 
 
 Reagents must be kept absolutely free from contamina¬ 
 tion of any kind. Do not interchange the stoppers of bot¬ 
 tles nor lay a stopper down while pouring a liquid out of a 
 bottle but hold the stopper between your first and second, 
 or third and fourth, fingers. Keep the reagent bottles on 
 your desk clean and in the proper order 6,7 . Never dip a 
 pipette nor a glass rod into a reagent bottle but pour out 
 what is needed. Never return any of a reagent to a stock 
 bottle. 
 
 As cleanliness and neatness are absolutely essential to 
 careful and. accurate work in qualitative analysis, keep the 
 interior and the exterior of your desk clean, neat, and in 
 order. 
 
 Clean all apparatus with care and keep it clean. Esti¬ 
 mates of the proficiency of your work will be made constant¬ 
 ly both from the general appearance of your desk and ap¬ 
 paratus and from the character of your work at the desk. 
 
 THE PRELIMINARY RECITATION 
 
 Read the notices on the bulletin boards on the first floor 
 of the chemical building and consult the lists of assign¬ 
 ments to laboratory and quiz sections posted to the left of 
 the stairway. See that your name appears on the right lists. 
 Attend punctually the preliminary recitation for your lab¬ 
 oratory section, receive your desk assignment and ascer¬ 
 tain that everything 3 is in your desk and in good 
 condition. Obtain your class and laboratory books 
 
4 
 
 ARRANGEMENT OF THE WORK 
 
 and write your name in ink on the front cover of each. 
 Without special permission, do not remove your labora¬ 
 tory guide from the room nor bring in for use there any other 
 text. The laboratory records are valuable as an aid to, not 
 as a substitute for, the memory, and the manner in which 
 they are kept shows the character of the student’s work as 
 nothing else can 19-25 . 
 
 HOW TO USE THE CLASS NOTEBOOK 
 
 The class study covers the same ground as does the labo¬ 
 ratory work. The class notebook is intended for use in con¬ 
 nection with the class work. While the laboratory records 
 give facts developed in experimental work, the class note¬ 
 book may include notes gleaned from any source and equa¬ 
 tions other than those required. It is best, however, to 
 state the source'of what is incorporated and these equations 
 and notes must be kept apart in the back part of the note¬ 
 book. In the front part of the notebook there should be 
 placed only the specific equations and problems called for 
 each week and the book should be handed promptly to your 
 instructor 27-30 . 
 
 ARRANGEMENT OF THE WORK IN QUALITATIVE 
 ANALYSIS 
 
 The work of the student in these courses includes four 
 distinct lines of activity; namely, the recitations, the 
 written quizzes and final examination, the preliminary 
 laboratory exercises and laboratory manipulations and 
 methods, and the “unknowns.” 
 
ARRANGEMENT OF THE WORK 
 
 5 
 
 The recitations, or class exercises, consist of two oral 
 quizzes per week upon assigned portions of this text, upon 
 certain pages in Smith’s General Inorganic Chemistry, upon 
 the preceding laboratory experiments, upon certain prob¬ 
 lems and equations involving the qualitative and quantita¬ 
 tive study of chemical reactions, and upon definite refer¬ 
 ences to a selected list 31 of books in which the various topics 
 in chemistry are treated fully and exhaustively. The re¬ 
 sults of the laboratory work are discussed in their proper 
 connection with the other phases of the class work. The 
 class work in combination with the laboratory work aims to 
 present a harmonious and unified development of the sub¬ 
 ject of qualitative analysis for beginners. 
 
 The written quiz and examination work is grouped as 
 follows; 
 
 i. Written quizzes given approximately once in three 
 weeks to review the class and the laboratory work. 
 
 ii. Laboratory quizzes given from time to time to test 
 the student’s knowledge and grasp of the work being done 
 by him in the laboratory. 
 
 iii. The final examination given for 3a at the end of 
 the semester and for 3b at the end of nine weeks. 
 
 The laboratory work requires ten hours per week in the 
 experimental study of the principles involved and the meth¬ 
 ods employed in qualitative analysis. 
 
 As soon as the preliminary study of solubility is' com¬ 
 pleted, the student takes up the study of a graduated series 
 of unknowns. These unknowns consist of a series of solu- 
 
6 
 
 THE STUDENT S STANDING 
 
 tions and solids arranged with the idea of developing both 
 the method of analysis and the student’s powers of applying 
 this method to substances of greater and greater complex¬ 
 ity. 
 
 THE OFFICE HOURS OF INSTRUCTORS 
 
 Each instructor keeps certain office hours as per the lists 
 posted on the bulletin boards and on each Office door. The 
 purpose of these office hours is to give the students in Chem¬ 
 istry 3a and 3b an opportunity to meet their instructors 
 individually and to obtain any necessary additional help. 
 During their office hours the instructors will be glad to make 
 the acquaintance of their students and students are urged to 
 make full use of this arrangement when really in need of 
 assistance. In the laboratory work also, the students 
 should feel free to seek the instructors for advice and 
 counsel at any time. This does not mean, however, that the 
 instructor should be consulted by the student before the lat¬ 
 ter has made full use of his own ingenuity and mental power. 
 
 THE STUDENT’S STANDING 
 
 It should be clearly understood at the beginning, that, 
 in order to obtain credit in either of these courses, it is 
 necessary for the student to make a grade of 70 per cent or 
 more in each of the four lines of work above mentioned. If 
 this is done the student’s final standing is represented by his 
 average grade in these four divisions of the work. A failure 
 in any one of these divisions of work precludes credit being 
 given for the course until the deficiency is made up. Each 
 of the four lines of work is graded separately and inde- 
 
definition of qualitative analysis 
 
 7 
 
 pendently and generally by different instructors. The 
 results of each month’s work may be obtained at stated 
 times from the general office, Room 102, as announced upon 
 the bulletin boards. 
 
 Definition and Aim of Qualitative Analysis 
 
 The science of chemistry deals with the composition of 
 the substances included in the material universe, with the 
 transformation of these substances into each other, and with 
 the phenomena accompanying such changes. Organic 
 chemistry is a study of certain compounds of hydrogen and 
 carbon, called hydrocarbons, and of their derivatives. In¬ 
 organic chemistry includes the study of all other substances. 
 Chemistry 1 dealt mainly with the non-metallic elements. 
 Chemistry 3a and 3b deal mainly with the characteristic re¬ 
 actions of a few of the commonly occurring metallic ele¬ 
 ments. The study of these reactions in the laboratory 
 may be synthetical or analytical. Synthesis is a putting to¬ 
 gether, a building up, of a more complex substance from 
 simpler ones. Analysis is the reverse of this process. It is 
 the separation of a compound into its constituents, or origi¬ 
 nal components, with a view of discovering what elements 
 enter into the combination. If the amount by weight or by 
 volume of one or more of the constituent elements is deter¬ 
 mined, the analysis is quantitative. If only the elements 
 present are determined and not their relative quantity, the 
 analysis is qualitative. 
 
 Qualitative analysis is that branch of chemistry which 
 treats of the recognition of the elements and of their com- 
 
8 
 
 THE CONTENT OF QUALITATIVE ANALYSTS 
 
 pounds. One of the first objects of chemistry is to ascer¬ 
 tain the composition of the substances which exist so abund¬ 
 antly and in such varied conditions in nature. The study of 
 qualitative analysis includes an investigation and a compar¬ 
 ison of the behavior of the several elements and of their com¬ 
 pounds, a study of the phenomena exhibited by them under 
 various conditions, and the determination of the particular 
 conditions essential to the manifestation of each. 
 
 THE BASIS OF QUALITATIVE ANALYSIS 
 
 Since the most important class of compounds which the 
 metals form are salts, the best method of becoming familiar 
 with the metallic elements consists in the study of the prop¬ 
 erties and of the reactions of the salts which they form. 
 One of the most important properties of salts is their solubil¬ 
 ity in water. Further, qualitative analysis is based pri¬ 
 marily upon the solubility and the insolubility of certain 
 metallic salts in water and in a few other common solvents. 
 We must not forget that the terms soluble and insoluble are 
 more or less relative, no substance being absolutely in¬ 
 soluble. Barium sulphate is one of the most insoluble com¬ 
 pounds, since one part dissolves in 344,000 parts of water. 
 Strontium sulphate is also said to be insoluble, but one part 
 of this compound dissolves in 6,900 parts of water. One 
 part of calcium sulphate dissolves in 467 parts of water. It 
 also is commonly said to be insoluble in water. 
 
 THE CONTENT OF 3a AND 3b 
 
 Fully ninety-five per cent of the reactions, involved in 
 the complete analysis of substances, take place in solution. 
 
PRELIMINARY CLASS WORK 
 
 9 
 
 For this reason the laboratory work in these courses begins 
 with a study of the solubilities of four series of compounds 
 which the twenty-six commonly occurring metals form with 
 certain non-metallic or acidic elements. The data here ac¬ 
 quired furnish the basis for the division of the metals into 
 six analytical-groups; the study of these groups, followed by 
 that of the acids, develops into the analysis of simple un¬ 
 knowns, and this in turn prepares for the analysis of mix¬ 
 tures of moderate complexity and of double salts. Further, 
 the student in 3a attempts in addition the analysis of mix¬ 
 tures of greater and greater complexity, of metals and al¬ 
 loys, of selected commercial and natural products, of a few 
 of the less commonly occurring substances, and of com¬ 
 binations whose ingredients mutually interfere with the 
 analysis of each other. 
 
 PRELIMINARY CLASS WORK 
 
 THE ELEMENTS 
 
 For convenience the elements are divided into metals 
 and non-metals, though a sharp line separating the two can 
 not be drawn. The metals can generally be readily dis¬ 
 tinguished from the non-metals by their physical and by 
 their chemical properties, i. The non-metals usually lack 
 the characteristic luster, which the metals possess, and the 
 non-metals are poor conductors of heat and of electricity, 
 while the metals are good conductors, ii. The non-met¬ 
 als unite with oxygen to give acidic anhydrides, that is, 
 compounds which are capable of combining with water to 
 form acids. The metals, combined with oxygen, form bas- 
 
10 
 
 PHYSICAL PROPERTIES OF THE METALS 
 
 ic anhydrides, that is, compounds which with the elements 
 of water give bases or hydroxides. Hydroxides are capa¬ 
 ble of neutralizing acids. The metals are capable of replac¬ 
 ing the hydrogen of acids. In both cases salts are formed. 
 
 THE METALS 
 
 OCCURRENCE AND EXTRACTION FROM ORES 
 
 According to the periodic classification 34 of the elements 
 most of the commonly occurring metallic elements are in 
 Families I, II, III, and VIII. The exceptions are as fol¬ 
 lows: Tin and lead occur in Family IV; arsenic, antimony, 
 and bismuth, in Family V; chromium, in Family VI; and 
 manganese, in Family VII. 
 
 The metals occur in nature in many different minerals 
 and ores. They usually occur most abundantly either as 
 oxides, sulphides, carbonates, or sulphates. The most com¬ 
 mon method of extracting the metals from their naturally 
 occurring compounds is that used in the case of iron, which 
 consists in heating its oxides with charcoal. If the ores are 
 not oxides they are converted into the oxides by heating 
 them in contact with the air. By this treatment the nat¬ 
 ural carbonates, hydroxides, and sulphides are changed into 
 the oxides, which may then be reduced by heating with 
 carbon. 
 
 PHYSICAL PROPERTIES OF THE METALS 
 
 At ordinary temperatures all of the metals excepting 
 mercury are solid, opaque bodies. In compact masses they 
 exhibit metallic luster and most of them possess a light grey 
 
CHEMICAL PROPERTIES OF THE METALS 
 
 11 
 
 color; gold and copper are, however, brilliantly colored. In 
 the form of a powder almost all of the metals are black. 
 
 The metals are good conductors of heat and of electric¬ 
 ity. The specific gravity of the metals varies widely, from 
 0.59 in the case of lithium to 22.5 in the case of osmium. In 
 general the specific gravities of the metals increase with the 
 atomic weights. Metals, whose specific gravities are below 
 5, are called light metals; and those, whose specific gravities 
 are above 5, are called heavy metals. Most metals are 
 malleable and tough and may be converted into foil and 
 wire. Gold and silver are the most malleable of the metals. 
 Arsenic, antimony, bismuth, and tin, which possess the 
 characteristics both of metals and of non-metals, are brittle. 
 
 CHEMICAL PROPERTIES OF THE METALS 
 
 As a rule metals do not combine with hydrogen but direct¬ 
 ly or indirectly they all form compounds with oxygen. Their 
 oxygen compounds generally have the character of basic an¬ 
 hydrides; that is, they form bases or hydroxides with the 
 elements of water. This is markedly true only of the alkali 
 and alkaline-earth metals. Under ordinary conditions, most 
 metals are not soluble in water, except in the cases where 
 they react chemically with water, for example the metals of 
 Groups I and II, according to MendeleefFs classification of 
 the elements, react with water forming more or less soluble 
 hydroxides of the metals and liberating hydrogen. Many 
 metals react directly with acidb forming salts. 
 
12 
 
 REVIEW QUESTIONS 
 
 Questions 
 
 Reference in Smith: Pages 530-539 
 
 From time to time, a number of questions upon the 
 class work and upon the laboratory experiments will be in¬ 
 cluded. These questions may also cover the work of last 
 semester in Chemistry 1. All of these questions can be 
 answered from the preceding pages of this manual, from 
 Smith’s General Inorganic Chemistry, from your notes upon 
 the class work, from the preceding laboratory experiments, 
 or from the reference books. These questions are the basis 
 for the oral quizzes and for the written quizzes and final ex¬ 
 amination. 
 
 What happens when a solution of sodium chloride is add¬ 
 ed to one of potassium nitrate? When a solution of hydro¬ 
 gen chloride is added to one of sodium sulphate? How may 
 we prepare any series of salts of the metals? What evi¬ 
 dence have we that any member of such a series is insoluble? 
 With what does the science of chemistry deal? inorganic 
 chemistry? Distinguish between synthesis and analysis'. 
 Between quantitative and qualitative analysis? Define 
 qualitative analysis. Upon what is qualitative analysis 
 primarily based. Show that the terms soluble and insolu¬ 
 ble are relative. Into what two classes may elements be 
 divided? Give the characteristic physical and chemical 
 properties of each class. Where do the metals appear in the 
 periodic table? How do they occur in nature? How are 
 they extracted from their ores? Mention the chief phys¬ 
 ical properties of metals. The chief chemical properties. 
 
NOMENCLATURE 
 
 13 
 
 Why are the physical properties of metals of great im¬ 
 portance to the chemist ? Show what is meant by each of the 
 following terms; metallic luster, crystallized form, specific 
 gravity, malleable, tenacity, melting point, boiling point, 
 alloy, amalgam, conductivity. Illustrate each term by ex¬ 
 amples. What are the chief chemical properties of the met¬ 
 als? Show how the hydrolysis of the halogen compounds 
 can be used to distinguish metals from non-metals? What 
 is a complex acid? Write the formulas for several salts of 
 complex acids. How do these salts behave in a reaction? 
 How may the metallic elements be grouped according to the 
 periodic system, that is, according to their chemical rela¬ 
 tions? Name the principal representatives of each of the 
 eleven families. Give their characteristic chemical prop¬ 
 erties. 
 
 SOME GENERAL PRINCIPLES OF THE NOMEN¬ 
 CLATURE OF INORGANIC COMPOUNDS 
 
 A. ACIDS 
 
 An acid consists of a non-metal, or of a group of non- 
 metals, joined to hydrogen, which is replaceable by a metal. 
 
 1. Hydracids 
 
 These are binary acids which contain but one negative 
 element or group of elements, and hydrogen. They are 
 named by prefixing “hydro-” to the name of the negative 
 elements, giving it the ending “-ic”, and adding the term 
 acid (see also C, 1, a, i.) 
 
14 
 
 NOMENCLATURE 
 
 H 2 F 2 , hydrofluoric acid H 2 S, hydrosulphuric acid 
 
 HC1, hydrochloric acid H 2 Te, hydrotelluric acid 
 
 HBr, hydrobromic acid HCN, hydrocyanic acid 
 
 HI, hydriodic acid H 4 Fe(CN) 6 , hydroferrocyanic 
 
 acid 
 
 2. Acids Other Than Hydracids 
 
 These acids contain oxygen, or sulphur in addition to an¬ 
 other negative element. They are named from their char¬ 
 acteristic negative element. 
 
 a. If only one acid, containing a given characteristic 
 negative element, exists, it is named by changing the ending 
 of this element to “-ic” and adding the term acid. 
 
 H 2 C0 3 , carbonic acid H 2 Mo0 4 , molybdic acid 
 
 b. If several acids, containing the same characteristic 
 negative element, exist, they are named as follows: 
 
 i. The oldest, the best known, or the most stable acid is 
 given the ending “-ic”. The acid, containing proportion¬ 
 ally less oxygen than the “-ic” acid, is given the ending 
 ‘ ‘ -ous ”. 
 
 HN0 3 , nitric acid H 2 S0 4 , sulphuric acid 
 
 HN0 2 , nitrous acid H 2 S0 3 , sulphurous acid 
 
 ii. The acid, containing proportionally more oxygen 
 than the “-ic” acid, has the prefix “per-” added to the 
 name of the “-ic” acid; while the acid, containing less oxy¬ 
 gen proportionally than the “-ous” acid, has the prefix 
 “hypo” added to the name of the “ous” acid. 
 
NOMENCLATURE 
 
 15 
 
 HCIO, hypochlorous acid H 2 S 2 0 4 , hyposulphurous acid 
 HC10 2 , chlorous acid H 2 S0 3 , sulphurous acid 
 HC10 3 , chloric acid H 2 S0 4 , sulphuric acid 
 
 HC10 4 , perchloric acid H 2 S 2 0 8 , persulphuric acid 
 
 c. The same acid anhydride may unite with varying 
 amounts of water to form acids in which the characteristic 
 negative element is in the same state of oxidation. In such 
 cases the preceding rules alone can not be applied. Such 
 acids are distinguished from each other by the prefixes 
 ‘‘ortho-”, “pyro-” or “di-”, and “meta-”. 
 
 P 2 0 5 + 3H 2 0 = 2H 3 P0 4 , orthophosphoric acid 
 P 2 0 5 + 2H 2 0 = H 4 P 2 0 7 , pyrophosphoric acid 
 P 2 0 5 + H 2 0 = 2HP0 3 , metaphosphoric acid 
 
 d. There are several acids, analogous to some of the 
 above oxygen acids, but with .one or more sulphur 35 atoms 
 substituted for the oxygen. They are named as in a,b, and 
 c, but with “thio-”, “sulpho-”, or “sulph-” prefixed to the 
 name of the characteristic negative element. 
 
 H 2 Sn0 3 , stannic acid H 2 S0 4 , sulphuric acid 
 H 2 SnS 3 sulphostannic acid H 2 S 2 0 3 , thiosulphuric acid 
 
 e. Acids are said to be monobasic, dibasic, tribasic, tet- 
 rabasic, etc., accordingly as they contain one, two, three, 
 four, or more replaceable hydrogen atoms. HC1, H 2 S0 4 , 
 H 3 P0 4 , etc. 
 
 B. BASES OR HYDROXIDES 
 
 Bases have the hydroxyl group, OH, united to a metal, 
 a. In naming bases, the name of the metal is first men¬ 
 tioned followed by the term hydroxide 36 . 
 
16 
 
 NOMENCLATURE 
 
 NaOH, sodium hydroxide 
 NH 4 OH, ammonium dydroxide 
 Sr(OH) 2 , strontium hydroxide 
 Al(OH) 3 , aluminum hydroxide 
 
 b. In case there are two hydroxides of the same metal, 
 the ending of the name of the metal is changed to “-ic-” or 
 “-ous” depending upon whether there is proportionally a 
 greater or a less number of hydroxyl groups in the com¬ 
 pound. 
 
 Co(OH) 3 ,. cobaltic hydroxide 
 Co(OH) 2 , cobaltous hydroxide 
 Sn(OH) 4 , stannic hydroxide 
 Sn(OH) 2 , stannous hydroxide 
 Fe(OH) 3 , ferric hydroxide 
 Fe(OH) 2 , ferrous hydroxide 
 
 c. Bases are said to be monacid bases, diacid bases, etc. 
 accordingly as they contain one, two, or more hydroxyl 
 groups. 
 
 NaOH, Ca(OH) 2 Al(OH) s , Sn(OH) 4 . 
 
 C. COMPOUNDS OTHER THAN ACIDS AND BASES 
 1. Compounds of Two Elements 
 This class consists of all binary compounds including 
 hydracids and their salts but the hydracids are usually 
 named in accordance with A, 1. 
 
 a, i. They are named by mentioning the more posi¬ 
 tive (metallic) element first, followed by the name of the 
 more negative (non-metallic) element with its ending 
 changed to “-ide”. 
 
NOMENCLATURE 
 
 17 
 
 Na 2 S, sodium sulphide 
 CaC 2 , calcium carbide 
 BaF 2 , barium fluoride 
 HC1, hydrogen chloride 
 
 KC1, potassium chloride 
 BN, boron nitride 
 MgO, magnesium oxide 
 H 2 S, hydrogen sulphide 
 
 ii. Sometimes a group of elements react as a single ele¬ 
 ment, for example: 
 
 (NH) 4 Br, ammonium bromide 
 K(CN), potassium cyanide 
 
 b. There may be more than one compound of the same 
 two elements. The rule in a is used with one of the follow¬ 
 ing modifications: 
 
 i. The ending of the name of the more positive element 
 is changed to ‘ ‘-ic ” or ‘ ‘-ous ” depending upon whether the 
 proportional amount of the more negative element is greater 
 or less. 
 
 FeCl 3 , ferric chloride Cu 2 0 2 (CuO), cupric oxide 
 FeCl 2 , ferrous chloride Cu 2 0, cuprous oxide 
 
 ii. The prefixes “mono-”, “di-”, “tri-”, “tetra-”, 
 
 “penta-”, etc., are applied depending upon whether there 
 are one, two, three, four, five, or more atoms of the more 
 negative element. 
 
 N 2 0, nitrogen monoxide 
 
 N 2 0 2 (N0), nitrogen dioxide 
 N 2 0 3 , nitrogen trioxide 
 
 N 2 0 4 (N0 2 ), nitrogen tetroxide 
 N 2 0 5 , nitrogen pentoxide 
 
 SbCl 3 , antimony trichloride 
 
 SbCl 5 , antimony pentachloride 
 
 SbH 3 , antimony trihydride 
 
18 
 
 NOMENCLATURE 
 
 H 2 0 2 , hydrogen dioxide 
 
 Mn 2 0 7 , manganese heptoxide 
 
 2. Salts of Acids Other Than Hydracids 
 Salts may be conceived of as derived from acids by the 
 replacement of the hydrogen of the acid by a metal. 
 
 a, i. The salt is usually named by mentioning the 
 metal first, followed by the name of the acid with the ending 
 “-ic” changed to. “-ate” or the ending “-ous”, to “-ite”. 
 
 HCIO, hypochlorous acid 
 KCIO, potassium hypochlorite 
 
 HC10 2 , chlorous acid 
 KC10 2 , potassium chlorite 
 
 HC10 3 , chloric acid 
 KCIO 3 , potassium chlorate 
 
 HC10 4 , perchloric acid 
 KC10 4 , potassium perchlorate 
 
 H 2 Sn0 2 , stannous acid 
 Na 2 Sn0 2 , sodium stannite 
 
 H 2 SnS 2 , sulphostannous acid 
 Na 2 SnS 2 , sodium sulphostannite 
 
 HP0 3 , metaphosphoric acid # 
 
 NaP0 3 , sodium metaphosphate 
 H 2 C 2 0 4 , oxalic acid 
 (NH 4 ) 2 C 2 0 4 , ammonium oxalate 
 
 ii. The salts of hydracids are not named according to 
 this rule for the reason that such salts consist of but two 
 
NOMENCLATURE 
 
 19 
 
 elements and hence take the ending “-ide” as in C, 1, a, i. 
 
 HC1, hydrochloric acid 
 
 NaCl, sodium hydrochlorate or, usually, sodium chloride. 
 
 iii. If the valence of the metal makes it possible for 
 two salts of the same acid to be formed, the ending “-ic” or 
 “-ous” is applied to the name of the metal depending upon 
 whether the proportional amount of the negative element is 
 greater or less. 
 
 Fe 2 (S0 4 ) 3 , ferric sulphate FeS0 4 , ferrous sulphate 
 
 b. When all of the hydrogen of an acid is replaced by a 
 metal, the salt is called a normal or neutral salt and then the 
 nomenclature in a, above, is used. If only a part of the hy¬ 
 drogen is replaced by the metal, the salt is called an acid salt 
 and the following modifications in nomenclature are intro¬ 
 duced 
 
 i. In the, case of acid salts of dibasic acids, the term 
 acid is placed before the name of the salt. 
 
 NaHS0 4 , acid sodium sulphate 
 
 KHC0 3 , acid potassium carbonate 
 
 Sodium bisulphate and potassium bicarbonate, respec¬ 
 tively, are frequently used also. Neutral or normal sodium 
 sulphate or potassium carbonate are sometimes used in 
 order to accentuate the difference between the two 
 sodium salts of sulphuric acid or the two potassium salts of 
 carbonic acid. 
 
 ii. In the case of salts of tribasic acids, the term pri¬ 
 mary or monobasic, secondary or dibasic, tertiary or tribasic, 
 is placed before the name of the salt depending upon wheth- 
 
20 
 
 NOMENCLATURE 
 
 er one, two, or three of the hydrogen atoms of the acid have 
 been replaced by a metal. 
 
 NaH 2 P0 4 , primary sodium phosphate, monobasic sod¬ 
 ium phosphate, or monosodium phosphate. 
 
 Na 2 HP0 4 , secondary sodium phosphate, dibasic sod¬ 
 ium phosphate, or disodium phosphate. 
 
 Na 3 P0 4 , tertiary sodium phosphate, tribasic sodium 
 phosphate, or trisodium phosphate. 
 
 iii. In the case of salts of acids, containing more than 
 three replaceable hydrogen atoms, the method outlined in i 
 or ii is usually adapted. 
 
 K 4 Sb 2 0 7 , potassium pyroantimonate 
 
 H 2 K 2 Sb 2 0 7 , acid potassium pyroantimonate 
 
 c. When all of the hydroxyl groups of the base are not 
 replaced by acid groups, the salt is called a basic salt. The 
 following examples indicate the nomenclature. 
 
 Cu 2 (0H) 2 C0 3 , basic cupric carbonate 
 
 BiOCl, basic bismuth chloride or bismuth oxychloride 
 
 BiON0 3 , basic bismuth nitrate, bismuth oxynitrate, or 
 bismuth subnitrate 
 
 KSb0C 4 H 4 0 6 , potassium antimonyl tartrate or tartar- 
 emetic 
 
 CaClOCl, ‘ ‘chloride of lime” or bleaching powder 
 
 d. When the hydrogen atoms are replaced partly by 
 one metal and partly by others, the salt is called a mixed salt 
 and is named accordingly. 
 
 CoNi(S0 4 ) 2 , cobalt nickel sulphate 
 
 MgNH 4 P0 4 , magnesium ammonium phosphate 
 
CLASSIFICATION OF SALTS 
 
 21 
 
 FORMATION OF SALTS 
 
 Salts are compounds of the metals with acid radicals. 
 They are formed in many cases by the reaction of a metal 
 with an acid. Salts are also formed by the reaction of a 
 base, or of a basic anhydride, with an acid, In place of the 
 acid, its anhydride may be substituted 22 . 
 
 Zn + 2HC1 = ZnCl 2 + H a 
 Fe + H 2 S0 4 = FeS0 4 + H 2 
 NaOH + HC1 = NaCl + H 2 0 
 Na 2 Q + H 2 S0 4 = Na 2 S0 4 + H 2 0 
 Ba(OH) 2 + H 2 S0 4 = BaSQ 4 + 2H 2 0 
 CuO + 2HN0 3 = Cu(N 0 3 ) 2 + H 2 0 
 2KOH + C0 2 - K 2 C0 3 + H 2 0 
 CaO + SO, = CaS0 4 
 
 3Cu + 8HN0 3 = 3 Cu(N0 3 ) 2 + 2NO + 4H 2 0 
 
 CLASSIFICATION OF SALTS 
 
 Salts may be arranged with reference to the periodic 
 classification of their characteristic negative elements. 
 
 a, i. Fluorides, chlorides, bromides, and iodides con¬ 
 sist of metals in combination with fluorine, chlorine, brom¬ 
 ine, and iodine. 
 
 ii. Chlorates and permanganates are salts of the chief 
 oxyacids of chlorine and manganese, respectively. 
 
 b, i. Sulphides consist of metals combined with sul¬ 
 phur. 
 
 ii. Sulphates, sulphites, and thiosulphates are salts of 
 the chief oxyacids of sulphur. 
 
22 
 
 REVIEW QUESTIONS 
 
 iii. Chromates and dichromates are salts of the corres¬ 
 ponding oxyacids of chromium. 
 
 c, i. Nitrates and nitrites consist of the acids of nitro¬ 
 gen (nitric and nitrous) in which the hydrogen has been re¬ 
 placed by metals. 
 
 ii. Phosphates, arsenates and arsenites, and antimo- 
 nates and antimonites, are salts of the oxyacids of phosphor¬ 
 us, arsenic, and antimony. 
 
 d, i. Carbonates are salts of carbonic acid. Salts of 
 other acids, containing carbon, are also included; as ace¬ 
 tates, oxalates, and tartrates. 
 
 ii. Silicates are derived from salts of the various silicic 
 acids. 
 
 e, Borates are derived from boric acid. 
 
 Questions 
 
 Reference in Smith: Pages 539 to 545 and 263 to 265 
 
 Students in this course should understand thoroughly 
 the meaning, and be able to define and to illustrate completely 
 the following terms which were met with in the work of the 
 the last semester:—Acid, base, salt, metal, non-metal, chem¬ 
 ical symbol, chemical formula; valence, univalent, bivalent, 
 trivalent, quadrivalent; basicity of acids, monobasic acids, 
 dibasic acids, tribasic acids, acidity of bases, monacid bases, 
 diacid bases, triacid bases, normal salt, acid salt, basic salt, 
 primary, secondary, and tertiary salts. 
 
 Of what does an acid consist? Define hydracids. Give 
 four examples. Define oxyacids. Give several examples. 
 How are hydracids usually named? How are oxyacids 
 
REVIEW QUESTIONS 
 
 23 
 
 named? How are two oxyacids containing the same char¬ 
 acteristic negative element distinguished from each other? 
 How are several such acids distinguished from each other? 
 How are several oxyacids, containing the same character¬ 
 istic negative element in the same state of oxidation, dis¬ 
 tinguished from each other? What is the relation of sul¬ 
 phur to oxygen in some acids? Give examples of each of 
 these classes of acids. 
 
 Of what does a base consist? How are they named? 
 How are two hydroxides of the same metal distinguished 
 from each other? What other classes of compounds are 
 there? What is a binary compound? How are they 
 named? How are two compounds' of the same two ele¬ 
 ments usually distinguished from each other? Give another 
 general method for distinguishing more than one com¬ 
 pound of the same two elements. Give examples of each of 
 these classes of compounds. 
 
 What is a salt? How are salts of oxyacids usually 
 named? Of hydracids. Give several examples of each. 
 What is the effect of the valence of the metal upon the 
 name of the salt? Define neutral salt. Acid salt. How 
 are acid salts of dibasic acids named? Of tribasic acids? 
 What is a basic salt? How are basic salts usually named? 
 What is a mixed salt? How are they named? Give ex¬ 
 amples of all these classes of substances. Name three ways 
 in which a salt may be formed. Give equations to illustrate 
 each method of preparation. How may salts be classified 
 according to the periodic system? 
 
24 
 
 REVIEW QUESTIONS 
 
 How do the metals usually occur in nature? Discuss 
 the metallurgy of ores in which the metals occur native. In 
 which the ore is an oxide. A carbonate. A sulphide. A 
 chloride or a fluoride. What use is made of electrolysis 
 in extracting metals from their ores? 
 
 What is an acid ? What is the replaceable part of an acid ? 
 What is meant by the basicity of an acid? Illustrate the 
 meaning. Define monobasic acids, dibasic acids, tribasic 
 acids, and give examples of each. What is the basicity of 
 the following acids:— HC1, HBr, HI, H 2 S, HC 2 H 3 0 2 , 
 H 3 P0 4 , H 2 S0 4 , H 3 As 0 4 , H 4 Si0 4 , H 2 S0 3 , HC10 3 , H 2 C 4 H 4 0 6 ? 
 
 What is the meaning of the term acidity of bases ? Give 
 examples which illustrate. Define monacid bases, diacid 
 bases, triacid bases, and give examples of each. What 
 is the acidity of the following bases:— KOH, 
 Al(OH) s , Ca(OH) 2 , Fe(OH) s , Zn(OH) 2 , NaOH, Fe(OH) 2 . 
 
 What is a normal salt ? A secondary salt ? A primary 
 salt? A tertiary salt? An acid salt? A basic salt? 
 Explain the uses of the prefixes mono, di, tri, etc., in naming 
 salts. Give examples of all of the above classes of salts. 
 
 Explain the use of the suffixes “ic” and “ous” in 
 naming acids, bases, and salts. Explain the use of the 
 termination “ate” and ’‘ite” in naming salts. Also ex¬ 
 plain the use of the.prefixes “hypo” and “per” in naming 
 salts and acids. Give examples which illustrate the use of 
 all of these terms. 
 
 What are oxides of metals? Give several methods of 
 
REVIEW QUESTIONS 
 
 25 
 
 preparation. What are their general physical and chemi¬ 
 cal properties ? What are hydroxides of metals ? Give two 
 methods of preparation. Give their chief physical and 
 chemical properties. What are salts? How are they 
 classified? What are chlorides and how may they be 
 prepared? Give their chief physical and chemical proper¬ 
 ties. What are sulphides? How may they be prepared? 
 Give their chief physical and chemical properties. What 
 other classes of salts are of importance? How are they 
 usually prepared? Give some of their physical and chem¬ 
 ical properties. Note the solublity of a few bases and salts 
 on page 544 in Smith. 
 
CHAPTER II 
 
 A PRELIMINARY STUDY OF SOLUBILITY 
 
 Experiment 1 
 
 THE SOLUBILITY OF CHLORIDES 
 
 a. In separate, clean test tubes, place about 2 cc. of each 
 of the twenty-six salt solutions listed in the appendix 8 and 
 label each test tube with the formula of its contents. To 
 each of these in turn, add hydrochloric acid 37 . If the first 
 
 r. 
 
 few drops of acid cause a precipitation 38 , continue to add the 
 acid as long as it gives a precipitate in the clear zone which 
 forms above after the precipitate has been allowed to settle. 
 Decant the liquid from each of the precipitates and add hy¬ 
 drochloric acid to them. Do any dissolve? Record your 
 results 19-25 and state your conclusions. Which chlorides 
 are soluble in water? Insoluble in water? Soluble in dilute 
 acid solutions ? Insoluble ? 
 
 b. Repeat a, using solutions of lead, silver, and mer¬ 
 curous nitrates and any soluble chloride, as ammonium 
 chloride 7 . Do these results agree with those in a? 
 
 Experiment 2 
 
 THE SOLUBILITY OF SULPHIDES 
 1. The Solubility of Sulphides in Dilute Acid Solutions 
 
 In separate, clean test tubes, labelled as before, place 
 about 2 cc. of each of the solutions of the salts of the metals 
 and make the solution in each test tube acid with a few 
 
 26 
 
THE SOLUBILITY OF SULPHIDES 
 
 27 
 
 drops of hydrochloric acid. Test with litmus paper. If 
 the hydrochloric acid gives a precipitate, use nitric acid in 
 its stead. Through a clean glass jet tube, slowly pass hy¬ 
 drogen sulphide in excess into each salt solution in turn. 
 Note accurately the effects 39 of the gas and record your re¬ 
 sults as in Experiment 1 19 ~ 25 . Save the precipitates for 
 2, below. 
 
 2 . The Solubility in Alkaline Polysulphides of the Sul¬ 
 phides Insoluble in Dilute Acids 
 
 In each of the cases in 1 in which a precipitate formed in 
 acid solution, decant the supernatant fluid, wash the residue 
 twice by decantation 40 , and to the solid still remaining in the 
 test tube add ten to twelve drops of yellow ammonium sul¬ 
 phide, diluted with an equal quantity of distilled water. Heat 
 the test tube gently. Which sulphides dissolve? 
 
 3. The Solubility of Sulphides in Alkaline Solutions 
 
 Arrange other 2 cc. samples of the salt solutions, which 
 failed to form precipitates in 1. To each add ammonium 
 hydroxide until the reaction is barely alkaline and then add 
 ammonium sulphide in slight excess. What precipitates 
 now form ? Write an equation for each 41 . 
 
 Summary 
 
 Tabulate the solubility of the metallic sulphides:— 
 
 i. In dilute acid solutions, 
 
 ii. In alkaline polysulphides, 
 
 iii. In dilute alkaline solutions, 
 
 iv. In water. 
 
28 
 
 CLASSIFICATION OF CHEMICAL REACTIONS 
 
 Enclose in a black line rectangle in the table the in¬ 
 soluble sulphides whose metals form insoluble chlorides. 
 
 CHEMICAL REACTIONS 
 
 Chemical reactions are the changes which take place be¬ 
 tween substances when they act chemically upon one an¬ 
 other. Nearly every element and every compound enter into 
 chemical reactions, but the ability to do so varies widely 
 with different substances. Some compounds are stable 
 only under very special conditions. Hence, these sub¬ 
 stances offer little resistance to an alteration in their com¬ 
 position. On the other hand, other compounds are very 
 stable except under special conditions. These offer more 
 resistance to an alteration in their composition. Gases and 
 liquids react with each other more readily than do solids 
 with either or with themselves. 
 
 CLASSIFICATION OF CHEMICAL REACTIONS 
 
 Most chemical reactions may be subdivided into four 
 general classes. 
 
 1. Reactions of Direct Combination 
 
 2Mg + 0 2 = 2MgO HC1 + NH 3 = NH 4 C1 
 
 CaO + H 2 0 = Ca(OH) 2 2BaO + O, = 2Ba0 2 
 
 2. Reactions of Direct Decomposition 
 
 2HgO = 2Hg + 0 2 2KC1Q 3 = 2KC1 + 30 2 
 NH 4 C1 = NH 3 + HC1 CaC0 3 = CaO + C0 2 
 
 2Ba0 2 = 2BaO + O. 
 
 H 2 C 2 0 4 = H 2 0 + CO + C0 2 
 
CHEMICAL EQUATIONS 
 
 29 
 
 3. Metathetical Reactions 
 
 AgN0 3 + HC1 = AgCl + HNO s 
 
 ZnS0 4 + (NH 4 ) 2 S = ZnS + (NH 4 ) 2 S0 4 
 
 BaHP0 4 + 2HN0 3 = Ba(N0 3 ) 2 + H 3 P0 4 
 
 NaOH + HC1 = NaCl + H 2 0 
 
 Fe(OH) 3 + 3HC1 = FeCl 3 + 3H 2 0 
 
 FeS + 2HC1 = FeCl 2 + H 2 S 
 
 K 2 C0 3 + H 2 S0 4 = K 2 S0 4 4- C0 2 + H 2 0 
 
 HgCl 2 4- Cu = CuCl 2 + Hg 
 
 CdCl 2 + H 2 S = CdS 4- 2HC1 
 
 FeCl 3 + 3NaOH = Fe(OH) 3 + 3NaCl 
 
 Al(OH), + NaOH = NaA10 2 + 2H 2 0 
 
 ZnO + 2HN0 3 = Zn(N0 3 ) 2 + H 2 0 
 
 Ba(OH) 2 + H 2 S0 4 = BaS0 4 + 2H 2 0 
 
 2NH 4 C1 + Ca(OH) 2 = CaCl 2 + 2NH 3 + 2H 2 0 
 
 2KBr +-C1* = 2KC1 + Br 2 . 
 
 4. Reactions of Oxidation and Reduction 
 
 3Fe + 4H 2 0 = Fe 3 0 4 4H 2 Cu.0 4" H 2 = Cu 4" H 2 0 
 
 3H 2 S + 8HN0 3 = 3H 2 S0 4 4- 8NO 4- 4H 2 0 
 6FeS0 4 4- 2HN0 3 4- 3H 2 S0 4 = 3Fe 2 (S0 4 ) 3 4- 4H 2 0 
 
 EQUATIONS TO REPRESENT CHEMICAL REACTIONS 
 
 One of the chief uses of the symbols of elements and the 
 chemical formulas of compounds is to enable us to express, 
 in a condensed and precise form, a considerable amount of 
 
30 CHEMICAL EQUATIONS 
 
 information respecting chemical changes. These changes 
 are called reactions and they are expressed in the form of 
 equations, i. Chemical equations show qualitatively what 
 substances enter into the reaction and what substances are 
 produced by the reaction, ii. They indicate the propor¬ 
 tions in which the reacting substances act upon one another, 
 iii. They show how much of each product is formed as a 
 result of the reaction.. A knowledge of the solubility of 
 acids, bases, and salts is absolutely necessary in order to be 
 able to give accurately and readily the equations that repre¬ 
 sent the reactions which result when substances act chemi¬ 
 cally upon one another. 
 
 In order to write a chemical equation three things are 
 essential: 1. We must know what substances react and 
 their correct chemical formulas. 2. We must know what 
 substances are formed and the correct chemical formulas 
 for them. 3. We must balance the equation, that is, we 
 must choose such proportions of the substances that the 
 number of atoms of each element represented in each mem¬ 
 ber of the equation is the same. 
 
 An equation states the proportions by weight of the sub¬ 
 stances which enter into the reaction. For example, barium 
 chloride reacts with sulphuric acid to form barium sulphate 
 and hydrochloric acid. This reaction may be represented 
 by the following equation: 
 
 BaCl 2 + H 2 S0 4 = BaSQ 4 + 2HC1 
 
 208.3 + 98.1 = 233.5 + 72.9 
 
 This equation means that by weight 208.3 parts of bar- 
 
ELECTROLYTIC DISSOCIATION 
 
 31 
 
 ium chloride always reacts with 98.1 parts of sulphuric acid 
 producing 233.5 parts of barium sulphate and 72.9 parts 
 of hydrochloric acid. For parts by weight we may substi¬ 
 tute any unit of weight, but the same unit must be used 
 throughout the calculations. It is thus evident that if we 
 know the weight of one substance taking part in the re¬ 
 action, all the other weights involved can be calculated. 
 
 THE THEORY OF ELECTROLYTIC DISSOCIATION 
 
 Since so many of the reactions of qualitative analysis 
 take place in solution, it is necessary at this time to consider 
 the theory of dissociation in solution somewhat in detail. 
 The most common and universal fluid medium or solvent is 
 water. The theory of electrolytic dissociation states that 
 the molecules of acids, bases, and salts, on entering into 
 water solution break up more or less completely into posi¬ 
 tively and negatively charged atoms, or groups of atoms, 
 called ions. These ions cannot exist except in solution in the 
 presence of other ions carrying equivalent charges of electric¬ 
 ity of the opposite kind. They react chemically independ- 
 dently of each other and of the molecules from which they 
 were originally derived. The nature of this dissociation in 
 these three classes of electrolytes is shown by the follow¬ 
 ing equations representing reversible reactions: 
 
 + 
 
 HC1 
 
 H + Cl 
 
 H 2 SO 
 
 2H + S0 4 
 
 + 
 
 + 
 
 NaCl 
 
 *=> Na + Cl 
 
 + 
 
 + + 
 
 NaOH <=± Na + OH Ba(OH) 2 <=± Ba + 20H 
 
32 
 
 COMMON POSITIVE IONS 
 
 The positively charged ions are called cations and the 
 negatively charged ions, anions. Ions, which are charged 
 with quantities of electricity equivalent to that of the hy¬ 
 drogen ion or of the chlorine ion, are called monovalent ions; 
 those charged with twice this quantity of electricity, diva¬ 
 lent ions; and those carrying a charge three times as great 
 as that of the ion of hydrogen or of chlorine, trivalent ions. 
 The valence of the ions and the number of unit charges of 
 electricity, which each ion carries, is denoted by signs placed 
 above, or at the right upper corner of, their chemical sym¬ 
 bols or formulas. In the case of electropositive ions, or 
 cations,the plus sign ( + ),oradot (*),is used and,in the case 
 of the electro-negative ions', or anions, the minus sign ( —) or, 
 an acute accent ('), is used. 
 
 The following table, taken with some modifications from 
 Newth’s Inorganic Chemistry, gives a number of the com¬ 
 mon positive and negative ions. 
 
 I. CATIONS 
 
 Monovalent 
 
 Divalent 
 
 Trivalent 
 
 + 
 
 
 + + 
 
 
 + + + 
 
 
 Ag, 
 
 Silver 
 
 Pb, 
 
 Lead 
 
 Bi, 
 
 Bismuth 
 
 Hg, 
 
 Mercurous 
 
 Hg, 
 
 Mercuric 
 
 As, 
 
 Arsenic 
 
 Cu, 
 
 Cuprous 
 
 Cu, 
 
 Cupric 
 
 Sb, 
 
 Antimony 
 
 Na, 
 
 Sodium 
 
 Cd, 
 
 Cadmium 
 
 Fe, 
 
 Ferric 
 
 K, 
 
 Potassium 
 
 Sn, 
 
 Stannous 
 
 Cr, 
 
 Chromium 
 
 nh 4 
 
 , Ammonium 
 
 Fe, 
 
 Ferrous 
 
 Al, 
 
 Aluminum 
 
 H, 
 
 Hydrogen 
 
 Co, 
 
 Cobalt 
 
 Tetra valent 
 
 
 
 Ni, 
 
 Nickel 
 
 
 
 
 
 Mn, 
 
 Manganese 
 
 + + + + 
 
 
 
 Zn, 
 
 Zinc 
 
 Sn, 
 
 Stannic 
 
 
 
 Ba, 
 
 Barium 
 
 
 
 
 
 Sr, 
 
 Strontium 
 
 
 
 
 
 Ca, 
 
 Calcium 
 
 
 
 
 
 Mg, 
 
 Magnesium 
 
 
 
COMMON NEGATIVE IONS 
 
 33 
 
 II. ANIONS 
 
 Monovalent 
 
 Divalent 
 
 Tri valent 
 
 F, Fluoride 
 
 Cl, Chloride 
 
 Br, Bromide 
 
 I, Iodide 
 
 CIO 3 , Chlorate 
 
 OH, Hydroxyl 
 
 NO 3 , Nitrate 
 
 C 2 H 3 0 2 ,Acetate 
 And the anions of 
 all other monobasic 
 acids 
 
 S0 4 , Sulphate 
 
 S, Sulphide 
 
 SO 3 , Sulphite 
 S 2 0 3 , Thiosulphate 
 CO 3 , Carbonate 
 C 2 0 4 , Oxalate 
 
 C 4 H 4 0 6 ,T art rate 
 And the anions of 
 all other dibasic 
 acids 
 
 P0 4 , Phosphate 
 As0 4 , Arsenic 
 As0 3 , Arsenious 
 And the anions of 
 all other tribasic 
 acids 
 
 Pure water, pure hydrogen chloride, and pure sugar do 
 not conduct the electric current. If sugar is dissolved in 
 water, the solution is still a non-conductor of electricity. 
 If hydrogen chloride is dissolved in water, the solution is a 
 fairly good conductor of electricity. This has been found to 
 be the case for all aqueous solutions of acids,bases, and salts, 
 and for them only. Hence, they are called electrolytes. 
 When an electric current is passed through a solution of hy¬ 
 drochloric acid,there is not a simple case of conduction as when 
 a copper wire is used; but hydrogen separates at the neg¬ 
 ative electrode (cathode) and chlorine, at the positive elec¬ 
 trode (anode). Now it is evident that something happens 
 either to the water or to the hydrochloric acid, when they 
 are mixed; because, after the mixing, the solution con¬ 
 ducts electricity while beforehand neither the water nor the 
 hydrogen chloride is a conductor. Since only the hydro¬ 
 chloric acid is affected by the passage of the current, it is 
 reasonable to suppose that the water is not altered in the 
 process of solution. 
 
34 
 
 ELECTROLYTIC DISSOCIATION 
 
 Ions have certain peculiar properties but when their 
 electrical burdens are discharged, the atoms, or the atomic 
 groups, of the former ion assume the properties of nascent 
 atoms, or atomic groups, and react accordingly. For 
 
 example, the ions of potassium sulphate, 2K and S0 4 , 
 when they exist in the presence of each other 
 in the ionic condition, do not decompose water; 
 but when the electric charges of these ions are discharged, 
 as by the passage of an electric current, then the atoms of 
 the element potassium react with the water, forming potas¬ 
 sium hydroxide and free hydrogen and the sulphu¬ 
 ric acid groups decompose water, forming sulphuric 
 acid and liberating oxygen. Atoms of elements, or groups 
 of atoms, which do not act upon water, when they 
 are freed at the electrodes by the discharge of the electricity 
 of the ions, combine to form free molecules, since after giving 
 up their electric charges they no longer repel each other. 
 For example, two negative bromine atoms combine to form 
 one bromine molecule, two negative hydroxyl groups com¬ 
 bine to form one hydrogen dioxide molecule, and one posi¬ 
 tive mercury ion is changed into a molecule of mercury. 
 
 The ions alone are the medium by which the electric cur¬ 
 rent is transmitted through solutions. The current of elec¬ 
 tricity which passes through a solution is, in fact, conveyed 
 by the ions. The molecules which are not dissociated into 
 ions do not take part in the conduction of the electric cur¬ 
 rent. The more ions there are in a unit volume, the better 
 the solution conducts electricity. In other words, the more 
 
ELECTROLYTIC DISSOCIATION 
 
 35 
 
 a substance is ionized, the greater the conductivity of its 
 solution. The extent of electrolytic dissociation varies 
 greatly with different electrolytes but in all cases it increases 
 with dilution. Ionization is practically complete with very 
 great dilution. For every degree of dilution there exists a 
 certain state of equilibrium between the ions and the undis¬ 
 sociated molecules. 
 
 In terms of the theory of electrolytic dissociation, acids, 
 bases, and salts may be defined as follows: 
 
 1. Acids are hydrogen compounds which upon electro¬ 
 lytic dissociation decompose in part or entirely into cations 
 
 + 
 
 of hydrogen, H, and anions of non-metals, or anions com¬ 
 posed of negative atomic groups. The hydrogen ion is the 
 characteristic cation of all acids and whenever it is present 
 acid properties are produced. 
 
 2. Bases are hydroxyl compounds which upon electro¬ 
 lytic dissociation are separated partly or entirely into hy¬ 
 droxyl ions, OH, and metallic ions. The hydroxyl ion 
 is the characteristic anion of all bases and whenever it is 
 present basic properties are produced. 
 
 3. Salts are compounds of metals which upon electro¬ 
 lytic dissociation are separated entirely or in part into basic 
 cations and acidic anions. 
 
 Chemical reactions, between electrolytes in water solu¬ 
 tion, are really reactions between the ions. That is to say, 
 the reactions which take place in aqueous solution are de¬ 
 pendent, for the most part, upon the presence of ions. 
 The greater the concentration of the ions of a substance in 
 
36 
 
 ELECTROLYTIC DISSOCIATION 
 
 the solution, the greater is its chemical activity, since it is 
 the free ions only which enter into reactions. 
 
 The chemical properties of aqueous solutions of salts, 
 acids, and bases, depend largely upon the properties of the 
 free ions which they contain. For example, in all solutions 
 
 H—h 
 
 of barium salts, the presence of the barium ion, Ba, can be 
 proved by one and the same reagent; namely, the sulphate 
 
 ion, S0 4 . The barium ion always, without regard to the 
 large number of combinations which it may form, unites 
 with the sulphate ion to produce slightly dissociated barium 
 sulphate, which is not soluble. 
 
 Again, silver nitrate is a reagent for the chlorine ion, Cl. 
 All the metallic chlorides and similar compounds give with 
 this reagent a precipitate of silver chloride. Silver nitrate 
 does not, however, react with all chlorine compounds. The 
 presence of chlorine in potassium chlorate is not indicated 
 by silver nitrate. Silver nitrate is not a reagent for chlo¬ 
 rine compounds in general. It is only a reagent for the chlo¬ 
 rine ion. When potassium chlorate dissolves in water,-it dis- 
 + — 
 
 sociates into the ions K and C10 3 and therefore it does not 
 contain chlorine as a separate ion but only as a constituent 
 
 .oi a more complex ion, C10 3 . When silver nitrate 
 is added to a solution of potassium chlorate, silver chlo¬ 
 ride is not formed,because chlorine ions are not jmesent and 
 a precipitate does not appear because all the possible com¬ 
 pounds are soluble in water. 
 
REVIEW QUESTIONS 
 
 37 
 
 It follows from these considerations that in qualitative 
 analysis we test for the ions which may be present. Since 
 the ions serve for the identification of the respective sub¬ 
 stances, a knowledge of the ionic conditions of salts, acids, 
 and bases is of much importance. In our future work in 
 this course we shall consider, therefore, the nature and the 
 relation of the ions of the various substances studied. 
 
 Questions 
 
 Reference in Smith: Pages 273 and 274 
 What are chemical reactions? What substances enter 
 into reactions? What substances react most readily? 
 Name the four general classes of chemical reactions. De¬ 
 fine each and give several examples. How are chemical re¬ 
 actions usually represented? What three things do chem¬ 
 ical equations show? What three things must we know in 
 order to write chemical equations? Discuss the equation 
 representing the reaction between barium chloride and sul¬ 
 phuric acid. 
 
 Under what conditions do most of the reactions of qual¬ 
 itative analysis take place? What is the most common sol¬ 
 vent? What probably occurs when acids, bases, or salts 
 dissolve in water? What are ions? How do they react? 
 Show by equations the nature of the dissociation of acids, 
 bases, and salts. What are cations ? Anions ? How is the 
 valence of an ion designated ? Name a few of the most com¬ 
 mon monovalent cations. Divalent cations. Trivalent cat¬ 
 ions. Monovalent anions. Divalent anions. Trivalent. 
 
 anions. 
 
38 
 
 REVIEW QUESTIONS 
 
 What is the effect of an electric current upon pure water? 
 Upon pure hydrogen chloride? Upon pure sugar? Is the effect 
 different if the sugar is dissolved in water? If the hydro¬ 
 gen chloride is dissolved in water? What happens when a 
 current of electricity passes through a solution of hydro¬ 
 chloric acid? Which is affected by the electricity, the water 
 or the hydrochloric acid? What happens when the electric 
 charges of the ions are removed? Illustrate this fully. 
 How is an electric current conducted through solutions? 
 What is the relation of the non-dissociated molecules to the 
 passage of an electric current ? What can you say of the ex¬ 
 tent of ionization ? 
 
 Define acids, bases, and salts in terms of the ionic theory. 
 What is the nature of chemical reaction in water solution ? 
 Upon what does the chemical reactivity of & solution de¬ 
 pend? The chemical properties of such solutions? Give 
 two illustrations. For what do we test in qualitative analy¬ 
 sis? 
 
 Which chlorides are insoluble in water? In acids? 
 Soluble in water? In acids? What is the action of any 
 soluble chloride on any soluble salt of lead, silver, or mer¬ 
 curous mercury? Why are precipitates not formed in the 
 solutions containing chlorides? In all the solutions? 
 What is the solubility of mercurous chloride in water? In 
 acids? Of silver chloride in water? In acids? Of cadmi¬ 
 um chloride in water? In acids? 
 
 Bearing in mind the solubility of chlorides complete the 
 following equations: 
 
SOLUBILITY OF HYDROXIDES 
 
 39 
 
 ZnS0 4 + NaCl = ? SbCl 3 + A1C1 3 = ? 
 
 HgN0 3 + KC1 = ? Ca(N0 3 ) 2 + HC1 = ? 
 
 Pb(N0 3 ) 2 . + CaCl 2 - ? 
 
 Which of the eleven sulphides, that are insoluble in di¬ 
 lute acid solutions, are soluble in alkaline poly sulphides? 
 What are the products- formed when these sulphides dis¬ 
 solve in yellow ammonium sulphide? Represent the reac¬ 
 tions by equations. Make a list of the formulas of the metallic 
 sulphides soluble in water. Of those insoluble in dilute 
 acids. Of those soluble in dilute acids but insoluble in water. 
 
 Bearing in mind the solubility of sulphides in water, in 
 dilute acids, and in alkaline polysulphides, complete the 
 following equations 25 : 
 
 BaCl 2 + H 2 S = ? As 2 S 3 + (NH 4 ) 2 S 2 = ? 
 
 Zn(N0 3 ) 2 + (NH 4 ) 2 S = ? CuCl 2 + H 2 S = ? 
 
 Sr(N0 3 ) 2 + (NH 4 ) 2 S = ? CdS0 4 + K 2 S = ? 
 
 MnS0 4 + H 2 S = ? SbCl 3 + (NH 4 ) 2 S 2 = ? 
 
 Show that substances can be separated from a mixture by 
 making use of the difference in solubility of the substances. 
 
 Experiment 3 
 
 THE SOLUBILITY OF HYDROXIDES 
 
 1. The Reaction of Fixed Alkali Hydroxide with the 
 Metallic Salt Solutions 
 
 Arrange and label as before about 2 cc. of each of the 
 twenty-six salt solutions. To each of these in turn, add a 
 few drops of the ten per cent solution of sodium hydroxide. 
 For calcium, strontium, and barium salts use the “carbon¬ 
 ate free” sodium hydroxide. If the r 
 
 'ffRST fzw of SO~ 
 
40 
 
 SOLUBILITY OF CARBONATES 
 
 ditim hydroxide cause a precipitation, continue to add the 
 sodium hydroxide as long as it produces a precipitate in the 
 clear zone which forms above after the precipitate is allowed 
 to settle. Then add a decided excess of sodium hydrox¬ 
 ide. Does the precipitate redissolve ? Keep notes as be¬ 
 fore and write equations in those cases in wdiich you are sure 
 that a reaction takes place 42,43 . 
 
 2. The Reaction of Volatile Alkali Hydroxide with the 
 Metallic Salt Solutions 
 
 Repeat 1, using ammonium hydroxide from your desk in 
 place of the ten per cent solution of sodium hydroxide 
 Keep notes as before and write the equations 43 ’ 44 as in 1. 
 
 3. The Effect of Ammonium Chloride in Preventing Precipi¬ 
 tation by Ammonium Hydroxide 
 
 Arrange other 2 cc. samples of those salt solutions which 
 have given permanent precipitates with ammonium hydrox¬ 
 ide in 2. To each of these in turn, add an equal volume of 
 ammonium chloride and then ammonium hydroxide as in 
 2. How t do these results differ from those in 2 ? 
 
 Summary 
 
 Tabulate all of the data obtained in 1 , 2, and 3 . 
 
 Experiment 4 
 
 THE SOLUBILITY OF CARBONATES 
 
 To about 2 cc. of each of the solutions of the metallic 
 salts in turn, add enough sodium carbonate solution to turn 
 litmus paper blue. Write notes and equations as before 
 but remember that, with sodium carbonate, silver, mer- 
 
NON-REVERSIBLE REACTIONS 
 
 41 
 
 curous mercury, cadmium, ferrous iron,manganese, calcium, 
 strontium, and barium form normal carbonates as BaC0 3 ; 
 lead, copper, cobalt, nickel, zinc, and magnesium form basic 
 carbonates, as Zn 2 (0H) 2 C0 3 ; ferric iron, chromium, and 
 aluminum form hydroxides; mercuric mercury forms a mix¬ 
 ture of carbonate and oxide, HgC0 3 , 3HgO; antimony, 
 an oxide; stannous tin, stannous acid, H 2 Sn0 2 ; stannic 
 tin, stannic acid, H 2 Sn0 3 ; and bismuth, a basic carbonate, 
 Bi 2 Q 2 CQ 3 . 
 
 Cd(N0 3 ) 2 + Na 2 C0 3 = CdC0 3 + ? 
 
 4Hg(NO s ) 2 + 4Na 2 C0 3 = HgCQ 3 , 3HgO 4- ? 4- 3C0 2 
 
 SnCl 2 + Na 2 C0 3 4- H 2 0 = H 2 SnQ 2 + ? 
 
 2Co(N0 3 ) 2 4- 2Na 2 C0 3 + H 2 0 = Co 2 (OH) 2 C0 3 4- ? 
 
 2Bi(N0 3 ) 3 4- 3Na 2 C0 3 4 Bi 2 0 2 C0 3 4- ? 
 
 REVERSIBLE AND NON-REVERSIBLE REACTIONS 
 
 From another viewpoint, chemical reactions may be 
 divided into two general classes; namely, reversible re¬ 
 actions and non-reversible reactions. 
 
 NON-REVERSIBLE REACTIONS 
 
 In these cases, the reaction can not be made to proceed 
 in the opposite direction, that is, they can not be reversed. 
 
 2Ag a O = 4Ag + 0 2 2KC1Q 3 = 2KC1 + 30 2 
 
 2Mg + O, 4 2MgO Fe.+ S - FeS 
 
 These reactions all run to completion from left to right, 
 provided sufficient time is allowed, but in none of the cases 
 
42 
 
 REVERSIBLE REACTIONS 
 
 can the products formed be converted directly into the 
 original starting substances. 
 
 REVERSIBLE REACTIONS 
 
 In these cases, on the other hand, the reaction is capable 
 of taking place in either direction and it may, or may not, 
 run to completion, depending upon the conditions of the ex¬ 
 periment. If steam is passed over red-hot iron, the reac¬ 
 tion is as follows : 
 
 3Fe+4H 2 0 = Fe 3 0 4 +4H 2 
 
 If the hydrogen that is formed is allowed to escape, the 
 iron is completely converted into the oxide; otherwise, it 
 is not. If hydrogen is passed over finely divided, incandes¬ 
 cent magnetic oxide of iron, Fe 3 0 4 , the reaction is as fol¬ 
 lows: 
 
 Fe 3 0 4 + 4H 2 = 3Fe+ 4H 2 0. 
 
 Here again, if the steam is allowed to escape, the reac¬ 
 tion runs to completion and none of the oxide is left. When 
 it is desired to call attention to the fact that a reaction is re¬ 
 versible, it is generally indicated by double arrows as fol¬ 
 lows: 
 
 Fe 3 0 4 + 4H 2 ^ 3Fe + 4H 2 0 
 
 Another typical reversible reaction is that of zinc sul¬ 
 phate and hydrogen sulphide in neutral solution. If hydro¬ 
 gen sulphide is passed into a neutral solution of zinc sul¬ 
 phate, a white precipitate of zinc sulphate and at the same 
 time free sulphuric acid are formed. 
 
 ZnS0 4 + H 2 S <=± ZnS + H 2 S0 4