Comprehensive
PRACTICAL CHEMISTRY FOR CLASS XII Strictly according to new curriculum prescribed by Central Board of Secondary Education (CBSE) and State Boards of Chhattisgarh, Haryana, Bihar, Jharkhand, Kerala, Mizoram, Meghalaya and other States following NCERT Curriculum
By Dr. N.K. VERMA Associate Professor Chemistry Department D.A.V. College Chandigarh Dr. B.K. VERMANI Associate Professor Chemistry Department D.A.V. College Chandigarh
Dr. NEERA VERMA Associate Professor Chemistry Department M.C.M. D.A.V. College Chandigarh
K.K. REHANI Former Lecturer of Chemistry S.G.G.S. College Chandigarh
LAXMI PUBLICATIONS (P) LTD BANGALORE N CHENNAI JALANDHAR
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COCHIN
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GUWAHATI
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HYDERABAD
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MUMBAI
N
RANCHI
NEW DELHI N BOSTON, USA
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CONTENTS Chapter
Pages
Syllabus
1.
(xiii)—(xiv)
INTRODUCTION TO BASIC LABORATORY EQUIPMENT Viva questions with answers
2.
...
SURFACE CHEMISTRY Exp-2.1 Exp-2.2 Exp-2.3 Exp-2.4 Exp-2.5 Exp-2.6 Exp-2.7
: : : : : : :
... ... ... ... ... ...
11 12 12 13 15 15
...
17
...
20
...
22
... ...
23 25
CHEMICAL KINETICS Exp-3.1 Exp-3.2
Exp-3.3
9
10–27
To prepare colloidal solution (sol) of starch To prepare a colloidal solution of gum To prepare colloidal solution (or sol) of egg albumin To prepare ferric hydroxide, [Fe(OH)3] sol To prepare aluminium hydroxide, [Al(OH)3] sol To prepare colloidal solution of arsenious sulphide, [As2 S3] To study the dialysis of starch sol containing sodium chloride through a cellophane or parchment paper Exp-2.8 : Compare the precipitation values of sodium chloride, barium chloride and aluminium chloride for arsenious sulphide sol Exp-2.9 : To study the effectiveness of different common oils (castor oil, cotton seed oil, coconut oil, kerosene oil, mustard oil) in forming emulsions Exp-2.10 : To compare the effectiveness of a number of emulsifying agents in forming emulsions Viva questions with answers
3.
1–9
28–37
: To study the effect of concentration on the rate of reaction between sodium thiosulphate and hydrochloric acid ... : To study the effect of change in temperature on the rate of reaction between sodium thiosulphate and hydrochloric acid ... : To study the reaction rate of reaction of iodide ions with hydrogen peroxide at different concentrations of iodide ions ...
(v)
29
31
33
( vi )
Exp-3.4
: To study the reaction rate of the reaction between potassium iodate (KIO3) and sodium sulphite (Na2SO3) using starch solution as indicator Viva questions with answers
4.
THERMOCHEMISTRY Exp-4.1 : Determine the enthalpy of neutralisation of hydrochloric acid with sodium hydroxide solution Exp-4.2 : Determine the enthalpy of dissolution of given solid copper sulphate (CuSO4.5H2O) in water at room temperature Exp-4.3 : Determinate the water equivalent (W) of polythene bottle (calorimeter) Exp-4.4 : Determine the enthalpy change during the interaction (hydrogen bond formation) between acetone and chloroform Viva questions with answers
5.
: To set up simple Daniell cell and determine its e.m.f. : To set up simple Daniell cell using salt bridge and determine its e.m.f. Exp-5.3 : To study the variation of cell potential in Zn | Zn2+ || Cu2+ | Cu cell with change in concentration of electrolytes (CuSO4 and ZnSO4) at room temperature Viva questions with answers
34 36
38–46 ...
39
...
41
...
43
... ...
44 45
ELECTROCHEMISTRY Exp-5.1 Exp-5.2
6.
... ...
47–52 ...
49
...
50
... ...
51 52
CHROMATOGRAPHY
53–59
Exp-6.1
: Separate the coloured components present in the mixture of red and blue inks by ascending paper chromatography and find their Rf values ... Exp-6.2 : Separate the coloured components present in the given grass/flower by ascending paper chromatography and determine their Rf values ... Exp-6.3 : Separate Co+2 and Ni2+ ions present in the given mixture by using ascending paper chromatography and determine their Rf values ... Viva questions with answers ...
7.
PREPARATION OF INORGANIC COMPOUNDS : To prepare a pure sample of ferrous ammonium sulphate (Mohr’s salt), [FeSO4 . (NH4)2 SO4 . 6H2O] Exp-7.2 : To prepare a pure sample of potash alum (Fitkari), [K2SO4.Al2 (SO4)3.24H2O] Exp-7.3 : To prepare a pure sample of the complex potassium trioxalatoferrate (III), K3[Fe(C2O4)3] . 3H2O Viva questions with answers
56
57
58 58
60–69
Exp-7.1
...
65
...
66
... ...
67 68
( vii )
8.
PREPARATION OF ORGANIC COMPOUNDS Exp-8.1 : To prepare a sample of acetanilide from aniline Exp-8.2 : To prepare a sample of dibenzal acetone Exp-8.3 : To prepare a sample of p-nitro acetanilide from acetanilide Exp-8.4 : To prepare 2-naphthol aniline dye Viva questions with answers
9.
70–77 ... ... ... ... ...
TESTS FOR THE FUNCTIONAL GROUPS PRESENT IN ORGANIC COMPOUNDS : Identify the functional group present in the given organic compound Viva questions with answers
70 72 73 75 76
78–96
Exp-9.1
... ...
10. STUDY OF CARBOHYDRATES, FATS AND PROTEINS IN PURE FORM AND DETECTION OF THEIR PRESENCE IN GIVEN FOOD STUFFS Exp-10.1 Exp-10.2 Exp-10.3 Exp-10.4
: : : :
To study some simple tests of carbohydrates To study some simple tests of oils and fats To study some simple tests of proteins To detect the presence of carbohydrates, fats and proteins in the following food stuffs : Grapes, potatoes, rice, butter, biscuits, milk, groundnut, boiled egg Viva questions with answers
94 95
97–107 ... ... ...
99 101 104
... ...
105 106
11. VOLUMETRIC ANALYSIS
108–162
M solution of oxalic acid from 10 crystalline oxalic acid N Exp-11.2 : Prepare 250 ml of a solution of oxalic acid from 10 crystalline oxalic acid
Exp-11.1 : Prepare 250 ml of
...
119
...
121
...
122
...
123
M solution of ferrous ammonium sulphate (Mohr’s 20 salt). Using this solution find out the molarity and strength of the given KMnO4 solution ...
128
Exp-11.3 : Preparation of 250 ml of Exp-11.4 : Prepare 250 ml of
M solution of Mohr’s salt 20
N solution of Mohr’s salt 20
Exp-11.5 : Prepare
( viii )
Exp-11.6 : Prepare a solution of ferrous ammonium sulphate (Mohr’s salt) containing exactly 17.0 g of the salt in one litre. With the help of this solution, determine the molarity and the concentration of KMnO4 in the given solution ... M ferrous ammonium sulphate (Mohr’s salt) 20 solution. Find out the percentage purity of impure KMnO4 sample 2.0 g of which have been dissolved per litre ... Exp-11.8 : Determine the equivalent mass and number of molecules of water of crystallisation in a sample of Mohr’s salt, M FeSO4(NH4)2 SO4 . nH2O. Provided KMnO4 ... 100
130
Exp-11.7 : Prepare
M solution of oxalic acid. With its help, determine 50 the molarity and strength of the given solution of potassium permanganate (KMnO4) ... Exp-11.10 : Find out the percentage purity of impure sample of oxalic M acid. You are supplied KMnO4 solution ... 100 Exp-11.11 : The given solution has been prepared by dissolving 1.6 g of an alkali metal permanganate per litre of solution. Determine volumetrically the atomic mass of the alkali metal. Prepare M Mohr’s salt solution for titration ... 20 Exp-11.12 : Determine the percentage composition of a mixture of
132
134
Exp-11.9 : Prepare
LM MN
OP PQ
136 138
140
OP PQ
LM MN
COOH COONa sodium oxalate ⏐ and oxalic acid ⏐ . 2H 2O . COOH COONa M KMnO4 solution ... 100 Exp-11.13 : You are provided with a partially oxidised sample of ferrous sulphate (FeSO4 . 7H2O) crystals. Prepare a solution by dissolving 14.0 g of these crystals per litre and determine
Provided
the percentage oxidation of the given sample. Given
M 100
KMnO4 solution ... 2+ Exp-11.14 : Calculate the percentage of Fe ions in a sample of ferrous sulphate. Prepare a solution of the given sample having strength exactly equal to 14.0 g/litre. Provided
143
M KMnO4 ... 100
145
147
( ix )
N Mohr’s salt solution. Using this solution, deter20 mine the normality and strength of the given potassium permanganate solution ...
Exp-11.15 : Prepare
N solution of oxalic acid. Using this solution, find 20 out strength and normality of the given potassium permanganate solution ... Exp-11.17 : Determine the percentage purity of the given sample of oxalic acid. Ask for your requirement ... Exp-11.18 : Determine the percentage composition of a mixture of
150
Exp-11.16 : Prepare
LM MN
OP PQ
LM MN
152 154
OP PQ
COOH COONa sodium oxalate ⏐ and oxalic acid ⏐ . 2H 2O . COOH COONa N KMnO4 20 Exp-11.19 : Determine the equivalent mass and number of molecules of water of crystallisation in a sample of Mohr’s salt
Provided
FeSO4 (NH4)2 SO4.nH2O. Provided
N KMnO4 20
Viva questions with answers
...
155
...
158
...
160
12. QUALITATIVE ANALYSIS Exp-12.1 : To analyse the given salt for acidic and basic radicals Exp-12.2 : To analyse the given salt for acidic and basic radicals Viva questions with answers
163–212 ... ... ...
201 203 206
INVESTIGATORY PROJECTS Projects
1.
STUDY OF OXALATE ION CONTENT IN GUAVA FRUIT Exp-1
2.
: To study the presence of oxalate ion content in guava fruit at different stages of ripening ...
STUDY OF THE QUANTITY OF CAESIN PRESENT IN DIFFERENT SAMPLES OF MILK Exp-1
: To study the quantity of caesin present in different samples of milk ...
215 215
216 217
(x)
3.
PREPARATION OF SOYABEAN MILK AND ITS COMPARISON WITH NATURAL MILK Exp-1
4.
Exp-2
: To compare the rates of fermentation of the following fruit or vegetable juices (i) Apple juice (ii) Orange juice (iii) Carrot juice ... : To compare the rates of fermentation of the given samples of wheat flour, gram flour, rice and potatoes ...
220
: To extract essential oils present on Saunf (Aniseed), Ajwain (Carum) and Illaichi (Cardamom) ...
: To detect the presence of adultrants in fat, oil and butter : To detect the presence of adultrants in sugar : To detect the presence of adultrants in samples of chilli powder, turmeric powder and pepper
: To prepare potash alum from scrap aluminium
222 223
225 225
227 ... ...
227 228
...
228
PREPARATION OF AN ALUM FROM SCRAP ALUMINIUM Exp-1
9.
: To study the effect of potassium bisulphite as food preservative under various conditions (Concentration, time and temperature) ...
STUDY OF ADULTRANTS IN FOOD-STUFFS Exp-1 Exp-2 Exp-3
8.
219
EXTRACTION OF ESSENTIAL OILS PRESENT IN SAUNF (ANISEED), AJWAIN (CARUM) AND ILLAICHI (CARDAMOM) Exp-1
7.
218
COMPARATIVE STUDY OF THE RATE OF FERMENTATION OF VARIOUS FOOD MATERIALS 221 Exp-1
6.
: Preparation of soyabean milk and its comparison with the natural milk with respect to curd formation, effect of temperature and taste ...
STUDY OF EFFECT OF POTASSIUM BISULPHITE AS FOOD PRESERVATIVE UNDER VARIOUS CONDITIONS Exp-1
5.
218
229 ...
229
STUDY OF THE EFFECT OF METAL COUPLING ON THE RUSTING OF IRON
230
Exp-1
231
: To study the effect of metal coupling on rusting of iron
...
10. PREPARATION OF RAYON THREAD FROM FILTER PAPER Exp-1
233
: To prepare rayon threads from filter papers using cuprammonium process ...
11. DYEING OF FABRICS Exp-1
: To dye wool and cotton clothes with malachite green
233
234 ...
236
( xi )
12. STERILIZATION OF WATER WITH BLEACHING POWDER Exp-1
237
: Determination of the dosage of bleaching powder required for sterilization or disinfection of different samples of water ...
13. SETTING OF CEMENT Exp-1
Exp-2
240
: To study the setting of mixtures of cement with lime, sand of different qualities, rice husk, fly-ash, etc. (with respect to volume and strength) ... : To study the setting of mixtures of cement with sand, lime and fly-ash with respect to time and strength ...
14. STUDY OF PRESENCE OF INSECTICIDES AND PESTICIDES IN FRUITS AND VEGETABLES Exp-1
: To study the presence of insecticides/pesticides (nitrogencontaining) in various fruits and vegetables
: To analyse the given samples of commercial antacids by determining the amount of hydrochloric acid they can neutralize
...
: To analyse a sample of brass qualitatively
APPENDICES APPENDIX-I Atomic Masses of Some Common Elements APPENDIX-II Preparation of Common Reagents used in the Chemical Laboratory LOGARITHMIC TABLES
242
243
244
...
16. STUDY OF CONSTITUENTS OF AN ALLOY Exp-1
241
242
15. COMPARATIVE STUDY OF COMMERCIAL ANTACIDS Exp-1
237
245
247 ...
248 249–254
...
250
...
251 (i)–(iv)
PREFACE We are pleased to present the revised edition of the ‘Comprehensive Practical Chemistry’ for Class XII students. The book has been written strictly according to the new syllabus prescribed by Central Board of Secondary Education. We hope that the book will be quite helpful to the students in acquiring the skills of various laboratory techniques. Some of the outstanding features of the book are: ¤ Simple language and lucid style. ¤ Wherever required, a large number of illustrations have been given to clarify the use of various apparatuses used in laboratory. ¤ The theoretical aspects of each experiment have been discussed briefly along with the experiment. ¤ In volumetric analysis calculations based on normality as well as on molarily have been given. ¤ In qualitative inorganic analysis, the various tests have been given in a systematic way in tabular form. ¤ In order to guide the students about recording the experiment in the notebook, a specimen record of analysis of a salt has been given in the chapter on qualitative analysis. ¤ A large number of solved viva questions have been included in each chapter. We sincerely hope that the book will be appreciated by our learned colleagues and students. We shall be glad to receive constructive suggestions for the further improvement of the book.
—AUTHORS
( xii )
SYLLABUS FOR PRACTICALS CHEMISTRY Class XII
Evaluation Scheme for Examination
Marks
Volumetric Analysis Salt Analysis Content Based Experiment Class Record, Project Work and Viva
10 8 6 6
Total
30
Micro-chemical methods are available for several of the practical experiments. Wherever possible, such techniques should be used. A.
B.
Surface Chemistry (Periods 5) (a) Preparation of one lyophilic and one lyophobic sol. Lyophilic sol—starch, egg albumin and gum. Lyophobic sol—aluminium hydroxide, ferric hydroxide, arsenious sulphide. (b) Dialysis of sol-prepared in (a) above. (c) Study of the role of emulsifying agents in stablizing the emulsion of different oils. Chemical Kinetics (Periods 4) (a) Effect of concentration and temperature on the rate of reaction between sodium thiosulphate and hydrochloric acid. (b) Study of reaction rates of any one of the following : (i) Reaction of iodide ion with hydrogen peroxide at room temperature using different concentration of iodide ions. (ii) Reaction between potassium iodate, KIO3 and sodium sulphite : (Na2SO3) using starch solution as indicator (clock reaction).
C.
Thermochemistry (Periods 4) Any one of the following experiments (i) Enthalpy of dissolution of copper sulphate or potassium nitrate. (ii) Enthalpy of neutralization of strong acid (HCl) and strong base (NaOH). (iii) Determination of enthalpy change during interaction (Hydrogen bond formation) between acetone and chloroform. D. Electrochemistry (Periods 2) 2+ 2+ Variation of cell potential in Zn | Zn || Cu | Cu with change in concentration of electrolytes (CuSO4 or ZnSO4) at room temperature. ( xiii )
( xiv )
E.
F.
G.
H. I. J.
K.
Chromatography (Periods 2) (i) Separation of pigments from extracts of leaves and flowers by paper chromatography and determination of Rf values. (ii) Separation of constituents present in an inorganic mixture containing two cations only (constituents having wide difference in Rf values to be provided). Preparation of Inorganic Compounds (Periods 4) (i) Preparation of double salt of ferrous ammonium sulphate or potash alum. (ii) Preparation of potassium ferric oxalate. Preparation of Organic Compounds (Periods 2) Preparation of any one of the following compounds (i) Acetanilide (ii) Di-benzal acetone (iii) p-Nitroacetanilide (iv) Aniline yellow or 2-Napthol aniline dye. Test for the functional groups present in organic compounds : (Periods 6) Unsaturation, alcoholic, phenolic, aldehydic, ketonic, carboxylic and amino (primary) groups. Characteristic tests of carbohydrates, fats and proteins in pure samples and their detection in given food stuffs. (Periods 4) Determination of concentration/molarity of KMnO4 solution by titrating it against a standard solution of : (Periods 8) (i) Oxalic acid (ii) Ferrous ammonium sulphate. (Students will be required to prepare standard solutions by weighing themselves). Qualitative Analysis (Periods 14) Determination of one cation and one anion in a given salt. Cations: Pb2+, Cu2+, As3+, Al3+, Fe3+, Mn2+, Zn2+, Co2+, Ni2+, Ca2+, Sr2+, Ba2+, Mg2+, NH4+ 2− − − 3− 2− – – – – Anions: CO32− , S2–, SO 2− 3 , SO 4 , NO 2 , NO 3 , Cl , Br , I , PO 4 , C 2 O 4 , CH3COO (Note : Insoluble salts excluded)
PROJECTS Scientific investigations involving laboratory testing and collecting information from other sources. A Few Suggested Projects • Study of presence of oxalate ions in guava fruit at different stages of ripening. • Study of quantity of casein present in different samples of milk. • Preparation of soyabean milk and its comparison with the natural milk with respect to curd formation, effect of temperature, etc. • Study of the effect of potassium bisulphate as food preservative under various conditions (temperature, concentration, time, etc.) • Study of digestion of starch by salivary amylase and, effect of pH and temperature on it. • Comparative study of the rate of fermentation of following materials : wheat flour, gram flour, potato juice, carrot juice, etc. • Extraction of essential oils present in Saunf (aniseed), Ajwain (carum), Illaichi (cardamom). • Study of common food adulterants in fat, oil, butter, sugar, turmeric powder, chilli powder and pepper. Note : Any investigatory project, which involves about 10 periods of work, can be chosen with the approval of the teacher.
1
CHAPTER
INTRODUC TION TO BASIC LABORATORY EQUIPMENT 1.1.
CHEMISTRY LABORATORY
A chemistry laboratory is a workshop for chemists. Here students learn the techniques of the preparation, identification and estimation of chemical substances. Before starting experiment, a student must know from where to get the apparatus required for the given experiment and the placement of the chemicals to be used. A student must know the proper use of each equipment and the precautions to be observed while working in the laboratory. A chemistry laboratory is provided with the following fittings with which the student must become familiar. 1. Demonstration Table Before starting experiment, the teacher gives instructions and demonstrates the concerned experiment on demonstration table. In chemistry laboratory, no seats are made available to the students, so students stand around demonstration table and note the instructions from teacher. 2. Students’ Working Table A number of wooden or concrete tables are provided for working. Generally, four students (two on each side) work on one table. Each seat is provided with: (a) Reagent shelves. Reagents or chemicals to be used are placed on the reagent shelf. These are the reagents which are commonly used. For example, all dilute and concentrated acids such as H2SO4, HCl, HNO3, etc. and bases like NaOH, NH4OH, etc. (b) Sinks and water taps. A sink and a water tap is fitted between every two reagent shelves. On either side of the sink, usually two taps are fitted for supply of water. (c) Gas taps. These taps are fitted on the seats for supply of petrol gas to the burners. Sometimes kerosene is used for producing gas in place of petrol. 3. Side Shelves Mostly there are two big shelves fitted on the walls of the laboratory. Reagents and chemicals, which are less frequently used, are placed in these shelves. Sometimes solid chemicals are placed in a separate shelf. 4. Fume Cup-board There is at least one fume cup-board in the corner of the laboratory. All experiments giving out poisonous gases or vapours are performed in this cup-board. 5. Balance Room It is a small room attached to each laboratory. Here, a number of balances are kept for weighing the substances. 1
2
COMPREHENSIVE PRACTICAL CHEMISTRY—XII
6. Exhaust Fans Two exhaust fans are provided at the two corners of the laboratory for the removal of the poisonous gases and vapours from the laboratory.
1.2.
COMMON LABORATORY APPARATUS
The apparatus which is commonly used by a student is described below:
Test tube
Centrifuging tube
Funnel stand
Tripod stand
Glass rod
Platinum wire
Boiling tube
Test tube brush
Gas detector
Funnel
Wash bottle
Wire gauze
China dish
Blue glass
Charcoal block
Watch glass
Mouth blow pipe
Fig. 1.1. Apparatus used in chemistry laboratory.
Charcoal borer
