CESSF L U UT - Universal Tutorials · 2 2 Universal Tutorials – X ICSE – Chemistry Volume 2 of 2 Procedure: Place some common salt in a flat bottomed flask and pour concentrated

[email protected] || www.universaltutorials.com

GUIDE

SE SC

FC

U

U

L

S

UT1

S8

RYEA

Guided effort leads to a bright futureUTUT

IX-XII

CBSE ICSE

State

Entrance

X - ICSE - CHEMISTRYVOLUME 2

Table of Contents

Volume 2 of 2 Universal Tutorials – X ICSE – Chemistry

Table of Contents CHAPTER 08: STUDY OF COMPOUNDS–HYDROGEN CHLORIDE ..................... 1

Hydrogen Chloride: ........................................................................................................................... 1 Preparation of hydrogen chloride gas: ......................................................................................... 1 Physical Properties of Hydrogen Chloride Gas: ........................................................................... 3 Chemical properties of Hydrogen Chloride Gas: ......................................................................... 4

Hydrochloric Acid: ............................................................................................................................. 4 Preparation of Hydrochloric Acid: ................................................................................................. 4 Physical Properties of Hydrochloric Acid: .................................................................................... 5 Chemical properties of Hydrochloric Acid: ................................................................................... 5 Uses of hydrochloric Acid: ............................................................................................................ 6

Tests for Hydrogen Chloride gas and Hydrochloric acid: .................................................................. 6 Tests for Chloride ion: .................................................................................................................. 7

PREVIOUS YEARS BOARD QUESTIONS: ........................................................................................................ 7 REVIEW EXERCISE: ..................................................................................................................................... 9 ANSWERS: ................................................................................................................................................ 11

CHAPTER 09: STUDY OF COMPOUNDS – AMMONIA ........................................ 15

Introduction: ..................................................................................................................................... 15 Occurrence: ..................................................................................................................................... 15 Preparation of Ammonia Gas: ......................................................................................................... 15

General methods: ....................................................................................................................... 15 Laboratory Preparation: ............................................................................................................. 16

Preparation of Aqueous Ammonia: ................................................................................................. 17 Manufacture of Ammonia (Haber Process): .................................................................................... 17 Physical properties of ammonia: ..................................................................................................... 18

Fountain Experiment: ................................................................................................................. 19 Chemical properties of ammonia: ................................................................................................... 19 Tests for ammonia gas and Ammonium ion: ................................................................................... 21 Uses of ammonia: ........................................................................................................................... 22

PREVIOUS YEARS BOARD QUESTIONS: ...................................................................................................... 22 REVIEW EXERCISE: ................................................................................................................................... 24 ANSWERS: ................................................................................................................................................ 27

CHAPTER 10: STUDY OF COMPOUNDS – NITRIC ACID .................................... 29

Introduction: ..................................................................................................................................... 29 Occurrence: ..................................................................................................................................... 29

Formation of nitric acid in atmosphere. ...................................................................................... 29 Laboratory Preparation: ................................................................................................................... 30

Formation of nitric acid by Ostwald’s process: (Industrial Preparation) ..................................... 30 Properties of Nitric acid: .................................................................................................................. 31 Uses of Nitric acid: .......................................................................................................................... 33

Test for nitric acid and nitrates: .................................................................................................. 33 PREVIOUS YEARS BOARD QUESTIONS: ...................................................................................................... 34 REVIEW EXERCISE: ................................................................................................................................... 36 ANSWERS: ................................................................................................................................................ 38

CHAPTER 11: STUDY OF COMPOUNDS – SULPHURIC ACID ........................... 39

Introduction: ..................................................................................................................................... 39

Universal Tutorials – X ICSE – Chemistry Volume 2 of 2

Occurrence: ..................................................................................................................................... 39 Preparation of Sulphuric Acid: ......................................................................................................... 39 Manufacture of Sulphuric Acid (Contact Process): ......................................................................... 40 Properties of Sulphuric Acid: ........................................................................................................... 42 Uses of Sulphuric Acid: ................................................................................................................... 43

PREVIOUS YEARS BOARD QUESTIONS: ...................................................................................................... 44 REVIEW EXERCISE: ................................................................................................................................... 47 ANSWERS .................................................................................................................................................. 49

CHAPTER 12: ORGANIC CHEMISTRY ................................................................. 50

12A: ORGANIC COMPOUNDS: .................................................................................................................... 50 Introduction: ..................................................................................................................................... 50 Organic Compounds: ...................................................................................................................... 51

Sources of organic compounds: ................................................................................................. 51 Unique Nature of Carbon Atoms: .................................................................................................... 51

Tetravalency of the carbon atom: ............................................................................................... 51 Catenation: ................................................................................................................................. 52 Isomerism: .................................................................................................................................. 52

Functional Group: ............................................................................................................................ 52 Hydrocarbons: ................................................................................................................................. 53

Classification of Hydrocarbons: .................................................................................................. 53 Comparison of Saturated and Unsaturated Hydrocarbons: ....................................................... 54

Alkyl Group: ..................................................................................................................................... 54 Structure and Isomers: .................................................................................................................... 54

Structure: .................................................................................................................................... 54 Isomers: ...................................................................................................................................... 55

Homologous series: ......................................................................................................................... 56 Examples of Homologous Series: .............................................................................................. 56 Characteristics of a homologous series: .................................................................................... 56

Nomenclature: ................................................................................................................................. 56 IUPAC names: ............................................................................................................................ 59 Writing Structural Formula From IUPAC name: ......................................................................... 60

12B ALKANES: ......................................................................................................................................... 61 Homologous series of alkanes: .................................................................................................. 61 Methane and Ethane: ................................................................................................................. 63 Chemical properties: .................................................................................................................. 65 Uses: .......................................................................................................................................... 66

12C ALKENES: ......................................................................................................................................... 66 Preparation of ethene (ethylene): ............................................................................................... 67 Properties of Alkenes: ................................................................................................................ 68 Reaction with ozone (ozonolysis): .............................................................................................. 69 Polymerization: ........................................................................................................................... 69 Oxidation: ................................................................................................................................... 69 Combustion of ethene: ............................................................................................................... 70 Uses of ethene: .......................................................................................................................... 70

12D ALKYNES: ......................................................................................................................................... 70 Ethyne (Acetylene): .................................................................................................................... 71 Chemical properties: .................................................................................................................. 72

12E ALCOHOLS: ....................................................................................................................................... 73 Laboratory preparation: .............................................................................................................. 74 Industrial method (large scale method): ..................................................................................... 74 Properties of alcohols: ................................................................................................................ 74

12F CARBOXYLIC ACIDS: .......................................................................................................................... 76

Table of Contents

Volume 2 of 2 Universal Tutorials – X ICSE – Chemistry

Carboxylic Acids: ........................................................................................................................ 76 Acetic acid CH3 COOH: .............................................................................................................. 77 Lab preparation: ......................................................................................................................... 77 Manufacture: .............................................................................................................................. 77 Physical properties: .................................................................................................................... 78 Chemical properties: .................................................................................................................. 78 Acetic acid is used: .................................................................................................................... 79

PREVIOUS YEARS BOARD QUESTIONS: ...................................................................................................... 79 REVIEW EXERCISE: ................................................................................................................................... 84 HOME WORK EXERCISE: ........................................................................................................................... 88 ANSWERS: ................................................................................................................................................ 90

Chapter 08: Study of Compounds – Hydrogen Chloride 1

Volume 2 of 2 Universal Tutorials – X ICSE – Chemistry 1

Chapter 08: Study of Compounds–Hydrogen Chloride

Hydrogen Chloride: Molecular formula: HCl Molecular mass: 36.5 Bond: Covalent

H + → H or H – Cl Dot diagram or Lewis structure

Occurrence: HCl gas occurs in volcanic emissions. HCl acid is present in gastric juice of mammals.

Preparation of hydrogen chloride gas: General Preparation:

By synthesis (Direct combination): Moist hydrogen gas combines with chlorine in the presence of diffused sunlight.

Hydrogen + Chlorine → Hydrogen chloride

H2(g) + Cl2(g) Sunlight

Diffused⎯⎯⎯ →⎯ 2HCl(g)

By heating metallic chloride with conc. sulphuric acid:

Metal chloride + Sulphuric acid [conc.] ⎯→⎯Δ Salt + Hydrogen chloride

Laboratory Preparation: In the laboratory, hydrogen chloride gas can be prepared by the action of concentrated

sulphuric acid on sodium chloride.

Reactants:

Sodium chloride and concentrated sulphuric acid.

Cl Cl

→ Occurrence

→ Hydrogen Chloride Gas

→ Preparation

→ Physical and Chemical Properties

→ Hydrochloric Acid

→ Preparation

→ Physical and Chemical Properties

→ Uses

→ Test for Hydrogen Chloride Gas and Hydrochloric Acid

Cl H

Orbital diagram

2

2 Universal Tutorials – X ICSE – Chemistry Volume 2 of 2

Procedure:

Place some common salt in a flat bottomed flask and pour concentrated sulphuric acid through the thistle funnel. On heating the mixture gently, HCl gas is evolved. The gas is dried by passing through concentrated sulphuric acid. It is collected by upward displacement of air.

Reaction:

NaCl + H2SO4 ⎯⎯⎯ →⎯< C200o NaHSO4 + HCl↑ Though it is a reversible reaction, yet it goes to completion as hydrogen chloride

continuously escapes as a gas. The reaction can occur upto the stage of formation of sodium sulphate on heating above 200° C.

NaHSO4 + NaCl ⎯⎯⎯⎯⎯ →⎯ C200above o Na2SO4 + HCl↑

i) Sodium chloride is cheap and therefore it is preferred for preparation of HCl over other metal chlorides.

ii) Conc. nitric acid is not used during the preparation of HCl because it is volatile and may volatilize out alongwith hydrogen chloride.

Purification of HCl gas: It is dried by passing through conc. sulphuric acid. The other drying agents like phosphorus

pentoxide (P2O5) and quick lime (CaO) cannot be used, since they react with hydrogen chloride as follows.

2P2O5 + 3HCl → POCl3 + 3HPO3 CaO + 2HCl → CaCl2 + H2O

Collection: Hydrogen chloride gas is collected by the upward displacement of air as it is 1.28 times

heavier than air. It is not collected over water, since it is highly soluble in water.

Identification: When the jar is completely filled with hydrogen chloride, fumes appear above the jar’s

mouth. When hydrogen chloride gas is exposed to air it gives white fumes, due to the formation of

hydrochloric acid on reacting with atmospheric water vapour.

Conc. Sulphuric Acid

Dry Hydrogen chloride

Air Conc. H2SO4 Air

Heat

Preparation of hydrogen chloride gas from common salt

NaCl + H2SO4 con.



In order to know whether the gas jar is full, bring a rod dipped in ammonium hydroxide near its mouth. HCl + NH4OH → NH4Cl + H2O

Dense white fumes of ammonium chloride will be produced proving thereby that the jar is full of hydrogen chloride gas.

Precautions: The lower end of the thistle funnel must be dipped in conc. sulphuric acid. Delivery tube should be dipped in drying agent i.e. conc. H2SO4. Temperature is maintained at nearly 200°C

At higher temperature i.e. above 200°C:

The apparatus which is made of glass may crack. Fuel is wasted. Sodium sulphate formed, forms a hard crust which sticks to the glass and is difficult to

remove.

Physical Properties of Hydrogen Chloride Gas: 1. Colour colourless gas 2. Smell pungent smell 3. Taste acidic taste (sour) 4. Physiological nature It is corrosive in nature. It irritates nose, throat and lungs. 5. Density It is about one and a quarter times heavier than air (V.D. of HCl is

18.25 and that of air 14.4). 6. Boiling point – 83°C 7. Melting point – 113°C 8. Liquefaction and

solidification When subjected to a high pressure (40 atm.) at low temperature (10°C), it is liquefied to a colourless liquid.

9. Solubility Hydrogen chloride gas is highly soluble in water (1 volume of water dissolves 452 volumes of the gas at room temperature). HCl being covalent is soluble in organic non polar solvents such as acetone and toluene.

Experiment:

To show that HCl gas is heavier than air. It can be proved by pouring the gas in a jar with a burning candle.

The candle gets extinguished because HCl gas being heavier occupies the lower portion of the jar and forces the air out of it.

Experiment:

To show that HCl gas is highly soluble. The great solubility of the gas can be demonstrated by means of Fountain Experiment

as illustrated below.

HCl gasAir

4

4

Fou

R

Chem C

b T

Wsw

W

Hydr Whe The

PrepaLab

Pro

untain Exp Take a d

HCl gas. Afig. On tstopper wlong jet tdropper win the bea

Press thesolution eforming a

Reason:

As thedue tobeing h

The bl

mical propCombustibilburn, and extThermal diss

With metalssodium, potawhen heatedWith ammon

rochloricen hydrogen

e covalent co

aration ofboratory m

Hydrochlo The gas

and conta

ocedure: An invert

Chloride ga way thtrough.

Since HCrises up i

U

periment: ry round botArrange the he mouth o

with two holestube, and th

with few dropaker containine dropper. It ienters the jered fountain

e water goeso its high sohigher pusheue litmus so

perties oflity: The gatinguishes a sociation: O

s: All active assium, calcd and liberatenia: It combi

c Acid: chloride gasmpound ioni

f Hydrochmethod: oric acid is pris passed in

ains about 36

ted funnel, gas supply, iat it just tou

Cl gas is higin the funne

Universal Tuto

ttomed flaskapparatus a

of the flasks. Through ohrough otheps of water. Png blue litmuis seen that et tube with n.

s in the flaskolubility, theres the blue lilution turns r

f Hydroges is neither burning splin

On heating a

2HCl ⎯metals that

cium, magnee hydrogen.nes with amm

NH3(g)

s is dissolvedizes in water

HCl +

hloric Ac

repared by dnto water unt6% of hydrog

connected is placed in tuches the w

hly soluble iel, back–suct

orials – X ICS

k filled with das shown in t, fix a rubb

one hole passr hole passPut the jet tuus solution. the blue litma great forc

k from the drreby loweringtmus solutio

red due to th

en Chloricombustible

nt. bove 500°, it

⎯⎯⎯ →⎯ °> C500 Hcome before

esium, zinc,

monia to form+ HCl(g) → N

d in water, hyr due to its poH2O → H3O

id:

dissolving hydtil no more ggen chloride

to the Hydthe beaker in

water taken

in water thetion occurs

SE – Chemistr

dry the ber s a s a be

mus ce,

ropper, HCl gg the pressun inside, throe acidic natu

de Gas:e nor a supp

t dissociates

H2 + Cl2 e hydrogen iron etc. fo

m dense whiNH4Cl(s)

ydrochloric aolar nature.

O+ + Cl–

drogen chlorgas is absorby mass.

drogen n such in the

water and in

HC

RedSolu

D

Je

ry

gas present ure inside. Tough the jet ture of hydrog

porter of com

into hydroge

in the electrrm their cor

te fumes of a

acid is formed

ride gas in wrbed, the pro

Cl Gas

d Litmus ution

Dropper

et Tube

Volu

in the flask The outside tube. gen chloride g

mbustion. It

en and chlor

rochemical srresponding

ammonium c

d.

water. oduct is con

ume 2 of 2

dissolves pressure

gas.

does not

ine.

series like chlorides

chloride.

centrated

Blue Fountain



turn the level outside the funnel falls creating an air gap between the rim of the funnel and the surface of water. The pressure outside and inside then becomes equal and the water which had risen in the funnel falls down again. This process continues till the water in the trough is saturated with hydrogen chloride gas resulting in the formation of hydrochloric acid.

The funnel arrangement: Prevents or minimizes back-suction of water. Provides a large surface area for absorption of HCl gas.

Why is funnel arrangement used? Hydrogen chloride gas is sufficiently soluble, so, it is absorbed in water more quickly than it

is being generated in the flask. In this case, the pressure in the delivery tube and flask is reduced and the atmospheric

pressure from outside forces the water back upto the delivery tube. This effect is called ‘back suction’.

HCl acid forms constant boiling mixture at 110°C: A dilute aqueous solution of hydrochloric acid gets gradually concentrated on distillation, till

the concentration of the acid reaches 22.2% HCl by weight and 77.8% water by weight which boils at 110°C. When this concentration is reached, no further increase in concentration of the acid is possible by boiling.

A constant boiling mixture is a solution which boils without any change in its composition.

Physical Properties of Hydrochloric Acid: 1. Colour colourless 2. Smell Pungent choking smell 3. Taste acidic 4. Physiological action Concentrated acid is corrosive and causes blisters on the skin. 5. Solubility Readily soluble in water in all proportions.

Chemical properties of Hydrochloric Acid: Nature: Aqueous solution is strongly acidic, and shows all properties of acids. Action on metals: Hydrochloric acid reacts with metals above hydrogen in the activity series

forming metallic chlorides and evolving hydrogen. Ca + 2HCl → CaCl2 + H2↑

Action on oxides and hydroxides: It reacts with oxides and hydroxides (bases) to form salt and water only.

MgO + 2HCl → MgCl2 + H2O With salts of weaker acids: It decomposes salts of weaker acids eg. carbonates,

bicarbonates, sulphites and sulphides. CaCO3 + 2HCl → CaCl2 + H2O + CO2↑; NaHCO3 + HCl → NaCl + H2O + CO2↑;

Ca(HCO3)2 + 2HCl → CaCl2 + 2H2O + 2CO2↑; Na2SO3 + 2HCl → 2NaCl + H2O + SO2↑;

Na2S + 2HCl → 2NaCl + H2S↑ Action on thiosulphates: Dilute hydrochloric acid reacts with thiosulphates to produce

sulphur dioxide gas and yellow sulphur is precipitated. Na2S2O3 + 2HCl → 2NaCl + H2O + SO2 + S↓

6


Action on metallic nitrites: On warming with metallic nitrites, dilute hydrochloric acid gives metallic chlorides and oxides of nitrogen.

2KNO2 + 2HCl → 2KCl + 2HNO2; 2HNO2 → H2O + NO + NO2 Reaction with nitrates: Dil. HCl does not normally react with nitrates. However on reaction

with silver nitrate solution it gives a thick curdy white precipitate of silver chloride. AgNO3 + HCl → AgCl↓ + HNO3

The white precipitate is insoluble in nitric acid but soluble in ammonium hydroxide solution, and forms a complex salt called diammine silver (I) chloride is formed.

AgCl + 2NH4OH → [Ag(NH3)2]+Cl– + 2H2O When exposed to light, silver (I) chloride blackens since it decomposes into chlorine and black

powder of Ag. 2AgCl → 2Ag + Cl2

Similarly, lead nitrate and mercury (I) nitrate react with hydrochloric acid to give white precipitate of lead and mercury (I) chloride.

Pb(NO3)2 + 2HCl → PbCl2↓ + 2HNO3 Hg2(NO3)2 + 2HCl → Hg2Cl2↓ + 2HNO3 Conclusion HCl can be readily oxidized to chlorine by strong oxidizing agents.

e.g. MnO2 + 4HCl → MnCl2 + 2H2O + Cl2 PbO2 + 4HCl → PbCl2 + 2H2O + Cl2 2KMnO4 + 16HCl → 2MnCl2 + 2KCl + 8H2O + 5Cl2 Pb3O4 + 8HCl → 3PbCl2 + 4H2O + Cl2 CaOCl2 + 2HCl → CaCl2 + H2O + Cl2

Uses of hydrochloric Acid: General uses:

In the laboratory as a reagent and for preparation of aqua regia. Industrial uses:

In the manufacture of Chlorine and chlorides e.g. ammonium chloride used in dry cells. Dyes, drugs, paints and photographic chemicals (silver chloride). Glucose from starch.

In industry to pickle steel, as HCl dissolves the oxides. Steel before being plated with tin or chromium has to be purified by pickling in HCl and some inhibitors.

For purifying bone black, because HCl dissolves the calcium phosphate present in bones. To remove rust from iron sheets. For cleaning metal surfaces before painting, electroplating, galvanizing, soldering etc. In the extraction of glue from bones. In tanning and calico printing industry.

Medicine: Dil. HCl is prescribed to patients with decreased activity of their gastric juices. HCl acid helps in the digestion of proteins and also in destroying microorganisms that enter the

alimentary canal alongwith the food.

Tests for Hydrogen Chloride gas and Hydrochloric acid: HCl gas possesses a characteristic irritating smell. HCl gas gives thick white fumes of ammonium chloride, when a glass rod dipped in ammonia

solution is held near the vapours of the acid.



NH3 + HCl → NH4Cl With silver nitrate solution, both the gas and the acid give a white precipitate of silver chloride.

AgNO3 + HCl → AgCl↓ + HNO3 The precipitate is insoluble in nitric acid but soluble in ammonium hydroxide.

A greenish-yellow gas i.e. chlorine, is liberated when concentrated hydrochloric acid is heated with oxidizing agent like manganese dioxide.

The gas liberated turns starch iodide paper blue black.

Tests for Chloride ion: If concentrated sulphuric acid is added to the salt, white pungent fumes of hydrogen chloride

gas are evolved. NaCl + H2SO4 → NaHSO4 + HCl

If the salt is warmed with manganese dioxide and concentrated sulphuric acid, chlorine gas is evolved which bleaches moist litmus paper. 2NaCl + 2H2SO4 + MnO2 → Na2SO4 + MnSO4 + 2H2O + Cl2

If silver nitrate solution is added to a solution of the salt containing chloride, a white curdy precipitate is formed. Cl–(aq) + AgNO3 → AgCl↓ + NO3

The precipitate is soluble in ammonium hydroxide but insoluble in nitric acid.

PREVIOUS YEARS BOARD QUESTIONS:

Year 2016: 1) Choose the correct answer from the options given below: The aim of the Fountain Experiment is to prove that: A) HCI turns blue litmus red B) HCl is denser than air C) HCI is highly soluble in water D) HCI fumes in moist air. 2) Write balanced chemical equations for each of the following: Action of Hydrochloric acid on sodium bicarbonate. 3) State your observations when: i) Dilute Hydrochloric acid is added to Lead nitrate solution and the mixture is heated. ii) Dilute Hydrochloric acid is added to Copper carbonate. iii) Dilute Hydrochloric acid is added to Sodium thiosulphate. 4) Identify the gas evolved and give the chemical test in each of the following cases: i) Dilute hydrochloric acid reacts with sodium sulphite. ii) Dilute hydrochloric acid reacts with iron (II) sulphide. Year 2015: 1) Choose the most appropriate answer for each of following: This gas produces dense white fames with ammonia gas. A) hydrogen chloride B) ammonia C) hydrogen sulphide D) ethyne 2) Identify the acid which matches the following description: i) The acid which is used in the preparation of a non–volatile acid. ii) The acid on mixing with silver nitrate solution produces a white precipitate which is soluble in

excess ammonium hydroxide. 3) The following questions are pertaining to the laboratory preparation of hydrogen chloride gas: i) Write the equation for its preparation mentioning the condition required. ii) Name the drying agent used and justify your choice.

8


iii) State a safety precaution you would take during the preparation of hydrochloric acid. 4) Identify the anion present in each of the following compounds: When barium chloride solution is added to salt solution E a white precipitate insoluble in dilute

hydrochloric acid is obtained. Year 2014: 1) Fill in the blanks from the choices given within brackets: Quicklime is not used to dry HCl gas because _________ (CaO is alkaline, CaO is acidic, CaO

is neutral) 2) Write balanced equations for the following: Action of dilute hydrochloric acid on sodium sulphide. 3) State your observation in each of the following cases: i) When dilute hydrochloric acid is added to sodium carbonate crystals. ii) When moist starch iodide paper is introduced into chlorine gas. 4) Study the figure given below and answer the questions that follow: i) Identify the gas Y. ii) What property of gas Y does this experiment demonstrate? iii) Name another gas which has the same property and

can be demonstrated through this experiment. Year 2012: 1) Identify the anion present in the compounds, When a solution of compound Y is treated with

silver nitrate solution a white precipitate is obtained which is soluble in excess of ammonium hydroxide solution.

2) State one chemical test between each of the following pairs: i) Sodium carbonate and sodium sulphite. ii) Manganese dioxide and Copper (II) oxide. 3) Refer to the flow chart diagram below and give balance equations with conditions, if any, for the

following conversions A to D. Year 2010: 1) The diagram shows an apparatus for the laboratory preparation of hydrogen chloride. [5] i) Identify A and B. ii) Write the equation for the reaction. iii) How would you check whether or not the gas jar is

filled with hydrogen chloride? iv) What does the method of collection tell you about

the density of hydrogen chloride? Year 2008: 1) What property of hydrogen chloride is demonstrated when it is collected by downward delivery

(upward displacement)? [1] 2) Why is hydrogen chloride not collected over water? [1]

Sodium Chloride

Hydrogen Chloride

Ammonium Chloride

Iron (II) Chloride

Lead Chloride

A

B

C

D

Chapter 0

Volume 2

3) W i) D ii) Year 200 1) W

fol i) I iii) v) Year 200 1) W 2) WYear 200 1) W Ma 2) i) ii)

iii)

Class W 1) Dr 2) W i) 3) Na i) ii) 4) Ca

dry 5) Ex i) ii)

iii)

iv)

v) vi) vii vii

ix)

08: Study of C

of 2

rite the equaDilute hydrocDilute hydro

07: rite balancedllowing: Iron Iron (II) sulpSodium thio

06: rite balancedhat do you o05: rite balancedanganese (IV

Name the e Which propthis experim

State the cbottomed fl

Work raw a labeledrite the reactbelow 200°

ame the dryinUsed in dry

Which cannalcium oxidey hydrogen cxplain why:

Anhydrous Only a verysolution wh

When the sair.

) A solution oa solution o

a) has no Hydrogen c

) Hydrochlori) Hydrogen ci) White thickof a bottle f

) Dry hydrogthe presenc

Compounds

U

ations for thechloric acid a

ochloric acid a

d chemical e

phide osulphate sol

d chemical eobserve when

d equation foV) oxide andexperiment ilperty of hydment? colour of theask.

d diagram fotions betweeC and ng agents: ying hydrogenot be used t and phosphchloride gas.

HCl is a pooy dilute solut

hile a very costopper of a

of hydrogen of the same g

effect on litmchloride gas ic acid conduchloride gas k fumes are full of HCl gaen chloride ce of a drop

– Hydrogen C

Universal Tuto

following reand sodium tand lead nitr

equations for

ution

quation for thn hydrochlor

or the followin concentratelustrated aborogen chlori

water that

REV

r the laboratoen common s

n chloride gato dry hydroghorus pentox Give reason

or conductor tion of hydro

oncentrated sbottle full of

chloride in wgas in toluenmus and does not conucts electric dissolve in toformed whe

as. gas does noof water.

Chloride

orials – X ICS

actions: thiosulphate.rate solution.

r the reactio

ii) Siv)

he reaction oic acid is add

ng reaction: ed Hydrochloove. ide is demo

has entered

VIEW EXERC

ory preparatsalt and conc

ii) a

as. gen chloride xide are goons for each.

while aq. HCogen chloridesolution woulf hydrogen c

water turns be:

b) dnduct electriccurrent. oluene but thn a glass rod

ot affect a dr

SE – Chemistr

.

.

n of dilute H

Sodium hydrSodium sulp

of zinc and dded to silver

oric acid.

nstrated by

the round-

CISE:

ion of hydrogcentrated sulat 200° C

gas? d drying age

Cl is an excee in water cad become le

chloride gas

blue litmus re

does not concity.

his solution dd dipped in N

ry strip of blu

ry

Hydrochloric

rogen carbonphite

ilute hydrochnitrate soluti

gen chloride phuric acid:

ents but they

llent conductan be conceess concentrais opened th

ed, and cond

nduct electric

does not condNH4OH is br

ue litmus pa

acid with ea

nate

hloric acid. ion?

gas.

y are not em

tor. entrated by bated when bohere are fum

ducts electric

city

duct electricirought near t

per but it tur

9

9

[2]

ach of the [5]

[1] [1]

[1]

[3]

mployed to

boiling the oiled.

mes in the

city, while

ity. the mouth

rns red in

10


x) Hydrogen chloride gas is not collected over water. 6) Write the main difference in hydrogen chloride gas and hydrochloric acid. 7) Describe briefly the method employed to dissolve hydrogen chloride gas in water as it is

prepared in the laboratory. 8) What is the purpose of using a funnel while preparing hydrochloric acid from hydrogen chloride

gas? 9) i) Name one element which reacts with hydrogen to form a compound which is strongly acidic

in water. ii) Explain why dilute hydrochloric acid cannot be concentrated by boiling beyond 22.2%. 10) i) With reference to given figure for the dissolution of hydrogen chloride gas in water, explain

briefly, how the device with the mouth of the funnel just below the surface of water prevents the back suction of water?

ii) How does solubility of hydrogen chloride gas in water change with temperature? 11) Describe an experiment, giving the arrangement of the apparatus you would use, to prove the

extreme solubility of hydrogen chloride gas. 12) i) Name two gases which chemically combine to form: (a) a solid (b) a liquid. ii) Name the chemical in which gold can be dissolved. 13) Silver nitrate solution can be used to distinguish HCl from HNO3. Why? 14) Which one of the following metals will not liberate hydrogen gas from hydrochloric acid? [Na, Cu, Fe, Mg] 15) State what you observe when silver nitrate solution is added to dilute hydrochloric acid. 16) What do you see when conc. hydrochloric acid is added to lead (IV) oxide with warming. 17) What must be added to sodium chloride to obtain hydrogen chloride? 18) What would you see when hydrogen chloride mixes with ammonia? 19) Hydrogen chloride dissolves in water forming an acidic solution. i) Name the experiment which demonstrates that hydrogen chloride is very soluble in water. ii) Give three distinct tests [apart from using an indicator] you would carry out with this solution

to illustrate the typical properties of an acid. 20) Name the gas produced with exposure of chlorine water to sunlight. Home Work 1) Write equation for the reactions of aqueous hydrochloric acid on: i) Silver nitrate solution ii) magnesium foil iii) caustic soda solution iv) iron wire v) zinc carbonate vi) copper oxide vii) lead nitrate solution 2) By what experiment can it be proved that HCl contains hydrogen and chlorine? Write equations

for the reactions. i) Name all the products formed when conc. hydrochloric acid is warmed with manganese

dioxide. ii) Name one metallic oxide which reacts with hydrochloric acid to give a coloured solution. iii) Name two colourless gases, which when mixed produce a white solid. 3) Complete the following reaction and balance them,

i) NaCl + H2SO4 ⎯⎯⎯ →⎯ °< C200 ii) NaCl + H2SO4 ⎯⎯⎯ →⎯ °> C200

HCl gas

Water

Air gap



iii) NH4OH + HCl → iv) NaHSO3 + HCl → v) Cu(NO3)2 + HCl → vi) Pb3O4 + HCl → 4) How will the action of dilute hydrochloric acid on sodium carbonate and sodium sulphite enable

you to distinguish between these two compounds? 5) Write the equation for the reaction of hydrochloric acid with each of the following: i) Lead nitrate solution ii) Manganese (IV) oxide. 6) Write the balanced equations for the following reactions of: i) Dilute hydrochloric acid and sodium sulphite. ii) The preparation of hydrogen chloride from sodium chloride and sulphuric acid. State whether

the sulphuric acid should be concentrated or dilute. iii) The reaction of hydrogen chloride with ammonia. 7) State how you would prove that HCl contains i) Hydrogen → using an active metal below Mg ii) Chlorine → using an oxidizing agent containing lead

ANSWERS:

Class Work 1)

2) i) NaCl + H2SO4 ⎯⎯⎯ →⎯ °< C200 NaHSO4 + HCl↑ ii) NaHSO4 + NaCl ⎯⎯⎯ →⎯ °> C200 Na2SO4 + HCl↑ 3) i) It is dried by passing it through conc. sulphuric acid. ii) P2O5 and quick lime, (CaO) cannot be used to dry HCl. 4) The other drying agents like phosphorus pentoxide, P2O5 and quick lime, CaO cannot be used,

since they react with hydrogen chloride. 2P2O5 + 3HCl → POCl3 + 3HPO3 CaO + 2HCl → CaCl2 + H2O 5) i) When hydrogen chloride gas is dissolved in water, hydrochloric acid is formed. The

covalent compound ionizes in water due to its polar nature. HCl + H2O → H3O+ + Cl–

Thus aqueous HCl is a good conductor. Dry hydrogen chloride gas or liquid hydrogen chloride does not conduct electricity, as it has

only molecules and no ions. It shows covalent nature of hydrogen chloride. ii) A dilute aqueous solution of hydrochloric acid gets gradually concentrated on distillation, till

the concentration of the acid reaches 22.2% HCl by weight and 77.8% water by weight which boils at 110°C. When this concentration is reached, no further increase in concentration of the acid is possible by boiling

A very dilute solution of HCl becomes concentrated by boiling but a concentrated solution of HCl becomes dilute on boiling.

Conc. Sulphuric Acid

Dry Hydrogen chloride

AirConc.H2SO4 Air

Heat

Preparation of hydrogen chloride gas from common salt

NaCl + H2SO4 con.

12


Reason: Vapours evolved in the first case consist mostly vapours of water but when concentrated HCl is boiled its vapours consist molecules of HCl.

iii) When the jar is completely filled with hydrogen chloride, fumes appear above the jar’s mouth. These fumes consist of hydrochloric acid which is formed by combination of HCl with moisture (H2O) contained in the air.

iv) When hydrogen chloride gas is dissolved in water, hydrochloric acid is formed. The covalent compound ionizes in water due to its polar nature. HCl + H2O → H3O+ + Cl–

These ions conduct electricity. Dry hydrogen chloride gas or liquid hydrogen chloride does not turn dry blue litmus paper, showing non–acidic character of the gas. Further, liquefied hydrogen chloride does not conduct electricity, as it contains only molecules. It shows covalent nature of hydrogen chloride.

v) Dry HCl gas or liquid hydrogen chloride does not conduct electricity as it is covalent in nature. Covalent compounds do not conduct electricity.

vi) Hydrochloric acid conducts electric current because hydrogen chloride gas when dissolved in water forms hydrochloric acid. This covalent compound ionises in water due to its polar nature. HCl + H2O → H3O+ + Cl–. Thus on ionization the H+ and Cl– ions conduct electric current.

vii) The gas is also soluble in dry toluene, but in that case it neither turns blue litmus red nor conducts electricity. This indicates the absence of H+ in toluene showing thereby that hydrogen chloride is a covalent compound. When hydrogen chloride gas is exposed to air, it gives white fumes due to the formation of hydrochloric acid on reacting with atmospheric water vapour.

viii) In order to know whether the gas jar is full, bring a rod dipped in ammonium hydroxide near its mouth. Dense white fumes of ammonium chloride will be produced proving thereby that the jar is full of hydrogen chloride gas.

ix) Dry hydrogen chloride does not ionize to give H+ and Cl– ions. Since Cl– ions are not released blue litmus paper is not affected by Cl– ions. But when a drop of water is added to HCl gas it dissolves in the water and ionizes as follows HCl + H2O → H3O+ + Cl–. The Cl– ions now turn blue litmus red.

x) It is not collected over water, since it is highly soluble in water. 6)

Hydrogen chloride gas Hydrochloric acid no effect on blue litmus paper turns blue litmus red HCl gas does not ionize to release Cl– ions

HCl acid ionizes in water releasing Cl– ions (HCl + H2O → H3O+ + Cl–) which turn blue litmus paper red.

7) Hydrochloric acid is prepared by dissolving hydrogen chloride gas in water by means of an inverted funnel arrangement. The gas is passed into water until no more gas is absorbed, the product is concentrated and contains about 36% by mass of hydrogen chloride.

Procedure: The rim of the funnel is placed such that it just touches the water taken in a trough. Back suction occurs, the water rises up in the funnel and in turn the level outside the funnel falls creating an air gap between the rim of the funnel and the surface of water. The pressure outside and inside then equalizes and the water which had risen in the funnel falls down again.

This process continues till the water in the trough is saturated with hydrogen chloride gas resulting in formation of hydrochloric acid.

8) The funnel arrangement: a) prevents or minimizes back–suction of water. b) provides a large surface area for absorption of HCl gas. 9) i) Chlorine



ii) A dilute aqueous solution of hydrochloric acid gets gradually concentrated on distillation, till the concentration of the acid reaches 20.2% HCl by weight and 77.8% water by weight which boils at 110°C. When this concentration is reached, no further increase in concentration of the acid is possible by boiling.

A very dilute solution of HCl becomes concentrated by boiling but a concentrated solution of HCl becomes dilute on boiling.

Reason: Vapours evolved in the first case consist mostly vapours of water but when concentrated HCl is boiled its vapours consist molecules HCl.

10) i) The rim of the funnel is placed such that it just touches the water taken in a trough. Back suction occurs, the water rises up in the funnel and in turn the level outside the funnel falls creating an air gap between the rim of the funnel and the surface of water. The pressure outside and inside then equalizes and the water which had risen in the funnel falls down again. This process continues till the water in the trough is saturated with hydrogen chloride gas resulting in formation of hydrochloric acid.

ii) It increases with increase in temperature. 11) The great solubility of the gas can be demonstrated by means of the Fountain experiment. Take a dry round bottomed flask filled with dry HCl gas. On the mouth of the flask, fix a rubber

stopper with two holes. Through, one whole pass a long jet tube and through other hole pass a dropper with few drops of water. Put the jet tube in the beaker containing blue litmus solution. Press the dropper. The blue litmus solution enters the jet tube with a great force, forming a red fountain.

Reason: As the water goes in the flask from the dropper, HCl gas present in the flask dissolves due to its high solubility, thereby lowering the pressure inside.

The outside pressure being higher pushes the blue litmus solution inside through the jet tube. 12) i) a) NH3(g) + HCl(g) → NH4Cl (white solid) b) 2H2 + O2 → 2H2O (liquid) ii) Aqua Regia 13) i) When AgNO3 is formed along with HNO3. This white ppt of AgCl does not dissolve in HNO3. AgNO3 + HCl → AgCl + HNO3 (white curdy ppt) This white ppt of AgCl is soluble in NH4OH to form a complex diammine silver chloride. AgCl + NH4OH → [Ag(NH3)3]+Cl– + 2H2O 14) Cu 15) When AgNO3 is added to HCl (acid) a white curdy ppt of silver chloride is formed along with nitric

acid. This white ppt is insoluble in HNO3. AgNO3 + HCl → AgCl↓ + HNO3.

16) Pb3O4 + 8HCl ⎯→⎯Δ 3PbCl2 + 4H2O + Cl2↑

17) NaCl + H2SO4 (conc.) ⎯⎯⎯ →⎯ °< C200 NaHSO4 + HCl 18) HCl(g) + NH3(g) → NH4Cl(s) dense white fumes of solid NH4Cl. 19) i) Fountain experiment. ii) a) First test: HCl when it reacts with metals above hydrogen on the reactivity series forming

metallic chlorides evolving hydrogen. (b) Second test: HCl reacts with a base to give salt and water, HCl + NaOH → NaCl + H2O. (c) Third test: HCl reacts with metallic sulphides to give salt and hydrogen sulphide.

HCl + Na2S → NaCl + H2S 20) HCl

HCl gas

Water

Air gap

14


Home Work: 1) i) AgNO3 + HCl → AgCl ↓ + HNO3

ii) Mg + 2HCl → MgCl2 + H2↑ iii) NaOH + 2HCl → NaCl + H2O iv) Fe + 2HCl → FeCl2 + H2 v) ZnCO3 + 2HCl →ZnCl2 + H2O + CO2↑ vi) CuO + 2HCl → CuCl2 + H2O vii) Pb(NO3)2 + 2HCl → PbCl2 ↓ 2HNO3

2) i) MnO2 + 4HCl ⎯→⎯Δ MnCl2 + 2H2O + Cl2↑ ii) FeO + 2HCl → FeCl2 (green) + H2O iii) HCl(g) + NH3(g) → NH4Cl (white solid)

3) i) NaCl + H2SO4 ⎯⎯⎯ →⎯ °< C200 NaHSO4 + HCl↑

ii) NaCl + H2SO4 ⎯⎯⎯ →⎯ °> C200 Na2SO4 + HCl↑ iii) NH4OH + HCl → NH4Cl + H2O iv) NaHSO3 + HCl → NaCl + H2O + SO2

v) Cu(NO3)2 + 2HCl → CuCl2 + 2HNO3

vi) Pb3O4 + 8HCl → 3PbCl2 + 4H2O + Cl2↑ 4) Na2CO3 + 2HCl → 2NaCl + H2O + CO2↑ NaHSO3 + HCl → NaCl + H2O + SO2↑ From the products formed; Na2CO3 and NaHSO3 can thus be differentiated from each other 5) i) Pb(NO3)2 + 2HCl → PbCl2↓ + 2HNO3

ii) MnO2 + 4HCl ⎯→⎯Δ MnCl2 + 2H2O + Cl2↑ 6) i) HCl (dil.) + NaHSO3 → NaCl + H2O + SO2↑ ii) 2NaCl + H2SO4 (conc.) → Na2SO4 + 2HCl iii) HCl(g) + NH3(g) → NH4Cl(s) (white cloud of NH4Cl solid) 7) i) Zn + 2HCl(g) → ZnCl2 + H2

ii) PbO2 + 4HCl ⎯→⎯Δ PbCl2 + 2H2O + Cl2

Pb3O4 + 8HCl ⎯→⎯Δ 3PbCl2 + 4H2O + Cl2

Documents

CESSF L U UT - Universal Tutorials · 2 2 Universal Tutorials – X ICSE – Chemistry Volume 2 of 2 Procedure: Place some common salt in a flat bottomed flask and pour concentrated