Hydrogen Chloride

Question 1

previous name of HCl

Answer 1

muriatic acid

Question 2

Glauber??

Answer 2

prepared HCl from rock salt and sulphuric acid

Question 3

Joseph Priestly?

Answer 3

obtained its pure form

Question 4

Davy??

Answer 4

gave the name hydrogen chloride

Question 5

occurence in free state

Answer 5

volcanic gases and gastric juices

Question 6

catalyst of synthesis reaction of hydrogen and chlorine

Answer 6

moisture

Question 7

laboratory preparation of gas

Answer 7

sodium chloride and conc. sulphuric acid

Question 8

drying agent of laboratory method of gas

Answer 8

concentrated sulphuric acid

Question 9

precautions in laboratory method of gas

Answer 9

1. initially heated very slowly to control the evolution of gas
2. thistle funnel should dip below the acid

Question 10

collection of gas in laboratory method and why

Answer 10

upward displacement of air:
1. highly soluble in water
2. heavier than air

Question 11

why is NaCl preffered in laboratory prep of gas

Answer 11

cheap and easily available

Question 12

why is conc. sulphuric acid used in laboratory prep of gas

Answer 12

non-volatile and has high boiling point (displaces volatile HCl from NaCl)

Question 13

why is conc. nitric acid not used in lab prep of gas

Answer 13

highly volatile and may volatize out with HCl

Question 14

why is temperature above 200 C not used during prep of gas

Answer 14

1. fuel is wasted
2. glass cracks
3. sodium sulphate sticks to glass

Question 15

why is calcium chloride and phosphorous pentoxide not used as drying agent of gas

Answer 15

react with HCl to form respective chlorides

Question 16

how many times is HCl gas heavier than air

Answer 16

1.28 times heavier (V.D of HCl is 18.25)

Question 17

gases heavier than air

Answer 17

HCl, SO2, O2, Cl2, CO2

Question 18

gases lighter than air

Answer 18

NH3 and H2

Question 19

gases highly soluble in water

Answer 19

HCl, NH3, SO2

Question 20

gases fairly/slightly soluble in water

Answer 20

fairly: H2S, Cl2, CO2
slightly: H2, N2, O2

Question 21

physical properties of HCl gas

Answer 21

colourless, pungent odour, sour taste, non-poisonous, burning when inhaled

Question 22

why does HCl gas fume in moist air?

Answer 22

due to its high solubility

Question 23

when does HCl liquefy

Answer 23

at 10 degrees, 40 atmos. p

Question 24

freezing and boiling point of HCl

Answer 24

boils at -83 degrees
freezes at -113 degrees

Question 25

chemical properties of HCl gas

Answer 25

non combustible, non supporter of combustion
dissociates into hydrogen and chlorine on heating about 500 degrees

Question 26

laboratory prep of hydrochloric acid

Answer 26

HCl gas is dissolved in water using funnel arrangement

Question 27

why is normal delivery tube not used in lab prep of hydrochloric acid

Answer 27

it causes back suction. when the gas is passed through the tube and into water, it immediately dissolves. the pressure in the tube decreases and water is pushed up the tube causing back suction, and damages the apparatus

Question 28

what is the funnel arrangement for prep of hydrochloric acid

Answer 28

it prevents back suction, and provides larger surface area for absorption of gas
the funnel is just touching the trough of water. when pressure decreases, water rises in the funnel but level in trough decreases, forming an air gap between funnel and trough. the pressure outside and inside equalize the pressure in the funnel and its water falls down. process continues until water in trough is saturated

Question 29

physical properties of hydrochloric acid

Answer 29

colourless, pungent, sharp sour taste, corrosive in nature, blisters skin,

Question 30

density of acid

Answer 30

1.2 gm/cc

Question 31

boiling point of acid

Answer 31

109.8 degrees C
a solution of HCl in water forms a constant boiling mixture with water

Question 32

why can’t HCl not be concentrated beyond a point by boiling

Answer 32

on boiling, mixture evolves out both acid and water in the same proportions as in the liquid

Question 33

chemical properties of hydrochloric acid

Answer 33

1. monobasic nature- HCl dissociates in aqueous solution to form 1 hydrogen ion per molecule
2. acidic nature caused by hydrogen ion

Question 34

what happens when HCl dissolves in toluene

Answer 34

toluene is not a polar compound so it does not dissociate HCl into free ions, hence the solution is not acidic and not an electrolyte

Question 35

what happens when sodium thiosulphate reacts with HCl

Answer 35

NaCl, SO2, S (yellow particles), H2O formed

Question 36

what happens when strong oxidising agents react with HCl

Answer 36

releases salt, water, and chlorine

Question 37

what is aqua regia?

Answer 37

mixture of 1 part conc. nitric acid and 3 parts conc. HCl

Question 38

reaction of aqua regia releases?

Answer 38

Nitrosyl chloride salt (NOCl)

Question 39

nascent chlorine reacts with noble metals to form

Answer 39

soluble chlorides (hence, aqua regia dissolves noble metals)

Question 40

tests for hydrochloric acid

Answer 40

1. glass rod dipped in ammonia solution brought near HCl vapours
2. silver nitrate soln. to dil. HCl
3. action of heat on mixture of manganese dioxide and conc. HCl

Question 41

uses of hydrochloric acid

Answer 41

1. industrial: dyes, drugs, paints, glucose from starch, tanning industry, soldering work
2. extraction of glue from bones
3. pickling of metals before galvanizing
4. prep of aqua regia