Hydrogen Chloride Flashcards

1
Q

previous name of HCl

A

muriatic acid

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2
Q

Glauber??

A

prepared HCl from rock salt and sulphuric acid

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3
Q

Joseph Priestly?

A

obtained its pure form

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4
Q

Davy??

A

gave the name hydrogen chloride

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5
Q

occurence in free state

A

volcanic gases and gastric juices

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6
Q

catalyst of synthesis reaction of hydrogen and chlorine

A

moisture

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7
Q

laboratory preparation of gas

A

sodium chloride and conc. sulphuric acid

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8
Q

drying agent of laboratory method of gas

A

concentrated sulphuric acid

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9
Q

precautions in laboratory method of gas

A
  1. initially heated very slowly to control the evolution of gas
  2. thistle funnel should dip below the acid
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10
Q

collection of gas in laboratory method and why

A

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

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11
Q

why is NaCl preffered in laboratory prep of gas

A

cheap and easily available

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12
Q

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

A

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

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13
Q

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

A

highly volatile and may volatize out with HCl

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14
Q

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

A
  1. fuel is wasted
  2. glass cracks
  3. sodium sulphate sticks to glass
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15
Q

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

A

react with HCl to form respective chlorides

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16
Q

how many times is HCl gas heavier than air

A

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

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17
Q

gases heavier than air

A

HCl, SO2, O2, Cl2, CO2

18
Q

gases lighter than air

A

NH3 and H2

19
Q

gases highly soluble in water

A

HCl, NH3, SO2

20
Q

gases fairly/slightly soluble in water

A

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

21
Q

physical properties of HCl gas

A

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

22
Q

why does HCl gas fume in moist air?

A

due to its high solubility

23
Q

when does HCl liquefy

A

at 10 degrees, 40 atmos. p

24
Q

freezing and boiling point of HCl

A

boils at -83 degrees
freezes at -113 degrees

25
Q

chemical properties of HCl gas

A

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

26
Q

laboratory prep of hydrochloric acid

A

HCl gas is dissolved in water using funnel arrangement

27
Q

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

A

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

28
Q

what is the funnel arrangement for prep of hydrochloric acid

A

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

29
Q

physical properties of hydrochloric acid

A

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

30
Q

density of acid

A

1.2 gm/cc

31
Q

boiling point of acid

A

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

32
Q

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

A

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

33
Q

chemical properties of hydrochloric acid

A
  1. monobasic nature- HCl dissociates in aqueous solution to form 1 hydrogen ion per molecule
  2. acidic nature caused by hydrogen ion
34
Q

what happens when HCl dissolves in toluene

A

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

35
Q

what happens when sodium thiosulphate reacts with HCl

A

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

36
Q

what happens when strong oxidising agents react with HCl

A

releases salt, water, and chlorine

37
Q

what is aqua regia?

A

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

38
Q

reaction of aqua regia releases?

A

Nitrosyl chloride salt (NOCl)

39
Q

nascent chlorine reacts with noble metals to form

A

soluble chlorides (hence, aqua regia dissolves noble metals)

40
Q

tests for hydrochloric acid

A
  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
41
Q

uses of hydrochloric acid

A
  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