hydrochloric acid Flashcards

1
Q

hydrogen chloride and water are examples of _______

A

polar covalent compounds

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2
Q

hydrogen chloride can be converted into chlorine by heating with _______ which acts as a _________

A

Lead (iv) oxide, oxidizing agent

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3
Q

addition of ________ to dilute hydrochloric acid results in the liberation of hydrogen sulfide gas

A

Iron (ii) sulphide

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4
Q

what is aqua regia

A

it is a mixture of
–> one part of conc.nitric acid
–> three parts of conc. hydrochloric acid
by volume and it reduces hydrochloric acid to chlorine

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5
Q

addition of silver nitrate to hydrochloric acid gives_____

where is it soluble and insoluble?

A

the insoluble precipitate of the respective chloride

the precipitate is soluble in excess of ammonium hydroxide

the precipitate is insoluble dilute nitric acid

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6
Q

ZnS + HCL

name the gas evolved

A

H2S

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7
Q

Na2S + HCL

name the gas evolved

A

H2S

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8
Q

Mg + HCL

name the gas evolved

A

H2

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9
Q

Ca(HCO3)2 (calcium bicarbonate) + HCL

name the gas evolved

A

CO2

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10
Q

Na2S2O3 (sodium thiosulphate) + HCL

name the gas evolved

A

SO2

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11
Q

magnesium (iv) oxide + HCL

name the gas evolved

A

Cl

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12
Q

(name the gas evolved)

NaHCO3 (sodium bicarbonate) + HCL

A

CO2

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13
Q

(name the gas evolved)

Na2SO3(sodium sulphite) + HCl

A

SO2

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14
Q

dilute hydrochloric acid is added to silver nitrate

A

curdy white precipitate is observed

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15
Q

lead nitrate solution is mixed with dilute hydrochloric acid and heated

A

a white precipitate of PbCl2 is formed

it dissolves in heating

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16
Q

action of dilute hydrochloric acid on Iron (ii) sulphide

A

gas with a rotten egg smell is evolved

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17
Q

dilute hydrochloric acid is added to lead nitrate and the mixture is heated

A

a white precipitate is formed

it is soluble on heating

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18
Q

dilute hydrochloric acid is added to copper carbonate

A

a colorless and odourless gas evolves with brisk effervesence

it turns lime water milky

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19
Q

dilute hydrochloric acid is added to sodium thiosulphate

A

SO2 gas is evolved which turns pottasium dichromate paper from orange to green

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20
Q

copper sulphide is treated with dilute hydrochloric acid

A

the gas having rotten egg smell is released (H2S)

it turns lead acetate paper black

21
Q

a few drops of dilute hydrochloric acid are added to silver nitrate solution followed by condition of ammonium hydroxide solution

A

a curdy white precipitate of AgCl is formed

it is insoluble in HNO3
it is soluble in NH4OH

22
Q

glass rod dipped in ammonium hydroxide is brought near the mouth of the concentrated hydrochloric acid bottle

A

dense white fumes of ammonium chloride are observed

23
Q

excess of ammonium hydroxide is added to a substance obtained by adding hydrochloric acid is silver nitrate solution

state an observation

A

a white precipitate first formed dissolves giving a clear solution

24
Q

magnesium strip is dropped in dilute hydrochloric acid

A

magnesium metal slowly dissolves with evolution of colourless and odourless gas which burns of with a pop sound

25
Q

platinum when added to aqua regia

A

platinum dissolves in aqua regia

26
Q

copper oxide treated with concentrated hydrochloric acid

A

a greenish yellow gas is released

which turns moist starch iodide paper blue black

then turns blue litmus to red and finally bleaches to white

27
Q

give balanced equation for the following

concentrated hydrochloric acid and potassium permanganate solution

A

2KMnO4 + 16HCl –> 2KCl + 2MnCl2 + 8H2O + 5Cl2

28
Q

give balanced equation for the following

red lead is warmed with concentrated hydrochloric acid

A

Pb3O4 + 28HCl –> 3PbCl2 + 4H2O + Cl2

29
Q

give balanced equation for the following

dilute hydrochloric acid and sodium thiosulphate

A

Na2S2O3 + 2HCL –> 2NaCl + H2O + SO2 + S

30
Q

give balanced equation for the following

manganese (iv) oxide and concentrated hydrochloric acid

A

MnO2 + 4HCL –> MnCl2 + 2H2O + Cl2

31
Q

what are the conditions for liquefaction of hydrogen chloride

A

pressure of 40 atm

temperature of 10 degrees celsius

32
Q

hydrogen and chlorine combine directly in the presence of sunlight

A

the reaction would be explosive

33
Q

distinguish between dil.HCL and dil.H2SO4 using barium chloride

A

when dil H2SO4 reacts with bacl2 a white ppt of BaSO4 is formed which is insoluble in acid.

when dil.HCL is added to BaCl2 no ppt is formed.

34
Q

chemical test to distinguish between lead nitrate solution and zinc nitrate solution

A

lead nitrate gives a white precipitate

zinc nitrate gives a colourless solution

35
Q

test to distinguish between manganese dioxide and copper 2 oxide

A

MnO2 + 4HCL –> MnCl2 + 2H2O + Cl2
(greenish yellow gas liberated)

CuO + HCl –> CuCl2 + H2O
(no gas liberated but solution turns blue)

36
Q

give a chemical test to distinguish between lead nitrate solution and zinc nitrate solution

A

by adding ammonium hydroxide in excess

lead nitrate solution gives a white precipitate while zinc nitrate gives a colourless solution

37
Q

why is anhydrous HCL a poor conductor of electricity while aqueous HCl is a good conductor

A

anhydrous HCl is a covalent compound which does not have any ions in it

whereas there are ions present in aq.HCL hence aqueous HCl conducts electricity

38
Q

why is it too dangerous to dilute the acid by adding water to concentrated H2SO4

A

if the acid is diluted by water to the conc.acid then the water may suddenly convert into steam and cause the acid to splash or spurt

39
Q

why is silver nitrate crystals dissolved in distilled water and not in tap water in order to prepare a solution of silver nitrate

A

tap water contains some amount of dissolved sodium chloride hence it reacts to form white precipitate of silver chloride

AgNO3 + NaCl –> AgCl + NaNO3

40
Q

odour of gas when sodium sulphite and HCl is react

A

SO2 suffocating GAs which causes coughing

41
Q

odour of gas when calcium carbonate and HCl is react

A

CO2 gas produces faint acidic smell

42
Q

odour of gas when magnesium ribbon and HCl is react

A

odourless hydrogen gas

43
Q

what is aqua regia used for

A

cleaning glassware

refinig noble metals like gold/platinum

44
Q

HCl when come in contact with methyl orange sol

A

turns red or pink

45
Q

HCl when come in contact with neutral litmus solution

A

turns red

46
Q

HCl when come in contact with alkaline phenolphthalein

A

it decolourizes

47
Q

how is HCl gas collected

A

upward displacement of air

48
Q

how is HCl prepared

A

when we pass hydrogen chloride in water hydrochloric acid is formed