7C Nitric Acid Flashcards

1
Q

Nitric acid was Initially called

A

Aqua Fortis

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2
Q

Nitric Acid Occurs in

A

Free and Combined state

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3
Q

Free State

A

During lightnings, atmospheric nitrogen is oxidised to Nitroc oxide
Nitric oxide is further oxidised to nitrous oxide.
NO2 combines with H2O to form nitric acid
Then combines with metallic carbonates to form Nitrates

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4
Q

Fixation of atmospheric nitrogen

A

Fixation of Free atmospheric nitrogen into uself nitrogenous compounds in the soil

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5
Q

Combined State:

A

Chile Salt Petre

Bengal Salt petre or Nitre

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6
Q

Laboratory Method:

A

From potassium or sodium Nitrate

and Conc. H2SO4

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7
Q

Equation:

A

KNO3 + H2SO4 —> (<200) KHSO4 +HNO3

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8
Q

Laboratory Method:

Reactants:

A

KNO3
Conc. H2SO4
in glass retort

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9
Q

Laboratory Method:

Products:

A

Potassium Bisulphate

Nitric acid Vapours

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10
Q

Laboratory Method:

Condition:

A

Temperature of reactants less than 200

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11
Q

Laboratory Method:

Procedure:

A

A mixturfe of equal parts by weright of sodium nitrateand conc. h2so4 are gently heated in glasss retort

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12
Q

Laboratory Method:

Observation:

A

On heating the misture in glass retort
The volatil nitric acid is displaced
The vapours are collected in receiver
Cooled from outside with cold water

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13
Q

Laboratory Method:

Collection:

A

Collected in water cooled Reservior

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14
Q

Laboratory Method:

Precaution:

A

Complete apparatus made of glass
HCl is not used
Temperature is maintained and controlled

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15
Q

Laboratory Method:

Identification:

A

Heating alone or with copper turining –> Reddish brown fumes of NO2

NO2 -> FeSO4 (acidified) —> Brown

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16
Q

Laboratory Method:

Why is H2SO4 used?

A

Strong non-volatile acid

Displaces more volatile nitric acid from its salt

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17
Q

Laboratory Method:

Why is HCl not used?

A

Being volatile it is not uswd to displace another volatile aCID

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18
Q

Laboratory Method:

Molar ratio of reactants:

A

1:1

Half of the hydrogen of the acid is used up.

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19
Q

Laboratory Method:

Apparatus:

A

An all glass apparatus
Consists of:
1. Glass retort —> Reactants are heated
2. Water cooled reservior –> Collect condensed vapours of Nitric acid

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20
Q

Laboratory Method:

Why glass?

A

Nitric acid is corrosive

Attacks Rubber, Cork etc.

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21
Q

Laboratory Method:

Temperature of the reaction:

A

<200

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22
Q

Laboratory Method:

High temperature:

A
  1. Damage to glass
  2. Further decomp. of Nitric acid
  3. Formation of a hard residual crust of the corresponding sulphate.
    Poor conductor of heat, Sticks to the surface of the glass and cant be removed easily
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23
Q

Why is Nitric acid obtained in laboratory Yellowish Brown

A

Decomposition of Nitric acid, Results in Formation of Reddish Brown Nitrogen Dioxide which remains dissolved in the acid, thereby imparting color to it

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24
Q

HNO3 —>

A

NO2 + H2O + O2

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25
Q

Yellow brown tinge can be remofved by:

A
  1. Bubbling of air or carbon dioxide

2. Dilution with water

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26
Q

Bubbling of air or carbon dioxide:

A

Drives out the NO2 gas from the warm acid

Further oxidises NO2 to Nitric acid

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27
Q
  1. Dilution with water:
A

Causes dissolution of NO2 gas which is soluble in water

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28
Q

Manifucture of Nitric acid is by

A

Ostwald’s Process

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29
Q

3 Steps In ostwald’s Process:

A
  1. Catalytic chamber
  2. Oxidation chamber
  3. Absorption tower
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30
Q
  1. Catalytic chamber:

Conversion:

A

Catalytic oxidation of ammonia to nitric oxide

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31
Q
  1. Catalytic chamber:

Reaction:L

A

NH3 + O2 —> (Pt, 700 to 800) NO + H2O + 21.5 Kcals

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32
Q
  1. Catalytic chamber:

Reactants:

A

a. Pure dry Ammonia

b. Dry air

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33
Q
  1. Catalytic chamber:

Ratio of Reactants:

A

Ammonia : Air

1:10 by volume

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34
Q
  1. Catalytic chamber:

Catalyst:

A

Platinum Gauze

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35
Q
  1. Catalytic chamber:

Temperature

A

700 to 800 (Maintained electrically)

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36
Q
  1. Catalytic chamber:

Nature of Reaction:

A

Exothermic

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37
Q
  1. Catalytic chamber:

Products:

A
  1. NO

2. Steam

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38
Q
  1. Catalytic chamber:

Conversion ratio:

A

95% of NH3 to NO

Rest burnt to N2 and Steam

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39
Q
  1. Oxidation Chamber:

Conversion:

A

Oxidation of NO to NO2

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40
Q
  1. Oxidation Chamber:

Reaction:

A

NO + O2 –> (50) NO2

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41
Q
  1. Oxidation Chamber:

Temperature:

A

50

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42
Q
  1. Absorption Tower:

COnversion:

A

NO2 to HNO3 by absorption in water in the presence of excess air

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43
Q
  1. Absorption Tower:

Equation:

A

NO2 + H2O + O2 —> HNO3

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44
Q
  1. Absorption Tower:

Temperature:

A

Ordinary Temperature

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45
Q
  1. Absorption Tower:

Product:

A

Nitric Acid

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46
Q

Nitric acid on skin

A

Extremely Corrosive action —> Painful blisters

Protein of the skin forming a yellow compound, Xanthoproteic Acid and hence stains the skin yellow

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47
Q

Why sistillation or boiling cant be used to concentrate nitric acid beyond certain concentration?

A

An aqueous solution of nitric acid forms

A constant boiling misture at 121, 68% acid.

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48
Q

What is Constant Boiling Mixture?

A

Is the one which bouils without the change in composition

Hence on boiling the above misture, Evolves out vapourws of both acid and water in the same proportion as in the liquid

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49
Q

Further concentration:

A

Distillation of the acid under reduced pressure in the presence of concentrated sulphuric acid. 98%

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50
Q

Stability of Nitric acid:

A

Ustable, Decomposed slightly in ordinary temp. and presence of sunlight

51
Q

Temperature for Bubbling:

A

60 to 80

52
Q

The chemical behaviour of nitric acid is dependent on its

A

Concentration

53
Q

Dilute Nitric Acid:

A

Almost completely ionized into H+ ions and nitrate ions

54
Q

Acidic nature of Nitric acid:

A

Higher concentration of H+ ions

55
Q

Dilute nitric acid behaves like a

A

Typical Acid

56
Q

Pure or Concentrated Nitric acid:

A

Poorly ionized and hence its oxidising properties tens to predominate

57
Q

Nitric acid has mainly

A

Oxidising properties.

58
Q

Reason for oxiding property in HNO3

A

It is based on the fact that when nitric acid undergoes decomposition, it yields nascent oxygen

59
Q

Nitric acid’s reduction products

A

Undergoes reduction in number of ways, NO, NO2, N2O.

Dependent on the Temp, and Acid conc.

60
Q

Case for Non-metals, Oxidation:

A

Conc. Nitric acid, Hot —> NO2

61
Q

Case for metals:

A
  1. Cold, Very dilute HNO3 (1% Acid) ->H
  2. Dilute Nitric acid (Cold) –> NO
  3. Conc Nitric Acid (Hot) -> NO2
62
Q

Passivity:

A

Pure conc, Nitric acid or fuming nitric acid renders iron and Al passive

63
Q

Cause of Passivity:

A

Due to formatuion of a thin oxide coating on the surface of the metal which prevents further reaction

64
Q

Aqua Regia:

A

Misture of Nitric acid and HCl in ratio 1:3.

Nitric acid oxidises HCl to Cl

65
Q

Oxidation of Inorganic Compounds:

A

Nitric oxide is formed.

66
Q

Oxidation of Organic compounds can be:

A

Oxidation

Nitration

67
Q

Bursting into flames:

A

HNO3 being a strong oxidising agent decomposes to give Nascent Oxygen, Oxidises Organic compounds to CO2 and WAter

68
Q

Nitration:

A

One or more hydrogen atoms of an organic compound are replaced by a nitro group (-NO2)

69
Q

Nitration of protein matter results in the formation of

A

Xanthoprotein acid which stains the skin yellow

70
Q

Tests for Nitric Acid:

A
  1. Conc. HNO3 Decomposition
  2. Cu + Conc. HNO3 (or Cu + Nitrate + Conc. H2SO4)
  3. Brown Ring test
71
Q
  1. Conc. HNO3:
A

HnNO3 —> h2o + NO2 + O2

72
Q
  1. Cu + Conc. HNO3
A

Cu + HNO3 –> (heat) Cu(NO3)2 + 2H2O + 2NO2

Dense reddish brown fumes of NO2 eveloved
Blue solution of CuNO3 remiains

73
Q
  1. Brown Ring Test:
A

For detection of NO1- Radical

74
Q
  1. Brown Ring Test:

Procedure:

A

Take a solution of a nitrate or Dilute nitric acid in a test tube
Add to it a freshly prepared saturated solution of iron [ii] Sulphate.
Add Conc. Sulphuric Acid from the sides
Cool the test tube outisde under a tab
Keep the test tube aside

75
Q

Why is conc. H2SO4 added from the sides

A

Reaction of Conc. H2SO4 with H2O is highly exothermic and the acid may spurt out

76
Q
  1. Brown Ring Test:

Obsrervation:

A

A brown ring appears at the junction of the 2 liquids

77
Q
  1. Brown Ring Test:

Reaction:

A

FeSO4 + H2SO4 + HNO3 —> Fe2(SO4)3 + H2O + NO

FeSO4 + NO—-> FeSO4.NO (nitroso Iron (2) sulphate, brown)

78
Q
  1. Brown Ring Test:

FactsL

A
  1. Freshly prepared Iron (2) Sulphate is used
  2. The browin ring Of nitroso ferrou sulphate decomposes on disturbing
  3. The brown ring of Nitroso Ferrous sulphate is formed at the juction of the 2 liquids
79
Q

Freshly Prepared iron 2 Sulphate solution is used in above test:

A

Iron 2 Sulphate on emposure to atmos is oxidised to iron 3 sulphate and the test will not answer with iron 3 sulphate

80
Q

The brown ring of notroso sulphate is formed at the junction of the 2 liquids:

A

The brown ring test the conc. sulphuric acid being heaver settles dfonw
the iron 2 sulphate layer remains above it resultin gin the formation of the brown ring at the junCTION

81
Q

The brown ring of nitroso ferrous sulphate decomposes on disturbing:

A

When the test tube is shaken, the conc. h2so4 may further mix with water and the heat evolved assists in decompiosing the unstable brown ring

82
Q

Oxidation of Non-Metals:

C + HNO3 (Hot COnc) –>

A

CO2 + H2O + NO2

83
Q

Oxidation of Non-Metals:

S + HNO3 –> (Hot, Conc)

A

H2SO4 + H2O + NO2

84
Q

Oxidation of Non-Metals:

P + HNO3 –> (Hot COnc)

A

H3PO4 + H2O + NO2

85
Q

Oxidation of Metals:

Mg + HNO3 (Cold, very dilute)—>

A

Mg(NO3)2 + H2

86
Q

Oxidation of Metals:

Mn + HNO3 (Cold, very dilute)—>

A

Mn(NO3)2 + H2

87
Q

Oxidation of Non-metals

Carbon

A

4HNO3->CO2+H20+4NO2

88
Q

Oxidation of Non-metals

Suphur

A

S+HNO3->H2SO4+H20+NO2

89
Q

Oxidation of Non-metals

Phosphorus

A

P+HNO3->H3PO4+H20+NO2

90
Q

Oxidation of Metals
Cold very Dilute Nitric Acid[1% acid]
Magnesium

A

Mg+HNO3->Mg(No3)2+H2

91
Q

Oxidation of Metals
Cold very Dilute Nitric Acid[1% acid]
Manganese

A

Mn+HNO3->Mn(NO3)2+H2

92
Q

Oxidation of Metals
Dilute Nitric Acid
Copper

A

Cu+HNO3->Cu(NO3)2+H20+NO

93
Q

Oxidation of Metals
Dilute Nitric Acid
Zinc

A

Zn+HNO3->Zn(NO3)2+H20+NO

94
Q

Oxidation of Metals
Dilute Nitric Acid
Iron

A

Fe+HNO3->Fe(No3)2+H20+NO

95
Q

Oxidation of Metals
Concentrated Nitric Acid [Hot]
Copper

A

Cu+HNO3->Cu(NO3)2+H20+NO2

96
Q

Oxidation of Metals
Concentrated Nitric Acid [Hot]
Zinc

A

Zn+HNO3->Zn(NO3)2+H20+NO2

97
Q

Oxidation of Metals
Concentrated Nitric Acid [Hot]
Iron

A

Fe+HNO3->Fe(NO3)3+H20+CO2

98
Q

AQUA REGIA

A

HNO3+3HCl->H20+NOCl+Cl
Au+Cl->Aucl3
Pt+Cl->Ptcl4

99
Q

Oxidation of Inorganic compounds

Suphur dioxide

A

SO2+H20+HNO3->H2SO4+2NO

100
Q

Oxidation of Inorganic compounds

Hydrogen sulphide

A

H2S+HNO3->oS+H20+NO

101
Q

Oxidation of Inorganic compounds

Iron[II] suphate

A

FeSo4+H2SO4+HNO3->Fe2(SO4)3+H20+NO

102
Q

Oxidation of Organic Compounds

Oxidation

A

C6 H10 O5 +Nitric acid (Hot concentrated)->

Carbon+Water+Nitrogen di oxide

103
Q

Oxidation of organic compounds

Nitration

A

C7H8+HNO3>oC7H5(NO2)3+H20

104
Q

Tests for Nitic acid and Nitrates

Heat

A

HNO3->H20+4NO2+O2

105
Q

Tests for Nitic acid and Nitrates

Reaction with Metallic Nitrate

A

Metallic Nitrate->Metallic oxide+NO2+O2

106
Q

Tests for Nitic acid and Nitrates

Reaction of Nitric acid with Copper

A

CU+HNO3->Cu(No3)2+H20+No2

107
Q

Tests for Nitic acid and Nitrates

Reaction of Nitrate with Copper

A

Cu+NaNO3+H2SO4->NaHSO4+Cu(No3)2+H20+NO2

108
Q

Brown ring test

A

FeSO4+H2SO4+HNO3->Fe2(SO4)3+H20+NO

FeSO4+NO->FeSO4.NO

109
Q

Brown compound

A

Nitroso Iron[II] Sulphate

FeSO4.NO

110
Q

Preparation of Nitrates

A

KOH+HNO3->KNO3+H20
Pb+HNO3->Pb(NO3)2+2H20+2NO2
CuO+2HNO3->Cu(NO3)2+H20

111
Q

Thermal decomposition of KNO3

A

KNO3->KNO2+O2

112
Q

Thermal decomposition of PH(NO3)2

A

Pb(NO3)2->PbO+O2+NO2

113
Q

Thermal decomposition of Cu(No3)2

A

Cu(No3)2->CuO+O2+NO2

114
Q

Thermal decomposition of silver/mercuric nitrate

A

silver/mercuric nitrate->Metal+Oxygen+Nitrogen di oxide

115
Q

Thermal decomposition of Ammonium nitrate

A

NO4NO3->N20+H20

116
Q

Physical properties of Nitric acid

Colour

A

Pure acid[98% concentration]-Colourless

Commercial acid[68% conc]-Yellowish brown

117
Q

Physical properties of Nitric acid

Odour

A

Suffocating

118
Q

Physical properties of Nitric acid

Taste

A

Sour taste

119
Q

Physical properties of Nitric acid

Physiological nature

A

Non-poisonous,highly corrosive

120
Q

Density

A

Heavier than water
Pure acid-specific gravity 1.54
Commercial acid-specific gravity 1.42

121
Q

Physical properties of Nitric acid

Solubility

A

High soluble in water

122
Q

Physical properties of Nitric acid

Constant boiling water

A

Forms a constant boiling mixture with water boiling at 121 degree containing 68 percent of the acid

123
Q

Physical properties of Nitric acid

Boiling point

A

Pure acid 86 degree celcius

124
Q

Physical properties of Nitric acid

Freezing point

A

Pure acid:Freezes to a white solid having m.p. -42 degree celcius