7C Nitric Acid Flashcards
(124 cards)
1
Q
Nitric acid was Initially called
A
Aqua Fortis
2
Q
Nitric Acid Occurs in
A
Free and Combined state
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
4
Q
Fixation of atmospheric nitrogen
A
Fixation of Free atmospheric nitrogen into uself nitrogenous compounds in the soil
5
Q
Combined State:
A
Chile Salt Petre
Bengal Salt petre or Nitre
6
Q
Laboratory Method:
A
From potassium or sodium Nitrate
and Conc. H2SO4
7
Q
Equation:
A
KNO3 + H2SO4 —> (<200) KHSO4 +HNO3
8
Q
Laboratory Method:
Reactants:
A
KNO3
Conc. H2SO4
in glass retort
9
Q
Laboratory Method:
Products:
A
Potassium Bisulphate
Nitric acid Vapours
10
Q
Laboratory Method:
Condition:
A
Temperature of reactants less than 200
11
Q
Laboratory Method:
Procedure:
A
A mixturfe of equal parts by weright of sodium nitrateand conc. h2so4 are gently heated in glasss retort
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
13
Q
Laboratory Method:
Collection:
A
Collected in water cooled Reservior
14
Q
Laboratory Method:
Precaution:
A
Complete apparatus made of glass
HCl is not used
Temperature is maintained and controlled
15
Q
Laboratory Method:
Identification:
A
Heating alone or with copper turining –> Reddish brown fumes of NO2
NO2 -> FeSO4 (acidified) —> Brown
16
Q
Laboratory Method:
Why is H2SO4 used?
A
Strong non-volatile acid
Displaces more volatile nitric acid from its salt
17
Q
Laboratory Method:
Why is HCl not used?
A
Being volatile it is not uswd to displace another volatile aCID
18
Q
Laboratory Method:
Molar ratio of reactants:
A
1:1
Half of the hydrogen of the acid is used up.
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
20
Q
Laboratory Method:
Why glass?
A
Nitric acid is corrosive
Attacks Rubber, Cork etc.
21
Q
Laboratory Method:
Temperature of the reaction:
A
<200
22
Q
Laboratory Method:
High temperature:
A
- Damage to glass
- Further decomp. of Nitric acid
- 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
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
24
Q
HNO3 —>
A
NO2 + H2O + O2
25
Yellow brown tinge can be remofved by:
1. Bubbling of air or carbon dioxide
| 2. Dilution with water
26
Bubbling of air or carbon dioxide:
Drives out the NO2 gas from the warm acid
Further oxidises NO2 to Nitric acid
27
2. Dilution with water:
Causes dissolution of NO2 gas which is soluble in water
28
Manifucture of Nitric acid is by
Ostwald's Process
29
3 Steps In ostwald's Process:
1. Catalytic chamber
2. Oxidation chamber
3. Absorption tower
30
1. Catalytic chamber:
| Conversion:
Catalytic oxidation of ammonia to nitric oxide
31
1. Catalytic chamber:
| Reaction:L
NH3 + O2 ---> (Pt, 700 to 800) NO + H2O + 21.5 Kcals
32
1. Catalytic chamber:
| Reactants:
a. Pure dry Ammonia
| b. Dry air
33
1. Catalytic chamber:
| Ratio of Reactants:
Ammonia : Air
| 1:10 by volume
34
1. Catalytic chamber:
| Catalyst:
Platinum Gauze
35
1. Catalytic chamber:
| Temperature
700 to 800 (Maintained electrically)
36
1. Catalytic chamber:
| Nature of Reaction:
Exothermic
37
1. Catalytic chamber:
| Products:
1. NO
| 2. Steam
38
1. Catalytic chamber:
| Conversion ratio:
95% of NH3 to NO
| Rest burnt to N2 and Steam
39
2. Oxidation Chamber:
| Conversion:
Oxidation of NO to NO2
40
2. Oxidation Chamber:
| Reaction:
NO + O2 --> (50) NO2
41
2. Oxidation Chamber:
| Temperature:
50
42
3. Absorption Tower:
| COnversion:
NO2 to HNO3 by absorption in water in the presence of excess air
43
3. Absorption Tower:
| Equation:
NO2 + H2O + O2 ---> HNO3
44
3. Absorption Tower:
| Temperature:
Ordinary Temperature
45
3. Absorption Tower:
| Product:
Nitric Acid
46
Nitric acid on skin
Extremely Corrosive action ---> Painful blisters
| Protein of the skin forming a yellow compound, Xanthoproteic Acid and hence stains the skin yellow
47
Why sistillation or boiling cant be used to concentrate nitric acid beyond certain concentration?
An aqueous solution of nitric acid forms
| A constant boiling misture at 121, 68% acid.
48
What is Constant Boiling Mixture?
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
49
Further concentration:
Distillation of the acid under reduced pressure in the presence of concentrated sulphuric acid. 98%
50
Stability of Nitric acid:
Ustable, Decomposed slightly in ordinary temp. and presence of sunlight
51
Temperature for Bubbling:
60 to 80
52
The chemical behaviour of nitric acid is dependent on its
Concentration
53
Dilute Nitric Acid:
Almost completely ionized into H+ ions and nitrate ions
54
Acidic nature of Nitric acid:
Higher concentration of H+ ions
55
Dilute nitric acid behaves like a
Typical Acid
56
Pure or Concentrated Nitric acid:
Poorly ionized and hence its oxidising properties tens to predominate
57
Nitric acid has mainly
Oxidising properties.
58
Reason for oxiding property in HNO3
It is based on the fact that when nitric acid undergoes decomposition, it yields nascent oxygen
59
Nitric acid's reduction products
Undergoes reduction in number of ways, NO, NO2, N2O.
Dependent on the Temp, and Acid conc.
60
Case for Non-metals, Oxidation:
Conc. Nitric acid, Hot ---> NO2
61
Case for metals:
1. Cold, Very dilute HNO3 (1% Acid) ->H
2. Dilute Nitric acid (Cold) --> NO
3. Conc Nitric Acid (Hot) -> NO2
62
Passivity:
Pure conc, Nitric acid or fuming nitric acid renders iron and Al passive
63
Cause of Passivity:
Due to formatuion of a thin oxide coating on the surface of the metal which prevents further reaction
64
Aqua Regia:
Misture of Nitric acid and HCl in ratio 1:3.
Nitric acid oxidises HCl to Cl
65
Oxidation of Inorganic Compounds:
Nitric oxide is formed.
66
Oxidation of Organic compounds can be:
Oxidation
| Nitration
67
Bursting into flames:
HNO3 being a strong oxidising agent decomposes to give Nascent Oxygen, Oxidises Organic compounds to CO2 and WAter
68
Nitration:
One or more hydrogen atoms of an organic compound are replaced by a nitro group (-NO2)
69
Nitration of protein matter results in the formation of
Xanthoprotein acid which stains the skin yellow
70
Tests for Nitric Acid:
1. Conc. HNO3 Decomposition
2. Cu + Conc. HNO3 (or Cu + Nitrate + Conc. H2SO4)
3. Brown Ring test
71
1. Conc. HNO3:
HnNO3 ---> h2o + NO2 + O2
72
2. Cu + Conc. HNO3
Cu + HNO3 --> (heat) Cu(NO3)2 + 2H2O + 2NO2
Dense reddish brown fumes of NO2 eveloved
Blue solution of CuNO3 remiains
73
3. Brown Ring Test:
For detection of NO1- Radical
74
3. Brown Ring Test:
| Procedure:
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
Why is conc. H2SO4 added from the sides
Reaction of Conc. H2SO4 with H2O is highly exothermic and the acid may spurt out
76
3. Brown Ring Test:
| Obsrervation:
A brown ring appears at the junction of the 2 liquids
77
3. Brown Ring Test:
| Reaction:
FeSO4 + H2SO4 + HNO3 ---> Fe2(SO4)3 + H2O + NO
FeSO4 + NO----> FeSO4.NO (nitroso Iron (2) sulphate, brown)
78
3. Brown Ring Test:
| FactsL
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
Freshly Prepared iron 2 Sulphate solution is used in above test:
Iron 2 Sulphate on emposure to atmos is oxidised to iron 3 sulphate and the test will not answer with iron 3 sulphate
80
The brown ring of notroso sulphate is formed at the junction of the 2 liquids:
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
The brown ring of nitroso ferrous sulphate decomposes on disturbing:
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
Oxidation of Non-Metals:
| C + HNO3 (Hot COnc) -->
CO2 + H2O + NO2
83
Oxidation of Non-Metals:
| S + HNO3 --> (Hot, Conc)
H2SO4 + H2O + NO2
84
Oxidation of Non-Metals:
| P + HNO3 --> (Hot COnc)
H3PO4 + H2O + NO2
85
Oxidation of Metals:
| Mg + HNO3 (Cold, very dilute)--->
Mg(NO3)2 + H2
86
Oxidation of Metals:
| Mn + HNO3 (Cold, very dilute)--->
Mn(NO3)2 + H2
87
Oxidation of Non-metals
| Carbon
4HNO3->CO2+H20+4NO2
88
Oxidation of Non-metals
| Suphur
S+HNO3->H2SO4+H20+NO2
89
Oxidation of Non-metals
| Phosphorus
P+HNO3->H3PO4+H20+NO2
90
Oxidation of Metals
Cold very Dilute Nitric Acid[1% acid]
Magnesium
Mg+HNO3->Mg(No3)2+H2
91
Oxidation of Metals
Cold very Dilute Nitric Acid[1% acid]
Manganese
Mn+HNO3->Mn(NO3)2+H2
92
Oxidation of Metals
Dilute Nitric Acid
Copper
Cu+HNO3->Cu(NO3)2+H20+NO
93
Oxidation of Metals
Dilute Nitric Acid
Zinc
Zn+HNO3->Zn(NO3)2+H20+NO
94
Oxidation of Metals
Dilute Nitric Acid
Iron
Fe+HNO3->Fe(No3)2+H20+NO
95
Oxidation of Metals
Concentrated Nitric Acid [Hot]
Copper
Cu+HNO3->Cu(NO3)2+H20+NO2
96
Oxidation of Metals
Concentrated Nitric Acid [Hot]
Zinc
Zn+HNO3->Zn(NO3)2+H20+NO2
97
Oxidation of Metals
Concentrated Nitric Acid [Hot]
Iron
Fe+HNO3->Fe(NO3)3+H20+CO2
98
AQUA REGIA
HNO3+3HCl->H20+NOCl+Cl
Au+Cl->Aucl3
Pt+Cl->Ptcl4
99
Oxidation of Inorganic compounds
| Suphur dioxide
SO2+H20+HNO3->H2SO4+2NO
100
Oxidation of Inorganic compounds
| Hydrogen sulphide
H2S+HNO3->oS+H20+NO
101
Oxidation of Inorganic compounds
| Iron[II] suphate
FeSo4+H2SO4+HNO3->Fe2(SO4)3+H20+NO
102
Oxidation of Organic Compounds
| Oxidation
C6 H10 O5 +Nitric acid (Hot concentrated)->
| Carbon+Water+Nitrogen di oxide
103
Oxidation of organic compounds
| Nitration
C7H8+HNO3>oC7H5(NO2)3+H20
104
Tests for Nitic acid and Nitrates
| Heat
HNO3->H20+4NO2+O2
105
Tests for Nitic acid and Nitrates
| Reaction with Metallic Nitrate
Metallic Nitrate->Metallic oxide+NO2+O2
106
Tests for Nitic acid and Nitrates
| Reaction of Nitric acid with Copper
CU+HNO3->Cu(No3)2+H20+No2
107
Tests for Nitic acid and Nitrates
| Reaction of Nitrate with Copper
Cu+NaNO3+H2SO4->NaHSO4+Cu(No3)2+H20+NO2
108
Brown ring test
FeSO4+H2SO4+HNO3->Fe2(SO4)3+H20+NO
| FeSO4+NO->FeSO4.NO
109
Brown compound
Nitroso Iron[II] Sulphate
| FeSO4.NO
110
Preparation of Nitrates
KOH+HNO3->KNO3+H20
Pb+HNO3->Pb(NO3)2+2H20+2NO2
CuO+2HNO3->Cu(NO3)2+H20
111
Thermal decomposition of KNO3
KNO3->KNO2+O2
112
Thermal decomposition of PH(NO3)2
Pb(NO3)2->PbO+O2+NO2
113
Thermal decomposition of Cu(No3)2
Cu(No3)2->CuO+O2+NO2
114
Thermal decomposition of silver/mercuric nitrate
silver/mercuric nitrate->Metal+Oxygen+Nitrogen di oxide
115
Thermal decomposition of Ammonium nitrate
NO4NO3->N20+H20
116
Physical properties of Nitric acid
| Colour
Pure acid[98% concentration]-Colourless
| Commercial acid[68% conc]-Yellowish brown
117
Physical properties of Nitric acid
| Odour
Suffocating
118
Physical properties of Nitric acid
| Taste
Sour taste
119
Physical properties of Nitric acid
| Physiological nature
Non-poisonous,highly corrosive
120
Density
Heavier than water
Pure acid-specific gravity 1.54
Commercial acid-specific gravity 1.42
121
Physical properties of Nitric acid
| Solubility
High soluble in water
122
Physical properties of Nitric acid
| Constant boiling water
Forms a constant boiling mixture with water boiling at 121 degree containing 68 percent of the acid
123
Physical properties of Nitric acid
| Boiling point
Pure acid 86 degree celcius
124
Physical properties of Nitric acid
| Freezing point
Pure acid:Freezes to a white solid having m.p. -42 degree celcius
