Nitric acid properties- Part 1

Nitric acid

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Chemical properties :

1) Acidic nature:

It is strong monobasic acid. It reacts with alkali, metal carbonate and metal bicarbonate to form salt.

HNO₃ + NaOH  ———> NaNO₃ + H₂O

2HNO₃ + Na₂CO₃ ——-> 2NaNO₃ + H₂O + CO₂

HNO₃ + NaHCO₃ ——-> NaNO₃ + H₂O + CO₂

2) Oxidizing properties of Nitric acid :

A) Oxidation of non metals : 

a) Reaction with Carbon:

2HNO₃  ——> H₂O + 2NO₂ + [O]   ] x 2

C  + 2[O] ——-> CO₂

Equation as a whole,

4HNO₃ + C ——> 2H₂O+ CO₂ + 4NO₂ 

b) Reaction with sulphur:

6HNO₃  ——> 3H₂O + 6NO₂ + 3[O]

S + 3[O] + H₂O ——-> H₂SO₄

Equation as a whole,

6HNO₃ + S  —-> 2H₂O + H₂SO₄ + 6NO₂

c) Reaction with Phosphorus :

2HNO₃  ——-> H₂O + 2NO₂ + O ] x 5

2P + 5[O]  + 3H₂O —-> 2H₃PO₄

Equation as a whole,

10HNO₃ +2P —-> 10  NO2  + 2H₃PO₄ + 2H₂O

d) Reaction with I₂:

2HNO₃ ——> H₂O+ 2NO₂ + O ]x5

10HNO₃ ——-> 5H₂O + 10 NO₂ + 5 [O]

I₂ + 5 [O] +H₂O ———>2HIO₃

Equation as a whole,

10HNO₃ + I₂ —-> 10 NO₂ + 2HIO₃+ 4H₂O

B) Oxidation of metalloids:

a)  With hot and concentrated HNO_3, Arsenic is oxidized into arsenic acid:

2HNO₃ ——> H₂O + 2NO₂ + O ]x5

2As + 5 [O] + 3H₂O —-> 2H₃AsO₄

Equation as a whole,

10 HNO₃ + 2As  ——-> 2H₂O + 10 NO₂ + 2H₃AsO₄

b)  Antimony is oxidized into antimonic acid:

10HNO₃ ——> 5H₂O + 10 NO₂ + 5 [O]

2Sb + 5[O] + 3H₂O —–>2H₃SbO₄

Equation as a whole,

10 HNO₃ + 2Sb ——> 2H₃SbO₄ + 10NO₂ + 2H₂O

ii) Pb + HNO₃ (concentrated) ——> Pb(NO₃)2 + NO₂ + H₂O

C) Oxidation of reducing agent :

a) H₂S is oxidized to S:

2HNO₃ —–> H₂O+ 2NO₂ + O

H₂S +O —–> H₂O + S

Equation as a whole,

2HNO₃ + H₂S —–> 2H₂O + S + 2NO₂

b) SO₂ is oxidizes into H₂SO₄ :

SO₂ + O + H₂O ——> H₂SO₄

2HNO₃ —–> H₂O + 2NO₂ + O

Equation as a whole,

SO₂ + 2HNO₃ —–> H₂SO₄ + 2NO₂

c) KI is oxidized into I₂:

2HNO₃ —–> H₂O + 2NO + 3[O]

2KI +2 HNO₃ + [O] —–> 2KNO₃ + I₂ +H₂O ] x 3

6KI +6HNO₃ + 3[O] —–> 6KNO₃ +3I₂ +3H₂O

Equation as a whole,

8HNO₃ + 6KI  ——> 4H₂O + 6KNO₃ + 3I₂ + 2NO

d) In presence of H₂SO₄ ,  ferrous sulphate is oxidized to ferric sulphate:

2HNO₃ —–> H₂O + 2NO + 3[O]

2FeSO₄ +H₂SO₄ + O —> Fe(SO₄)₂ +H₂O ] x3

Equation as a whole,

2HNO₃ + 6 FeSO₄ + 3H₂SO₄ —-> 4H₂O + 2NO + 3Fe₂(SO₄)₃

FeSO₄ + NO —–> FeSO₄. NO [Nitroso ferrous  sulphate(Brown complex)]