Question

zn + HNO3 » n (NO3)₂ + NH4 NO3 + H₂O​

Answer 1

Writing oxidation numbers of all the atoms,

0

+1+5 -2

+2 +5-2

-3 +1 +5-2 -2

+1 -2

Zn + HNO3 Zn(NO3)2 + NH4₂NNO3 + H₂O The oxidation numbers of Zn and N have

changed.

+2

Zn → Zn(NO3)2

+5

-3

.(i)

HNO3 → NH₂NO3 .(ii) Increase in Ox. no. of Zn = 2 units per Zn

atom

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Decrease in Ox. no. of N = 8 units per

HNO3 molecule

Eq.(i) should be multiplied by 4 and added to eq. (ii),

4Zn + HNO3 → 4Zn(NO3)2 + NH4NO3.

To balance nitrogen, 9 molecules of HNO3 should be added on LHS.

To balance hydrogen and oxygen, 3H₂O molecules should be added on RHS. Hence, the balanced equation is 4ZN + 10HNO3 4Zn(NO3)2 + NH4NO3 + t

3H₂O.