Question

Balance the equation in acidic medium by oxidation number method: Cu+ NO3- --->Cu2+ + NO2.

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Answer 1

$\mathfrak{\huge\underline{Answer:}}$

→The unbalanced redox equation is as follows:

Cu + NO3 + Cu²+ + NO2

All atoms other than Hand O are balanced.

The oxidation number of Cu changes from O

to 2. The change in the oxidation number of

Cu is 2.

The oxidation number of N changes from 5

to 4. The change in the oxidation number of

Nis 1.

The increase in the oxidation number is

balanced with decrease in the oxidation

number by multiplying Noz and NO2 with

2..

Cu + 2NO3 → Cu2+ + 2NO2

O atoms are balanced by adding 2 water

molecule on RHS.

Cu + 2NO3 → Cu²+ + 2NO2 + 2H2O

To balance H atoms, add 4 H+ on LHS.

Cu + 2NO3 + 4H+ + Cu2+ + 2N O2 + 2H2O

Since the reaction occurs in basic medium,

add 4 hydroxide ions on both sides of the

equation.

Cu + 2NO3 + 4H+ + 40H + Cu2+ +

2N O2 + 2H2O + 40H-

On LHS, 4 H+ ions combine with 4 OH-ions

to form 4 water molecules out of which 2

water molecules cancel out with 2 water

molecules on RHS.

Cu + 2NO3 + 2H2O + Cu2+ + 2N O2 +

40H

This is the balanced chemical equation.

Answer 2

Answer:

Explanation:

The unbalanced redox equation is :-

Cu+NO3− →Cu2+ +NO 2

All atoms other than H and O are balanced.

The oxidation number of Cu changes from 0 to 2. The change in the oxidation number of Cu is 2.

The oxidation number of N changes from 5 to 4. The change in the oxidation number of N is 1.

The increase in the oxidation number is balanced with decrease in the oxidation number by multiplying NO3− and NO2 with 2

Cu+2NO3− →Cu2+ +2NO2​

O atoms are balanced by adding 2 water molecule on Right hand side.

Cu+2NO3− →Cu2+ +2NO2​+2H2O

Since the reaction occurs in basic medium, add 4 hydroxide ions on both sides of the equation.

Cu+2NO3− +4H + +4OH− →Cu2+ +2NO2 +2H 2​O+4OH −

On Left hand side, 4 H + ions combine with 4 OH- ions to form 4 water molecules out of which 2 water molecules cancel out with 2 water molecules on right hand side.

Cu+2NO3− +2H2 →Cu2+ +2NO2​+4OH −

This is balanced equation in acidic medium.