Classify the following redox reactions:

(a) N2(g) + O2 (g) → 2NO(g)

(b) 2Pb(NO3)2(s)

_____________________________

(a) In this reaction, nitric oxide is formed by combination of the elemental substances, nitrogen and oxygen. So, it is an example of combination redox reaction.

(b) It involves breaking down of lead nitrate into three components. So, it is an example of decomposition redox reactions.

______________________________

Answer:

Explanation:

Classify the following redox reactions:

(a) N2(g) + O2 (g) → 2NO(g)

(b) 2Pb(NO3)2(s)

In this reaction, the compound nitric oxide is formed by combination of elemental substances like nitrogen and oxygen. Since the oxidation number of nitrogen increases from 0 to +2 and of oxygen decreases from 0 to -2 therefore, it is a combination redox reaction.

(b)

In this reaction, lead nitrate decomposes to form three products, viz, lead oxide, nitrogen dioxide and oxygen. Since the oxidation number of nitrogen decrease from +5 in lead nitrate to +4 in NO2 in O2, therefore, it is a decomposition redox reaction.

(c)

In this reaction, hydrogen of water has been displaced by hydride ion to form dihydrogen gas. Therefore, it is a displacement reaction. Since in this reaction, the oxidation number of hydrogen increases from -1 in hydride ion to zero in dihydrogen gas and that of hydrogen decreases from +1 in water to zero in dihydrogen, therefore, it is a displacement redox reaction.

(d)

This is a disproportionation reaction since here the oxidation state of nitrogen decreases from +4 in NO2 to +3 in NO2– ion, as well as increases from +4 in NO2 to +5 in NO3 ion.