Question

Indicate whether the following balanced equations involve oxidation-reduction. Check all that apply. Check all that apply. 2H2SO4(aq) 2NaBr(s)→Br2(l) SO2(g) Na2SO4(aq) 2H2O(l) 3SO2(g) 2HNO3(aq) 2H2O(l)→3H2SO4(aq) 2NO(g) NaI(aq) 3HOCl(aq)→NaIO3(aq) 3HCl(aq) PBr3(l) 3H2O(l)→H3PO3(aq) 3HBr(aq)

Answer 1

Answer :  The balanced equations involve oxidation-reduction are:

(a) $2H_2SO_4(aq)+2NaBr(s)\rightarrow Br_2(l)+SO_2(g)+Na_2SO_4(aq)+2H_2O(l)$

(b) $3SO_2(g)+2HNO_3(aq)+2H_2O(l)\rightarrow 3H_2SO_4(aq)+2NO(g)$

(c) $NaI(aq)+3HOCl(aq)\rightarrow NaIO_3(aq)+3HCl(aq)$

Explanation :

Redox reaction or Oxidation-reduction reaction : It is defined as the reaction in which the oxidation and reduction reaction takes place simultaneously.

Oxidation reaction : It is defined as the reaction in which a substance looses its electrons. In this, oxidation state of an element increases. Or we can say that in oxidation, the loss of electrons takes place.

Reduction reaction : It is defined as the reaction in which a substance gains electrons. In this, oxidation state of an element decreases. Or we can say that in reduction, the gain of electrons takes place.

(a) The given chemical reaction is:

$2H_2SO_4(aq)+2NaBr(s)\rightarrow Br_2(l)+SO_2(g)+Na_2SO_4(aq)+2H_2O(l)$

This reaction involve oxidation-reduction reaction because the oxidation state bromine changes from (-1) to (0) which shows oxidation and sulfur changes from (+6) to (+4) which shows reduction.

(b) The given chemical reaction is:

$3SO_2(g)+2HNO_3(aq)+2H_2O(l)\rightarrow 3H_2SO_4(aq)+2NO(g)$

This reaction involve oxidation-reduction reaction because the oxidation state sulfur changes from (+4) to (+6) which shows oxidation and nitrogen changes from (+5) to (+2) which shows reduction.

(c) The given chemical reaction is:

$NaI(aq)+3HOCl(aq)\rightarrow NaIO_3(aq)+3HCl(aq)$

This reaction involve oxidation-reduction reaction because the oxidation state iodine changes from (-1) to (+5) which shows oxidation and chlorine changes from (+5) to (-1) which shows reduction.

(d) The given chemical reaction is:

$PBr_3(l)+3H_2O(l)\rightarrow H_3PO_3(aq)+3HBr(aq)$

This reaction does not involve oxidation-reduction reaction because the oxidation state of element present on reactant and product side are same.