Question

Which of the following is not an oxidation-reduction reaction?

A. Ca + 2 HCl ---> CaCl2 + H2
B. H2 + Cl2 ---> 2 HCl
C. NaCl + LiNO3 ---> NaNO3 + LiCl
D. 2 CO + 2 NO ---> 2 CO2 + N2

Answer 1

I think the correct answer from the choices listed above is option C. The reaction NaCl + LiNO3 ---> NaNO3 + LiCl is not an example of an oxidation-reduction reaction. It is a double replacement type of reaction. Hope this answers the question.

Answer 2

Answer: option C. NaCl + LiNO₃ ---> NaNO₃ + LiCl

Step-by-step explanation:

1) An oxidation-reduction reaction is the oxidation of at least one element and the reduction of at least one element.

2) Oxidation is the increase of the oxidation number, due to the loss of electrons.

3) Reduction is the reduction of the oxidation number, due to the gain of electrons.

4) You can tell whenever a reaction is an oxidation-reduction by observing the oxidation numbers: if two elements changed its oxidation number (one increases and one reduces) it is an oxidation - reduction, else it is not.

5) Oxidation numbers:

i) NaCl

Na: 1+, Cl: 1-.

ii) LiNO₃

Li: 1+, N: 5+, O: 2-

iii) NaNO₃

Na: 1+, N: 5+, O: 2-

iv) LiCl

Li: 1+, Cl: 1-.

There you have that the oxidation numbers of the five elements (Na, N, O, Li, and Cl) remained unchanged.

None element was reduced and none element was oxidized, so you conclude that this is not an oxidation-reduction reaction.