Which equation represents a redox reaction? 1.  2agno3(aq) + cu(s) → cu(no3)2(aq) + 2ag(s) 2.  bacl2(aq) + na2cro4(aq) → bacro4(s) + 2nacl(aq) 3.  h3po4(aq) + 3koh(aq) → 3h2o(l) + k3po4(aq) 4.  caco3(s) → cao(s) + co2(g)?

2agno3(aq) + cu(s) → cu(no3)2(aq) + 2ag(s)

Explanation:

Now let us take a good look at the reaction presented in the answer.

If we look at silver on the lefthand side of the reaction equation, we will realize that silver is in the +2 oxidation state but on the right hand side of the reaction equation, silver is in the zero oxidation state. This implies that silver has been reduced. Reduction refers to a decrease in oxidation number.

Now let us move to copper. Copper is in the zero oxidation state on the lefthand side of the reaction equation but on the right hand side of the reaction equation, it is in the +2 oxidation state. Hence, there is an increase in the oxidation number of copper- oxidation of cooler has occurred. Oxidation rs to a positive increase in oxidation number.

Hence the reaction involves oxidation and reduction, thus it s a redox reaction.

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