Question

Which of the following chemical reactions is an oxidation-reduction reaction? Fe2O3 + 3CO yields 2Fe + 3CO2 MgSO4 + 2KIyields K2SO4 + MgI2 NaNO3 + KCl yields KNO3 + NaCl Cu(NO3)2 + 2HBryields CuBr2 + 2HNO3

Answer 1

I hope I am right on this, but the answer is
Fe₂O₃ + 3CO --> 2Fe + 3CO₃

Answer 2

Answer : The reaction that is an example of oxidation reduction reaction is "Fe2O3 + 3CO yields 2Fe + 3CO2 "

Explanation :

The oxidation reduction reaction is the one in which one of the elements undergo oxidation and the other undergoes reduction.

The oxidation number of the element that undergoes oxidation increases .

The oxidation number of the element that undergoes reduction decreases.

Let us find out which of these reactions show an increase and decrease in oxidation numbers.

$Fe_{2}O_{3}+3 CO\rightarrow 2Fe + 3CO2$

Let us find out the oxidation numbers of the elements involved in this reaction.

The standard oxidation state of O is -2

The overall charge on the compound Fe₂O₃ is 0.

Let us set up an equation to find oxidation number of Fe in Fe₂O₃.

2 ( oxidation number of Fe) + 3 ( Oxidation number of O) = Overall charge

2 ( oxidation number of Fe) + 3 ( -2) = 0

2 (oxidation number of Fe) - 6 = 0

oxidation number of Fe = 6/2 = +3

Oxidation number of Fe on reactant side is +3.

On product side Fe is present in its standard state. Therefore its oxidation number is 0.

Oxidation number of Fe on product side is 0.

Oxidation number of Fe changes from +3 to 0 which shows a decrease.

That means Fe undergoes reduction.

Let is find oxidation number of C on both the sides.

Oxidation number of C in CO is

oxidation number of C + (-2) = 0

oxidation number of C = +2

Oxidation number of C on reactant side is +2

Oxidation number of C in CO₂ is

Oxidation number of C + 2 x (-2) = 0

Oxidation number of C = +4

Oxidation number of C on product side is +4

Oxidation number for C changes from +2 to +4, which shows an increase.

Therefore C undergoes oxidation.

We can say that in the above reaction, one element ( Fe) undergoes reduction and the other (C) undergoes oxidation. This is an example of oxidation-reduction reaction.

Hence the correct option is "Fe2O3 + 3CO yields 2Fe + 3CO2 "