Question

In the reaction 2Mg (s) + O2 (g) + 2H2O (l) → 2Mg2+ (aq) + 4OH– (aq), how many electrons are transferred?

A. 0
B. 1
C. 2
D. 3
E. None of the Above (This is not a redox reaction.)

Answer 1

Answer : The correct option is, (A) 0

Explanation :

The given chemical reaction is:

`2Mg(s)+O_2(g)+2H_2O(l)\rightarrow 2Mg^(2+)(aq)+4OH^-(aq)`

This chemical reaction is a balanced chemical reaction because in this reaction the number of atoms of individual elements present on reactant and product and charges are completely balanced.

In the reaction, (+4) charge present on magnesium will be balanced by the (-4) charge present on hydroxide ion.

So, zero (0) number of electrons are transferred that means there is no electrons are transferred.

Hence, the correct option is, (A) 0

Answer 2

F. None of the above (Four electrons are transferred).

2Mg → 2Mg^(2+) + 4e^(-)

O_2 + 2H_2O + 4e^(-) → 4OH^(-)

2Mg + O_2 + 2H_2O + 4e^(-) → 2Mg^(2+) + 4OH^(-) + 4e^(-)

2Mg + O_2 + 2H_2O → 2Mg^(2+) + 4OH^(-)

This is a redox reaction in which two atoms of Mg transfer four electrons to one molecule of O_2.