Question

Given the unbalanced ionic equation:
3Mg + ____ Fe3+ ==> 3Mg2+ + ____ Fe
When this equation is balanced, both Fe3+ and Fe have a coefficient of
(1) 1, because a total of 6 electrons is transferred
(2) 2, because a total of 6 electrons is transferred
(3) 1, because a total of 3 electrons is transferred
(4) 2, because a total of 3 electrons is transferred

Answer 1

The answer is (2) 2, because a total of 6 electrons is transferred. We can know the electron transferred number form Mg to Mg2+ ion. There is 3 Mg involved and two electrons per atom. So total is 6,

Answer 2

Answer: The correct answer is Option 2.

Explanation:

For the given redox reaction, magnesium is getting oxidized because it is loosing electrons and iron is getting reduced because it is gaining electrons.

The half reaction for oxidation and reduction is given by the equations:

Oxidation half reaction:  $Mg\rightarrow Mg^{2+}+2e^-$       ×  3

Reduction half reaction:  $Fe^{3+}+3e^-\rightarrow Fe$      ×  2

Net ionic reaction: $3Mg+2Fe^{3+}\rightarrow 3Mg^{2+}+3Fe$

Total number of electrons transferred are 6.

So, the correct answer is Option 2.