Question

In the reaction ______ H2 + N2 ----> 2 NH3, what coefficient should be placed in front of H2 to balance the reaction?

Answer 1

2NH3 is equivalent to N2 + H6 since the 2 at the beginning gets distributed to both atoms. Knowing this you can rewite the equation as

H2 + N2 = H6 + N2

The N2 can cancel out leaving

H2 = H6

You now have to ask ‘2 times what equals 6?’ The answer is obviously 3 at this point.

Answer: C. 3