The A Hrxn for the reaction A+B C 16 kJ What is AHrxn for the reaction 3C* 3A+3B in kJ?

Answer 1

You mean ∆Hrxn not A Hrxn, right?

A + B ==> C ... ∆H = 16 kJ

3C ==> 3A + 3B ... ∆H = ? = -48 kJ

Since the second reaction is the reverse of the first, we must change the sign to negative (-).

Since the second reaction is 3 x the first, we must multiply by 3.

The answer would thus be 3 x - 16 kJ = -48 kJ