How much heat is absorbed/released when 20.00 g of NH2 reacts in the presence of excess O2 to produce NO and H2O according to the following chemical equation:

Question

How much heat is absorbed/released when 20.00 g of NH2 reacts in the presence of excess O2 to produce NO and H2O according to the following chemical equation: 
4NH3 + 5O2 --> 4NO + 6H2O, deltaH= +1168 kJ.

The answer is 342.9 kJ of heat absorbed. I want to know how to complete this problem.

Jenny · Accepted Answer

I figured it out, deltaH is in kJ/grams which is 68. So 20.0gx(1168kJ/68g)=342.9 kJ.

DrBob222 · Answer

Yes, or you could have converted 20g to mols which is 20/17 = 1.176, then 1168 kJ/4mol = 292 kJ. Then 292 x 1.176 = 343 kJ