J.R. S. answered 04/17/20
Ph.D. University Professor with 10+ years Tutoring Experience
Since the GIVEN enthalpy change for 1 mole of N2 is -92.6 kJ, all we have to do is find out how many moles of N2 is in 2.98 g of N2, and then multiply that by 92.6. Right?
2.98 g N2 x 1 mol N2/28.0 g = 0.106 moles N2
0.106 moles N2 x -92.6 kJ/mole = -9.86 kJ (answer)