Question

In the reaction 5 F2 (g) + 2NH3 (g) --> N2F2 (g) + 6 HF (g), the change in enthalpy is -96.3 kJ. Calculate the amount of heat released when 12.7 g of N2F2 (g) is formed. Answers: -185 kJ 53 kJ -18.5 kJ452 kJ

Answer 1

In this question, we have the following reaction:

5 F2 + 2 NH3 -> N2F2 + 6 HF

The enthalpy change is -96.3 kJ

As we can see, in order to form 1 mol of N2F2 it is released -96.3 kJ, but we need to know how much energy is released with 12.7 grams, and using the molar mass of N2F2, 66.01g/mol, we can find how many moles we have:

66.01g = 1 mol

12.7g = x moles

x = 0.192 moles of N2F2 in 12.7 grams

Now, if 1 mol released -96.3 kJ, what abour 0.192 moles:

1 mol = -96.3 kJ

0.192 moles = x kJ

x = -18.5 kJ of energy is released, letter C