Question

Hydrogen cyanide is produced in the following balanced reaction.

2NH3 (g) + 3O2 (g) + 2CH4 (g) → 2HCN (g) + 6H2O (g)

Given the following standard heats of formation, calculate the approximate ΔH°rxn of this reaction.

Substance
ΔHf°(kJ/mol)


NH3
-46


CH4
-75


HCN
135


H2O
-242


Choose one answer.
a. -500 kJ
b. -1000 kJ
c. 500 kJ
d. -1500 kJ
e. -4519
f. not enough information is given to make the calculation

Answer 1

dHrxn = (n*dHf products) - (n*dHf reactants)

Answer 2

When i did that I got -940 kJ but that isn't and option and neither is -1000kJ. So by default would the answer be F.

Answer 3

No, I wouldn't do that because there is enough information to actually calculate the delta H reaction. I ran through the calculation and came up with -940 kJ also so I would pick the closest answer which is -1000 kJ

Answer 4

Okay... but I tried that answer and it was incorrect.