Question

The combustion of 1 mole of CO according to the reaction CO(g) + ½O2(g) → CO2(g) + 67.6 kcal gives off how much heat?

Answer 1

When the enthalpy value is given, we can calculate how much heat is use or produces in a given equation. 

67.6 kCal ---> 67.6 kCal= 1 mol of reaction
1 mol of reaction=  1 mol of CO (based on the coefficient)

so 1 mole of CO gives us 67.6 kCal of heat.

calculation:

1 mol CO$\frac{67.5 kcal}{1 mol CO} = 67.5 kcal$