Question

A quantity of 1.922 g of methanol (CH₃OH) was burned in a constant-volume bomb calorimeter. Consequently, the temperature rose by 5.56°C. If the heat capacity of the bomb plus water was 8.09 kJ / °C, calculate the molar heat of combustion of methanol.

Answer 1

Well, if 1.922g of methanol causes a5.56°C change, then find molar mass of methanol. 1 mole methanol = 32.05g, so 32.05 times as much energy will be released by a mole and the temp will change 32.05 times as much. 32.05 x5.56°C = 178.198 degree C change per mole of methanol.

If it takes 8.09 kJ / °Cto raise it one degree C, and the temp rose178.198 degrees C, just multiply5.56 by 178.198. The answer is 990.780 Kj, and since it is exothermic and 3 sig figs, the answer is
-990