Problem
Problem
Calculate the enthalpy of combustion of ethanol from the following data. Assume all the heat from the reaction is absorbed by the water. Compare your value with the data booklet value and suggest reasons for any differences.| Mass of water in copper calorimeter / g | 200.00 |
| Temperature increase in water / °C | 13.00 |
| Mass of ethanol burnt / g | 0.45 |
Intuitive explanation
Enthalpy of combustion measures the heat released per mole of fuel burned—here you'll use the calorimeter data to find how much energy the ethanol actually released, then scale it to a molar basis. The key is working backwards: calculate total heat absorbed by water using , convert that to moles of ethanol burned, and divide to get per mole. Real experiments always differ from theory because some heat escapes to the surroundings, the calorimeter itself absorbs energy, and combustion may be incomplete.
Intuitive explanation
Enthalpy of combustion measures the heat released per mole of fuel burned—here you'll use the calorimeter data to find how much energy the ethanol actually released, then scale it to a molar basis. The key is working backwards: calculate total heat absorbed by water using , convert that to moles of ethanol burned, and divide to get per mole. Real experiments always differ from theory because some heat escapes to the surroundings, the calorimeter itself absorbs energy, and combustion may be incomplete.