Question

Calculate the enthalpy of combustion of methane if 2.56 g of methane was burnt completely in a bomb calorimeter containing excess oxygen, causing a temperature rise of 4.58 °C in the calorimeter, which has a heat capacity of 1.26 kJ/°C. The balanced chemical equation for the combustion of methane is as follows: CH4(g) + 2O2(g) → CO2(g) + 2H2O(l) + energy.

Answer 1

To calculate the enthalpy of combustion of methane, we first need to determine the amount of heat released during the combustion process. We can do this using the heat capacity of the calorimeter and the temperature change.q = heat capacity  Tq = 1.26 kJ/C  4.58 Cq = 5.7688 kJNow, we need to determine the number of moles of methane burned. The molar mass of methane  CH4  is 12.01 g/mol  C  + 4  1.01 g/mol  H  = 16.05 g/mol.moles of CH4 = mass / molar massmoles of CH4 = 2.56 g / 16.05 g/molmoles of CH4 = 0.1595 molNow, we can calculate the enthalpy of combustion per mole of methane:H_combustion = -q / moles of CH4H_combustion = -5.7688 kJ / 0.1595 molH_combustion = -36.18 kJ/molThe enthalpy of combustion of methane is approximately -36.18 kJ/mol.