Question

A student determined that 2.5 grams of methane, CH4, produced 139kJ of heat in a bomb calorimeter. What is ΔErxn for the combustion of methane in kJ/mole CH4?

A) 5.56 kJ/mole
B) 55.6 kJ/mole
C) 55.6 kJ/mole
D) 556 kJ/mole

Answer 1

The change in enthalpy for the combustion of methane in kJ/mol CH4 is 890.4 kJ/mol.

Step-by-step explanation:

To calculate the change in enthalpy for the combustion of methane, we need to first convert the mass of methane to moles. The molar mass of methane (CH4) is 16.04 g/mol, so 2.5 g of methane is equal to 2.5 g / 16.04 g/mol = 0.156 mol. Then, we can use the given heat produced (139 kJ) and the number of moles of methane to calculate the change in enthalpy per mole of methane.

ΔErxn = Heat produced / Moles of methane = 139 kJ / 0.156 mol = 890.4 kJ/mol

Therefore, the change in enthalpy for the combustion of methane in kJ/mol CH4 is 890.4 kJ/mol.