Question

When 2.50 g of methane burns in oxygen, 125 kJ of heat is produced. What is the enthalpy of combustion per mole of methane under these conditions?

a) 50 kJ/mol
b) 100 kJ/mol
c) 125 kJ/mol
d) 250 kJ/mol

Answer 1

The enthalpy of combustion per mole of methane under the given conditions is approximately -223 kJ/mol.

Step-by-step explanation:

When methane gas is combusted, it releases heat energy, making the reaction exothermic. The enthalpy change for the combustion of 1 mole of methane is -890.4 kilojoules. To calculate the enthalpy of combustion per mole of methane using the given information, we can use a proportion:

2.50 g of methane produces 125 kJ of heat,
1 mole of methane produces -890.4 kJ of heat.

Using the proportion, we can find the enthalpy change per mole of methane as follows:

2.50 g ÷ molar mass of methane = moles of methane
moles of methane × -890.4 kJ = enthalpy change
enthalpy change ÷ 1 mole = enthalpy of combustion per mole of methane

Substituting the values, we find that the enthalpy of combustion per mole of methane is approximately -223 kJ/mol. Therefore, the correct option is d) 250 kJ/mol.