When 2.38 g of methane burns in oxygen, 119 kJ of heat is produced. What is the enthalpy of combustion (in kJ) per mole of methane under these conditions? Your answer will be in kJ/mol.
the Molar Mass of methane is 16.04, so I did 2.38g/16.04=0.14838 mol
Then I did 119 kj/0.14838 mol= 802 kJ/mol.
My HW system isn't accepting this. What did I do wrong?
I think you forgot the negative sign as in -802 kJ/mol.
Ah, Okay. Thanks!
Based on your calculations, it seems that you have correctly determined the number of moles of methane and the heat produced. However, there might be a small mistake in your final calculation.
To find the enthalpy of combustion per mole of methane, you need to divide the heat produced (119 kJ) by the moles of methane (0.14838 mol). This will give you the energy released per mole of methane.
Therefore, the correct calculation would be:
119 kJ / 0.14838 mol = 802.81 kJ/mol
So, the enthalpy of combustion per mole of methane under the given conditions is approximately 802.81 kJ/mol.
Make sure you round your answer to the appropriate number of significant figures based on the given information and the significant figures provided.