CHEMISTRY ENTHALPY HSC MCQ

[sangarp]

Hey need some help on this asap
How do you do this?

[r1ckworthy]

Hey need some help on this asap
How do you do this?

Hey! There might be a quicker way, but from what I can see, I would divide each value on the table to convert it from kJ/ g to kJ/mol. The value that matches 3218 is the correct fuel.

[sangarp]

hey
I actually did that
But I don't seem to get any of the values that have been given

[r1ckworthy]

Sorry! I made a silly mistake- you have to multiply all combustion values with it's molar mass in order to convert it to kJ/mol.

Molar mass comes in the form of g / mol. So, if we multiple the heat of combustion (kJ /g) of each fuel by it's molar mass (g/ mol), we convert the value to kJ /mol. Attached is an example of how I did it for one of the fuels.



Again, sorry for the silly mistake! Another lesson of why you shouldn't do things in your head