Calc Mass Propane Needed to Raise Air Temp by 50K

[a150daysflood]

1. Homework Statement
The standard enthalpy change of combustion of propane (C3H8)
is -2220kJ/mol. It requires 1.0J of energy to raise the temperature of 1.0g of air by 1.0K.

Calculate what mass of propane needs to be burned to raise the temperature of the air in the balloon by 50K.


2. Homework Equations 3. The Attempt at a Solution

For the air in balloon to raise by 50K,50J is needed I suppose.
50/(mass of propane/44.0)=2220x10^3
mass of propane = 9.91x10^(-4)g
The answer given is (1.85x10^3)g.
Can anyone correct me?

 

[mgb_phys]

You need to know the mass of air in the balloon or it's initial volume / temperature / pressure.
Otherwise your answer is correct per g of air.