Hi Abigail, what a good question this is!
First, I want you to think about a propane grill and how it works. The propane canister is filled with propane, you light the grill and then pump in propane. The propane mixes with the ambient oxygen in the air, and you get fire to grill and water [which we usually don't see because it is steam]. Does it make sense that delta H is on the right side of this equation?
Second, what units should your answer be in? What is the only number that includes this unit? I bet that's the number we need to use to get the right answer. Additionally, notice that we're told how much propane there is in kilograms, but we're told the molecular mass of propane in grams per mole. Don't forget to convert between kilograms and grams!
Third, notice that the reaction can be multiplied. If we have 1 mole of propane, we will need 5 moles of oxygen. After the reaction, we'll have 3 moles of CO2, 4 moles of water, and -2044 kJ. If we have 2 moles of propane, we will need 10 moles of oxygen. After the reaction, we'll have 6 moles of CO2, 8 moles of water, and -4088 kJ. We can multiply by whatever we want, it will just create more heat!
Now, let's do the math!
13.2 kg of propane * 1000 g / 1 kg = 13,200 g of propane
13,200 g of propane * 1 mol / 44.1 g = 299 mols of propane
299 mols of propane * -2044 kJ / 1 mol of propane = -612,000 kJ
Hope this helps, have fun!
