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**1. Homework Statement**

The combustion of the fuel gas butane is given by:

2(C4H10) +13(O2) --> 8(CO2) + 10(H2O) del(H)= –5760kJ/mol

What mass of butane would be needed to produce 33440J of energy?

**2. Homework Equations**

**3. The Attempt at a Solution**

First of all how do you interpret del(H)= –5760kJ/mol

Per mol of what?

I assume a mol is the complete reaction of

[2(C4H10) +13(O2) --> 8(CO2) + 10(H2O)]

33440J/(5760kJ/mol)=0.0058mol of the reaction

So a total of 0.0058*2=0.0116 moles of butane?

Which would be 0.012*(12.01*4 + 10.1)=0.675g of butane but the answers suggested 0.337g which is a half of what I worked out. Hence they didn’t multiply by 2. This confusion comes back to my first question. ‘Per mol of what?’ In del(H)= –5760kJ/mol