The reaction is C8H18 +25/2 O2 --> 8CO2 + 9H2O?

Question

When 1.02 g of gasoline is burned in a bomb calorimeter it raises the temperature of 1 kg of water from 22 °C

to 35.3 °C. The atomic weight of carbon is 12 g/mol and of hydrogen 1 g/mol. The specific heat of water is

4.18 J °C/g. Show your work to answer the following questions.

How many moles of gasoline are burned in this experiment? What is the heat of combustion of gasoline?

Answer 1

You are going to use the equation, Heat = (specific heat) (mass) ( change in temperature)

Heat = (4.18)(1.02)(13.3)= 56.7 J

To find moles, just convert 1.02 grams to moles using the molecular mass of C8H18.

8*12 + 18*1= 114 g/mol

1 g (1 mol/114 g) = .0088 moles gasoline

Heat of combustion is simply Joules per mol

56.7 J / .0088 mol = 6,400 J/mol or 6.4 kJ/mol