Key points

- When fuels and energy react with oxygen, energy is released in an exothermic reaction
- Calorimeter's can be used for the comparison of energy released by different fuels/foods in a school laboratory

Study tip

*Remember the specific heat capacity of water, and the value used to convert joules to calories is given to you. Remember that to calculate the energy released by burning a fuel use the equation: Q=mc delta T. You should be able to calculate the energy released from burning a known massof fuel in kJ/g and also when given the formula of fuel or is relative formula mass in kJ/mol*

*Worked example; 0.50g of a fuel was burned and used to heat 200g of water in a calorimeter. The temperature of the water increased by 14 degrees celcius, the specific heat capacity of water is- c=4.2J/g degrees celcius. Energy released=200 X 4.2 X 14=11760J=11.76kJ, energy released per g of fuel=11.76/0.5=23.52kJ/g*

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