Snack manufacturers print the amount of energy in 100g of snack on the pack. You can find out if low fat snacks have less energy in them.

What to do

• use a top pan balance to measure the mass of a snack
• put 100ml of water in a copper beaker
• measure the temperature of the water and record it
• put on safety goggles

Eye Protection Shall be Worn

• hold your snack with tongs
• set light to your snack and burn it just under the copper beaker
• when your snack has burned stir the water
• record the highest temperature
• repeat with a different snack

Analysing your results
Use a spreadsheet like the one below to calculate the energy in 100g of your snack. You can enter the results for all the groups in your class. The spreadsheet will work out an average.

Hint: To work out the change in temperature type =C3-B3 in cell D3. To work out the energy in 100g type =4.2*D3*10/A3 in cell E3.

Explaining and Evaluating
1. Compare your results for low and high fat snacks. Can you explain the difference?
2. Compare your results with the information on the packet. Can you explain why your results are much lower?