1. Plants, Energy and Food
Junior Science

3. Plants our Primary Food Source
Our food chain begins with plants….
What happens when we eat food?
We need food to give us energy…
What type of energy do you think food contains?
How could you show that food contains energy?

4. Investigation: To show the conversion of food energy (chemical energy) into heat energy.

5. Introduction
Food provides us with chemical energy, when burned this converts to heat energy.
Energy is measured in Joules
Different foods provide us with different amounts of energy.
Fat provide 38kJ/g while protein and carbohydrates provide 17kJ/g.

6. Planning and preparation
3 Boiling tubes Retort stand Thermometer Electronic balance Forceps Water Food samples Bunsen burner.

7. Procedure
Place 20mls of water into a boiling tube and record the temperature of the water. Clamp the boiling tube to a retort stand.
Measure out 1-2g of a food sample.
Place the sample on a forceps and ignite it using the bunsen burner.
Hold the burning food sample under the boiling tube until it stops burning and record the new temperature of the water.
Repeat for different food samples and record the results in a table.

8. Results
Food Initial Final Temp Comment Temp Temp Change

9. Observations
The breads did not ignite well, and just turned black on the surface. The crisps dripped fat and burned for a long time. The doritos burned with the most consistent and even flame.

10. Conclusion
In most cases the temperature increased, this was caused by the heat energy produced by burning the substance.
All food contains chemical energy and this can be converted into heat energy.
Fatty foods seem to contain the most chemical energy.

11. Results Food Initial Final Change Comment Temp Temp White Bread 21o 23
Brown Bread o
Crunchie Cornflakes o
McVities o
Crisps o
Rancheroes o