Energy value in

food samples.....

.EXPERIMENT 6.1

AIM

• To determine the energy value in food samples.

PROBLEM STATEMENT

• What is the energy value of different food samples?

HYPOTHESIS

• The energy values of different food samples are different.

VARIABLES

• Manipulated variable: food samples

• Constant variable : volume of water

• Responding variable: energy value of food samples

MATERIALS

• Distilled water, food sample (groundnut, green bean, flour) and plasticine.

APPARATUS

•A thermometer, a boiling tube, a retort stand and clamp, a pin, an electronic balance, wind shield and a Bunsen burner

TECHNIQUE

• Calorimetry- measuring of the amount of heat released in its combustion.

PROCEDURE

• 1. 10ml of water (mass=10 g) is poured into a boiling tube and the boiling tube is clamped to the retort stand in an upright position.

• 2. a small piece of food is weighed and recorded.

• 3. the initial temperature of the water in the boiling tube is recorded.

• 4. the food is fixed at the end of the mounted pin.

• 5. the food is burned using the Bunsen burner.

• 6. as soon as the food burns, hold it about 1cm below the boiling tube.

• 7. the water in the boiling tube is stirred with a thermometer and the temperature rise is recorded when the food stops burning.

• 8. the boiling tube is emptied and refilled with another 10ml of water.

• 9. repeat steps 1 – 8 using a different food sample each time.

• 10. the energy value of food is calculated with the following formula:

• Energy value= mass of water (g) x temperature rise (oC)

x 4.2J/goC• mass of food (g)

measurement

Types of foods

groundnut green bean

flour

Mass/g 0.33 0.1 5

Initial temperature/oC

29 29 29

Final temperature/oC

44 31 45

Change in temperature/oC

15 2 16

Energy value (J/g)

1909 840 134.4

CONCLUSION

• Experimental results show that groundnut, green bean and flour have different food values.

• Decision: hypothesis is accepted