PEANUT and CHEETOE CALORIMETRY LAB



PEANUT and CHEETOE CALORIMETRY LAB

The evening before a marathon, runners are advised to eat a huge plate of pasta. Why? Because pasta, a carbohydrate, is a terrific source of energy, or fuel for the body. Different foods contain varying amounts of energy, which is calculated as calories or kilocalories. In other words, calories are a way to measure the energy you get from the food you eat.

In this activity, you will demonstrate how calories are measured. First, you need to build an inexpensive calorimeter. A calorimeter is a device that measures the transfer of heat energy during a chemical or physical change. One type of calorimeter contains a combustion chamber surrounded by water. When matter is placed in the chamber and physically or chemically changed (usually by burning), the temperature change of the surrounding water is measured and used to determine the energy (calorie) content of the sample. This lab indirectly measures food Calories (kilocalories) using a homemade calorimeter.

MATERIALS:

• goggles

• ring stand

• wire ring

• large cork

• matches or lighter

• balance scale

• water

• 200ml beaker

• Test tube

• Celsius thermometer

• gloves or forceps

• shelled peanut

• cheetoe

• Cork

• Straight pin

• foil

CAUTION: Be sure the room is well-ventilated. Use gloves or forceps to handle hot equipment and burned peanut.

PROCEDURE:

1. Place a test tube clamp on the ring stand. Add 20ml of water to the test tube. Place the test tube carefully in the test tube clamp. This apparatus is your calorimeter.

2. Turn the cork upside down and poke the pin through the cork. Place a square of foil over the pin to keep the cork from burning.

3. Place the thermometer into the test tube. Remember to suspend the thermometer in the water when taking a temperature reading. Before going any further, check the apparatus to make sure that everything is secured.

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4. Choose a peanut, measure its initial (beginning) mass and record in the data table (below).

5. Take an initial temperature reading of the water in the test tube and record in the data table.

6. Place the peanut on the point of the pin. (Note: don’t stick the pin into the crack of the peanut or it will break).

7. Put on goggles!!! Tie your hair back!! Use a match or lighter to set the peanut on fire. This may take several tries. Closely observe the nut as it burns. If the peanut falls off the pin, start over immediately.

8. As soon as the peanut stops burning, immediately take a final water temperature reading and record it in the data table.

9. As soon as the peanut has cooled, use forceps to lift the burned remains onto the balance scale. Take a final peanut mass and record in the data table.

10. Pour the water from the test tube into a graduated cylinder to see how much water evaporated.

11. Repeat the experiment using a cheese puff.

DATA TABLES:

Volume of water in test tube:

| Initital reading: |20 ml |

| Final reading: | |

Mass:

|Food Tested |Initial Mass |Final Mass |Δ Mass |

|Peanut | | | |

|Cheese Puff | | | |

Water temperature:

|Food Tested |Initial Temperature |Final Temperature |Δ Temperature |

|Peanut | | | |

|Cheese Puff | | | |

CALCULATIONS:

l Calculate the energy released from each food by using this formula.

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4.2 is the value of the specific heat capacity of water, in joules per gram per degree Celsius – the number of joules taken to raise the temperature of water by 1 °C.

1 cm3 of water has a mass of 1 g.

Calories of the Peanut:

Calories of the Cheese Puff:

Compare your results for each food with the rest of the class.

ACTIVITY ANALYSIS:

Discuss the sources of heat loss during this experiment. Can you suggest a better design?

Discuss the pros and cons of eating peanuts as a staple in the average American diet.

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