PHYSICS LAB – NUT ENERGY

PHY 110A Conceptual Physics Lab

Lab 08 Nut Energy

How much energy is in a nut? Burn it and find out!

The heat of the flame is energy released upon the formation of chemical bonds (carbon dioxide, CO2, and water.)

MATERIALS

Paper clip (bend one portion to hold the nut while the clip will rest on the table)

Nut (pecan or walnut half)

Can of water held above the table (with tongs?)

Thermometer (measures Celsius preferably)

PROCEDURE

1. Pierce a nut with a bent paper clip that will hold the nut above the table. (I did this outside on the sidewalk to avoid any accidents to my kitchen counter.)

2. Secure a can of water above the clip. (I held mine with tongs.)

3. Fill the can with about 100 milliliters (3 1/3 ounces) of water. Measure the temperature of the water. (If using a Fahrenheit thermometer, convert your degrees to Celsius.)

4. Ignite the nut and place directly below the can of water (about an inch from the bottom of the can). Stir the water in the can slowly as long as the nut burns.

5. As soon as the flame burns out, record the increase in the water temperature. (Be sure to suspend the thermometer in the water and do not let it touch the can.)

CALCULATIONS

1. The density of water is 1g/1ml. Using the density = mass / volume, calculate the mass of the water used in this experiment. Enter your answer in the table.

2. Calculate the temperature change of the water (in Celsius)

3. The number of calories released by the burning nut can be calculated by the formula Q = c m [T] , where c is the specific heat of the water, m is the mass of the water, and [T] is the change in temperature (in Celsius degrees).

a) Find the answer will be in Joules.b) Convert Joules to calories by dividing by 4.184. Find the number of calories.

4. The energy in food is expressed in terms of the dietetic Calorie, which is one thousand of the calories you measured above. Now find the number of dietetic Calories (by dividing your answer by 1000.)

 

       

Density of water	Initial water temp	Final water temp	Change in temp	Q=cm[T] in Joules	Convert to calories	Answer in dietetic Calories

5.  Check yourself. Check the nutrition label of nuts. How does your number compare? (Don’t be alarmed if your number is very different.) Why is your number different?