Lab: Energy Value of a Goldfish Cracker
Name:
Period:
2
3
4
Problem:
How much energy is available from the combustion of a goldfish cracker? Can this heat
energy be measured?
Introduction:
When organic substances, such as nuts or other crackers or other food, are combusted
in the presence of oxygen in the air, the byproducts include carbon dioxide gas, water
vapor, and carbon (in the form of soot). Perhaps most important is the energy which is
released as heat. All of us depend on food as a fuel, and when we digest and metabolize
food, energy is always released. Many people monitor their caloric intake, which is the
amount of energy that is available in the foods we eat. In this experiment, a goldfish
cracker will be ignited with a candle and allowed to burn as completely as possible. The
energy released as heat is absorbed by a volume of water in a can. At the conclusion of
the experiment, you will compare the energy value of your goldfish to that given by the
manufacturer.
Materials:
soda can
water
ring stand with ring
Glass stir rod
thermometer
balance
Cork with paper clip
goldfish cracker
Procedure:
1. Set up the calorimetry apparatus as shown by your teacher.
2. Mass and record the mass of a soda can.
3. Fill can about ¼ full of water. Find the mass and record in your data table.
4. Take and record the temperature of the water.
6. Take and record the mass of the goldfish cracker.
7. Carefully poke the paperclip in the goldfish, place it under the can of water and lower
the soda can so that it sits directly above the goldfish cracker.
8. Carefully light the goldfish cracker on fire. Once the cracker has burned as much as
possible, quickly and gently take the temperature of the water once again. Make sure
the thermometer does NOT touch the bottom of the can.
9. Carefully remove the charred goldfish craker and record its new mass.
10. Repeat experiment with a new cracker
Data:
Trial 1
Trial 2
Mass of soda can (g)
Mass of soda can +
water (g)
Mass of unburned
goldfish (g)
Mass of charred
goldfish (g)
Temperature of
water before (°C)
Temperature of
water after (°C)
Analysis:
Show all your work to receive credit, include units!!!!!!!
1. Determine the change in mass of the goldfish cracker for both trials.
Trial 1:
Trial 2:
2. Determine the change in temperature of the water for both trials.
Trial 1:
Trial 2:
3. Determine the heat (qH2O) absorbed by the water using the equation, qH2O =
mH2OCΔT. The specific heat capacity of water is 4.184J/g°C.
Trial 1:
Trial 2:
4. Determine the heat (qcan) absorbed by the soda can. The specific heat capacity of
aluminum is 0.897J/g°C. qcan = mcanCΔT
Trial 1:
Trial 2:
5. Determine the total heat absorbed by the water and the can, qtotal = qH2O + qcan.
Trial 1:
Trial 2:
6. Determine the total heat (qgoldfish) released by the goldfish cracker. (Hint, we are
assuming that all the heat released by the goldfish went directly to the soda can and
the water. Only difference is that one process is exothermic and the other is
endothermic.)
Trial 1:
Trial 2:
7. Calculate how much heat energy is in the goldfish per gram. Divide the heat
released by the goldfish, qgoldfish, by the mass of the goldfish that was burnt away.
Trial 1:
Trial 2:
8. Using information from the manufacturer, determine the amount of energy per
gram of goldfish cracker. You will need to convert from Calories to Joules. Then
divide the energy by the mass of the goldfish cracker listed on the label.
Conclusion:
Answer the following questions in complete sentences.
1. Compare the amount of heat per gram of gold fish from trial 1 and trial 2. Were the values
similar? Why or why not?
2. Compare the amount of heat per gram of goldfish from your two trials with the heat energy per
gram of goldfish from the manufacturer? Were the values similar? Why or why not?