Calorimetry

Beginning Questions:

  1. Which types of food contain the greatest amount of energy?

Background:

Different types of food provide different amounts of energy to sustain our

daily activities. This energy comes from a process called cellular respiration which occurs in our cells. In this investigation, you will estimate the amount of energy some foods release. Which of these foods will give you the most energy? Which of these foods have the most calories? You will estimate the energy of different pieces of food.

Safety Considerations:

Procedures and Tests:

  1. Choose at least two types of food: banana chips, sunflower

seeds, marshmallows, or pretzels to test.

  1. When given the food samples, make a hypothesis about

which of the foods will contain the most energy per gram.

  1. Set up a ring stand with a ring and wire gauze, and put

this high enough so that an evaporating dish with your food sample can fit beneath the apparatus.

  1. Gather a pop can, stirring rod, TI-84 calculator, and Vernier Temperature probe. The stirring rod will run across the ring and extend through the pop can tab to suspend the can. The probe should be run into the can. One may need to hold it so that it doesn’t touch the bottom of the can.
  2. Record the mass of your food sample using the electronic

balance. Record this in your data table along with the other information you collect.

  1. Use a graduated cylinder to measure 100 mL of water for the pop can. Use the probe to take the initial temperature in Celcius. Record this in the data table.
  2. Place the food into the evaporating dish and light the food with a match.
  3. Let the food burn completely. Record the final temperature after the food has burned. Write a description about the burning of the food (Fast, slow, smoky, etc.). If the flame burns out before the food burns, start over.
  4. Empty the water and repeat the process with the other food items.
  5. Use the equation Q=mcΔT to calculate the calories of your food items.

Q= the amount of energy (calories), m= mass of food,

c=specific heat of water (1 cal/g*OC), ΔT=the difference of your final

and initial temperatures.

11. What should you use to help you empty out the hot pop can and the

evaporating dish?

12. What is your hypothesis?

Data, Observations, Calculations, and Graphs:

Calorimetry Data

Food Sample / Mass of sample / Initial water temp / Final Water temp
g / (OC) / (OC)
  1. Describe the burning of the first sample.
  1. Describe the burning of the second sample.

Using Q=mcΔT, find the energy content of your food items in calories.

Item 1:

Item 2:

Item 3:

Convert the above answers to Calories. Remember 1 Calorie=1000 calories.

Item 1:

Item 2:

Item 3:

Convert the above answers to joules. Remember, 1 Calorie=4,187 joules

Item 1:

Item 2:

Item 3:

Claims:

Evidence and analysis:

Reading, Reflection, and Post-Laboratory Questions:

  • Consider sources of error
  • How do your results compare with classmates
  • What did you learn, what new questions do you have

Additionally, address:

  1. Was your hypothesis supported by your data? Why or why not?
  2. How does the package’s estimate of calories compare with your estimate?

Why do you think there is a difference?

  1. How could you improve your experiment to attain more accurate results?
  2. How did your different food samples compare in terms of calories? What might account for their differences?