Name:______Block:______Date:______

Lab: Amount of Energy in Food

Purpose:To measure the heat energy, in calories and joules, by water when a sample of food is burned. The heat energy gained is equal to the heat energy lost by the burning food.

Materials:

Large Paper Clip / Soap / Flask / Matches / Thermometer
Ring stand / Test Tube Clamp / Aluminum pan / Food Sample

Procedure:

  1. Wipe soap on the bottom of the flask to be used.
  2. Fill the flask with 100 mL of water
  3. Clamp the flask onto the ring stand.
  4. Measure and record the initial temperature of water.
  5. Carefully straighten the paper clip.
  6. Stick the paperclip through the piece of food sample.
  7. Food sample should be in the center of the paper clip.
  8. Position the paper clip so that the ends rest on the edges of the pan
  9. Place the pan under the flask set-up
  10. Use a match to ignite the food sample.
  11. Once the food begins to burn, blow out the match.
  12. Run the used match under water, and then throw it away.
  13. Let the food sample completely burn and then measure the final temperature of water.
  14. Empty out the water and add fresh for each trial.

Data Tables:

Food Sample / Mass of Water / T (initial) / T ( final)

Calculations: Show your work.

  1. Calculate the heat energy gained by the water in the flask as the each food item burned:

Food Sample / Heat gained by the water
qwater= mwaterCwaterTwater / Heat given off by the Food Sample
qwater= - qsample

Post-Lab Questions:

  1. Conclude: Which food sample released the most energy? The least?
  1. Classify: Is the reaction exothermic? Explain how you know.
  1. Infer: Most of the heat energy lost by the burning food was absorbed by the water in the flask. What might happen to any heat energy that was not absorbed by the water?
  1. Observe and Infer: Describe the reactants and products of the chemical reaction. Was the reactant completely consumed? What evidence supports your answer?

Application:

Application Continued:

  1. How many Calories are there in half of a cheese pizza?
  1. How many minutes of bicycle riding would be required to utilize the Calories in half of a cheese pizza?
  1. Calculate the approximate number of Calories that are burned per minute when:

Resting: / Swimming:
Walking: / Running:
Bicycle riding:
  1. How long would a person have to walk in order to burn off the Calories in a meal consisting of a glass of soda, a hamburger sandwich, and a serving of potato chips?
  1. Cont. How long would it take to burn off the same meal if the person rode a bicycle?

What if the person went running?

  1. Why is it important not to consume an excess of Calories on a daily basis?
  1. The calories in food come from the burning of carbohydrates, fats, & proteins. Carbohydrates provide 4 Cal/g and fats provide 9 Cal/g. A glass of milk, which has 150 Cal, has 8g of fat, and 11g of carbohydrate. Calculate the number of Calories that come from fats and from carbohydrates.

What percentage of the total Calories in milk come from fats?

From carbohydrates?

  1. A meal consisting of a hamburger sandwich, a serving of potato chips, and a glass of soda, contains 67g of carbohydrates and 21 g of fat. Calculate the percentage of total Calories in the meal that come from carbohydrates and thepercentage that come from fats. ( Hint: Use the chart to calculate that total number of Calories in the meal.)
  1. Basal metabolic rate (BMR) is the measurement of the rate at which the body expends energy under normal resting conditions. For the average 70 kg person, the BMR is 72 Calories/hour. This represents the minimum amount of energy required to sustain life functions. Calculate the minimum required Calories for a 70 kg person in a day.

Summary: Write a summary on what calories are, how did you mathematically determine the amount of calories, what are calories used for, where do they come from, what happens if you consume too much, what happens if you do not consume enough. (at least 5 sentences)