Those Potato Chips Are PHAT!

Objective:

Test the validity of the label on chips (Doritos/Tostitos, and Lays).

Use equations to calculate heat produced by combustion of food.

Materials: 2 varieties of chips (1 each); aluminum can 50 mL graduate; sheet of aluminum foil; paper clips; thermometer; ring stand and ring; wire mesh; matches; stirring rod; balance; splint

Procedure: (you can find a picture of the set up at the bottom of this document)

  1. Take the mass of the empty aluminum can.
  1. Add exactly 50 mL of water to the aluminum can. Record as a mass in your data table.
  1. Measure and record the temperature of the water.
  1. Set up a ring stand and ring, so that the wire mesh is about 1 inch above the surface of a small sheet of aluminum foil. Place the beaker of water on the wire mesh.
  1. Attach the chip to a paper clip by inserting it into a small hole in the chip.
  1. Measure and record the mass of the paper clip with the chip attached to it.
  1. Place the chip to be tested (now attached to the paper clip) under the beaker of water and light it (near the bottom) with a match. Stir the water with a stirring rod (do NOT stir with the thermometer!) while the chip is burning. Use the thermometer to measure the highest temperature reached by the water in the beaker and record that temperature. (INCLUDE UNITS IN TABLE)

Lays / Tortilla chip
Mass of Water (1g = 1 mL of water)
Mass of Chip (before burning)
Initial Temp of Water
Highest Temp of water
Change in Temp of Water

CALCULATIONS:

  1. Calculate the heat produced by the combustion of each chip by finding the amount of heat GAINED by the water. Use 1 cal/g-C for the specific heat of water. (Which equation do you use?) Your answer will be in calories—convert this to Calories (remember 1 Cal= 1000 cal or 1 Cal= 1 kcal) SHOW THE CALCULATION AND CONVERION! Put your final answer into the table.

Lays : Q =

Tortilla chip : Q =

Chip / Q in cal / Q in Cal
Lays
Tortilla chip
  1. Divide the heat produced (in Cal) by the burning chip (the heat gained by the water) by the number of grams for each chip.

Lays:

Tortilla chip

  1. Look at the label of the chip bag (pictures of the labels can be found on the blog). Determine the total number of Calories per gram by using the following formula: Number of Calories in one serving/Number of grams for one serving =

Lays:

Tortilla chip:

POST LAB QUESTIONS:

  1. Compare this to the calculation you did from the chip bag. How does it compare?

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  1. Determine the percent error for both chips (SHOW YOUR WORK).
  1. Explain why there is a difference between the Calories/gram on the chip bag and the Calories/gram you obtained in the lab. (There are at least 4 good reasons, and none of them are “human error” or “measurement error” or the chip company lied.)

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