Phys Sc Lab

Calorimetry: Calories in a Peanut

Purpose: To find the number of food Calories in a Peanut

Procedure:

1.         Find the mass of 1 peanut. Record your answer to one decimal place, even if it's zero.

 Mass of peanut (g)

2.         Place an empty and clean paper cup on the balance. Press tare.

3.         Use a graduated cylinder to measure 100 mL. To make sure of its mass, add the water to the empty paper cup and record the mass.

 Mass of water (g)

4.         Place the cup of water on a triangle that is sitting on a ring stand.

5.         Record the initial temperature of the water.

 Initial temperature of water (oC)

6.         Have your partner hold the nut sideways with tongs, about an inch below the paper cup. Using matches, set fire to the nut.

7.         Record the highest temperature reached by the water. To do so, you should keep track of the temperature, and draw a rough sketch of temperature versus time

 Final(maximum) temperature of water (oC)

Analysis

1.         Calculate the amount of energy in joules released by the nut. Show the formula and work.

2.         Convert the energy to kJ.

3.         Now convert it to food Calories by dividing the number kJ by 4.19.

4.         Figure out the amount of Calories released per gram of peanuts.

5.         How many Calories would you take in if you ate half a can of peanuts (200 g)?

6.         Calculate DT if you repeated the same experiment using 100 mL of water but by burning a 1 g nut (other kind of nut) which contains 5.85 food Calories.

7.         A 1 gram cornflake caused the temperature of 20.0 oC water(100 ml) to climb to 56.4 oC. How many food calories are there in a 100 g bowl of cornflakes cereal without milk?

8.         Why didn't the paper cup burn when the peanut burnt under it?

These will be marked separately as a THINK TANK homework, not a lab. You can bring them home if you're stuck.

9.         (430 only)

Calculate the specific heat of a molybdenum in J/[g C] if its specific heat in the old system is 0.061 calories/(g C).            1 calorie = 4.19 J.

10.       By stirring too vigorously, a student added 120 J of energy to the water in his calorimeter. The water was attached to a resistor from a 3.00 V source delivering 1.50 A of current for 9.00 minutes. 80.0 J escaped into the air. The temperature went up by 6o C. How many mL of water were in the calorimeter? Report your answer to 1 decimal place.

11.       What is the Siemens unit equivalent to in terms of J, C and seconds?