Calorimetry Lab

The Production of Heat

Introduction

Electrical energy is a form of energy that is relatively easy to deliver to the consumer via a network of conductors called the grid. The real question is: What form of energy do you use as a nation, as a planet, to convert into electrical energy? Each form used has its benefits and drawbacks. Currently, no pun intended, around 70% of the world’s electricity is generated by burning fossil fuels like coal, natural gas and oil. Another 20% is generated using nuclear fission. Both fossil fuels and nuclear boil water to produce steam, which spins the turbine rotating the generator to produce electricity. So, around 90% of the source energy to produce electricity gets converted to heat before it is converted into mechanical energy involved in rotating the generator.

In this activity, you will examine different ways of producing heat. You will measure the heat being produced using calorimetry in the first activity. Then you will design an activity that begins with a different form of energy that can be converted to heat.

Purpose

To transform the chemical energy in a food sample into heat by combustion. Use a calorimeter to capture and calculate the heat absorbed.

Materials

• a large pin
• a pop can with the opening tab still attached
• matches, ring-stand with ring, a can of mixed nuts
• glass stir rod
• 100 mL graduated cylinder
• triple beam balance
• thermometer
• cardboard piece
• water

Procedure

Stick the large pin through a small piece of cardboard, so that the pin will remain upright. Carefully, and with a slight twisting motion, skewer the nut sample onto the pin. Suspend the pop can from the ring of a ring-stand using a glass stir rod. Place the rod through the tab on top of the can. Add 100 ml of water to the can and lower it just above the sample. Take the temperature of the water and light the nut on fire with a match. Allow sample to burn to ash.

Record the final temperature.

Data

Type of nut:                        

Mass of:        

1. Pin & cardboard:
2. Nut & pin & cardboard:
3. Aluminum can:
4. Aluminum can & about 100 ml of water:

Temperature of water after burning:        

Questions

1. Calculate the heat gained by the water from burning the nut.

2. How many grams of sample were burned?

3. Based on your answer in # 1 above, calculate the calories of heat given off per gram of nut burned.

4. How many food Calories (kcals) per gram is this?

5. Besides going into the water, where did some of the heat from the nut go? List at least two places.

6. Draw a conclusion about energy transformation from this experiment. You may want to comment about the fact that Planters Mixed Nuts average about 6 Calories per gram or 170 Calories per ounce. (1 oz = 28.4 g)

Now consider a different form of energy (not chemical energy) and convert it into heat that can be measured. Calculate the amount of heat that is collected and estimate the original amount of energy present before it was converted to heat using mathematical based evidence to support your estimate. Calculate the efficiency of the transformation.