IB Physics: Calorimetry Investigation

IB Physics: Determination of an Unknown’s Specific Heat Capacity

Purpose: To use calorimetry (the relationship between thermal energy lost by one substance and thermal energy gained by another substance) to determine the specific heat capacity of an unknown metal sample and to identify that sample based on its specific heat capacity

Note: Each person is responsible for 1 unique metal sample, even though you are assigned to stations in groups of 2-3. Use each other for assistance in data collection, but you each need your own individual set of data.

Materials Needed:

- Calorimeter

- Metal sample, heated (note: a hot plate, 600 mL glass beaker, and 3 metal samples will be set up and will be heating prior to your arrival in class).

- Cool tap water

- Triple-beam balance

- 2 thermometers (digital and/or alcohol)

Note: Please remember to put the metal back in the beaker when you are done with it so it heats up for next period!

6th period only: please leave the metal on the counter next to the hot plate. Please turn off the hotplate when you’re done with both metals.

Procedure:

1. Measure and record the mass of the inner cup of the calorimeter
2. Add cold water (tap water) to the cup until it is about half full. Measure and record the mass of the cup with water.
3. Using one of the thermometers, measure and record the temperature of the cold water that you placed in the calorimeter cup. Be sure you wait for the thermometer to stabilize on a temperature.
4. Using a second thermometer, measure and record the temperature of the hot water bath holding the metal samples at your lab station. It is assumed that the metals will be in equilibrium with the hot water bath. Be sure you wait for the temperature to stabilize as much as you can, and to not rest the tip of the thermometer on the bottom of the beaker.
5. Carefully and quickly transfer the assigned metal sample from the water bath to your calorimeter and immediately cover the calorimeter and its contents.
6. Carefully stir the mixture and watch the temperature; record the mixture’s temperature after it has reached thermal equilibrium. (this may take several minutes)
7. Remove the metal sample; dry it completely, then measure and record its mass
8. Record physical characteristics of the metal sample, and record the color of the label on its tag
9. Return the metal sample to the hot water bath so it will heat up again for the next class period.
10. Remove the water from the inner cup in preparation for the next person’s data collection.

Post-data collection (at the end of the period when all in your group have collected data):

- Please make sure that the water is fully covering the metal samples in the hot water bath. There should be about 2-3 cm of water above the top of the samples while the water is boiling. Add hot water from the tap, if possible, to the beaker before you leave your station.

- Please wipe up any spills and make everything look better than when you arrived. 

Table 1: Measured values necessary to determine the specific heat capacity of the unknown metal

Table 2: Values calculated to ease the determination of the specific heat capacity of the unknown metal

Physical Characteristics of the Metal Sample:

Reminder: Energy gained = Energy lost

1. Show your Calculation for the determination of the specific heat capacity of your metal sample:

1. My metal sample was: ______

The actual specific heat capacity of my metal sample should be: ______

1. Determine the percent difference between your experimental value and the actual value for your metal’s specific heat capacity. Show your calculation.