Laboratory Preparation & Procedure

Materials:

• DI water
• 1000-mL beaker
• hot plate
• thermometer
• unknown metal cylinder
• 2 nested Styrofoam cups
• insulated lid with hole for thermometer & stirring rod

Safety:

You will be working with hot materials in this lab – the unknown metals will be hot. Use tongs or forceps — never touch hot metal with your hands. Be careful when working with hot water – it can burn.

Procedure:

1. Place approximately 400 mL of water into a 600–800 mL beaker and heat it on a hot plate until it reaches a rolling boil. Continuously monitor the water level in the beaker (water bath) and add more water as needed to maintain a sufficient volume, preventing the beaker from boiling dry.
2. Obtain an unknown metal cylinder and measure its mass using a balance. Record this mass in your lab notebook, and note the metal’s appearance (for example, its color and any distinguishing features).
3. While waiting for the water to boil, assemble the calorimeter apparatus. The calorimeter consists of two nested Styrofoam cups with a lid and a thermometer inserted through the lid.
4. Determine the mass of the empty Styrofoam cups (calorimeter) by weighing it on a balance and record this value.
5.  Add approximately 50 mL of room-temperature water to the cups – enough to completely submerge the metal sample – and then weigh the cup again with the water. Record the combined mass of the cup plus water and calculate the mass of just the water by subtracting the empty cup’s mass from the combined mass.
6. Use the thermometer to measure and record the water’s temperature in the cup at 30-second intervals for about 2 minutes. The final temperature reading (after roughly 2 minutes) will serve as the initial temperature of the water.
7. Once the water bath reaches boiling, use tongs to carefully lower the metal sample into the boiling water.
8. Allow the metal to remain in the boiling water for approximately 10 minutes so that it fully reaches the water’s temperature.
9. Measure the initial temperature of the metal by measuring the temperature of the boiling water using the thermometer at the conclusion of the 10-minute boiling period.
10. After 10 minutes, use tongs to remove the metal from the water bath. Quickly shake off any excess hot water clinging to the metal and immediately transfer the metal into the calorimeter cup of water, ensuring that the metal is completely submerged. Caution: Do not allow the hot metal to touch the thermometer directly.
11. While stirring continuously, record temperature and time data every 30 seconds for a total of 5 minutes.
12. Determine the ∆T value for both the metal and the water.
13. Use tongs to remove the metal from the cup and place it back into the boiling water bath to reheat. While waiting for the metal to reheat, carefully empty the water from the Styrofoam cup and dry the cup thoroughly.
14. Refill the calorimeter cup with a fresh portion of room-temperature water and repeat Steps 5–12 to perform a second trial with the same metal sample. This repeat trial will improve the accuracy of your results. Remember to record all measurements (masses, temperatures, etc.) for the second trial just as you did for the first trial.