Pre-Lab

Before we get started I want you to make some predictions. First, consider the scenario in which you follow these instructions:

• Measure out 100. mL of water into the coffee cup calorimeter.
• Record the initial temperature of the water in the calorimeter to the nearest 0.1^oC. (N.B.: That is two certain digits and one estimated digit if you are using an analog thermometer.)
• Add 25 +- 3 grams of ice.
• One student should stir the mixture while calling out temperature readings. The other student should record the data while calling out the time prompts.
• Take temperature measurements (estimated to the nearest 0.1^o Celsius) every 10 seconds for the first minute and once every 30 seconds thereafter until you have collected data for a total of 15 minutes.
• Graph the data.

Before you actually perform the experiment, I want you to make a hypothesis. Actually two.

1. Predict the temperature of the mixture at exact time the ice cubes have completely melted.
2. Predict the shape of the temperature vs. time curve. (You should draw this out.)

Getting Started

• Set up your coffee cup calorimeter.
• Perform the experiment described above.
• After the first three or four minutes, you should start plotting your data. If necessary, limit your temperature readings to once every minute at this point.
• When you have finished, empty out your calorimeter and return to your desks for a brief discussion and instructions for the next part of the lab.

The next step is Determining the Calorimeter Constant