set
up of calorimeter
During melting, heat is absorbed by the melting solid. In this experiment, you will determine how much heat is needed to melt 1 g of ice. Heat has units of joules (J). The heat used to melt the ice will come from the cooling of warm water and will be measured with a calorimeter. A calorimeter is an insulated container fitted with a device for measuring temperature. You will use a simple calorimeter made of a Styrofoam cup, a 250-mL beaker, and a temperature probe.
OBJECTIVES
In this experiment, you will• use a calorimeter• use a computer to make temperature measurements
• use a computer to analyze the data collected
• determine heat of fusion for ice (in J/g)
MATERIALS
Macintosh or IBM-compatible computer
balance
Serial Box Interface or ULI
warm water
Logger Pro
100-mL graduated cylinder
Vernier Temperature Probe
one ice cube
Styrofoam cup
one paper towel
250-mL beaker
set
up of calorimeter
PROCEDURE
1. Prepare the computer for data collection by opening "Exp 08" from the Physical Science with Computers experiment files of Logger Pro. The vertical axis will have temperature scaled from 0 to 40°C. The horizontal axis will have time scaled from 0 to 300 seconds.2. Get a 250-mL beaker and a Styrofoam cup. Place the Styrofoam cup into the beaker, as shown in Figure 1. Use a balance to measure the mass of the 250-mL beaker and the Styrofoam cup. Record this mass in your data table.
3. Use a 100-mL graduated cylinder to measure out 100 mL of the 30°C water into the Styrofoam cup. Measure the mass of the 250-mL beaker, Styrofoam cup, and 100 mL of warm water. Record this value in the data table.
4. Place the temperature probe into the warm water inside the cup to warm the probe to the temperature of the water. The probe must be in the warm water for at least 45 seconds before ice is added in Step 5.
5. Break an ice cube into a few pieces in a paper towel. Click
to begin data collection. After 2 or 3 temperature readings appear on the monitor, add the ice pieces to the water in the Styrofoam cup. The computer will measure and save the initial water temperature.
6. Gently stir the contents of the cup as the ice melts. The temperature will stop dropping and level off when the ice has all melted. When the temperature stops dropping, click
to end data collection.
7. Measure and record the mass of the 250-mL beaker, Styrofoam cup, and water (original water + ice melt).
8. Click the Statistics button,
. Record the initial (maximum) and final (minimum) temperatures.
DATA
mass of beaker and cup ______ gmass of beaker, cup, and warm water ______ g
mass of beaker, cup, and water
(original + ice melt) ______ g
initial water temperature (maximum) ______ °C
final water temperature (minimum) ______ °C
PROCESSING THE DATA
1. Determine the mass (in g) of warm water used (mass of beaker, cup, and warm water &emdash; mass of beaker and cup).
2. Calculate the change in water temperature, Ęt (tmax &emdash; tmin).
3. Calculate the heat (in J) lost by the cooling water using the equation
where H = heat (in joules), Ęt = change in temperature (in °C), and m = mass of water cooled (in g).
4. Determine the mass (in g) of ice melted (mass of beaker, cup, and water (original + ice melt) &emdash; mass of beaker, cup, and warm water).
5. Use your answers to Steps 3 and 4 to calculate the heat needed to melt 1 g of ice (J/g).
6. An accepted value for the heat of fusion of ice is 334 J/g. Calculate your percent error using the formula
% Error = X 100
7. What assumption did we make about heat lost by the water in the calorimeter as compared to heat gained by the melting ice?
8. Describe how the polar ice caps help to stabilize the temperature of the planet.
EXTENSION
1. Design an experiment to find out if an ice cube taken from a freezer and immediately placed into a calorimeter needs the same amount of energy per gram for melting as does an ice cube that has been outside the freezer for ten minutes.2. Estimate the amount of heat needed to melt the polar ice caps.
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