SPECIFIC HEAT OF LEAD
EXPERIMENT 13
1
PURPOSE
To determine the specific heat of a substance.
DEFINITIONS
Heat, temperature, specific heat (specific heat capacity), calorimetry.
BACKGROUND
On a sunny day, the water in a swimming pool may warm up a degree or two while the concrete around
the pool may become too hot to walk on in your bare feet. This may seem strange because both the
concrete and the water are being heated by the same source—the sun. This evidence suggests it takes
more heat to raise the temperature of some substances than others. This, in fact, is true: The amount of
heat that is required to raise the temperature of 1 g of a substance by 1 oC is the called the specific heat
capacity, or simply the specific heat, of that substance. Water, for instance, has a specific heat capacity of
4.18 J/(g oC). This value is high in comparison with the specific heats for other materials, such as
concrete. In this experiment, you will use a simple calorimeter and your knowledge of the specific heat of
water to determine the specific heat of lead.
MATERIALS
plastic-foam cup
lead shot, Pb
, copper,
SAFETY
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Wear your safety goggles.
Lead is a toxic metal. Wash your hands thoroughly after use.
Do not touch hot equipment.
Never use a thermometer as a stirrer.
Return the wet lead to the drying vessel on the back-bench.
PROCEDURE
As you perform the experiment, record your data in Data Table 1.
1. Fill a 250-mL beaker 3/4 full with water and heat until it is boiling gently.
2. While the water is heating, use a weighing boat to measure ~40 g of lead shot. Record the mass of the
lead shot to the nearest 0.01 g. Be careful not to spill the lead shot, and if you do, pick it all up! Lead
is toxic.
3. Transfer the lead shot to a large, dry test tube. Use the utility clamp to suspend the test tube in the
boiling water as shown in Figure 1. The lead shot should be below the level of the water in the
beaker. Leave the test tube in the boiling water bath for at least 10 minutes.
4. While the lead shot is heating, measure 25 mL of distilled water in graduated cylinder. Pour the water
into a plastic foam cup and place the cup in another 250-mL beaker for support.
5. Measure and record the temperature to the nearest 0.1oC of the boiling water.
6. Measure and record the temperature to the nearest 0.1oC of the water in the plastic cup just before
performing the next step.
7. Remove the test tube from the boiling water and quickly pour the lead shot into the water-filled,
plastic foam cup. Place a thermometer and a glass stirring rod into the cup. Use the stirring rod to
gently stir the lead shot. Do not stir the shot with the thermometer. Note the temperature frequently
and record the maximum temperature, again to the nearest 0.1oC, reached.
8. Pour the water off and return the lead shot the drying vessel.
9. Clean you lab area, and wash you hands with soap and water.
SPECIFIC HEAT OF LEAD
EXPERIMENT 13
2
utility clamp
test tube
beaker
ring stand
lead
wire gauze
ring support
Figure 1.
ANALYSIS (be careful with significant figures)
1.
2.
3.
4.
5.
State the most important safety concern in this lab and the required precaution you took.
Determine the change in temperature of the water in the plastic foam cup (Twater).
Determine the change in temperature of the lead shot (Tlead).
Calculate the heat gained by the water in the plastic foam cup.
Remembering that the heat gained by the water is equal to the heat lost by the lead, calculate the
specific heat of lead.
6. Calculate the percent error in the specific heat value that you determined experimentally. Use the
accepted value for the specific heat of lead of 0.128 J/(g oC).
7. Honors: You assumed that the initial temperature of the lead shot was the same as that of the boiling
water. If the lead shot were actually at a lower temperature than the water, how would your value for
the specific heat be affected, too high or too low? Explain.
8. Honors: What was the most probable source of measurement error that would lead to an incorrect
density determination?
OBSERVATIONS
DATA TABLE 1. MEASUREMENTS OF MASS & TEMPERATURE
Mass of lead shot
Initial temperature of water in foam cup
Initial temperature of lead shot
(temperature of boiling water)
Maximum temperature of lead + water
Mass of water