OBJECTIVE: To determine the specific heat of various solids by the method of heat
transfer.
APPARTUS:
Calorimeter with stirrer weighing scale
Thermometer boiler (beaker and hotplate)
Small pieces of ice two metal solids (made of different materials)
Paper towels
INTRODUCTION:
Heat capacity of a body is the quantity of heat required to raise the temperature of the
body by 1o
C. The specific heat of a substance is the heat capacity per unit mass.
Thus, heat capacity = mass x specific heat. T
he specific heat is essentially a measure
of how thermally insensitive a substance is to the addition of energy. The water
equivalent of a body is the mass of water, which would require the same amount of
heat as the body in order to raise the temperature through one degree Celsius.
The method of mixtures makes use of the principles that when two bodies at different
temperatures exchange heat, the quantity of heat lost by the warmer body is equal to
the heat gained by the cooler body, and some intermediate equilibrium temperature is
finally reached. This is true provided no heat is lost or gained from/to the
surroundings. The purpose of the calorimeter is to prevent heat lose to the
surroundings. There are three methods of heat transfer: conduction, convection and
radiation.
In this experiment, a heated solid of known mass and temperature is dropped in the
calorimeter containing known mass of cold water. The equilibrium temperature is
then measured. The magnitude of the heat lost by the solid must be equal to the
magnitude of the heat gained by the water, and calorimeter with stirrer.
Mass of the solid (metal) in kg = m
Specific heat of the metal = c
Initial temperature of (hot) solid = T1
Mass of calorimeter with stirrer = m1
Mass of cold water = m2
Initial temperature of cold water = T2
Final equilibrium temperature of mixture = T3
Specific heat of calorimeter( Aluminum) = c1 = 900 J/kgCo
Specific heat of water = c2 = 4186 J/kgCo
Heat lost = -Heat gained
Heat lost by the solid = ( m )( c )[(T2 - T1)]
Heat gained by water + (calorimeter & stirrer) = (m2)(c2)(T3 – T2) + (m1)(c1)(T3 – T2)
Equating heat lost to heat gained:
-(m )(c)(T3 – T1) = m2 (c2) (T3 – T2) + m1c1(T3 – T2) equation 1.
This equation is used to compute the unknown specific heat, c, of the metal.
PROCEDURE:
1. Fill the beaker about half way with water and start heating it.
2. Record the name of the metal being used in the data table.
3. Weigh the solid (m) metal, and then lower it into the beaker of hot water by
means of a thread, to avoid burns.
4. While the solid is being heat go to step 5.
5. Weigh the inner chamber of calorimeter and the stirrer, together.
6. Fill the inner chamber of the calorimeter about half way with cool water and
add one or two small pieces of crushed ice to the water.
7. Weigh the inner chamber of the calorimeter, stirrer and cold water (m1 + m2).
8. Place the inner chamber of the calorimeter into the outer calorimeter jacket
and place the lid on, then record the temperature of the cold water (T2). Be
sure to stir the water first.
9. Record the temperature of the hot solid when the temperature becomes steady
(T1). This should occur after the water boils. Hint: The metal should be the
same temperature as the hot water.
10. Now quickly transfer the solid from the hot water to the calorimeter without
splashing any water. You must do this very quickly.
11. Place the lid onto the calorimeter and stir the water very gently and record the
final equilibrium temperature (T3). Don’t break the thermometer, while
stirring.
11. Repeat the previous steps for a different metal.
DATA TABLE
METAL #1________________ METAL #2________________
Quantity: Metal 1: Metal 2:
Mass of the solid metal
(kg)
Initial Temperature of the
hot metal (o
C)
Specific heat of calorimeter
(J/kgCo
)
900 J/kgCo 900 J/kgCo
Mass of calorimeter and
stirrer (kg)
Mass of calorimeter, stirrer,
and water (kg)
Mass of cold water
(kg)
Specific heat of cold water
(cal/gCo
)
4186 J/kgCo 4186 J/kgCo
Initial Temperature of cold
water (o
C)
Final equilibrium
Temperature
(
o
C)
CALCULATIONS:
1. Calculate the experimental value of the specific heat of each of the metals, using
equation 1.
2. *Calculate the percent error using the experimental value of specific heat and the
accepted value of the specific heat for each of the metals.
*The accepted value of the specific heat for each of the metals may be listed in your
textbook or posted in the lab.
QUESTIONS:
1. Why were you asked to add pieces of ice to the water? Hint: Think of phase change
and temperature.
2. What are the sources of error and how can one minimize the error?
3. Why should you stir the water in the calorimeter?
4. By what method of heat transfer was the metal heated?
5. What method(s) of heat transfer was used during the entire experiment? Indicate
when.
6. What is the purpose of using a calorimeter in this experiment?
7. Why is it important to transfer the hot metal quickly into the cold water?
