The Specific Heat Capacity of Metals
Every substance has a definite specific heat capacity at a given temperature. This is
used as a characteristic property together with density, melting point, and freezing
point to identify substances. However, it is difficult to determine the specific heat
capacity of a solid directly. The heat source and the thermometer canoot be easily
immersed in the solid. As a result, the Principle of Heat Exchange is used to
determine the specific heat capacity of solids. The Principle of Heat Exchange
states that if no heat is lost to the surroundings, the heat gained by the object at the
lower temperature is equal to the heat lost by the object at the higher temperature.
To determine the specific heat capacity of a solid, the solid is first heated to a known
temperature in a liquid bath. They the hot solid is immersed in a cold liquid. A
liquid is used which does not react chemically with the solid. Heat is transferred
until both components of the mixture reach the same final temperature. In this
investigation you use the method of mixtures and the Principle of Heat Exchange to
determine the specific heat capacity of a metal.
Materials:
A metal sample (aluminum, copper, iron, lead, zinc)
Hotplate
insulated cup
200 ml beaker
thermometer
100 ml graduated cylinder
electronic balance
Procedure:
1. Choose a sample metal. Find the mass of the metal. Record this mass in the
table provided.
2. Attach a thread to the metal sample. Suspend the metal in a beaker. Do not
let it touch the bottom. Heat the water in a beaker to the boiling point. Allow
it to boil for about five minutes so that the metal reaches the temperature of
the boiling water. Take the temperature of the water. Assume this is also the
temperature of the metal. Record this temperature in the table.
3. Add 100 g of cold water to an insulated cup. Quickly remove the metal
sample from the hot water bath. Shake it to remove the excess water.
Transfer to the cold water in the cup.
4. Stir thee mixture gently. Record the maximum temperature of the mixture.
5. Use the Principle of Heat Exchange to calculate the specific heat capacity of
the metal.
Data:
Component
of Mixture
Metal A
Water
Metal B
Water
Metal C
Water
Mass
(kg)
Temperature (℃)
Initial
Final
Change
Specific
Heat
Capacity
(𝐽/(𝑘𝑔 ℃))
4186
Heat
Exchanged
(J)
4186
4186
Discussion:
1. Compare the value you obtain with other values obtained for the same metal
by the class.
2. Compare the specific heat capacities of the different metals used with their
densities. Do this by arranging the metals in order of increasing specific heat
capacity in terms of the kinetic molecular model of heat.
3. List possible sources of error whether it raises or lowers the value of specific
heat capacity. Suggest modifications to the experiment to overcome the
errors.