Today’s lesson
• Define specific heat capacity
• Solve problems involving specific heat
capacities
Specific heat capacity
Specific heat capacity is the amount of energy
needed to raise the temperature of unit mass of a
substance by 1°C.
So if a substance has a higher specific capacity, then it
takes more energy to raise or lower its temperature.
Specific heat capacity of water = 4.186 J/g.°C
Specific heat capacity of kerosene = 2.010 J/g.°C
Specific heat capacity of mercury = 1.40 J/g.°C
Calculations using S.H.C.
Energy absorbed = Mass x Specific Heat capacity x Temp rise
J
g
J.g-1.C-1
Q = mcΔT
C
For example
500 g of olive oil is heated until its temperature rises by
120 C. If the specific heat capacity of olive oil is 1.97
J.g-1.C-1, how much heat energy was used?
Energy absorbed = Mass x Specific Heat capacity x Temp rise
Energy absorbed = 500 x 1.97 x 120
Energy absorbed = 118200 J
Things to note:
• If specific heat capacity is constant, the
temperature will rise at a uniform rate so long
as the power input is constant and no energy
is lost to the outside.
• There are large potential heat losses if the
substance is not well insulated. These can be
accounted for in some experiments (how?).
• You should be able to think of a number of
reasons why your value does not match that
in the data book.