Download Calorimetry Notes

CALORIMETRY
• Calorimetry: the science associated with
determining the changes in energy of a system by
measuring the heat exchanged with the
surroundings
• the heat lost (-q) by a system equals the heat gained
(+q) by the surroundings.
qsurroundings = -qsystem
Remember:
q = Cm∆T
• A calorimeter is used to measure the
amount of heat absorbed or released
during a chemical reaction.
Stirring rod
• We will use a calorimeter that is made out
of 2 Styrofoam coffee cups filled with
water.
• In this experiment,
 Heat gained by the water in the cup = Heat lost by the system
qwater = - qsystem
or
mwaterCwater∆Twater = - (msystemCsystem ∆Tsystem)
Experimentally Determine Specific Heat
• A hot piece of Aluminum that was 0.65g and
105.0°C was placed into a calorimeter containing
200.0 mL of 23.6°C water. The temperature of the
water rose to 25.1°C. If the specific heat of water
is 4.186 J/g°C, determine the specific heat of
Aluminum.

qwater = - qaluminum
qwater = - qaluminum
• Water
 C = 4.186 J/g°C
 Mass = 200.0 g (200.0 mL = 200.0 g)
 ∆T = (25.1°C - 23.6°C)
= 1.5°C
• Alumunium
C=?
Mass = 0.65g
∆T = (25.1°C -105.0°C)
= -79.9°C
qwater = - qaluminum
• Cwater x mwater x ∆Twater = - CAl x mAl x ∆TAl
• 4.186J/g°C x 200.0g x 1.5°C = - C x 0.65g x -79.9°C
• -24 J/g°C = - CAl
• 24 J/g°C = CAl
• 10.0 g of metal X at 280.0 °C is dropped
into 200.0mL of H2O at 20.0 °C in a coffee
cup calorimeter. Metal X and H2O reach
thermal equilibrium at 25.0 °C. Calculate
the specific heat capacity of X.
• 1.6 J/g°C
• A 30.0 g hot piece of lead was dropped into a
calorimeter containing 50.0 mL of water at
19.5°C. After reaching equilibrium, the
temperature of the water was 27.8°C.
– How much energy did the water absorb?
– What was the original temperature of the lead?
• (C lead = 0.128 J/g°C)
• You put a 25.0 g piece of zinc in a beaker
containing 520.0 mL of boiling water. You then
take the zinc and put it into a calorimeter
containing 150.0 mL of water at 21.7°C. The
temperature of the water in the calorimeter rises
to 24.3°C. What is the specific heat of zinc?