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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 . q surroundings = - q system. Remember: q = Cm∆T.
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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. • We will use a calorimeter that is made out of 2 Styrofoam coffee cups filled with water. Stirring rod • In this experiment, • Heat gained by the water in the cup = Heat lost by the system qwater = - qsystemor 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.
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?