17.1 Calorimetry (p. 661  676 McGraw-Hill Ryerson)
6.1.5 Suggest suitable experimental procedures for measuring enthalpy changes of reactions in aqueous solution.
Calorimetry Ä…ð the technological process of measuring changes in kinetic energy (temperature).
Calorimeter  a container that:
·ð is insulated to reduce heat lost from the system,
·ð has a stirrer to ensure homogeneous temperatures within the calorimeter, and
·ð a device for measuring the temperature (thermometer)
Types:
(a) Coffee- cup Calorimeter = 1 polystyrene (styrofoam) cup and a lid (optional)
- measure "T for the reaction / state change directly
- used for state changes, heat of solution, aqueous replacement reactions
* Assumptions
1. The system is isolated.
No heat exchanged with the surroundings
The reaction is insulated from the environment
The amount of heat exchanged with the calorimeter itself is insignificant
2. Aqueous solutions retain the properties of pure water
The density of the solution is the same as for water (Á = 1.00 g mL-1)
The specific heat capacity of the solution is the same as for water (c = 4.18 J g-1 K-1)
When a reaction is carried out in water, the water will gain or lose heat from the reaction.
"H = Q (c = 4.18 kJ kg-1 K-1 = 4.81 J g-1 C°-1)
rxn H2O H2O
This "H value can then be calculated back to fine the enthalpy change for each mol of reactants.
The solution should be placed in a container as insulated as possible, to keep as much heat as
possible from escaping. The temperature should be measured continuously , and the value used in the
equation is the maximum change in temperature from the initial position.
(b) Bomb Calorimeter = a cup within a cup
The reaction vessel transfers its heat to a cup of water.
The temperature change of the water is measured.
The heat of reaction is measured indirectly.
- used for combustion and non-aqueous reactions
Practice Problems #1  4 p. 664  665, # 5  7 p. 667 (coffee-cup calorimeter)
#8  10 p. 675 (bomb calorimeter)