Principles of Calorimetry Flashcards
What can calorimetry be used to measure?
Calorimetry can be used to measure the amount of heat released or absorbed in a chemical reaction or physical process, such as the combustion of a food or fuel
What is a solution calorimeter used for?
To find the energy changes in aqueous solutions
What does a solution calorimeter consist of?
An insulated container (polystyrene) and a lid (with stirrer and space for a thermometer)
What are the steps for using a solution calorimeter?
1) calibrate
2) measure mass of chemicals required (using same volume of solution as in calibration)
3) record initial temperature of solution
4) add solids/solutions to calorimeter
5) record the highest/lowest temperature reached
6) perform calculations to find the energy released during the reaction
What is the formula used to calculate energy change?
Energy change = CF x ∆Tr
What is the formula used to calculate ∆H?
∆H = energy change / n (n = moles)
What are the limitations of the solution calorimeter?
- the polystyrene can absorb some heat, therefore the change in temperature will be lower
- consequently, the calculated value for heat released or absorbed is lower than it should be
- cannot measure the energy content of food
What does ∆Tr represent?
The change in temperature caused by the reaction
Why is a stirrer included in both types of calorimeters?
To ensure there is an even distribution of heat energy
What is a bomb calorimeter used for?
To determine the heat of combustion of a reaction, which a solution calorimeter is unable to find
What is the purpose of the oxygen supply in a bomb calorimeter?
To allow a constant supply of oxygen, enabling complete combustion of the food or fuel to occur, thus producing the most accurate energy content calculations
