Calorimeter

Calorimeter
- device used to measure the heat released (or absorbed) by a  
  physical or chemical process
- there are two types of calorimeter :
     + bomb calorimeter (constant pressure)
     + coffee-cup calorimeter (constant volume)

Bomb Calorimeter



- to measure heat released in combustion reaction

How a bomb calorimeter works?

1. With continual stirring, the initial temperature of preweighed water bath is noted.

2. The sample is ignited electrically

3. Heat released from the combustion react is transferred to the rest of the calorimeter.

4.The maximum temperature is measured.

Coffee-cup Calorimeter

- to measure heat released in non-combustion reaction such as heat of neutralization and heat of solution.


How a coffee-cup calorimeter works?

1.The calorimeter consist of a known mass of water (or solution) in an insulated container equipped with a thermometer and stirrer.
2. Initial temperature of the water is measured.
3. The process take place (addition of acid and base of soluble salt)
4. The contents are stirred.
5. Final temperature of water is measured.



Calculation of ΔHrxn

qsys = qwater + qcal + qrxn

no heat enters or leave the system

qsys = 0

qrxn = -(qcal + qwater)

qwater = mcΔT

qcal = CcalΔT