5 experimental techniques in calorimetry:
Calorimetry :the measurement of quantities of heat energy. The first essential in calorimetry
is an instrument which will measure temperature sufficiently accurately and with maximum
convenience. There are three types of thermometers :- The three main techniques used
have been mercury-in glass thermocouples, platinum resistance thermometers and
thermocouples.
The mercury in-glass thermometer must have a fine bore and a large mercury reservoir to
give the necessary accuracy. Such instruments can be read to 0.001 ℃ and relatively cheap
and simple to operate .
Platinum resistance thermometers give over 5 times the accuracy of the mercury in glass
thermometers , depending on the electrical measuring instruments employed and the
platinum resistance wire can be built into the structure of the calorimeter ,care being taken
to eliminate strains and mount the element with a good insulator.
Thermocouples are usually used in series with several other couples to give increased
sensitivity and this also allows a number of couples to be distributed over large bodies to
read an average temperature of the body.
Radiation pyrometers can be used where it is difficult to approach the object being heated,
a rapid response is required and there is to be no heat conduction from the system via the
instrument , bt in general their accuracy and sensitivity are less than those of the other three
techniques.