Heat Exchange
Class:
Section:
Instructor:
Name(s):
Date:
Theory:
The Principle of Heat Exchange (a special case of the Law of Conservation of Energy) states that
when two substances at different temperatures are mixed, the amount of heat lost by the warmer
substance equals the amount of heat gained by the cooler substance - assuming no heat is lost to
the surroundings.
Heat lost = Heat gained
The heat loss from the 100g of 80°C water is gained by the 100g of 20°C water resulting in a final
temperature of 50°C.
Procedure:
1) Measure the mass of the pyrex glass and
record it in the Data section below. Add
about 30 ml of tap water in the Pyrex
glass beaker, measure its weight and
record it in the Data section, and place it
to heat on top of the Heating plate. Set
the temp of the plate to be about 100
degree Celsius. Leave it there for about
10-15 min.
2) Measure the mass of the calorimeter and record it in Data section.
3) Add about 20-30 ml of tap/cold water, measure the weight, and record it in the Data section.
4) Connect the PASCO temperature sensor to Channel A and open program Specific Heat.cap.
The display consists of a graph which will record temperature of the system with time. In the
lower mid-section of the graph is a display which shows the instantaneous temp recorded by
the temperature sensor.
READ all the steps below before performing starting the experiment.
5) Put the temperature sensor inside the calorimeter and click on RECORD. The graph will start
recording the temp with respect to time and the display shows the temp of cold water. Note
this temperature on the Data section.
6) Transfer the sensor from calorimeter to the Pyrex beaker containing hot water and note the
temperature in the Data section.
7) Now open the lid of the calorimeter, pour all the hot water, close the lid, insert the
temperature sensor and use the stirrer to stir the mixture. You will see on the graph that the
temperature will start to fall and will attain a steady state about a minute. STOP the program
now. Note this equilibrium temperature in the Data section.
Data:
Mass of the Pyrex glass =
Mass of Pyrex glass + water (hot) =
Mass of Hot water, Mhot =
Mass of the calorimeter, Mc= gm
Specific Heat Capacity of calorimeter, Cc = 0.215cal/gmoC
Specifig Heat Capacity of water, Cwater = 1cal/gmoC
Mass of calorimeter + cold water =
Mass of cold water, Mcold = gm
Temp of cold water, Tcold =
Temperature of Hot water Thot =
Equilibrium Temperature, Teq=
Calculation:
gm
According to the theory of heat transfer, the heat lost by one system should be equal to the heat gained
by other system if there is no heat loss to the surrounding.
Heat lost by hot water =MhotCwater(Thot-Teq)
Heat gained by cold water = McoldCwater(Teq-Tcold)
Heat gained by calorimeter =McalCcal(Teq-Tcold)
Since, Heat lost = Heat gained, use the information above to determine the equilibrium temperature of
the mixture theoretically.
Equilibrium Temperature:
Percent Difference =