CALORIMETRY

There is a pan of water that been equilibrating with the room for a sufficient time that it has reached room temperature at the back of the lab.  Use this for your 'room temperature' water.

In this lab you will study heat energy as it is transferred between objects. The historical measure of heat energy is the calorie, which is the amount of heat energy that must be added to 1 gram of water at 14.5 oC to raise its temperature by 1oC.

For the first part of the experiment, you will be investigating the transfer of heat energy from warm water to cool water. Heat lost by the warm water will be gained by the cool water until thermal equilibrium is attained. The amount of heat exchanged depends on the kind of material (water in this case); the amount of material; and the temperatures involved. Heat energy is given the symbol Q. The heat gained of lost by an object is defined by:

Q=Mc(Delta-T) (1274 bytes)

where M is the mass of the object, c is its specific heat capacity (1 cal/g oC for water),  Delta-T is the change in temperature of the object. You will use Logger Pro to acquire a graph of temperature versus time.  The graph should show three distinct regions: a horizontal line starting at t = 0 that gives you room temperature; an increasing region with a fairly steep (and possibly irregular) slope when you are adding the hot water; and a gradual rise to a maximum followed by a slight fall in temperature due to losing heat from the warmer water into the cooler room. You have the information to calculate the mass of the room temperature water and the mass of the hot water that was added.  By applying conservation of energy - i.e. Qrt + Qh = 0, you can find the temperature of the hot water before it was mixed with the room temperature water.

In the second part of the experiment, you will measure the specific heat of a metallic object by investigating how the object effects the temperature of a known amount of water.   In preparation, start a beaker of water heating on the electric hot plate. We will use boiling water to bring our metallic sample for the second part to a known initial temperature. In this experiment you will measure all of the temperatures and masses.  Using the accepted value for the specific heat of water you will be able to find the specific heat capacity of the metal mass.  You will compare your results to the accepted values for various metals and allows and choose the most likely candidate for the metal that makes up your mass.

Before you begin either experiment, check the room temperature reading of your temperature probe against the liquid-in-glass thermometer.  The two need not exactly agree, but they should be close.  Once this has been done you are ready to start the first part of the experiment.

Part 1 - Mixtures of water.

Part 2 - Finding the specific heat of a metal

 

Last modified Feb  18, 2016