Objective: To determine the specific heat of an unknown metal through the use of a calorimeter.
Background: The specific heat of any substance represents the quantity of heat energy in joules required to heat one gram of the substances by one °C. The specific heat of a substance is dependent upon the temperature; this means that there is a temperature range for which the specific heat of a substance applies. For metals and metallic substances, this temperature range is usually large, but at lower temperatures. Their specific heats are very small because they only need a relatively small amount of energy to increase their temperature. On the other hand, insulating substances, such as the plastic foam in coffee cups, require a large amount of energy to increase their temperatures. Anyways, the equation used to figure out energy needed to increase temperature is: Q (Heat Energy) = mass x Specific heat x Change in Temperature
To determine the specific heat with the use of a calorimeter , the equation is : QSubstance = -[ Qwater + QCalorimeter] which translates into
(mcΔT)Substance = - [(mcΔT)Water + (CΔT)Calorimeter]
Unknown Metal Sample
Triple Beam Balance (or other mass measuring equipment)
600 ml Beaker
1. Follow all safety guidelines prior to starting. Clear lab station. Gather all materials.
2. Set up the coffee-cup calorimeter as shown in the previous experiment in Figure 17-1.
3. Pour 75 ml, with a graduated cylinder, of cold water into the calorimeter and then cover the calorimeter.
4. Weigh out about 30 g of the unknown metal sample and record its identification number.
5. Pour 450 ml of water in a 600 ml beaker. Clamp the beaker onto a ringstand, place the hot plate underneath the beaker, and heat the water to