Question

Lab report on identification of two unknown metal, based on their specific heat capacities. The introduction must include the purpose of the experiment, background information thermal energy, and the law of conservation of energy. Hypothesis. Step by step method. Materials. Variables (independent-dependant-and control) and how to manipulate them. Safety precaution. Analysis and conclusion.

Answer 1

Aim:

To identify two unknown metals based on specific heat capacities.

Materials/Requirements:

Water bath(beaker of 500 ml or so),two unknown metal samples,Styrofoam cup, lid,thermometer,scale,weighing machine,notebook etc.

Theory/Hypothesis;

We know that heat is a form of energy that is transferred between objects or materials that have difference in temperatures. Heat always flows from high temperature to low temperature as we have learnt in the laws of thermodynamics. The amount of heat released or gained by an object (q) depends on the mass of the object (m)

q = mCs∆T

where we have change in temperature of the object (∆T ).

In the above equation proportionality constant Cs is often referred to as the specific heat capacity

Experimental procedure:

In this experiment we want to determine the specific heat capacities of two different unknown metals as stated in our aim.This can be achieved by observing the transfer of heat from a heated piece of metal to the water which we shall keep at room temperature say (300K)

1. Using a hot plate, heat about few hundred litres of water to a rolling boil in beaker preferably.

2.Now find the unknown metal and weigh it and make a note of the values on your book

3. Use the vernier callipers to measure the length, width and height (in cm) of the metal bars that you have .

4. Set up the calorimeter apparatus (Styrofoam cup, lid and thermometer) .

5. Weigh the empty cup, add enough room temperature water (about 50 mL) to completely put your metal sample in water and then weigh the cup again. Determine the mass of water by difference. Now record a baseline temperature for the water in the cup every thirty seconds for approximately two minutes. The last temperature reading is the initial water temperature.

6. Once the water bath on the hot plate is at a rolling boil, carefully add the metal to the hot water using tongs. After the metal has been heated for about say 3 minutes, usepair of tongs to remove it from the hot water bath. and quickly place the metal in the Styrofoam cup, making sure the metal is completely submerged.Record the the temperature display on the thermometer.

7)As you would expect the temperature rises rapidly reaches a maximum temperature and then starts to dectrase again.Keep an eye out when this is about to happen and quickly note down the maximum temperature that you get. This maximum temperature is your equilibrium temperature.

8) Once your done with this,repeat the same with the second metal.Be careful not to touch the hot tongs with your hands.

Precautions:

See to it that cord for the hot plate does not touch the surface of the hot plate.

Also do not touch the hot tongs and the plate when it is at high temperature.

Observations;

Analysis;

The heat lost by the metal (q(metal) = m(metal)Cs(metal)∆T(metal) as per our previous equation discussed in theory.

m(metal)Cs(metal)∆T(metal) = −m(H2O)Cs,(H2O)∆T(H2O)

By comparing the experimental value of specific heat we can compare with the standard value that is charateristic of the material from the catalog and find the identity of the unknown metal.

Conclusion;

Therefore by finding the specific heat of the metals provided we can find the identity of the metals by comparing it with the standard values.