Specific Heat Lab



Specific Heat Lab Name:________________________

Chemists identify substances on the basis of their chemical and physical properties. One intensive physical property is specific heat (Cp) – the amount of heat energy needed to raise the temperature of one gram of a material by one degree Celsius. In this lab, a calorimeter will be used in order to calculate a heat change. If the law of conservation of energy is true, heat released by a hot object (metal) must be equal to the absorbed by a cool object (water in calorimeter).

Purpose: The purpose of this experiment is to determine the specific heat of a metal and compare it to the actual value.

Materials: foam cup thermometer ring stand burner

250-mL beaker ring clamp test tube metal balance

Procedure:

1. Mass an empty test tube. Obtain a sample of the metal (between 5-7 grams) and put it in the test tube. Mass the test tube and metal together.

2. Fill a 250-mL beaker about ¾ full of water. Set up the heating apparatus as shown in the diagram so the test tube is in the water bath and all of the metal is under the water bath level. Allow water to boil and heat for about 5 minutes.

3. Before the metal is done heating, prepare the calorimeter with a foam cup and an amount of water with known mass (50-100 grams). Measure the initial temperature of the water in the foam cup.

4. When the five minutes of boiling are up, measure the temperature of the boiling water (assume it is the same as the hot metal), allow the thermometer to cool back down, quickly dump the metal into the water in the foam cup, and get an immediate temperature reading.

5. Continue to monitor the temperature while stirring gently with the thermometer for 30 seconds and record the most extreme temperature.

6. When finished, pour off the water down the sink and put the wet metal in the designated container.

7. Repeat steps 1 – 6 for a second trial. Work efficiently.

Data: (don’t forget units and sig digs)

Mass of test tube ___________ __________

Mass of test tube + metal ___________ __________

Mass of metal ___________ __________

Mass of water in foam cup ___________ ___________

Initial temp of water in foam cup ___________ ___________

Temp of boiling water / metal ___________ ___________

Temp of water + metal in foam cup ___________ ___________

Calculations: (don’t forget units and sig digs) – you should have 2 answers for each calculation because you did 2 trials.

1. Calculate the specific heat of the metal (J/goC). Hint: heat absorbed by the water in the foam cup is equal to the heat lost by the metal.

2. The metal in the lab is actually aluminum with an actual specific heat of 0.9025 J/goC. What is your percent error with three sig digs?

Conclusions: (don’t forget units and sig digs)

1. Using the actual specific heat of aluminum, how many Joules of heat are required to raise the temperature of 325 g of metal from 34.8oC to 42.7oC?

2. Determine the specific heat of a metal if 6.30 g of the metal is heated to 102.9oC and then put into a foam cup with 625 g of water at 25.0oC. The temperature of the water/metal mixture after mixing them is 51.6oC.

3. Using the actual specific heat of aluminum, determine the mass of a piece of aluminum from the following data:

temp. of hot metal…………...102.5oC

initial temp. of water...............25.0oC

temp. of metal and water

in calorimeter..............28.5oC

mass of water in calorimeter...36.8 g

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