Download Specific Heat of a Metal

Specific Heat of a Metal
Honors Chemistry Laboratory Activity
Chemists identify substances on the basis of their chemical and physical properties. One physical
property of a substance is the amount of energy it will absorb per unit of mass. This property can be
measured quite accurately and is called specific heat (Cp). Specific heat is the amount of energy,
measured in joules (or calories), needed to raise the temperature of one gram of a substance one
Celsius degree. Often applied to metallic elements, specific heat can be used as a basis for comparing
energy absorption and transfer.
To measure specific heat in the laboratory, a calorimeter of some kind must be used. A calorimeter is a
well-insulated container used in measuring energy changes. The calorimeter is insulated to reduce the
loss or gain of energy to or from the surroundings. Energy always flows from an object at a higher
temperature to an object at a lower temperature. The heat gained by the cooler substance equals the
heat lost by the warmer substance, if we assume no loss of heat to the surround environment.
Heat Lost = Heat Gained
In this experiment you will determine the specific heat of a metal sample. The metal sample will be
heated to a high temperature than placed into a calorimeter containing a known quantity of water at a
lower temperature. Having measured the mass of the water in the calorimeter, the temperature change
of the water ( T), and knowing the specific heat of water (4.184 J/g*oC), the heat gained by the water
(lost by the metal) can be calculated as follows:
Heat gained by water (Q) = mass of water (g) x T (oC) x specific heat of water (J/g*oC)
The specific heat of the metal can now be calculated:
Specific heat of metal (Cp)
=
Heat gained by water (J)
Mass of water (g) x
T of metal (oC)
Objectives:
In this experiment, you will
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
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Measure the mass and temperature of water in a calorimeter
Heat a metal sample of known mass to a specific temperature
Calculate the change in water temperature caused by adding the hot metal sample
Calculate the specific heat of the metal using your mass and temperature data
Procedure and Data
1. Measure the mass of the empty foam cup ___________ g
2. Measure the mass of the foam cup and water __________ g
3.
4.
5.
6.
7.
Measure the temperature of the water in the foam cup _________oC
Record the temperature of the container holding metal cylinder ___________oC
Record the final temperature of the cup/water/cylinder system ___________oC
Dry the cooled cylinder and measure the mass of the cylinder __________ g
Describe cylinder’s appearance and “feel”.
YOUR ASSIGNMENT
*Analysis, Conclusions and Further Investigations are to be completed on separate piece(s) of paper,
either neatly handwritten (calculations may be offered in pencil but body of text should be in dark ink)
or typed (calculations may be neatly hand written). Assignment needs to have a proper heading and the
name(s) of partners. No group should be larger than three (2 preferred) and there should be no groups
with duplicate data.
Analysis
1.
Prepare a table for your data, include materials, masses, temperature and heat gained by water
and change in temperature and observations made about the appearance and “feel” of cylinder.
2. Calculate the heat gained by the water (lost by the metal) in the calorimeter using the equation
in the introduced in chapter and lab. List known variable values, equation to be used…circle
answers to calculations. This calculation answer along with change in temperature should be
included on data table. Remember to name Data table, ex. Table 1.
3. Calculate the specific heat of the metal using the answers from number 2 and equation given in
the introduction.
Conclusions
1.
What physical properties, other than specific heat, could you use to help you identify the
sample used in the experiment?
2. Why is water an excellent material to use in a calorimeter? Try to list, at least, two.
3. Given that the specific heat of Copper is 0.386 J/g*oC, Iron is 0.448 J/g*oC, Aluminum is 0.900
J/g*oC , lead is 0.138 J/g*oC, Carbon (graphite) 0.71 J/g*oC and brass is 0.38 J/g*oC can you
identify your metal, take into consideration appearance and apparent density when holding
cylinder.
Further Investigations:
1.
Determine the percent error of your experimentally determined specific heat to that of the
given (literature value). Show formula used and calculation set up. Circle answer. Then list
possible reasons for error from your laboratory experience.
2. Calculate the specific heat of a metallic element if 314 joules of energy are needed to raise the
temperature of a 50.0 g sample from 25.0oC to 50.0oC.