GC Determination of The Specific Heat Capacity of A Metal Lab

Experiment E-305: Determination of the Specific Heat Capacity of a MetalThe amount of heat required to raise the temperature of 1 g of a substance by 1 degree is called the
specific heat capacity or specific heat of that substance. Water, for instance, has a specific heat capacity
of 4.184 J/g.C. This value is high in comparison with the specific heats for other materials, such as
concrete or metals. In this experiment, you will use a simple calorimeter and your knowledge of the
specific heat of water to measure the specific heat of a metal.
Procedure: You will be assigned a metal for analysis. The set up will be demonstrated.
1. Set up a hot plate with a clamp stand and test tube clamp. Place a 1 L beaker containing approx. 700
mL of deionized water on the hot plate and begin heating the water (use maximum heating setting)
until it reaches boiling. Throughout the experiment, monitor the level of water in the beaker so that
it does not run dry. Add more water and keep the water boiling as necessary.
2. Weigh out about 50 g of the metal pellets using a top-loader balance. Use a weigh boat to contain
the pellets on the balance. Tare the balance to zero with the empty weigh boat first, then add
approx. 50 g pellets and record the mass of the pellets shown on the balance (to the nearest 0.01 g).
3. Carefully transfer the metal pellets to a large test tube (25 x 200 mm). Pour the pellets in slowly,
with the test tube angled, to avoid breaking the tube.
4. Set up a calorimeter consisting of two nested Styrofoam cups plus a lid. Weigh out approx. 60 g of
deionized water into the inner Styrofoam cup using a top-loader balance. Tare the balance to zero
with the empty calorimeter first, then add approx. 60 g of deionized water and record the mass
shown on the balance (to the nearest 0.01 g). Note: You can estimate 60 g of water by using a
graduate cylinder to add approx. 60 mL of water.
5. When the water in the beaker on the hot plate reaches boiling, do the following:
a. Place the test tube containing the metal into the beaker of hot water and wait at least 5 minutes
for the metal to reach the same temperature as the hot water.
b. Place the probe of a digital thermometer through the lid into the water in the calorimeter. Wait
until the temperature has reached a steady value and then record the initial temperature of the
water in the calorimeter to the nearest 0.1 C.
c. Place the probe of the digital thermometer into the beaker of hot water. Wait until the
temperature has reached a steady value and then record the temperature of the water to the
nearest 0.1 C. Record this value as the initial temperature of the metal. Remove the probe from
the hot water to allow it to cool.
d. Using test tube holders or a paper towel folded several times, remove the test tube of metal
from the boiling water, wipe dry the outside (to avoid adding hot water to the calorimeter) and
then pour the metal into the calorimeter (avoid splashing) and replace the calorimeter lid.
e. Place the probe of the digital thermometer into the water in the calorimeter. Monitor the
temperature while gently swirling the calorimeter to stir the contents. Record the maximum
temperature (to the nearest 0.1 C) that the water in the calorimeter reaches. This temperature
is the final temperature of the metal AND the final temperature of the water in the calorimeter.
6. Carefully pour out the water in the calorimeter at a sink, capturing the metal pellets using a strainer.
Place the used metal pellets in the container provided in the lab.
7. Repeat steps 2 through 5 as directed by your instructor to obtain data for multiple trials. Use fresh
dry metal pellets for each trial.
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Post-Lab Analysis Questions:
1. For each experiment trial, calculate the specific heat capacity of the metal in J/g.C.
Show the steps and equations used in your work for full credit. The specific heat capacity of water,
cwater = 4.184 J/g.C.
2. Calculate the average of the individual values for the specific heat capacity of the metal.
3. Calculate the percent error in the specific heat value that you determined experimentally. Your
instructor will provide the accepted answer for your assigned metal.
% 𝐸𝑟𝑟𝑜𝑟 =
|𝑦𝑜𝑢𝑟 𝑎𝑛𝑠𝑤𝑒𝑟 − 𝑎𝑐𝑐𝑒𝑝𝑡𝑒𝑑 𝑎𝑛𝑠𝑤𝑒𝑟|
× 100
𝑎𝑐𝑐𝑒𝑝𝑡𝑒𝑑 𝑎𝑛𝑠𝑤𝑒𝑟
4. What effect would the following have on your calculated specific heat capacity? In each case, would
the calculated specific heat capacity value be higher than expected, lower than expected, or would
there be no effect? Explain your reasoning in each case.
a. Some hot water from the test tube of metal dropped into the calorimeter when adding the
metal.
b. Some metal pellets stick in the test tube and did not enter the calorimeter (and this was not
noted or accounted for during the experiment).
c. Some water splashes out of the calorimeter when adding the metal.
d. The metal pellets were not left in the beaker of hot water long enough to reach thermal
equilibrium.
5. Consider step 5d of the procedure. How does the way this step is carried out influence the accuracy
of your calculated value for the specific heat capacity of the metal? Will your value be higher or
lower than expected or is there no effect? Explain your reasoning. How could you minimize any
errors from this step.
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11:24 PM Mon Oct 4
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Chem 141 Chapter 5 Study Guide
Chapter 5: Energy and Chemical Reactions
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Understand the basic principles of energy discussed in lecture, including the law of
conservation of energy.
Know the relationship between Joules and calories.
Describe the various forms of energy.
Understand the meaning of the system and its surroundings in the context of
thermodynamics.
Understand the concept of heat transfer and thermal equilibrium.
Understand the difference between an exothermic process and an endothermic
process.
Understand sign conventions in thermodynamics
Assess the transfer of energy as heat associated with changes in temperature and
changes of state.
Understand specific heat capacity and be able to use it in thermodynamic
calculations.
Understand and be able to apply the First Law of Thermodynamics.
Understand the concept of internal energy and its relationship to heat and work.
Understand the concept of and equation for work (specifically, P-V work as discussed
in lecture)
Understand the concept of enthalpy (energy transferred under conditions of constant
pressure).
Define and understand state functions
Be able to solve stoichiometry problems using thermochemical equations.
Be able to solve constant pressure and constant volume calorimetry problems.
Use Hess’s Law to determine the enthalpy change for a reaction.
Be able to write out the formation reaction for a given compound.
Be able to determine the enthalpy change for a reaction using standard molar
enthalpies of formation (or be able to solve for standard enthalpies of formation if
given the enthalpy change for a reaction).
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