Friday September 29
Thermal Energy and Calorimetry
Here is how we can use a calorimeter to find the specific heat capacity of a block of an unknown metal.
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First, place a known mass of water in the calorimeter and measure its temperature.
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Next, measure the mass of the metal block, and then heat it to a convenient temperature greater than that of the water.
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Finally, drop the warm block into the cool water and wait for the system to reach thermal equilibrium.
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Measure the final temperature of the water—which is the same as that of the block.
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These measured quantities can be used to calculate the specific heat capacity of the block, as we shall see.
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The final temperatures of the block and the water are equal, since the system is in thermal equilibrium.
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The total energy of the system is conserved.
In particular, the second condition means that the amount of thermal energy lost by the block is equal to the amount of thermal
energy gained by the water.
We can write this condition as follows:
Qb + Q w = 0
Measure the specific heat of a solid material.
Objectives:
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Observe the difference between heat and temperature.
Monitor the transfer of heat from one substance to another.
Calculate the specific heat of an unknown material.
Estimate the amount of error in an experimental value.
Examine a procedure for sources of experimental error.
Go to: https://media.pearsoncmg.com/bc/bc_0media_chem/chem_sim/calorimetry/Calor.php

Open the experiment tab.

Select Run the experiment.
a.
Below the beaker select choose a liquid: water.
b.
Select the mass of the water – 50 g
c.
Select the initial temperature of the water to 100 C.
d.
Select show the specific heat.
e.
Press Next.
f.
Below the calorimeter select choose a liquid: water.
g.
Select the mass of the water – 100 g.
h.
Select the initial temperature of the water to 900 C.
i.
Select show the specific heat.
j.
Predict the equilibrium temperature. ______________
k.
Select “show graphs” and “show microscopic level:
l.
Run the experiment.
m. Record the Equilibrium Temperature: _________
n.
Take a print screen of the graph and paste it here.
Select Reset
a.
Below the beaker select choose a liquid: Ethanol.
b.
Select the mass of the water – 50 g
c.
Select the initial temperature of the water to 100 C.
d.
Select show the specific heat.
e.
Press Next.
f.
Below the calorimeter select choose a liquid: water.
g.
Select the mass of the water – 100 g.
h.
Select the initial temperature of the water to 900 C.
i.
Select show the specific heat.
j.
Predict the equilibrium temperature. ______________
k.
Select “show graphs” and “show microscopic level:
l.
Run the experiment.
m. Record the Equilibrium Temperature: _________
n.
Take a print screen of the graph and paste it here:
Explain why in the second experiment the equilibrium temperature has been higher that the first experiment.
Select Reset
a.
Below the beaker select choose a SOLID – Copper (if your seat is on the right of the desk)/ SOLID /Aluminum (if
your seat is on the left side of the desk) .
b.
Select the mass – 20 g.
c.
Select the initial temperature of the solid to 1000 C.
d.
Select show the specific heat.
e.
Press Next.
f.
Below the calorimeter select choose a liquid: water.
g.
Select the mass of the water – 100 g.
h.
Select the initial temperature of the water to 100 C.
i.
Select show the specific heat.
j.
Predict the equilibrium temperature. ______________
k.
Select “show graphs” and “show microscopic level:
l.
Run the experiment.
m. Record the Equilibrium Temperature: _________
n.
Take a print screen of the graph and paste it here:
Calculations
Use the data (mass of copper and water, their initial temperature and equilibrium temperature)
Use the specific heat of water and calculate the specific heat of copper.
Heat transmitted by the block: 𝑄𝑐𝑜𝑜𝑝𝑒𝑟 = 𝑚𝑠𝑜𝑙𝑖𝑑 × 𝑐𝑠𝑜𝑙𝑖𝑑 × ∆𝑇𝑠𝑜𝑙𝑖𝑑 = ________________
Heat received by cold water: 𝑄𝑤𝑎𝑡𝑒𝑟 = 𝑚𝑤𝑎𝑡𝑒𝑟 × 𝑐𝑤𝑎𝑡𝑒𝑟 × ∆𝑇𝑤𝑎𝑡𝑒𝑟 = __________________
The amount of heat transmitted = - The amount of water received
Solving for specific heat of the block 𝑐𝑐𝑜𝑝𝑝𝑒𝑟 =
𝑚𝑤𝑎𝑡𝑒𝑟 ×𝑐𝑤𝑎𝑡𝑒𝑟 ×∆𝑇𝑤𝑎𝑡𝑒𝑟
𝑚𝑆𝑜𝑙𝑖𝑑 ×∆𝑇𝑐𝑜𝑝𝑝𝑒𝑟
Accuracy:
%𝐸𝑟𝑟𝑜𝑟 =
|𝐴𝑐𝑐𝑒𝑝𝑡𝑒𝑑 𝑉𝑎𝑙𝑢𝑒 − 𝑀𝑒𝑎𝑠𝑢𝑟𝑒𝑑 𝑉𝑎𝑙𝑢𝑒|
× 100 =
𝐴𝑐𝑐𝑒𝑝𝑡𝑒𝑑 𝑉𝑎𝑙𝑢𝑒
Select Reset
a.
Below the beaker select choose a SOLID UNKNOWN METAL I (if your seat is on the right of the desk) / SOLID
UNKNOWN II (if your seat is on the left side of the desk).
b.
Select the mass – 20 g.
c.
Select the initial temperature of the unknown metal to 1200 C.
DO NOT SELECT SHOW SPECIFIC HEAT!
d.
Press Next.
e.
Below the calorimeter select choose a liquid: water.
f.
Select the mass of the water – 100 g.
g.
Select the initial temperature of the water to 5.00 C.
h.
Select show the specific heat.
i.
Predict the equilibrium temperature. ______________
j.
Select “show graphs” and “show microscopic level:
k.
Run the experiment.
l.
Record the Equilibrium Temperature: _________
m. Take a print screen of the graph and paste it here:
Use your data and calculate the specific heat of the unknown metal. Use the table below to identify the material.
Material
Aluminum
Cupper
Iron
Zinc
Lead (Pb)
Water
Ice
Brass
Specific Heat
J/g0C
0.89
0.39
0.45
0.39
0.13
4.18
2.09
0.35