Specific Heat
Heat
Students will distinguish between specific heat capacity and specific latent heat, and know how
to calculate them.
Comprehension Strategies Emphasized
Visualization:
 This comprehension strategy involves you making mental pictures and/or mind maps of ideas and
how they interconnect.
 You may say statements like…
 I am getting a picture…
 I have a picture in my head…
 I’m visualizing…
Summarizing and Synthesizing:
 This comprehension strategy involves you recalling, retelling, creating new meaning, and
remembering information.
 You may say statements like…
 I never knew… now I know…
 I think the big idea is…
 Now I understand that…
 This gives me an idea…
Before you explore…
Any substance on earth will likely have a number of
physical properties. For example, the pieces of metal
on the left may be described as being solids, being
malleable, having a melting point of 1811 K, and
having a density of 7.86 g·cm-3. Many of these
properties are known and scientists can use them to
help identify unknown substances. (Can you find out
the indentity of this metal?)
Another useful physical property is called specific
heat capacity. This is the amount of energy, measured in joules, that is needed to raise the
temperature of one kilogram of the material one degree Celsius (or Kelvin). If this value is
known, we can easily determine the amount of heat gained (or lost) by an object. If the
value is unknown (as in this lab) we can obtain the value experimentally
Q:
What is the formula for specific heat capacity?
Accessed from: _______________
Q:
What are the units for mass, temperature, heat energy and specific heat
capacity in the above formula?
Accessed from: _______________
Purpose
The purpose of this lab is to experimentally determine the specific heat
capacity of two different metals and compare these values against their latent
heat of fusion values.
Predictions
Q:
Will the specific heat capacity be different for two different metals?
Why or why not?
Accessed from: _______________
While you explore…
Materials
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String (60 cm)
Safety goggles
250 mL beaker
Calorimeter (Styrofoam cup)
Hot plate (or bunsen burner)
Stirring rod
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Tap water
Thermometer
Balance
Graph paper
Specific heat set (aluminum, iron, copper, etc.)
Procedure
PART A: Determining Specific Heat Capacity
1. Safety goggles must be worn for this laboratory activity. Fill the beaker about half
full of water, or enough to completely cover each piece of metal you will use in this
experiment. Place the beaker of water on the hot plate and begin the heating process.
2. While the water is beginning to boil, find the mass of the two metals you will be
using in the lab. Also, find the mass of the calorimeter (Styrofoam cup). Record
these values in the Table 1 below.
3. Attach some string to each of the metals you will be using. Put these metals into the
beaker with the boiling water. Allow the metals to stay in rapidly boiling water for at
least 5 minutes.
4. While the metal is in the boiling water, fill the calorimeter at least half full of room
temperature water (enough to cover the pieces of metal). Find the total mass of the
water and the cup. Record this value in Table 1. Find the temperature of the water in
the cup. Record this value in Table 1 as well.
5. Find the temperature of the boiling water in the beaker. This temperature also
represents the temperature of the metal in the water. Record this value in Table 1.
6. Remove the metal from the boiling water and quickly place it in the water in the
calorimeter. Stir the water gently with stir stick while recording the temperature of
the water with a thermometer. When the water reaches a consistent temperature,
record this in Table 1 as the final temperature.
7. Remove the metal sample and repeat directions 3-6 for the other metal sample you
have.
Table 1
Metal #1
Metal type
Mass of calorimeter (kg)
Mass of calorimeter and water (kg)
Mass of metal (kg)
Initial temp of room temp water (oC)
Temperature of hot metal (oC)
Final Temperature of metal and water (oC)
Metal #2
8. For both trials, calculate the mass of the room temperature water, the change in
temperature of the metal, and the change in temperature of the room-temperature
water. Enter this data into Table 2. Use this data to answer the questions below.
Table 2
Metal #1
Metal #2
Mass of room temp water (kg)
∆T metal (oC)
∆T room temperature water (oC)
Q:
Calculate the heat gained by the water (heat lost by the metal) in each
trial?
Q:
Using the above information, what is the specific heat capacity of
each metal?
PART B: Comparing specific heat capacity and latent heat of fusion values.
In this experiment you found the specific heat of water. The accepted value for specific heat
capacity of liquid water is 4180 J/kg·K.
Using your experimental value and the accepted value for the specific heat of
water, calculate they percent error in your calculation.
What information does specific heat give us? If we add 4180 J of heat to 1
kg of water, what happens? (Look at the units for clues!)
As you may be aware, water will change state to a gas if enough heat is absorbed. While
this is happening there is no temperature change. Heat energy is being used to change the
state of the water, not increase the temperature.
PART C: Heating water.
1. Safety goggles must be worn for this laboratory activity. Fill the beaker about half
full of water. Place the beaker of water on the hot plate and begin the heating
process.
2. At regular intervals of one minute, insert a thermometer into the water and record
the temperature. At the same time, note what is happening in the beaker/water. Add
this information to table 3.
3. Continue step 2 until the water reaches a rolling boil for 5 minutes. Once this is
complete, allow the water to cool while you create a water temperature vs. time
graph based upon the information in table 3.
Table 3: Heating Water to a Rolling Boil
Time
Temperature
(min)
(degrees Celsius)
Observations
The amount of heat that is required to change one kilogram of water from liquid to gas is
known as the latent heat of vaporization. Similarly the amount of heat needed to change 1
kg of water from ice to liquid is known as the latent heat of fusion.
Q:
What is the formula for latent heat of fusion? What do the symbols mean?
What are the units for each term?
Accessed from: _______________
Q:
What is the formula for latent heat of vaporization? What do the symbols
mean? What are the units for each term?
Accessed from: _______________
Q:
What takes more heat? To raise the temperature of 2.0 kg of water from 20 oC
to 90 oC, to change 2.0 kg of water to steam, or to change 2.0 kg of ice to water?
2.0 kg of water from 20 oC to 90 oC
2.0 kg of water to steam
2.0 kg of ice to water
Using the graph below, label the parts of the graph where we would calculate
specific heat, where we would calculate latent heat of fusion, and where we
would calculate latent heat of vaporization.
After you explore…
Conclusion
Write a conclusion that includes at least the following:
 terms: specific heat capacity, calorimeter, latent heat of vaporization, latent heat
of fusion
 a summary of what you discovered in this lab
 a connection to theory
 a comparison of the results of this lab with your predictions
 list at least 2 systematic sources of error
C:
Post exploration
1. The specific heat of a material can be used to identify the material. If a 100.0 g
sample of a substance is heated to 100.0 oC and placed in a calorimeter containing 150.0
g of water at 25 oC, what is the identity of the substance if the material raised the
temperature of the water in the calorimeter to 32.1 oC?
2. How much heat energy is needed to change 7.0 kg of water to steam?
3. How much water will 780,000 J of energy turn from ice to water?
Extension Activities
1. Get a sample of an unknown metal from your teacher. Determine the specific heat
capacity for this metal. Use this information and a table of specific heat capacities to
identify the metal.