Identification of an Unknown Metal - LabQuest
In this experiment, you will use the intensive properties of color, density and specific heat capacity to determine the
identity of an unknown metal. According to the Law of Conservation of Energy, energy or heat lost by one object
must be transferred to or absorbed by another object.
To calculate the heat that flows into or out of an object, use the relationship Q = m x c x T
To calculate the density of an object, use the relationship
PROCEDURE
1. Prepare a hot water bath by placing at least 400 mL water in a 600 mL beaker on a hotplate and turning the hotplate
on high. Do this now or it will not be ready when you need it.
2. Record the number of your metal and the color of the metal in the blanks above the data table.
3. Plug the Temperature Probe into any channel of the Lab Quest.
4. Turn on the LabQuest.
5. On the meter screen (looks like a speedometer), tap “mode.” Check the following and make changes as necessary:
a. In the “Mode” box, select “time based” from the drop down menu.
b. In the “Rate” box, enter 2.0.
c. In the “Length” or “duration” box, enter 250.
6. Look on the bottom of your sample and record the number of your unknown in the data table.
7. Determine the mass of your unknown metal; record in your data table (1).
8. Fill your 100-mL graduated cylinder between 1/2 and 3/4 full. Record the EXACT volume of the water in the data
table (2).
9. Carefully place the metal sample into the water. Tilt the graduated cylinder and slide the object into the water slowly.
Be sure the object is completely submersed and that there are no drops clinging to the side of the cylinder. Record the
new EXACT volume in your data table (3).
10. Determine the mass of the Styrofoam cup and record in the data table (4)
11. Use a graduated cylinder to obtain approximately 50.0 mL of water
a. Pour this into the Styrofoam cup.
b. Determine the mass of the Styrofoam cup and water and record in the data table (5)
12. Place the Styrofoam cup into a 250-mL beaker.
13. Place the Temperature Probe into the Styrofoam cup.
14. When the water bath begins to boil, (100.0 oC) carefully hold your metal sample in the hot water bath for at least 5
minutes. DO NOT let it rest on the bottom of the beaker!
15. After heating the metal sample for 5 minutes, you are now ready to begin collecting data. Do not remove your metal
sample from the hot water bath until you are ready to place it in the Styrofoam cup.
a. While your metal sample is still in the hot water bath, start data collection by pressing the “play” button in the
bottom left corner.
b. 20 SECONDS AFTER PRESSING the start button, quickly transfer your metal sample from the boiling water into
the Styrofoam cup of water.
c. Use your temperature probe to continually stir the mixture throughout data collection.
16. When data collection is complete, a graph of temperature vs. time will be displayed.
17. Use the data table (T-chart icon) to find:
a. The initial temperature of the water, Ti (just before you added the metal --- at about 15 seconds) and record in
your data table (6).
b. The final temperature of the mixture, Tf --- NOT AT THE END OF THE DATA TABLE (scroll through the
data and find the temperature value highest temperature after addition of metal sample) and record in your data
table (8).
18. Empty the contents of the Styrofoam cup. Beginning with step 9, run a second trial using the same metal sample. Be
sure to get new water for the Styrofoam cup only.
19. Cleanup lab area and rinse all equipment and glassware with normal tap water.
Identification of an Unknown Metal - LabQuest
PARTNER’S NAME ____________________________
NAME ________________________________
DATA TABLE
UNKNOWN# ______________
1. Mass of unknown metal sample
2. Volume of water in graduated cylinder before
metal sample
3. Volume of water in graduated cylinder after metal
sample
4. Mass of Styrofoam cup
5. Mass of Styrofoam cup + water
6. Initial water temperature, Ti
7. Initial unknown metal temperature, T i
8. Final temperature of mixture, T f
Metal
Aluminum
Cadmium
Cobalt
Copper
Lead
Tin
Zinc
Specific Heat Capacity
0.900 J/g °C
0.232 J/g °C
0.421 J/g °C
0.387 J/g °C
0.128 J/g °C
0.210 J/g °C
0.390 J/g °C
COLOR OF METAL _________________
TRIAL 1
TRIAL 2
g
XXXXXXX
mL
XXXXXXX
mL
XXXXXXX
g
g
g
g
°C
°C
100.0 °C
100.0 °C
°C
°C
Density
2.70 g/cm3
8.65 g/cm3
8.86 g/cm3
8.96 g/cm3
11.36 g/cm3
7.28 g/cm3
7.13 g/cm3
Calculations: Complete the following calculations on a separate sheet of paper. Be sure to show all of your work!
1. Calculate T for all trials for the water.
2. Calculate T for all trials for the metal.
3. Calculate the mass of the water.
4. Calculate the heat absorbed by the water for all trials.
5. Calculate the specific heat of your metal for all trials.
6. Calculate the volume of your metal.
7. Calculate the density of your metal.
Questions
1. Based on your data, what is the identity of your unknown metal sample?
2. Based on the specific heats of the metals listed, which metal would heat up and cool off the fastest? Why?
3. What effect would a delay in transferring the hot metal sample into the calorimeter (Styrofoam cup) have on the value of the
change in temperature?
4. What effect would this delay in transfer have on the calculated specific heat value of the metal (would it cause you to have a
higher or lower expected specific heat)? Why?