CHM 130LL Rio Salado College Calorimetry Chemistry Lab Report

CHM130LLLab 13 – Calorimetry
Name: _Kristina Gamez_ MEID: KRI2193767
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Part I: Determining the Specific Heat Capacity of Aluminum
A. Data Table 1
Complete the Data Table. (7 pts)
ALUMINUM METAL (Trial 1)
Pre-weighed aluminum metal mass (g)
20.04g
Initial temperature of cool water in the calorimeter (oC)
24oC
Initial temperature of aluminum metal (same as the boiling water in the pot) (oC)
97 oC
Final temperature of water/aluminum metal in calorimeter (oC)
27 oC
ALUMINUM METAL (Trial 2)
Pre-weighed aluminum metal mass (g) [Copy this from above since you are using the 20.04 g
same metal sample for both trials.]
Initial temperature of cool water in the calorimeter (oC)
25 oC
Initial temperature of aluminum metal (same as the boiling water in the pot) (oC)
96 oC
Final temperature of water/aluminum metal in calorimeter (oC)
26.5 oC
B. Insert the following photo with your name and MEID showing in the photo:
Photo A: Insert a photo of your calorimeter showing your aluminum metal submerged in the water.
The photo should be taken from above. (6 pts)
C. Calculations (Show all calculations with units on each number and the final answer rounded to the
correct significant figures for full credit.)
1. Calculate the mass of the water by using the water’s density (assume it is 1.00 g/mL) and the
volume of the water. Remember, density = mass/volume. (4 pts)
Aluminum (Trial 1) –
Aluminum (Trial 2) –
2. Calculate the change in temperature for the water caused by the addition of the metal by
subtracting the initial temperature of the water from the final temperature of the water. ΔT =
Tf – Ti (4 pts)
Aluminum (Trial 1) –
Aluminum (Trial 2) –
3. Calculate the change in the metal’s temperature by subtracting the initial temperature of the
metal from the final temperature of the metal. ΔT = Tf – Ti (4 pts)
Aluminum (Trial 1) –
Aluminum (Trial 2) –
4. Use the equation: q = m(SH)ΔT to solve for the amount of energy gained by the water from
metal. Remember to use the specific heat capacity of water in this calculation. (8 pts)
Aluminum (Trial 1) –
Aluminum (Trial 2) –
5. Use the equation: q = m(SH)ΔT to solve for the specific heat capacity of the metal. For q,
you found how much energy was gained by the water so you know that same amount of
energy was lost by the metal. Therefore, -qmetal = qwater. (8 pts)
Aluminum (Trial 1) –
Aluminum (Trial 2) –
6. Determine the percent error using the equation below and the specific heat capacity of the
aluminum from the chart provided in the Background Information portion of the lab as the
accepted value. The experimental value is your calculated answer for the specific heat
capacity of aluminum from Question 5. (4 pts)
Aluminum (Trial 1) –
Aluminum (Trial 2) –
D. Follow-Up Questions
7. The first law of thermodynamics states that energy lost by one object is gained by another.
Explain how you used this law to find the specific heat capacity of aluminum. Reference the
work you did in Questions 4 and 5. (6 pts)
8. To determine the specific heat of the metal, you assumed that the amount of heat lost by the
metal equals the amount of heat gained by the water. Do you think this is a valid
assumption? Explain your reasoning and be sure to discuss your percent error for each trial in
your response. (6 pts)
9. Were the results of the second trial better than the first trial? Explain why or why not. Your
explanation should compare the percent error for each trial and discuss TWO potential
sources of error from the procedure (not “human error” or “calculator error”). (6 pts)
10. Why do you think scientists run multiple trials when they are conducting experiments?
Discuss TWO potential reasons they would do so. (4 pts)
Part II: Identifying an Unknown Metal
A. Data Table 2
Complete the Data Table. (5 pts)
UNKNOWN METAL
Letter identifying your unknown metal sample (either A, B, C or D)
C
Pre-weighed unknown metal mass (g)
19.94g
Initial temperature of cool water in the calorimeter (oC)
26 oC
Initial temperature of unknown metal (same as the boiling water in the pot) (oC)
95 oC
Final temperature of water/unknown metal in calorimeter (oC)
27.8 oC
B. Insert the following photo with your name and MEID showing in the photo:
Photo B: Insert a photo of your calorimeter showing your unknown metal submerged in water. The
photo should be taken from above. (6 pts)
C. Calculations (Show all calculations with units on each number and the final answer rounded to the
correct significant figures for full credit.)
11. Calculate the mass of the water by using the water’s density (assume it is 1.00 g/mL) and the
volume of the water. Remember, density = mass/volume. (2 pts)
Unknown metal –
12. Calculate the change in temperature for the water caused by the addition of the metal by
subtracting the initial temperature of the water from the final temperature of the water. ΔT =
Tf – Ti (2 pts)
Unknown metal –
13. Calculate the change in the metal’s temperature by subtracting the initial temperature of the
metal from the final temperature of the metal. ΔT = Tf – Ti (2 pts)
Unknown metal –
14. Use the equation: q = m(SH)ΔT to solve for the amount of energy gained by the water from
metal. Remember to use the specific heat capacity of water in this calculation. (4 pts)
Unknown metal –
15. Use the equation: q = m(SH)ΔT to solve for the specific heat capacity of the metal. For q,
you found how much energy was gained by the water so you know that same amount of
energy was lost by the metal. Therefore, -qmetal = qwater. (4 pts)
Unknown metal –
D. Follow-Up Question
16. Identify the unknown metal by comparing the specific heat capacity you calculated in
Question 15 to the chart provided in the Background Information portion of the lab. Explain
your choice. Be sure to use numerical data related to specific heat capacity to support your
claim. (8 pts)