Internal Energy Lab Essay, Research Paper

Procedures:

The purpose of this lab was to determine the specific heat of two different metals. In order to do this, specific directions were executed in order to discover the specific heat. First, we needed to obtain and record the weight of the Styrofoam calorimeter cup. Next, we filled the cup 2/3 full with cool tap water and recorded the temperature of the water. After this was done, we filled a glass beaker half full with water and placed it on a hot plate in order to have the water reach boiling point. When boiling point was reached, the temperature was then taken and also recorded. Next, we obtained two different pieces of metal, (my group had lead and copper) weighed them, recorded the weight, and placed them in the boiling water for a minute. The metal was then placed in the calorimeter cup until the temperature reached equilibrium. This temperature was then recorded. This experiment was performed two times for each of the metals. By using the Heat Loss = Heat Gained formula, the recorded information was then used to find the specific heat of the metals.

Observations:

Through the course of this lab, our group realized that the specific heat correlated with the rate the metal reached equilibrium. The faster the metal reached equilibrium, the lower the specific heat, thereby having an inverse relationship. We also realized that in order to have accurate results, the metal must be left in the boiling water long enough to reach the same temperature of the water. Along with this, the temperatures and the weights must be accurately measured. If not correctly done, the results may not be correct. Finally, it is important to be extremely careful in this lab. Because of an unexplained phenomenon, our group’s beaker shatters, spilling water all over the counter, close to electrical outlets. This also may have caused our results on the final experiment to be off.

Data:

#1 LEAD

Weight of lead- 118.64g

Mass of calorimeter cup and water-72.57g

Mass of calorimeter cup-9.61g

Mass of only water- 62.96g

Temp of Boiling water- 98.4 C

Temp of cool tap water- 26.9 C

Final temp of water and metal- 30.4 C

#2 LEAD

Weight of lead- 118.64g

Mass of calorimeter cup and water-72.57g

Mass of calorimeter cup-9.61g

Mass of only water- 62.96g

Temp of Boiling water- 98.4 C

Temp of cool tap water- 28.8 C

Final temp of water and metal- 34.3 C

#3 COPPER

Weight of copper-61.46g

Mass of calorimeter cup and water- 72.57g

Mass of calorimeter cup-9.61g

Mass of only water- 62.96g

Temp of Boiling water- 96.8 C

Temp of cool tap water- 29.0 C

Final temp of water and metal- 32.3 C

#4 COPPER

Weight of copper-61.46g

Mass of calorimeter cup and water- 72.57g

Mass of calorimeter cup-9.61g

Mass of only water- 62.96g

Temp of Boiling water- 98.6 C

Temp of cool tap water- 28.8 C

Final temp of water and metal- 33.4 C

Calculations:

#1 LEAD

Qlost=Qgained

mc T=mc T

(118.64g)(c)(98.4 C-30.4 C)=(62.96g)(4.19kJ/kg C)(30.4 C-26.9 C)

(118.64)(c)(68.0)=(62.96)(4.19)(3.5)

8067.52c=923.3084

c=.11kJ/kg C

%ERROR

((our-acc)/acc )*100

((.11kJ/kg C-.13kJ/kg C)/.13kJ/kg C)*100=18%

#2 LEAD

Qlost=Qgained

mc T=mc T

(118.64g)(c)(98.4 C-34.3 C)=(62.96g)(4.19kJ/kg C)(34.4 C-28.8 C)

(118.64)(c)(64.1)=(62.96)(4.19)(5.5)

7604.824c=1450.9132

c=.19kJ/kg C

%ERROR

((our-acc)/acc )*100

((.19kJ/kg C-.13kJ/kg C)/.13kJ/kg C)*100=32%

#3 COPPER

Qlost=Qgained

mc T=mc T

(61.46g)(c)(96.8 C-34.3 C)=(62.96g)(4.19kJ/kg C)(34.3 C-29.0 C)

(61.46)(c)(62.5)=(62.96)(4.19)(5.3)

3841.25c=1398.15272

c=.36kJ/kg C

%ERROR

((our-acc)/acc )*100

((.36kJ/kg C-.39kJ/kg C)/.39kJ/kg C)*100=8%

#4 COPPER

Qlost=Qgained

mc T=mc T

(61.46g)(c)(98.6 C-33.4 C)=(62.96g)(4.19kJ/kg C)(33.4 C-28.8 C)

(61.46g)(c) (65.2)=(62.96)(4.19)(4.6)

4007.192c=1213.49104

c=.30kJ/kg C

%ERROR

((our-acc)/acc )*100

((.30kJ/kg C-.39kJ/kg C)/.39kJ/kg C)*100=30%

Results:

For our specific heats of Lead we got .11kJ/kg C and .19kJ/kg C. The specific heats of Copper we got were .36kJ/kg C and .30kJ/kg C. The Accepted for Lead was .13kJ/kg C and accepted for Copper is.39kJ/kg C. So the answers that we calculated were pretty close to accepted.

Sources of Error:

Some sources of error we could have come across were measuring the weights of items wrong. We also could have rounded to soon. Our group could have taken the temperature of the waters to late or to soon. Or we could have allowed some wrong calculations for the Qlost=Qgained.

Questioned Answered:

1.. At what temperature did your water boil? Our groups water boiled at 98.4 C, 96.8 C, and 98.6 C.

2.. Was boiling the same temperature each time? No the temperature was not the same each time.

3.. Did your system boil at the same temperature as the other groups? If not, where did the error come from? No, every group had a different amount of water in their cup and they took the temperature at different times and held the thermometer in the water for a different length of time, so we got different temps.

4.. What would happen to the accuracy of the experiment if you used a large quantity of water in the calorimeter cup? It depends on the size of the cup so that when you put the metal in you will not loose any water. And it will also take longer for the water to heat up.

5.. What would happen to the accuracy of the experiment if you used a small quantity of water in the calorimeter cup? If you used a small amount of water you might not be able to cover the cup completely and it will not get evenly heated.

6.. What variable in this experiment will be the cause for the greatest source of error? How long you keep the metal in the water for and how long you will take the temperature so it is at the perfect temperature.

7.. How could you improve the reliability of the experiment? You could get some new equipment, or use the same amounts and temperature each time.

8. Is there a systematic error, which could be adjusted to obtain a small % error? If so explain how and what could be changed. Well when you did the mc T’s you came out with the specific heat of that object you could look at the answer you got and change the temperature so that you would get a closer number to the specific heat that you were suppose to get.