Specific Heat
Submitted by:
[Your Full Name]
Lab Partner:
[Their Full Name]
Due Date
[Example: 25October 2006]
Purpose:
The reason for this lab is to find the specific heat of the given metal. The first law of thermodynamics states that matter (or energy) can not be created nor destroyed.In this experiment, water was heated with the metal in it then placed into water at room temperature. A heat change occurred showing that the heat from the metal was transferred through the water. This explains why energy cannot be created nor destroyed.
Introduction:[L1]
Specific heat, by definition, is the amount of energy it takes to raise the temperature of 1 gram of a substance by 1 degree Celsius. For example, the specific heat of water is 4.184 J/g°C; this means that it takes 4.184 Joules of energy to raise 1 gram of water 1 degree Celsius.[1] This is not to be confused with heat capacity which is the amount of energy required to raise the temperature of a substance (in varying amounts) by 1 degree Celsius. The study of specific heat falls under the category of Thermochemistry which is further divided into the category of Calorimetry. An instrument called a calorimeter is used to measure specific heat.[2] A piece of metal is placed in a container of water. This is then boiled. The piece of metal is then taken out of the boiling water and placed in a calorimeter which contains room temperature water. The heat that was absorbed by the metal is measured by the temperature change the metal causes in the room temperature water.[3]
James Joule was one of the first to determine the mechanical equivalent of heat. He did this in the 1870s using a calorimeter of his own invention. The energy (or heat) unit of the Joule was named after him.[4] The invention of an accurate calorimeter can be traced back to American chemist Theodore William Richards. Richards received his PhD from Harvard in 1888. He is credited with the invention of a calorimeter used to measure precise heat quantities in substances. He was awarded the Nobel Prize in Chemistry in 1915.[5]
The first law of thermodynamics states that energy can neither be created nor destroyed. Instead of creating or destroying energy, it is actually traded back and forth from the system to its surroundings. There are two different kinds of reactions involving this law, endothermic and exothermic reactions. Endothermic reactions occur when heat flows into the system from the surroundings. An example of an endothermic reaction is the melting of ice. Exothermic reactions are the exact opposite; heat flows into the surroundings from the system. An example of an exothermic reaction is the boiling of water.[6]
Due to the background provided, the hypothesis for the experiment is that any metal will heat the room temperature water in the calorimeter. It is also believed, however, that the specific heat measured by the calorimeter will not be accurate compared to the verified data. It is predicted that there will be a slight error in the data due to the loss of heat during the transfer process. Depending on the type of metal given, it is predicted that the error will be at least 5 Joules. Also it is believed that the heavier the metal then the greater the heat difference will be after placed into the calorimeter due to the increase of surface area.
Procedure:[L2]
Materials:
Electronic balanceTest Tubes (3)
Hot PlateTest Tube Rack
Thermometers (2)Test Tube Clamp
Stirring Rod450mL Beaker
Styrofoam Cups (2 big, 2 little)600mL Beaker
Unknown Metal50mL Graduated Cylinder
Fill the 600mL beaker around 2/3 the way full and place it on the hot plate to be heated. Place a big styrofoam cup inside the other big cup and place 50mL of water in the stacked cups. Record the mass of the water on the data table (mL = g). Then place the stacked cups in the 450mL beaker. Next place the little styrofoam cup in the other little cup. Then make two small holes on the side of the little cups and insert a thermometer and stirring rod through each hole. Then place the stacked little cups upside down on top of the bigstacked cups. This will be the calorimeter. Make sure the thermometer is in the water and find the temperature then record it on the data table (Room Temp Water). Next weigh each unknown metal and record data (Mass of Metal).Place each unknown metal into a test tube then place them into the beaker that is being heated. Find the temperature of the heated water then record on data table (Heated Metal Temp).Quickly remove a test tube from the heated beaker and place the metal into the calorimeter. Continue to stir the water in the calorimeter and record the change in temperature. (Heated Temp Water & Cooled Metal Temp) Repeat the same process for each of the metal being heated.Plug in all data into the formulas and find the specific heat of each metal. Then calculate the average specific heat of all three and compare it with what it is suppose to be (mossy tin). Last calculate the percent error and record the data.
Data and Calculations:[L3]
Actual Specific Heat
Quantity Heat Equation:q = Quantity of Heat Transferred
q = s x m x (Tf – Ti)s = Specific Heat
g = Grams of Substance
Specific Heat Equation:Tf = Final Temperature
s = ___q ___Ti = Initial Temperature
m x (Tf – Ti)
Specific Heat of Water = 4.184J
Sample 1: Sample 2:
q = (4.184J)(50g)(22°C – 21°C)q = (4.184J)(50g)(23.5°C – 22°C)
q = (4.184J)(50g)(1°C)q = (4.184J)(50g)(1.5°C)
q = 209.2Jq = 313.8J
s = ______-209.2J______s = ______-313.8J______
(1.33g)(22°C – 100°C) (4.0g)(23.5°C – 100°C)
s = ___-209.2J___s = ___-313.8J___
(1.33g)(-78°C) (4.0g)(-76.5°C)
s = __-209.2J__s = -313.8J_
-103.74g°C -306g°C
s = 2.016579911 J/g°Cs = 1.025490196 J/g°C
Sample 3:Average:
q = (4.184J)(50g)(22.8°C – 21°C) 2.016579911 J/g°C
q = (4.184J)(50g)(1.8°C) 1.025490196 J/g°C
q = 376.56J + 3.275745081J/g°C
6.317815188 J/g°C
s = ______-376.56J______
(1.47g)(22.8°C – 101°C) 6.317815188 = 2.105938396
s = ___-376.56J___ 3
(1.47g)(-78.2°C)Final Average = 2.106 J/g°C
s = __-376.56J__
-114.954g°C
s = 3.275745081 J/g°C
------
Percent Error:
Measured – Actual x 100
Actual
Sample 1:Sample 2:
2.017 – 0.222 x 100 1.025 – 0.222 x 100
0.222 0.222
1.795 x 1000.803 x 100
0.2220.222
8.085585586 x 1003.617117117 x 100
806% Error362% Error
Sample 3:Average:
3.276 – 0.222 x 100 2.106 – 0.222 x 100
0.222 0.222
3.054 x 1001.884 x 100
0.2220.222
13.75675676 x 1008.486486486 x 100
1376% Error849% Average Error
Questions:
- What is the final average specific heat of your metal?
After thorough examination, the final average specific heat of the metal tin was 2.106 J/g C.
- How did this compare to the known specific heat of the metal? What was your percent error?
The comparison of the final average with the actual specific heat of tin showed a 1.884 J/g C difference. With the actual specific heat of the tin at 0.222 J/g C, this showed an 849% error. [L4]
Discussion:
The observations of the results show that the experimental procedure was performed in a correct manner. The results of Sample #2 showed the least amount of error with it being at 362%. The reason for this could be because Sample #2 weighed the most while the other two samples were similar in lighter weight. Another thing that was observed was that the calorimeter itself may not be completely accurate as the original that was made by Theodore William Richards. The one that Richards used was made out of metal and used in a contained environment to get an accurate read of heat change in each metal.
The outcome of the experiment was similar to what was hypothesized. The metal did heat the water in the calorimeter even though it was around 1 degree. It was known that some factors could have affected the outcome. This is the reason why it was hypothesized that there would be a 5 Joules difference between the actual and outcome data. The second heaviest metal, sample #3, seemed to give off a larger heat difference than sample #2 (the heaviest). Sample #2 weighs at least twice as much as the other two but it only gave off the second highest amount of heat. This conflicted with what was hypothesized in which the heavier metal would cause a higher change in the room temperature water.
The large percent in error could be due to numerous factors. The construction of this experiments calorimeter was made by stryofoam cups which can not contain heat as well as metal can. Another indication in error could be that some of the heat could have leaked out through the holes where the stirring rod and thermometer was inserted. Some of the heat could have been lost during the transfer of the metal from the heated beaker to the calorimeter.
Conclusion:[L5]
In conclusion the performance of the group went very well. There was no conflict amongst any group members. The experiment was a success and data was obtained with no performance errors. To improve the experiment some tape and corks could be used to contain the heat better in the calorimeter. It was learned from the results that it is possible to obtain the specific heat of a metal in this experiment even though that it is not a 100 % accurate. The difficulty in this report was obtaining the background information on the subject of specific heat. Many sources gave different points of view and caused conflict with writing the procedure. The most enjoyable part of the whole report would be the experiment itself and the calculation of the data section.
Works Cited
Austin, Nancy Jo. “Specific Heat.”University of CentralArkansas, 2006. Online at
Brown, Theodore & Eugene Lemay, Jr & Bruce Bursten. Chemistry the Central Science,
10th ed. (Pearson Education, 2006).
Foley, Robert. “Specific Heat Capacity.”University of Wisconsin, 2006. Online at
Greenslade,Thomas B. Jr. “Nineteenth-Century Measurements of the Mechanical
Equivalent of Heat.” Phys. Teach., 40, 243-248 (2002), Online at
Nobel Lectures, Chemistry 1901-1921, Elsevier Publishing Company, Amsterdam, 1966,
Online at
[1] Austin, Nancy Jo. “Specific Heat.” University of CentralArkansas, 2006. Online at
[2] Brown, Theodore & Eugene Lemay, Jr & Bruce Bursten. Chemistry the Central Science, 10th ed. (Pearson Education, 2006).
[3] Foley, Robert. “Specific Heat Capacity.” University of Wisconsin, 2006. Online at
[4] Greenslade, Thomas B. Jr. “Nineteenth-Century Measurements of the Mechanical Equivalent of Heat.” Phys. Teach., 40, 243-248 (2002), Online at Thermodynamics/Calorimeter/Calorimeter.html
[5] Nobel Lectures, Chemistry 1901-1921, Elsevier Publishing Company, Amsterdam, 1966, Online at
[6] Brown, Theodore & Eugene Lemay, Jr & Bruce Bursten. Chemistry the Central Science, 10th ed. (Pearson Education, 2006).
[L1]Cite any source you use in this section.
[L2]AKA the materials and Methods section. You can also write the methods/procedure in numbered step format.
[L3]AKA the results section. Keep it organized and neat.
[L4](Some lab reports will have questions, if they do they go here)
[L5]Remember no personal pronouns in the last two sections.