Miss KB 10/18/10

Specific Heat Investigation

A.  Purpose:

This experiment is about the specific heat of a metal object. In this experiment, two Styrofoam cups are used to make a calorimeter, in which room-temperature water is placed. A thirty or more gram metal object is placed inside a boiling pot of water for five minutes. After heating up the metal object, the object is place directly into the calorimeter and the temperature is recorded regularly. The data is recorded by the student, or scientist. By using the formulas learned in chemistry, the specific heat of a metal object can be found.

All element are classified as metals, metalloids, and nonmetals (Mebane), however, one of these elements is set apart from all of the other elements. Metal is an earthly substance that is very useful and important. Metal is a natural material that is strong, ductile, and malleable (Kjelle). Metals are strong because of the chemical makeup that metal obtains, thus metal is used in many buildings and bridges acting as a support. Metal is ductile which means that metal can be pull into a very thin string of wire. The malleability of metal is the most unique characteristic of metal, metal can be formed, molded, melted, and or flattened. Metal also has luster, which means that metal has a certain specific shine that sets metal apart from the other elements. Metal has a high electrical and thermal conductivity because of the electrons, often called a valence, that flow freely throughout the solid (Krebs). Metal can be classified as ferrous or nonferrous. Metal that contains fifty percent or less of iron is considered to be ferrous, as long as the metal has more iron than any other metal. A metal is considered to be nonferrous if it contains less iron than any other metal. Metal is a very intricate substance, which makes metal very useful for various jobs.

Substances warm up or cool down when heat is added or taken away. Measuring the amount of heat that one gram of a substance requires to warm up or cool down by one degree Celsius; this number is useful for comparing the heat capacities of different metals. The number is called the specific heat of the metal. Specific heat is necessary because specific heat tells how easily a substance can be heated. The equation for used for finding the temperature change in an object is: q = m x c x delta T. In this equation "q" stands for the temperature change in the equation. The "m" stands for the mass of the object. The "c" stands for the specific heat of the object. The "delta T" represents the change in the unknown temperature (Wile). This equation can also be modified to fit the needs for finding the specific heat: c = q / m x delta T.

The experiment hopes to show how to correctly find the specific heat of an unknown metal. By using the formula for finding specific heat (q = m x c x delta T), this experiment hopes to give experience on working with calculations in chemistry. This experiment also hopes to show how to make and use a calorimeter made out of simple household objects. Finally, this experiment hopes to show how a calorimeter works, as well as, how helpful this device is in chemistry.  

This topic is of interest to science because learning the specific heat of metals is very important. Metal is used for so many different things in the world today, whether in structures, locomotive purposes,  or simple household items. There always comes a time when the ability of certain kinds of metals needs to be tested for specific uses. For example, in cookware metal is put stress each time a frying pan is used, and if tests were not made for how fast the metal could be heated up evenly, the food that the person is cooking could burn very easily. Therefore without finding out how the metal heats, the world could be doomed to burnt crusty food. Thankfully, finding the specific heat of the metal has proven effective. Scientists use those formulas to find the specific heat of other metals that are needed for specific purposes for the advancement of modern technology.

Hypothesis: If the formulas for finding specific heat are remembered correctly, then the specific heat of the metal object will be found without error.

B.  Equipment:  (5 points possible)

1.  A calibrated Thermometer.
2.  A scale that reads mass (preferably in grams).
3.  Two Styrofoam cups.
4.  Boiling water (in either a pot or a beaker).
5.  A hunk of metal that has mass of at least 30 grams (a lead sinker or a very large steel nut, for example).
6.  Kitchen tongs.
7.  Safety goggles.
8.  A calculator (if needed).
9.  Notebook (for recording data).

C.  Procedure:  (5 points possible)

1.  Heat water in a pan or beaker until the water is boiling vigorously.
2.  While waiting for the water to boil, measure the mass of the metal with the scale. Remember to report the answer to one more decimal places than what is marked off by the scale.
3.  Once the water on the stove is boiling, drop the metal into the pot and let the metal sit for 5 minutes. 
4.  While the metal is heating, take the two Styrofoam cups and nest the cups one inside the other. The Styrofoam works as insulation for the calorimeter.
5.  Measure the mass of the calorimeter with your scale.
6.  After measuring mass, fill the calorimeter with about three-quarters full of room-temperature water.
7.  Measure the mass of the calorimeter again.
8.  Place the calibrated thermometer in the water for about 3 minutes. Use the calibration to correct any errors in the thermometer. 
9.  Once the metal has been boiling for 5 minutes, quickly pull out the metal from the boiling water using the kitchen tongs. Transfer the metal to the calorimeter.
10.  Stir the water carefully with the thermometer and check the temperature periodically. Read and record the temperature of the water, however do not pull the thermometer out of the water.
11.  Continue the process until the temperature stops increasing. Write down the final temperature.
12.  Determine how much heat the metal transferred to the water.  In this case, ignore the heat created by the calorimeter. Use the change in temperature in degrees Celsius, the mass of the water in grams, and the specific heat of water as 4.184 Joules/ (grams degrees C). This will put the answer in Joules. Be careful to use the correct number of significant figures when calculating the absorbed heat by the water.
13.  Since the calorimeter is ignored in the experiment, q calorimeter = 0. In the last step q water was calculated, so q metal can now be determined. The answer should come out as a negative number because heat was lost.
14.  Once q metal is calculated, calculate the specific heat of the metal. However, to complete the task, the mass and delta T needs to be found. The mass has already been measured, therefore calculate the difference between the initial heat and the final heat of the object to find delta T. The initial temperature of the metal was 100.0 degrees C and the final temperature of the metal was the same as the final temperature of the water. With these two temperatures calculate and find delta T. The number will turn out to be negative, which will cancel out the negative sign on the "q".
15.  Now that all of the parts of Equation 2.3 are found, plug in the information and find the specific heat of the metal. Be sure to keep track of the significant figures in the problem.
16.  The specific heat of the metal should turn out to be less than 1 Joules/ (grams degrees C).
17.  Clean up any mess from completing the experiment.

D.  Observations:  (10 points possible)

1.  The bolt had a mass of  99.5 grams and was placed gently into the pot of boiling water.
2.  The Styrofoam cups, or calorimeter, had a mass of 7.5 grams. The cups held 20 ounces and were white.
3.  When the water was added to the calorimeter, which was left on the scale, the weight fluctuated violently and quickly settled down to be about 232.5 grams.
4.  The temperature of the room-temperature water inside the calorimeter was 20.8 degrees C.
5.  The water was boiling lightly and had small bubbles forming on the bottom of the pot.
6.  After the five minutes were up, the bolt and the boiling water were the same temperature, which was 100.0 degrees C.
7.  The bolt was taken out of the boiling water and was placed into the calorimeter easily with no error.
8.  The first recorded measurement of the calorimeter with the bolt was 22.4 degrees C.
9.  The second recorded measurement of the calorimeter was 23.9 degrees C.
10.  After the temperature stopped increasing, the final recorded temperature for the calorimeter was taken and was about 23.9 degrees C.
11.  After all the data was collected, the calculations to find the specific heat of the metal were started.
12.  The first step in finding the specific heat was to find the heat gained by the water. Equation 2.3 (q = m x c x delta T), from the Chemistry textbook, was used to begin the calculations:

q water = mass x specific heat x delta T
q water = (225.0 grams) (4.184 Joules/grams degrees C) (24.0 - 20.8 degrees C)
q water = (225.0 grams) (4.184 Joules/grams degrees C) (3.2 degrees C)
q water = 3010 Joules  or  3.01 x 10 ^ 3 Joules

13.  After the gained heat was found, this information was used to fill in the formula to find the specific heat of the metal. Equation 2.3 (q = m x c x delta T), from the Chemistry textbook, was also used to solve the problem, but was slightly modified to solve for specific heat:

specific heat = q metal / mass x delta T
specific heat = 3010 Joules/(99.5 grams) (100.0 - 24.0 degrees C)
specific heat = 3010 Joules/(99.5 grams) (76.0 degrees C) 
specific heat = 3010 Joules/7562 grams degrees C
specific heat = 0.398 Joules/grams degrees C  or  3.98 x 10 ^ -1 Joules/grams degrees C

14.  All of the calculations were completed with a Texas Instruments TI-30x calculator.

E.  Conclusions:  (10 points possible)

The hypothesis was, "If the formulas for finding specific heat are remembered correctly, then the specific heat of the metal object will be found without error." In this experiment, the hypothesis was supported by the data collected. The formulas for specific heat were memorized, that made it easier to complete the calculations. The data collected from completing the experimental portion of the project was a vital role in finding the specific heat. Also, a calculator was used to prevent mathematical errors. However, a tiny mistake while writing down the data for the specific heat calculation messed up the entire problem; because of this, the whole problem had to be erased and started from the beginning. As humans we are born imperfect and are going to make mistakes. However, the hypothesis does apply as a true statement as long as the data is entered into the formula correctly.

There are several ways that the experiment can be improved. When the thermometer was calibrated, the thermometer was discovered to be about eleven degrees off the actual temperature. By having a more exact thermometer, the experiment could be improved because the temperature could be found correctly and a lot easier. The Styrofoam cups could be replaced by a sturdier object. The cups could withstand heat, but are fragile and could be easily torn or ripped. Another way to improve this experiment would be to use a timer. The metal inside the boiling water was easy to forget about, thus the timer would help the student to remember to take the metal out after five minutes.

This experiment generated several ideas for further research. Using a different shape of the same type of metal would generate further research. By having a different amount of surface area, the specific heat of the object might not be the same. Also, after the experiment has been completed, look at the results of the specific heat of the object and try to figure out what type of metal the object is from the specific heat found by the calculations. One could also find out what type of metal the object is before completing the experiment and check the results found by completing experiment. By doing so, the specific heat calculated during the experiment can be verified by the actual specific heat, thus leaving less room for error.

F.  Bibliography:  (10 points possible)

Kjelle, Marylou Morono. The Properties of Metals. New York: Powerkids Press, 2007.

Krebs, Robert E. The History and of Our Earth's Chemical Elements: a reference guide. Westport, Connecticut: Greenwood Press, 1998.

Mebane, Robert C. Metals. New York: Twenty-first Century Books, 1995.

Rosenoff, Steven. Class Lecture. October 8, 2010.

Wile, Dr. Jay. Exploring Creation with Chemistry, Second Edition. CJK: Apologia Educational Ministries, 2009