Chelsea+and+Ashley's+Calorimetry+Lab

=Lab Report Title= October 27, 2009


 * Participants**: Ashley Murphy, Chelsea Hart
 * Purpose**: The purpose of this lab is to identify a known metal by its specific heat and to measure the latent heat of fusion for paraffin.


 * Brief Description of Experiment**: The calorimeter is a metal container with another smaller container inside the larger one. The inner container has a flat, circular stirring rod with a handle that goes through the lid. The lid has a small hole for the stirring rod, and a hole with a stopper inside it. The stopper also has a hole where the thermometer is inserted. Its design attempts to create a closed system by using the outer container to stop the air from affecting the temperature inside. Also by keeping the cover closed tight to protect the contents to stop outside forces from affecting the results.
 * Data Analysis**: The data was collected by using the calorimeter and using LoggerPro to collect the temperature from the thermometer. The calorimeter's inner container was filled ¾ of the way full with water, and the temperature was recorded for about 10-15 seconds. Then a metal cylinder was added to the water, and the top was quickly replaced. The temperature was then taken until it began to plateau, and for about 15 seconds after. The data was analyzed to find the heat capacity and latent heat of fusion of paraffin using the **Q**//added// = (m*c*deltaT) + (m*c*deltaT) and **Q**//added// = (m*L) = (m*c*deltaT) + (m*c*deltaT)
 * Sample Calculations:**

Qlost = Qgained ||
 * ======//Conservation of Energy//====== || The heat lost is equal to the heat gained.
 * ======//Heat Capacity//====== || ======The heat added is equal to mass times heat capacity times the change in temperature.======

Qaddded = m*c*deltaT
||

Qadded = m*L ||
 * < //Latent Heat// ||< The heat added is equal to the mass times the latent heat.

The coefficient of static friction was determined to be 0.45. This was calculated from a measured angle using Newton's first law as desribed in the calculations.
 * Results:** The results of our analysis were that the specific heat of the metal was .373, and the metal was Gallium. The latent heat of fusion of paraffin is 94.09 J/g.
 * Lab Questions**:
 * 1) **In what ways did you attempt to make your results as accurate as possible? Describe how each way contributed to a more accurate result.** //Our attempts to make your results as accurate as possible were to only uncover the calorimeter when the initial temperature was being recorded, and only when the metal bad just been taken out of the water. This provides a more accurate result by reducing the effects of the air temperature on not only the cylinder, but also the water. While doing the paraffin, we had to hold our hands around the lid because the tube was a bit too big, so the heat could escape faster. Therefore, using hands as an insulator helps paraffin not be affected by outside temperatures, and to not let the heat escape and get a more accurate reading on the thermometer.//
 * 2) **In what ways does the calorimeter fail as a closed system? What mathematical effect on your result would these failures have?** //The calorimeter fails as a closed system because it has to open to incorporate the metal cylinder. It also has a hole for the stirring rod, but the rod cannot fill the hole completely, letting heat in or out. This changes the results bu the heat escapes faster from the system, this causes the temperature to decrease from what it would have been otherwise. Heat also escapes from the system from the cylinder escaping into the air when it's transferred to the calorimeter; affecting the amount of heat transferred to the water.//
 * 3) **Suppose you were asked to measure the latent heat of vaporization of water (the amount of heat required to turn liquid water into gas). You propose to do this by heating a bar of the metal used in this experiment to a very high temperature (500°C) and dropping it into a calorimeter with water initially at 95°C. Describe what you think will happen and what measurements you would need to make in order to calculate the latent heat. Approximate how much water would be turned to steam if the bar had a mass of 0.7kg and the final temperature of the 0.35kg of water in the calorimeter was 100C°.** //By dropping the bar into the calorimeter, it will cause the water to boil and begin to turn to steam. The measurements needed to determine the latent heat are the mass of the water, the calorimeter, and the bar of metal. Approximately 0.022 kg of water will turn to steam.//
 * Conclusion**: The experiment produced reproducible results; however, due to the loss of heat through misuse of the calorimeter, the results may be invalid/inaccurate. When using the calorimeter with the paraffin we lost heat due to the cover not fitting over the test tube. An improvement for this experiment would be a larger calorimeter, and/or a smaller test tube of paraffin. An easier way of transferring the paraffin tube and the metal cylinder into the calorimeter would make the experiment easier and safer.