Heat+of+Combustion+Project+Page

=Heat of Combustion Project Page Final= = =

Introduction
The purpose of this experiment is to determine the heat of combustion of three fuels using calorimetry. Heat of combustion is the caloric energy released during the chemical reaction combustion. Calorimetry is the measure of heat in chemical reactions, via a calorimeter. Calorimeters come in all shapes and sizes, ranging from expensive laboratory computers to insulated test tubes with a thermometer.

For this experiment, the fuel must undergo combustion. The heat released from the chemical reaction will be measured using a calorimeter. Typically, the heat released by the fuel will be measured by the change of temperature in another substance. For this experiment, we propose to heat a fixed amount of water using fixed amounts of different fuel, and using the change in temperature in the water, calculate the heat released by the fuel. The method will be further discussed in the calculations section.

After conducting the experiment we will be able to determine the calorific values for each specific fuel, and make observations based on our results.

Materials
The following is a list of the materials to be used in our experiment:


 * Fuel A - Paraffin Wax
 * Fuel B - Cooking Oil
 * Fuel C - Butane
 * Water
 * Bunsen burner
 * Glass beaker
 * Calorimeter
 * Safety goggles

Procedure

 * 1) Measure out 100mL of water into the smaller compartment in the calorimeter and determine temperature
 * 2) Place the Paraffin wax (tea candle) in the larger compartment
 * 3) Assemble calorimeter and light candle, leave gap for oxygen to keep the fuel burning
 * 4) Once all of the fuel has burned up, measure the temperature of the water again
 * 5) Record the change in temperature and calculate delta //t//
 * 6) Empty and clean the calorimeter
 * 7) Repeat steps 1 through 6 for butane
 * 8) Repeat steps 1 through 6 for cooking oil
 * 9) Replace all equipment and clean lab area

Safety Precautions

 * All hair must be tied back
 * Safety goggles must be worn
 * Extra caution must be used while handling thermometers
 * Caution to be used when handling the flame and combustible fuels
 * No food or drink during the course of the experiment

Data Table
//Fuel and Container// ||= **Final Mass (g)** //Fuel and Container// ||= **Starting Water Temperature (°C )** ||= **Final Water Temperature (°C )** ||
 * = **Fuel** ||= **Starting Mass (g)**
 * < Cooking Oil ||= 22.5 ||= 24.5 ||= 9.534 ||= 9.510 ||
 * < Paraffin Wax ||= 22.5 ||= 29.5 ||= 19.322 ||= 19.248 ||
 * < Butane ||= 22 ||= 39 ||= 210.443 ||= 210.170 ||

Calculations
Using the formula: Q = MCT, where Q = energy (heat released by the fuel), M = mass of water, C = specific heat of water (which is a constant) and t = the change of temperature with respect to time, the heating value of the fuel can be determined. Heating value is measured in terms of energy released over mass. Since Q is a measure of all the fuel, in order to find the calorific value of the fuel, the formula required is Q over X, where x is the mass of the fuel. (Note: all energy measured in Joules, and mass in grams.)

Mass of Paraffin Wax used: 19.322 - 19.248 = 0.074g Rise in temperature of water: 29.5 - 22.5 = 7 degrees
 * Paraffin wax**

Calorific value = [(100g)(7deg C)(1cal/gram)]/0.074g = 9459 cal = **9.459 kcal**

Mass of Cooking Oil used: 9.534 - 9.510 = 0.024g Rise in temperature of water: 24.5 - 22.5 = 2 degrees
 * Cooking Oil**

Calorific value = [(100g)(2degC)(1cal/gram)]/0.024g = 8333.33 cal = **8.333 kcal.**

Mass of Butane used: 210.443 - 210.170 = 0.273g Rise in temperature of water: 39-22 = 17 degrees
 * Butane**

Calorific Value = [(100g)(17degC)(1cal/gram)]/0.273 = 6227.1 cal = **6.227 kcal**.

Calorific Values
Paraffin wax: 9.459 kcal Cooking oil: 8.333 kcal Butane: 6.227 kcal

Conclusion
Combustion is a sequence of exothermic chemical reactions between a fuel and an oxidant accompanied by the production of heat or both heat and light in the form of either a glow or flames. In our experiment, we calculated the heat of combustion of three fuels using calorimetry. By following the procedure carefully, we were successfully able to determine the calorific values for Paraffin Wax, Cooking Oil and Butane. Despite the change of equipment (specifically, calorimeters) during the experiment, we obtained fairly accurate results for each of the fuels.

After analyzing the results, we found that out of the three fuels that went through combustion, the Paraffin wax had the highest calorific value (rather, released the most heat with respect to the total amount used) of 9.459 kcal. Although the Butane caused a significantly larger change in water temperature, a much larger amount of Butane was required to do so, compared to the Paraffin wax and cooking oil.

Calorimetry is a very practical branch of science. Larger companies use more sophistic machines to find which fuels would be more efficient for burning. This is important because efficiency is one of the virtues that companies strive for. It also makes it cost effective. Calories are also displayed on the side of food packages. These have to measured with a calorimeter. Calorimetry can be applied in many ways and it can have very far reaching effects.

Suggestions for Improving the Project
For this experiment, it was necessary to use two different calorimeters, because the butane lamp could not fit into the first calorimeter. Unfortunately, it was necessary to make a new calorimeter, which may not have been consistent in terms of thickness and insulation as the other calorimeter. It is possible that the calorific value may be inaccurate because of this inconsistency. Furthermore, the water we used was not well insulated either, only in a mere foam cup. Also, there are more accurate calorimeters that could be used. Furthermore, our results would be more accurate if we did the experiment several times, and then taken the average calorific value.

Sources of Error
During this experiment, there were many components that caused sources of error. The fuels that were used were paraffin wax, butane and cooking oil. The three fuels burned for different amounts of time, the wax for more than eight minutes and the cooking oil for less than a minute, for example. The original procedure for the experiment that we had deliberated upon had to be edited and revised to overcome the unforeseen inconsistencies in combustion time. The original procedure had measurements of the water temperature at 2, 4, 6 and eight minutes. This worked for the paraffin wax, however, when it came to the cooking oil this was not possible. The procedure was edited to simply allow the fuel to burn out and measure the end temperature once the entire combustion had been completed. During the course of this experiment, the group became aware that a main source of error could be the interchanging equipment. As different parts of the experiment were spread across a long period of time, there were often changes in our equipment. Different calorimeters and different thermometers were used in the different fuels. Also, a larger, homemade calorimeter was used to accommodate the large butane burner we had to use to accomplish the combustion of butane. The change in equipment made it more difficult to have reliable comparisons between the fuels.