Engineering Heat Report Essay

HEAT AND SPECIFIC HEAT CAPACITY ENB130 SEM 1 PRAC 2 JOSHUA KEARNEY; n8351937, PARTNER: Mike Lagendyk 2011 Joshua Kearney Queensland university of Technology 5/16/2011 H8 HEAT AND SPECIFIC HEAT CAPACITY ENB130 SEM 1 PRAC 2 JOSHUA KEARNEY; n8351937, PARTNER: Mike Lagendyk 2011 Joshua Kearney Queensland university of Technology 5/16/2011 Aim To measure the Latent heat of fusion of ice - Engineering Heat Report Essay introduction. Introduction/ Background Within this experiment all units implemented were converted to SI units and all data was recorded to four significant digits. Therefore, all distances were measured in metres, time in seconds and weight in kilograms.

In order to determine the Latent heat of fusion of ice the following equations were utilized: * Q=miLf [1] * Q=mc? T [2] * Qi= mFLF+micw? T i [3] * Qw+Qc=mwcwT2-T1+mccc(T2-T1) [4] * miLf+micw? Ti+mwcwT2-T1+mcccT2-T1=0 [5] * LF = mwcwT2-T1+mcccT2-T1-micw? Timi [6] * c = Qm? T [7] * mmcmTf-Tm+mwcwTf-Tw+mcccTf-Tc=0 [8] * cm= (mccc+mwcw)(Tf-Tw)mm(Tm-Tf) [9] Notation used in this report: * C = Specific Heat * m = mass * T = temperature * Q = Energy * Lf = Latent heat of fusion Experimental Method: PART A – Latent Heat 1. The calorimeter and stirrer were weighed by themselves.

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The calorimeter was then half filled with water and weighed again. Calculations were then conducted to find the mass of water inserted. 2. Diagram of a Calorimeter, Retrieved from: http://honolulu. hawaii. edu/distance/sci122/Programs/p21/p21. html Diagram of a Calorimeter, Retrieved from: http://honolulu. hawaii. edu/distance/sci122/Programs/p21/p21. html The timing procedure labelled ‘Apparatus and Description’, located in the appendices, was followed, recording the temperature before, during and after the ice was added at 30 second intervals.

The ice-water mixture was also stirred slowly and continuously throughout the experiment. The set-up of the calorimeter can be seen in the diagram to the right. 3. The mass of the ice added to the calorimeter was then determined by weighing the calorimeter after the ice had finished melting. The difference in weight from before and after the experiment was understood to be the mass of the ice. 4. A graph was then plotted for the test showing the temperature versus time and an estimated temperature drop due to the ice being added was recorded. . Equation 6 was then used along with the Specific heat of water and copper in order to calculate the Latent heat of fusion of ice. PART B – Specific Heat Capacity 1. Enough tap water was added to the calorimeter so that it just covered the thermometer bulb. The calorimeter was then weighed. The mass of water inserted was then calculated using the previous weight of the calorimeter. 2. The temperature of the calorimeter and water was recorded. 3. Diagram of Electronic hot plate used in experiment, Retrieved from: http://www. humboldtmfg. om/c-8-p-498-id-8. html Diagram of Electronic hot plate used in experiment, Retrieved from: http://www. humboldtmfg. com/c-8-p-498-id-8. html The metals being used within the experiment were then weighed and immersed in continuously boiling water until it was believed the metals were at approximately the same temperature as the boiling water. The diagram of the heat plate located to the right was used to heat the water and metal. 4. The heated metal was then quickly and carefully transferred to the calorimeter using the tongs supplied. 5.

The water within the calorimeter was continuously stirred and the maximum temperature was recorded. 6. Steps 1 to 5 were then repeated for the other 2 samples of metal. 7. From the data recorded the specific heat of one metal was calculated. Results Table of masses (for calculations): ITEM| MASS (g)| Wooden Lid| 22. 80| Calorimeter, Stirrer and Lid| 140. 5| Calorimeter, Stirrer, Lid and Water| 223. 0| Calorimeter, Stirrer, Lid, Water and Melted Ice| 236. 7| Copper| 117. 8| Water| 82. 50| Ice| 13. 70| Results of PART A – LATENT HEAT: TIME (s)| TEMPERATURE (?

C)| 0| 21. 2| 30| 16. 9| 60| 12. 2| 90| 9. 50| 120| 8. 40| 150| 8. 20| 180| 8. 30| 210| 8. 30| 240| 8. 30| Results of PART B – SPECIFIC HEAT CAPACITY: | STEEL| BRASS| ALUMINIUM| Mass of Wooden Lid (g)| 22. 70| 22. 70| 22. 70| Mass of Calorimeter, stirrer and lid (g)| 140. 5| 140. 5| 140. 5| Mass of calorimeter and stirrer (g)| 49. 10| 49. 10| 49. 10| Mass of calorimeter, stirrer, lid and water (g)| 146. 6| 146. 6| 146. 6| Mass of water (g)| 6. 100| 5. 800| 5. 200| Temperature of Calorimeter and water (? C)| 19. 00| 24. 10| 26. 40| Mass of material (g)| 17. 0| 30. 80| 10. 30| Max. Temp of water and calorimeter (? C)| 22. 90| 27. 10| 29. 70| The specific heat capacity of steel was calculated and produced a value of JKg. °C . Data Analysis In order to effectively analyse the data collected two sets of calculations were conducted. The first for the Latent heat of fusion required to melt ice and the second to determine the heat capacity of one of the metals tested. In order to calculate the Latent heat of fusion the following equation was used: LF = mwcwT2-T1+mcccT2-T1-micw? Timi Lf= 0. 08? 4. 18? 103? 8. +0. 12? 0. 38? 103? 8. 7+(0. 0137? (4. 18? 103)? 8. 4)0. 0137 Lf=2909. 28+1440. 72+481. 030. 0137 Lf=3. 71? 105JKg.? To calculate the heat capacity of steel the following calculations were conducted: METAL 1 cm= (mccc+mwcw)(Tf-Tw)mm(Tm-Tf) cm= 0. 1178? 0. 38? 103+0. 061? 4. 18? 103? (295. 9-290)0. 017? (373-295. 9) cm=[44. 46+254. 98]? 5. 91. 3107 cm=1. 35? 103JKg. K METAL 2 cm= (mccc+mwcw)(Tf-Tw)mm(Tm-Tf) cm= 0. 1178? 0. 38? 103+0. 061? 4. 18? 103? (300. 1-297. 1)0. 031? (373-300. 1) cm=[44. 46+254. 98]? 3. 02. 259 cm=0. 397? 103JKg. K METAL 3 m= (mccc+mwcw)(Tf-Tw)mm(Tm-Tf) cm= 0. 1178? 0. 38? 103+0. 052? 4. 18? 103? (302. 7-299. 4)0. 0103? (373-302. 7) cm=[44. 46+254. 98]? 3. 30. 7241 cm=1. 19? 103JKg. K Experimental Discussion Question 1: If the ice was not dry, how would the result for the latent heat, Lf, be affected? Within the experiment conducted, a certain variable has been questioned; will the state of the ice before the experiment effect the latent heat of fusion? The answer is simple; if the ice was not dry at the beginning of the experiment the results would be inaccurate to a certain degree.

This is because the water covering the outer surface of the ice cube has a higher thermal conductivity value than that of air; causing it to melt at a faster rate than a dry ice cube would [1]. According to ‘The Engineering Toolbox’, water is a better thermal conductor than air with a thermal conductivity value of 0. 58 as opposed to 0. 024 for air at 25 ? C [1]. From this comparison of thermal conductivity it can be understood that when wet, an ice cube will melt at a much higher rate than if it were dry, lowering the Latent heat of fusion.

Within this report two principals were tested, these being the Latent heat of fusion of ice and the Specific heat capacity of three different metals. These principals were tested using simple methods which were easily conducted. However, there were certain limitations within these methods that lead to a measure of uncertainty and error within the values calculated. Within the first experiment, in which the latent heat of fusion of ice was tested, a value of 3. 71? 105JKg. was calculated. This value is relatively close to the accepted value of 3. 34 x 105J/Kg with only 0. 7×105 J/Kg in error [3]. This value can be contributed to a few variables which, without the right equipment were quite hard to bypass. The first variable affecting the accuracy of this test was the accuracy and precision of the equipment used. The thermometer was not tested beforehand to ensure it was working properly, nor were the scales calibrated to ensure the measurements they were reading were precise. Also, the contents of the calorimeter had to be constantly stirred to ensure there was an even distribution of temperature change throughout the entire content of the water.

It cannot be guaranteed that this mixture was evenly stirred and therefore, the actual temperature recorded may have been slightly inaccurate as a result of this. Another limiting factor within this experiment is the efficiency of the calorimeter used. The calorimeter used consisted of a copper cup and Styrofoam holster, this apparatus would not be 100% effective in ensuring there was not heat loss or gain during the experiment; this factoring producing more inaccuracies and error within the value calculated. The final identified limiting factor of this experiment was the ice used within the test.

It cannot be certain that the ice used was completely dry when dropped into the calorimeter and therefore may have already lost some of the energy it has previously possessed. All of these factors add up to create quite a large amount of inaccuracy. Therefore, it can be stated that an effective and high quality test was produced with the equipment provided and an overall accurate value for the latent heat of fusion of ice was recorded. The second experiment conducted was a test to determine the specific heat capacity of three different materials with the ultimate goal of identifying what these three metals were.

For these metals a heat capacity was calculated, these values being: * Metal 1 – 1. 35? 103JKg. K * Metal 2 – 0. 397? 103JKg. K * Metal 3 -1. 19? 103JKg. K From these values the metals were identified based on weight, specific heat capacity and appearance. The first metal was identified as aluminium, the second as copper and the third as stainless steel. Some of the vales collated in the experiment were very inaccurate and were identified based on appearance and density rather than the heat capacity. Metal 1 produced a specific heat capacity of 1. 35? 103JKg.

K and was identified as Aluminium with a local value of 0. 90? 103JKg. K; the value calculated is significantly inaccurate. Metal 2 produced a specific heat capacity of 0. 397? 103JKg. K and was identified as Copper with an accepted heat capacity value of 0. 38? 103JKg. K; a rather accurate calculation. Lastly, metal 3 had a calculated heat capacity value of 1. 19? 103JKg. K and was identified as Stainless Steel with a local heat capacity value of 0. 510? 103JKg. K ; this identification made by materialistic properties rather than the value calculated [2].

The inaccuracies present can be taken into account for by assessing the variables involved in this experiment. Within this experiment there were many variables identified and also a few errors which led to the vast number of inaccuracies within the values produced. One of the most significant errors within this test was that the water used was not changed after each metal was tested and the maximum temperature of the water from the previous test was recorded as the initial for the metal tested after. This alone shows how inaccurate this data, yet, there are even more factors which contributed to these inaccuracies.

The accuracy of the equipment used was a limiting factor of this experiment. This was because none of the equipment was tested to ensure that each piece of equipment was working effectively and precisely. Another limiting factor of this experiment was the calorimeter used. This apparatus was made up of a Styrofoam holster and copper cup and was not effectively designed. This calorimeter would not have been efficient in controlling external heat loss or gain and therefore may have proved to cause inaccuracies with the results acquired.

Another factor identified was whether or not the metal was really at 100? C when extracted from the boiling water. Although the water was boiling, it was unknown how long the metal should have been left in the water and therefore the actual temperature of the metal was unknown and was just assumed to be the same as the water. The last variable identified within this experiment was the energy loss when the metal was transferred from the boiling water to the calorimeter.

This process would have taken a minimum of 10 seconds to complete, and even though this is only a small period of time, an amount of heat energy would have been lost; contributing to the inaccuracies present within the values collated. References: * [1]The engineering toolbox, 2011, Thermal Conductivity of some common materials and gases, retrieved from: http://www. engineeringtoolbox. com/thermal-conductivity-d_429. html * [2] Direct Delta, 2011, Specific Heat Capacity, Retrieved from: http://www. diracdelta. co. uk/science/source/s/p/specific%20heat%20capacity source. html * [3] H8 Latent heat and specific heat capacity information sheet. Retrieved from: QUT Blackboard Appendices Real World Context Report The topic of thermodynamics is a vast topic covering many areas of our everyday lives. The two topics of thermodynamics which were studied within this report are latent heat of fusion and the specific heat capacity of metals. Hot water heating system – Retrieved from: http://fallonservices. com/_blog/Handy_Hints/post/How_does_a_Heat_Pump_Hat_Water_System_work/ Hot water heating system – Retrieved from: http://fallonservices. om/_blog/Handy_Hints/post/How_does_a_Heat_Pump_Hat_Water_System_work/ The specific heat capacity of metals is defined by The Engineering Toolbox as, ‘Specific heat is the amount of heat required to change temperature of one kilogram of a substance by one degree’[1]. By this definition there are endless real world applications for this aspect of thermodynamics, the most predominant being hot water systems. The coils in hot water systems have a known heat capacity in order to minimise the amount of energy used when heating the water.

They do this by implementing a metal coil, as seen in the diagram to the left, which takes the least amount of energy to heat up and maintains this heat the best also. In order to do such a thing the producers of this device must find a metal with the lowest heat capacity rating and therefore implement the concept studied within this experiment. Steam Powered Engine, retrieved from: http://science. howstuffworks. com/transport/engines-equipment/steam1. htm Steam Powered Engine, retrieved from: http://science. howstuffworks. com/transport/engines-equipment/steam1. tm Latent heat of fusion is defined by B. M. Odom as, ‘The latent heat of fusion represents the energy required to melt one gram of a material when its temperature is already at the melting point’ [2]. From this definition one key real world example of this concept was understood to be global warming. This issue affects the entire world and one of the biggest factors involved with this is the melting of the ice caps and icebergs in the arctic and Antarctic [3]. This is such a threat to the human population because as temperatures around the world slowly rise more and more of this energy is

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