8 51 Am Tue Jun 7 Done 83 A Comparing Heats Of Combustion Of A Series Of Linear Alcohols Docx Comparing The Heat Of Com 1 (61.29 KiB) Viewed 56 times
8 51 Am Tue Jun 7 Done 83 A Comparing Heats Of Combustion Of A Series Of Linear Alcohols Docx Comparing The Heat Of Com 2 (44.55 KiB) Viewed 56 times
8:51 AM Tue Jun 7 Done 83% A Comparing Heats of Combustion of a Series of Linear Alcohols.docx Comparing The Heat Of Combustion of Alcohols In this lab you will compare the molar heats of combustion of several alcohols. Lab Design: To accomplish this the researcher has placed a known amount of water into a calorimeter Samples of each of the alcohols are burned and the rise in the temperature of the water is measured. Once the data is processed you will compare the heats of combustion of each of the alcohols and create a plot of the heat of combustion versus the number od carbons in the alcohols. You will need to create a table to record your data. This should be well organized and clearly labeled. You will need space to record the initial and final weighs of the spirit burners and the initial and final temperatures for the water in each calorimeter. It might help to watch the video once as a dry run and then again to be sure you have the data you need. From these observations you will need to first calculate the mass of each alcohol burned and the change in temperature of the water in each calorimeter. With these initial calculations, you will be able to then calculate the heat of combustion for each reaction and then the molar heat of combustion for each alcohol Data Calculations: The assumption you are making is that all the heat from burning the alcohol is transferred to the water in the calorimeter. So, for the reaction DH-m.c.AT. You may remember from general chemistry that this is the specific heat equation. Where DH is reported in joules m is the mass of the water e is the specific heat lig - °C, (water's specific heat is 4.18 J/g °C) AT is in °C Step 1: Calculate the mass (in grams) of water used, density of water = 1.0 g/mL. Step 2: Calculate the thermal energy (in Joules) added to heat your water. It took energy to heat your water. You can determine it by multiplying the mass of your water times 4.18 J/g °C (the specific heat of water) times the water temperature difference. Step 3: Now calculate your final heat of combustion (in Joules/gram). This is done by dividing the thermal energy to heat your water by the mass of fuel you used to heat the water. Heat of combustion should be given in kJ/g Step 4: Calculate the molar heat of combustion (answer should be in kJ/mole). Of course, you will need to figure out how many moles of alcohol burned in een TERCHOD AD pen spare that to AH/mole
8:51 AM Tue Jun 7 Done 83% Comparing Heats of Combustion of a Series of Linear Alcohols.docx Step 3: Now calculate your final heat of combustion (in Joules/gram). This is done by dividing the thermal energy to heat your water by the mass of fuel you used to heat the water. Heat of combustion should be given in kJ/g Step 4: Calculate the molar heat of combustion (answer should be in kJ/mole). Of course, you will need to figure out how many moles of alcohol burned in each reaction and then scale that to AH/mole Once you have accomplished this create a graph of AH versus number of carbons. This should be done in Excel and the graph should be completely labeled. Add a linear trend line to determine the slope of your line. What is the interpretation of this slope? Your lab write should include the following Abstract: What was done? How was it done? What did you leam? (250 words or less Introduction: Explain what you are doing and the reasons/ concepts behind the design. Also include A balanced equation for the complete combustion reaction of each alcohol Data: Present your data in a well organized table Calculations: Use your data to calculate the molar heat of combustion of cach alcohol, Analysis: Graphs go here alone with your analysis and interpretation Also look up the actual values for the heats of combustion of these alcohols. (You want the heats of combustion, not to be confused with the heats of formation.) Compare this data with the data from this experiment. Offer some explanation for any variation. Reflections: What procedures in this investigation could lead to errors? How would each emor affect your data? Be specific. How might the design or execution of this experiment be improved?
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