Q: Please help answer question . The rest of the questions help give background.

Question

Q: Please help answer question . The rest of the questions help give background.

1) Given that Al burned in excess oxygen releases 31.1 kJ/g, how many kJ were released during combustion of your Al sample?-->sample of Al was 8.890 g so I mulipled 31.1 kj/1 g times 8.890 g=276.5 Kj

2) what is the value of the temperature difference, tmax-tinitial, for the calibration run using al metal? 575.5-20.9=554.6

3) using the measured temperature change of the calibration run with Al, and the Kj of heat generated that you computed above, what is the response factor of the calorimeter in c/kj? 554.6/276.5=2

4) determine the energy released by combustion of the unknown organic compound. enter below the measured temperature change, tmax-tinitial for your data set unknown. 208-21.1=186.9

5) With the response factor of the calorimeter that you calculated, and the measured temperature change for the unknown run, calculate the heat (in Kj) released during the combustion of the unknown. 186.9/2=93.45 kJ

***question I need help with**** 6) Using the number of grams of the unknown compound added to the calorimeter and the calculated KJ of heat released, express the heat of combustion of the unknown compound in kJ/g?? the number of grams of the unknown compound was 10.003 g

Explanation / Answer

93.45 kJ/10.003 g = 9.317 Kj/g or 9.32 Kj/g

1st three set you have done calibration of calorimeter

(1) you put Al inside and burnt it and knowing tthe heat of combustion of Al you obtained the total heat released.
(2)now you found total temperature change
(3)you found how much Temperature(oC ) is changing per Kj heat change in oC/Kj or no. of temperature in degree change per unit Kj
(4) you found change in temperature of unknonown sample
(5) you already got from previous experiments how much change in oC occurs per Kj change in energy(from 3) and you have oC change that is 186.9 oC and 2 oC/kj (from 3) and got heat released
(6) you know the heat evolved for 10.003g sample is 93.45 kJ and to get it per gram you just need to divide it by 10.003g

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