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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: Wateriswet1212 on November 11, 2014, 11:47:15 PM

Title: I really such at calorimetry.
Post by: Wateriswet1212 on November 11, 2014, 11:47:15 PM

The following substances undergo complete combustion in a bomb calorimeter. The bomb calorimeter assembly (including the water) has a heat capacity of 4.881 kJ/degrees C. In each case, what is the final water temperature if the initial water temperature is 24.62 degrees C.

a. 0.5187 grams of cyclohexanol (C6H12O)
    heat of combustion = -3727 kJ/mol.

So I tried setting up a proportion to get the q(rxn) -3727/1=x/.00518 so the q(rxn) would be -719647 kJ but I don't know what to do form there.

I feel like this should be really easy but I just can't wrap my head around it. Any help would be appreciated.

The correct answer is 28.58 degrees C.

Title: Re: I really such at calorimetry.
Post by: sjb on November 12, 2014, 02:25:02 AM

Quote from: Wateriswet1212 on November 11, 2014, 11:47:15 PM

The following substances undergo complete combustion in a bomb calorimeter. The bomb calorimeter assembly (including the water) has a heat capacity of 4.881 kJ/degrees C. In each case, what is the final water temperature if the initial water temperature is 24.62 degrees C.

a. 0.5187 grams of cyclohexanol (C6H12O)
    heat of combustion = -3727 kJ/mol.

So I tried setting up a proportion to get the q(rxn) -3727/1=x/.00518 so the q(rxn) would be -719647 kJ but I don't know what to do form there.

I feel like this should be really easy but I just can't wrap my head around it. Any help would be appreciated.

The correct answer is 28.58 degrees C.

How many moles of cyclohexanol have you used?

Title: Re: I really such at calorimetry.
Post by: Wateriswet1212 on November 12, 2014, 09:48:55 AM

Quote from: sjb on November 12, 2014, 02:25:02 AM

Quote from: Wateriswet1212 on November 11, 2014, 11:47:15 PM

The following substances undergo complete combustion in a bomb calorimeter. The bomb calorimeter assembly (including the water) has a heat capacity of 4.881 kJ/degrees C. In each case, what is the final water temperature if the initial water temperature is 24.62 degrees C.

a. 0.5187 grams of cyclohexanol (C6H12O)
    heat of combustion = -3727 kJ/mol.

So I tried setting up a proportion to get the q(rxn) -3727/1=x/.00518 so the q(rxn) would be -719647 kJ but I don't know what to do form there.

I feel like this should be really easy but I just can't wrap my head around it. Any help would be appreciated.

The correct answer is 28.58 degrees C.

How many moles of cyclohexanol have you used?

.00518

Title: Re: I really such at calorimetry.
Post by: DrCMS on November 12, 2014, 10:36:50 AM

OK
1) how much energy do you get from the combustion of that many moles of cyclohexanol?
2) how much does that amount of energy raise the temperature of the calorimeter by?
3) what is the final temperature going to be given you know the starting temperature?