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Topic: Calorimetry  (Read 10879 times)

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Offline highschoolhelp16

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Re: Calorimetry
« Reply #15 on: April 15, 2012, 09:12:23 PM »
or is 9.86kJ the energy required to convert the 100g from solid to boiling point?

Offline UG

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Re: Calorimetry
« Reply #16 on: April 15, 2012, 09:14:59 PM »
No, 9.86 kJ is the energy needed to convert solid to liquid. Now you need to find how much energy is needed to transform the liquid into gas, because the question states that you want gaseous methanol. I have stated in my previous post how to do this.

Offline highschoolhelp16

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Re: Calorimetry
« Reply #17 on: April 15, 2012, 09:19:01 PM »
so the energy needed to convert from liquid to gas should be 110.136kJ?

Offline UG

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Re: Calorimetry
« Reply #18 on: April 15, 2012, 09:20:25 PM »
Yes (I am assuming you used the correct Hvap value)

Offline highschoolhelp16

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Re: Calorimetry
« Reply #19 on: April 15, 2012, 09:21:46 PM »
so do I need to put these values into my original equation of (100.0g)(.424cal/gc)(337.2k-175.5k)? or was that just completely off track?

Offline UG

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Re: Calorimetry
« Reply #20 on: April 15, 2012, 09:23:28 PM »
Yes you add the two values onto whatever you got from (100.0g)(.424cal/gc)(337.2k-175.5k) but you will need to change the units so that they match, either convert kJ into cal or vice versa.

Offline highschoolhelp16

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Re: Calorimetry
« Reply #21 on: April 15, 2012, 09:28:54 PM »
So if I get 3,684.58kJ from that equation, I should add 110.14kJ, and 9.86kJ, to get 3768.58kJ total.

Offline UG

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Re: Calorimetry
« Reply #22 on: April 15, 2012, 09:37:44 PM »
So if I get 3,684.58kJ from that equation
That seems to be an awfully large number...(check again) but if thats what you got, then adding 110.14 kJ and 9.86 kJ onto it is correct.

Offline highschoolhelp16

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Re: Calorimetry
« Reply #23 on: April 15, 2012, 09:40:52 PM »
could the equation be wrong. Im using q=mass*specific heat*delta T

Offline UG

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Re: Calorimetry
« Reply #24 on: April 15, 2012, 09:46:15 PM »
Well initally you got 6,877.28 cal, how many kJ is this?

Offline highschoolhelp16

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Re: Calorimetry
« Reply #25 on: April 15, 2012, 09:48:53 PM »
I got 3684.58 kJ

Offline UG

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Re: Calorimetry
« Reply #26 on: April 15, 2012, 10:01:14 PM »
In thermochemistry 1 calorie is about 4.184 J

http://en.wikipedia.org/wiki/Calorie

Offline highschoolhelp16

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Re: Calorimetry
« Reply #27 on: April 15, 2012, 10:03:41 PM »
so 28.75kJ?

Offline UG

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Re: Calorimetry
« Reply #28 on: April 15, 2012, 10:08:07 PM »
Well going by your equation (100.0g)(.424cal/gc)(337.2k-175.5k), this should give 6856.08 cal. Then converting to kJ gives 28.69 kJ. But maybe you did some rounding somewhere.

Offline highschoolhelp16

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Re: Calorimetry
« Reply #29 on: April 15, 2012, 10:11:13 PM »
You're right I made a calculation error. so 28.69kJ is the heat required to convert 100.0g of solid methanol to gaseous methanol?

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