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Homework Help: Calculate the molar heat of combustion of anthracene

  1. Nov 16, 2017 #1
    1. The problem statement, all variables and given/known data
    A 2.56g sample of anthracene, C14H10, was burned to heat an aluminum calorimeter (mass=945 g). The calorimeter contained 1.50 L of water with an initial temperature of 20.5 C and a final temperature of 34.3 C.

    a) Calculate the molar heat of combustion of anthracene.

    2. Relevant equations
    n=m/M
    Q=mcΔt

    3. The attempt at a solution

    My work:

    https://i.imgur.com/WYNiBRD.png

    WYNiBRD.png

    https://i.imgur.com/LNjq3CG.png

    LNjq3CG.png

    Did I do the steps correctly? Did I include the correct sig figs? How would I convert my final answer to J/mol instead of kJ/mol? Thanks! If you need me to type out the work instead of using pictures I can!
     
  2. jcsd
  3. Nov 17, 2017 #2

    mjc123

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    Science Advisor

    Your procedure looks correct (I haven't checked the arithmetic). Your given data are all to 3 sig figs, so your answer should be given to 3 sig figs. (You were right to use more sig figs in the intermediate calculations, but your final answer should be to 3 s.f.)
    After getting so much right, you can't convert kJ to J?
    PS Thanks for offering to type it out; many people don't and post illegible scribble, but your pictures are very clear and legible.
     
  4. Nov 17, 2017 #3

    Borek

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    Staff: Mentor

    That's preferable (check the forum rules) - not only it usually makes things easier to follow, it also makes it possible to quote the solution and mark places were something is wrong.
     
  5. Nov 17, 2017 #4
    Thanks! I ended up figuring out how to convert kJ to J... It was very easy :biggrin:
     
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