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-   -   Erm.Enthalpy/heat capacity (https://www.askmehelpdesk.com/showthread.php?t=58658)

  • Jan 30, 2007, 11:19 AM
    Evil dead
    Erm.Enthalpy/heat capacity
    a) how much heat is required to raise the temperature of the water from 12oC to 22oC?
    (this is the amount of heat produced when 0.92g of ethanol burns)

    volume of water = 400cm3
    initial temperature of water = 12
    final temperature of water = 22
    mass of ethanol burnt = 0.92g
    specific heat capacity of water = 4.2


    b)How much heat would be produced when 1 mole of ethanol burns? (call this the heat combustion of ethanol)

    im not asking you to do everything for me just tips on how to do it.
  • Feb 8, 2007, 02:59 AM
    thisoneleft
    energy = mass x specific heat capacity x temp change
    mass=400g( 1cm of h2o = 1g) =0.4kg
    s.h.c. =4200J/(kg/K)
    temp. = 10 oC
    energy =.4 x 4200 x 10 = 16800J
    for pt (b)... find out how much one mole of ethanol weighs
    find what fraction of 1 mole is 0.92g and calculate the heat that would be released using proportionality.
  • Feb 10, 2007, 02:42 PM
    Evil dead
    Before you answered the question, I did along the line of what you did, but as usual my way of thinking is flawed:D
  • Feb 11, 2007, 02:48 AM
    thisoneleft
    Quote:

    Originally Posted by Evil dead
    Before you answered the question, I did along the line of what you did, but as usual my way of thinking is flawed:D

    :confused: something is wrong... who set the question?
    As for as I know that's correct... if thar is not correct then something is wrong with my knowledge... enlighten me if you can... but for now , with the knowledge I have I will take that answer to be correct.

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