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How to calculate the molar enthalpy

  1. Jan 19, 2009 #1
    1. The problem statement, all variables and given/known data

    1) add 60 ml of 1.0 mol/L Sodium Hydroxide solution to a polystyrene calorimeter.
    2) mix it with 40-ml sample of 1.0 mol/L sulfuric acid solution in a graduated cylinder.

    3) Add the acid to the base, stirring slowly with the thermometer. record the highest temperature recorded

    initial temp: 22.5
    highest: 26

    ------------------------------------------------------
    Cacluate the number of moles of the base (the limiting reagent)

    2) Calculate the change in molar enthalpy with respect to sodium hydroxide.
    2. Relevant equations



    3. The attempt at a solution
    I think, I solved it. n = c.v
    n = 0.06 * 1 = 0.06 mol NaOH


    2nd) H = m.c.t/n

    100g * 4.184 * 3.5 / 0.06
    = 24.4 KJ
    is this correct?

    the reason why I am confused is because the accepted value is 56kj/mol. My answers is way off. Wither I messed up during the experiment or in my writtten solution or in both
    Plz help
     
  2. jcsd
  3. Jan 20, 2009 #2

    Borek

    User Avatar

    Staff: Mentor

    IMHO solution looks OK, so most likely there was something wrong with the experimental part.
     
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