Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Molar Enthalpy of Neutralization

  1. Jan 3, 2010 #1
    1. The problem statement, all variables and given/known data

    WHat is the molar enthalpy of neutralization of NaOH (aq) when 50.0 mL of aqueous 1.00 mol/L of NaOH (aq) reacts with an excess of 1.00 mol/L H2SO4 (aq)?

    Initial temperature of H2SO4 - 21.3 degrees celcius
    Initial Temperature of NaOH - 20.6 degrees celcius

    Final temperature of solution - 28 degrees celcius

    2. Relevant equations

    n(molar enthalpy) = vc(change in temperature)

    Where c = 4.19 J/mL x degrees celcius

    3. The attempt at a solution

    molar enthalpy = ( vct) / (n)

    = ( 50 mL x 4.19 (28 - (21.3 + 20.6 / 2)) / (1.00 mol/L x 50.0 mL)

    = 29 KJ / mol

    I'm not entirely sure if this answer and its units are correct, or if averaging the two initial temperatures was correct. Any verification of my answer would be great.
  2. jcsd
  3. Jan 5, 2010 #2


    User Avatar

    Staff: Mentor

    Averaging is not a good idea, and I don't think you can solve the question not knowing exact volume of sulfuric acid used. You should do full heat balance and assume solution to have specific heat of pure water - while this is not exactly true it would be probably close enough to the reality.
    Last edited by a moderator: Aug 13, 2013
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook