What Is the Molar Enthalpy of Neutralization of NaOH?

[cybernerd]

Homework Statement

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 celsius
Initial Temperature of NaOH - 20.6 degrees celsius

Final temperature of solution - 28 degrees celsius

Homework Equations

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

Where c = 4.19 J/mL x degrees celsius

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.

 

[Borek]

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.