# How to calculate the molar enthalpy

1. Jan 19, 2009

### supahsain

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

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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. Jan 20, 2009

### Staff: Mentor

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