Wednesday
June 19, 2013

# Homework Help: chemistry

Posted by Marium on Thursday, June 3, 2010 at 7:28pm.

I have solved the following question but i am not sure whether it is right or wrong..

Calculate the molar heat of reaction for the NaOH(aq) using the data obtained from this experiment. (this is a neutralization question)

H2so4
Volume= 30ml
Concentration=1.0mol/l
Initial temp. = 29.9

NAOH
Volume= 50ml
C = 1.0 mol/L
Initial temp. = 29

Final temp of the two contents = 32.9

This is my solution:

El = Eg
NaOH H2O

nH = mc∆t

0.05mol x H = 0.08L x 4.19 x 3.9

H = 26.15

The standard molar heat of neutralization of sodium hydroxide,
is -57 kJ/mol.

so shouldn't my calculated value be close to the standard value? Please tell me whether my solution is right or wrong!

• chemistry - DrBob222, Thursday, June 3, 2010 at 8:03pm

1. Yes, I think the value should be closer to the standard listed.
2. I think you should take into account that the temperature of the NaOH and the H2SO4 were not the same initially.
[50 x 4.184 x (32.9-29.0)] + [30 x 4.184 x (32.9-29.9)] = 1,192 joules or 1.192 kJ.
1.192 kJ/0.05 mol = 23.8 kJ/mol but that isn't much improvement.

• chemistry - Marium, Friday, June 4, 2010 at 4:04pm

could it be that H needs to be negative??

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