Sodium hydroxide and hydrochloric acid

[Jan Hill]

Homework Statement

We break down the rxn of NaOH with HCl into putting solid NaOH pellets in water and determine the delta H value. Next, we mix aqueous NaOH with a HCl (aq) and determine the delta H.
Then we mix solid NaOH pellets in HCl(aq) and measure the delta H. Can we say that the delta H values for the first two rxns should add up to roughly the value of the third delta H allowing for some difference due to experimental error?

Homework Equations

The Attempt at a Solution

 

[chemisttree]

The answer is '42'.