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'.

 

[Blueshift5]

I can confirm that the delta H values for the first two reactions should add up to roughly the value of the third delta H, assuming all reactions are carried out under the same conditions and there are no significant errors in the experimental procedure. This is because the overall enthalpy change of a reaction is the sum of the enthalpy changes of its individual steps. Therefore, if the first two reactions are the individual steps of the third reaction, their enthalpy changes should add up to the enthalpy change of the third reaction. However, it is important to note that experimental error can lead to slight variations in the measured values, so the sum of the first two delta H values may not exactly equal the third delta H value.