I need some help if my lab report so: Can someone tell me why the reaction 1 and
ID: 797224 • Letter: I
Question
I need some help if my lab report so:
Can someone tell me why the reaction 1 and 2 should add up to reaction 3?
NaOH(s)?NaOH (aq) ? H1
NaoH (aq) + HCL (aq)?H20(l)+NaCL (aq) DElta H 2
__________________________________________
NaOH(s) + HCL(aq) ?H20(l)+NaCL (aq) Delta H 3
part B
when I add up Delta H 1 = -50.6 kj
and Delta H2 = -54.2
I found Delta H3 = -104.8 kj but Delta H 3 was supposed to be -110 kj. Can you explain to me what I could have done wrong in my experiment?
Explanation / Answer
1. The enthalpy of a reaction does not depend on the elementary steps, but on the final state of the products and initial state of the reactants. Enthalpy is an extensive property and hence changes when the size of the sample changes. This means that the enthalpy of the reaction scales proportionally to the moles used in the reaction.
We must add the equations to get the final reaction and we can find the enthalpy.
2. I think the experimental values collected by you are wrong as Hess law is always valid.