Question

Determine the enthalpy change for NaOH (s) + HCl (aq) → NaCl (aq) + H2O (l) using Hess's Law.

a. Write the balanced chemical reaction and enthalpy change for Part I
b. Write the balanced chemical reaction and enthalpy change for Part II
c. Calculate the enthalpy change using Hess's Law. Refer to the lesson for an example of Hess's Law.

Answer 1

@Mertsj @robtobey

Answer 2

@Frostbite please help

Answer 3

Right...
do I need to know what part I and II are. Do you have other information you haven't written?

Answer 4

And I suppose I can write Hess's law right away:
"The standard enthalpy of an overall reaction is the sum of the standard enthalpies of the individual reactions into which a reaction may be divided."

Answer 5

Determine the enthalpy change, per mole of sodium hydroxide dissolved. Show your work.
3010 J / 0.06338 mol NaOH = 4.75X10^4 J/mole X 1 kJ/1000 J = 47.5 kJ/mol NaOH thats for A

4. Determine enthalpy per mole of NaOH. Show all of your work.
-2.514 kJ/0.05 mol = -50.28 kJ/mol thats for b

Answer 6

I'm not sure I understand your notation.

Answer 7

@aaronq maybe you can find head and tail in this?

Answer 8

hm i don't see the difference between part I and part II.. lol

Answer 9

You got a point + hess law suggest that reactions can be used to calculate another reaction... but does this question suggest we use enthalpy of formation?

Answer 10

ohh, i think the first one is the enthalpy of the dissociation of NaOH

NaOH + heat -> Na+ + OH-

and the second is the enthalpy of formation of NaOH, as you mentioned.

Answer 11

Think you are right, but that leave us with HCL and NaCl...
I think we need a little more information else this question can't be answered... unless we use our own tables.

Answer 12

yeah, those 2 values would have to be looked up in a table somewhere, i guess.