# Simple Hess's Law question. Difference between kJ and kJ/mol

I have a sheet on Hess's Law where Enthalpy change is sometimes given as kJ and other times kJ/mol.
Why? What's the difference?

The latter is given as "The heat of vaporisation of water is 44kJ/mol. Calculate the heat of reaction﻿ [gaseous ethanol]..."
Why is it kJ/mol and should the heat of reaction be given as kJ or kJ/mol?

 ebaines Posts: 10,046, Reputation: 5534 Expert #2 Jun 11, 2012, 08:00 AM
Enthalpy is measured in kJ/mole. The heat of reaction may also be expressed in kJ/mole, but if you know how many moles of material are involved yuo can calculate the total heat released (or absorbed) by a reaction in kJ. Converesely, in a lab experiment you might measure the heat produced in kJ, and the calculate the enthalpy of the materials in terms of kJ/mole.

## Check out some similar questions!

Chemistry Hess's Law problem [ 2 Answers ]

"Water gas" is an industrial fuel composed of a mixture of carbon monoxide and hydrogen gases. When this fuel is burned, carbon dioxide and water forms as a result. From the information given below, write a balanced equation and determine the enthalpy of this reaction: CO(g) + ? 1/2 O2(g) ?...

In the case of Macaura vs Nothern Assurance Company 1925, need to know how it was held.considering the results of incorporation. Thanks

Hess's Law (simple) [ 1 Answers ]

1) NaOH(s)--> Na+(aq) + OH- (aq) 2) Na+(aq) + OH(aq) + H+(aq) + Cl-(aq) --> H2O + Na+(aq) + Cl-(aq) Target equation: NaOH(s) + H+(aq) + Cl(aq)--> H20 + Na+(aq) + Cl-(aq) I need help solving this..Thanks