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# Hess Law Help watch

1. When do you multiply the given enthalpy value, if the number of moles is not 1?

For example, If the equation for one part of the cycle is:

H2SO4(aq) + 2NaOH (s) ---> H2SO4 (aq) + 2NaOH(aq)

And you had an enthalpy value of -50KJ mol for this reaction. Would it have to be multiplied by 2, as there are 2 moles of NaOH?

Thanks
2. (Original post by ViolinGirl)
When do you multiply the given enthalpy value, if the number of moles is not 1?

For example, If the equation for one part of the cycle is:

H2SO4(aq) + 2NaOH (s) ---> H2SO4 (aq) + 2NaOH(aq)

And you had an enthalpy value of -50KJ mol for this reaction. Would it have to be multiplied by 2, as there are 2 moles of NaOH?

Thanks
For enthalpy change, you need to multiply the standard enthalpy values(kJ/mol) by no.of mol hence giving you kJ. But suppose this enthalpy change is for the combustion of a compound X, then standard enthalpy of combustion for X = enthalpy change(kJ)/no of mol of X combusted(in mol)

does it just say enthalpy value of -50 kJ/mol or does it have a specific name as stated in the question?

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