## enthalpy

annikaying
Posts: 94
Joined: Sat Sep 14, 2019 12:16 am

### enthalpy

What is the relationship between work and heat when calculating enthalpy? Not just a formula but conceptually what it means.

PranaviKolla2B
Posts: 114
Joined: Fri Aug 30, 2019 12:17 am

### Re: enthalpy

Also, what does it mean that enthalpy is always heat but heat is not always enthalpy?

Posts: 104
Joined: Fri Aug 09, 2019 12:16 am

### Re: enthalpy

The sum of the work done on/by a system and the heat given off/absorbed by a system is equal to the enthalpy of a reaction. This being said, when there is a constant pressure, the delta H value is simply equal to the heat transfer.

Hussain Chharawalla 1G
Posts: 100
Joined: Sat Jul 20, 2019 12:15 am

### Re: enthalpy

A slight correction to the previous definition. I believe that the sum of work and heat given off in a reaction is equal to change in internal energy (U). Enthalpy is related to heat given off in a reaction during a constant pressure. The heat given off in a reaction is generally denoted by q but in conditions of constant pressure (qp) this is enthalpy. Heat exchanged (q) is an overarching concept and the heat exchanged under a constant pressure condition is enthalpy.

Return to “Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)”

### Who is online

Users browsing this forum: No registered users and 4 guests