0 kj 120 j 19 kj 62 enthalpy and calorimetry enthalpy

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 1.3 J/(L atm) = -120 J ∆E = q + w = (2.0 kJ) + (-120 J) = 1.9 kJ 6.2 Enthalpy and Calorimetry Enthalpy H = E + PV where E = internal energy of the system P = pressure of the system V = volume of the system Since internal energy, pressure, and volume are all state functions, enthalpy is also a state function. H = E + PV. Therefore ∆H = ∆E + ∆(PV) for a process at constant pressure, ∆(PV) = P∆V so ∆H = ∆E + P∆V 6-2 Chapter 6 Thermochemistry at constant P, ∆E = qp + w = qp – P∆V (subscript p means P is constant), so ∆H = qp - P∆V + P∆V = qp ∆H = qp H can be thought of as the heat content of the system, ∆H = heat flow For processes which occur at constant volume, ∆V = 0 so w = 0, therefore ∆E = qP Enthalpy Changes in Chemical Reactions In an exothermic reaction, chemical potential energy is converted into thermal energy which is released to the surroundings as a positive heat flow. In an endothermic reaction, thermal energy absorbed from the surroundings is converted into chemical potential energy which results in a negative heat flow. For a reaction reactantsÆ products ∆H = Hproducts - Hreactants ∆H>...
View Full Document

This note was uploaded on 04/05/2014 for the course CHEM 1211 taught by Professor Jackduff during the Spring '13 term at SPSU.

Ask a homework question - tutors are online