internal energy

Chapter 5: Thermochemistry ?Introduction- Energy is defined as the capacity or the ability the to do work i.e. in order to do work energy must be involved Mathematically Represented- Work or Energy = Force x Distance The view of energy can be thought of as physical in nature and contact via the exerted force Chemistry, however, must view energy differently. The study of energy and its transformation, as it applies to chemistry, is know as THERMOCHEMISTRY, along with spontaneity, the two are referred to as THERMODYNAMICS Section 5.1- Nature of Energy The study of chemistry and thermodynamics will involve the concepts of energy, work, and heat KINETIC and POTENTIAL Energy Kinetic ? energy due to an objects motion

Hess's Law

Subject:

Chemistry

Rating:

No votes yet

SocialTags:

Chemistry

hess

hess's

Law

internal

Energy

Tags:

water

hess's

law

internal energy

Notes Enthalpy / Hess?s Law 2/13/13 CH 4(g) + 2O 2(g) ? CO 2(g) + 2H 2 O (g) ?H? rxn =? ?H? rxn = ??H? f products - ??H? f reactants Electron Affinity: Energy change associated with adding electrons to atoms (anions) Ionization Energy: Energy change associated with removing electrons from atoms (cations) Methods for calculating ?H rxn Hess?s Law: if a reaction can be written as the sum of two or more steps the overall enthalpy of reaction is equal to the sums of the enthalpies of reaction for each of the steps A + B ? G + H ? ?H rxn =? A + B ? C + D ? ?H rxn = x KJ C + D ? E + F ? ?H rxn = y KJ E + F ? G + H ? ?H rxn = z KJ +___________ A + B ? G + H ? ?H rxn = x + y + z KJ