Chapter 8 Chemical Bonding

Values q this is only an approximate hrxn this 5

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: q Use bond energies to calculate the enthalpy Use change for the following reaction: change N2(g) + 3H2(g) → 2NH3(g) (g) q ∆ Hrxn = DN ≡ N + 3DH-H - 6DN-H rxn ∆ Hrxn = 942 + 3(432) - 6(386) = -78 kJ measured value = -92.2 kJ q Why are the values different? 5 Sample Problem q Use bond energies to calculate the Use enthalpy change for the following reaction: reaction: 2CO(g) + O2(g) → 2CO2(g) (g) DC ≡ O = 1072 kJ DO = O = 492 kJ DC = O = 799 kJ q ∆ Hrxn = 2DC ≡ O + DO = O - 4DC = O 2D rxn ∆ Hrxn = 2(1072) + 492 - 4(799) = -560 kJ 5 Bond Energy and Bond Length q The distance between the nuclei of the atoms The involved in a bond is called the bond length. involved q Multiple bonds are shorter than single Multiple bonds. bonds. q Multiple bonds are also stronger than single Multiple bonds. bonds. q As the number of bonds between two atoms As increases, the atoms are held closer and more tightly together. more 6 Bond Lengths 6...
View Full Document

This note was uploaded on 09/24/2012 for the course CHM 113 taught by Professor Anbar during the Spring '06 term at ASU.

Ask a homework question - tutors are online