# Nov_07 - Enthalpy of Formation Standard States Definitions...

This preview shows pages 1–15. Sign up to view the full content.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Enthalpy of Formation
Standard States Definitions of Standard States : • Gases: gas at partial pressure of 1 atm • Solutes: a conc. of 1M at an applied P of 1atm • Pure liquids or solids: the pure liquid or solid • Elements: the elemental form that exists at 1 atm

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Standard Enthalpy of Formation ( H f °) ∆Η f º - enthalpy change for the formation of 1 mole of a compound from its elements all at standard states H f º for an element in its standard state equals zero • Normally reported in kJ per mole of the compound • There is no standard temperature. ∆Η f º depends on temperature and is often reported for 298 K
reactants → products ΔHº reaction ΔHº reaction = Σ ΔH f º (products) – Σ ΔH f º (reactants)

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
H Δ f º - example e.g. Calculate Hº Δ reaction at 298 K for : 4 NH 3 (g) + 7 O 2 (g) -----> 4 NO 2 (g) + 6 H 2 O(l) Look up in table of H Δ f º values at 298 K: H Δ f º (NH 3 (g)) = - 46 kJ/mol H Δ f º (O 2 (g)) = 0 kJ/mol <----- Definition H Δ f º (NO 2 (g)) = 34 kJ/mol H Δ f º (H 2 O(l)) = - 286 kJ/mol Δ reaction

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document

This preview has intentionally blurred sections. Sign up to view the full version.

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

{[ snackBarMessage ]}

### Page1 / 15

Nov_07 - Enthalpy of Formation Standard States Definitions...

This preview shows document pages 1 - 15. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online