{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Enthalpy Characteristics

# Enthalpy Characteristics - H=HproductsHreactants 1...

This preview shows pages 1–3. Sign up to view the full content.

Enthalpy Characteristics Because enthalpy is a state function we can always write for a chemical reaction that H = H Δ products  - H reactants Some other characteristics of enthalpy are... 1. If the reaction is reversed then the sign of  H Δ  is also reversed. For example, for  the reaction CH 4 (g)  + 2 O 2 (g)    CO 2 (g)  + 2 H 2 O (g) the  H Δ  is -802 kJ, that is, it is  exothermic . In contrast, the reverse reaction CO 2 (g)  + 2 H 2 O (g)    CH 4 (g)  + 2 H 2 O (g) has a  H Δ  of +802 kJ, that is, it is now  endothermic . 2. H Δ  is extensive. If the coefficients in a balanced reaction are multiplied by an  integer, then the value of  H Δ  is multiplied by the same integer. For example, Xe (g)  + 2 F 2 (g)    XeF 4 (g)        H = -251 kJ. Δ but... 2 Xe (g)  + 4 F 2 (g)    2 XeF 4 (s)       H = -502 kJ. Δ Hess' Law Since enthalpy is a state function, the change in enthalpy in going from some initial state  to some final state is independent of the pathway. This leads us to Hess' Law... Hess' Law

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

View Full Document
In going from a particular set of reactants to a particular set of products, the
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

### Page1 / 5

Enthalpy Characteristics - H=HproductsHreactants 1...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online