# CHEM 1310 Lecture Notes - Stoichiometry, Rate Equation, Joule

∆G reaction = products - reactants

∆S - what can you conclude about the sign and magnitude?

∆G = ∆H - T∆S

o ∆H = 34.5

o ∆T = 450

o ∆G = -1

o -1 = 34.5 kJ -450∆S

o - 35500 = -450∆S

o ∆S = 78.9

Q.Calculate standard reaction entropy at 298 K for:

o 2CH3CHO + O2 → 2CH3COOH

A. Sᵒ = 159.8(2) - 263.8(2) - 205.2

Gibb's Free Energy

Is a state function (constant)

Gives the amount of useable energy in the universe

May be calculated using ∆G = ∆H - T∆S

∆G < 0 means reaction is spontaneous

The value for a reaction may be manipulated using the same methods as ∆H and ∆S

∆Hᵒ and Temperature

Clausius-Clapeyron often used to relate ∆Hᵒ and ∆Sᵒ to temperature and pressure

Is the equation of a straight line graph on lnP(y-axis) vs. 1/T(x-axis with m=slope= ∆Hᵒ/R and

b=∆Sᵒ/R

There are several ways to rearrange this equation mathematically and it is closely related to the

van't Hoff and the Arrhenius equations

o

o M =

o X =

o B =

Q.What is the pressure of H2O vapor @ 64 ᵒC, if the pressure is 22.4 mmHg @ 23 ᵒC and the molar

enthalpy is 44 kJ/mol

A.

∆H = 44 kJ/mol

Constant = 8.3145

Use ln

P1 = 22.4 mmHg

P2 = ? mmHg

Hint: pick set 2 to have the higher temperature