Reaction rate constant kHow fast will the reaction proceed?Activation Energy E

Reaction rate constant k

How fast will the reaction proceed?

Activation Energy E_a for the reaction.

Arrhenius (1890’s) (Forced global warming predicted 1896)

Eyring, Polanyi, Evans Rate Theory

Gasoline in a gas tank does not explode due to kinetic limitations.

Gasoline is reactive but kinetically stable

Reaction equilibrium constant K_a Will the reaction proceed?

Endergonic, Exergonic Endothermic, Exothermic

What are the equilibrium concentrations?

Gibbs free energy change in the reaction.

Gasoline in an engine can ideally produce 46.4 MJ/kg at equilibrium.

Gasoline is not thermodynamically stable.

Rate Constant vs. Equilibrium Constant

K_a aA+ bB¬ ®¾ cC + dD

r_Forward = k_ForwardA^mBⁿ m and n are the orders of reaction m and n are not necessarily related to a, b, c, d

r_Backward = k_BackwardC^pD^q k = exp -E_a

RT æ

èç ö

ø÷ E_a is the activiation energy Arrhenius (1880), Eyring, Polanyl, Evans (1920)

aA+ bB¬ ®¾ cC + dD K_a = exp -DG

RT æ

èç ö

ø÷

DG=y_C^cy_D^d

y_A^ay_B^bP^c+d-a-b

Le Châtelier's principle (1884) Gibbs (1872)

ˆf_i fugacity of component "i"

in a mixture at tempreature T, press. P f_i⁰ fugacity of component "i"

in a pure state at standard T,P,comp.

typically T, P and pure

ˆf_i fugacity of component "i"

in a mixture at tempreature T, press. P f_i⁰ fugacity of component "i"

in a pure state at standard T,P,comp.

typically T, P and pure

Standard heat of reaction Standard heat of reaction

-7.5

Assume all species same size and all g or all l Assume ΔCp = 0

So J =ΔH_R⁰

Example 17.4

Example 17.6 excel

P²

P²

Section From Chapter 3

Kcalc.xls

These are molar for pure components, y_i = 1; n_i = 1

17.7 17.22

Practice Problems 17.1, 17.4, 17.9 Test-yourself’s OK but short