Chapter 16: Equilibria

Question 1

product favored reaction

Answer 1

once equilibrium is reached, there is a greater concentration of prodcuts than reactants

K > 1

Question 2

equilibrium constant expression

Answer 2

K_eq = [C]^c [D]^d / [A]^a [B]^b

for the rxn. aA + bB <–> cC + dD

*don’t include pure solids or pure liquids (water)

Question 3

reactant favored reaction

Answer 3

once equilibrium is reached, there is a greater concentration of reactants than products

K < 1

Question 4

Reaction Quotient, Q

Answer 4

Same as equilibrium constant expression, except the concentrations are not equilibrium concentrations

Q = K equilibrium

Q < K reactants must be converted to products to reach equilibrium

Q > K products must be converted to reactants to reach equilibrium

Question 5

quadratic equation

Question 6

method of successive approximations

Answer 6

100 x K < [A]₀

When K is very small, you can remove x, b/c [A]₀ - x is approximately equal to x.

Question 7

equilibrium constants and stoichiometric coefficients

Answer 7

When stoichimoetric coefficients are multiplied by some factor, the equilibirum constant for the new expression is the old equilibrium constant raised to the power of the multiplication factor.

A Rxn and its reverse:

K₂ = 1 / K₁

Adding 2 equations:

multiply equilibrium constants

Question 8

Le Chatelier’s Principle

Vol.

Temp.

Answer 8

Changing temp., concentration or volume (for a system with gases) will cause the system to change in such a manner as to reduce / counteract the effect of the change.

Change in vol:

Vol. decrease: (increased pressure) shifts toward side with less molecules in gas phase

Vol. increase: (decreased pressure) shifts toward side with larger # of gas molecules

No change in gas molecules: vol. change has no effect

Change in Temp.

Increase: endothermic direction

Decrease: exothermic direction

Question 9

endothermic

Answer 9

heat is a “reactant”

Question 10

exothermic

Answer 10

heat is a “product”

Question 11

K_p = K_c(RT)^{change in number of moles}

Answer 11

R = .08206

T = Kelvin temp.

change in number of moles of gas for the rxn. as written (moles of products - moles of reactants)