Equilibrium

Equilibrium Expressions

100

H_2(g) + I_2(g) < > 2HI_(g)

[HI]²   / [I₂][H₂]

200

CH_4(g) + H₂O_(g)< >CO_(g) + 3H_2(g)

[H₂]³[CO]  / [H₂O] [CH₄]

300

3O_2(g) 2H₂S_(g)< > 2SO_2(s) + 2H₂O_(g)

[H₂O]²  / [O₂]³[H₂S]²

400

SnO_2(s) + 2CO_(g) < > Sn_(s) + 2CO_2(g)

[CO₂]² / [CO]²

500

P_4(s) + 6Cl_2(g) < > 4PCl_3(l)

1 / [Cl₂]⁶

Vocabulary

100

the rate of the reaction forward and the backwards reaction level out, so reactant and product concentrations don’t change

Equilibrium

200

relative concentrations of reactants and products at equilibrium in terms of quantity

Equilibrium constant

300

used to determine if a reaction is at equilibrium

Reaction Quotient

400

The brackets around a number mean this

Molarity

500

a change in conditions is imposed on a system at equilibrium, the equilibrium position will shift in the direction that tends to reduce that change in conditions

Le Chatelier's Principle

Keq & Q

100

At equilibrium, what is the relationship between Keq and Q

they are equal

200

Which way will the reaction shift if Q is less then Keq

products / right

300

Given the reaction below, what is the equilibrium constant if the concentrations are [N₂] = 3.0x10^-2M , [H₂] = 3.7x10^-2M and [NH₃] = 1.6x10^-2M. Which side is favored?

2NH_3(g) <  >  N_2(g) + 3H_2(g)

0.0059    or   5.9x10^-3       reactants favored

400

If the Keq of the following reacton is 7.7x10^-15. Is the reaction at equilibrium if [CO] = 0.034M, [CO₂] = 3.6x10^-17M (show value).  If not which way will it shift?

2CO_(g) < > C_(s) + CO_2(g)

3.11x10^-14 reactants / left

500

The reaction below has a Keq of 0.064, given that [H₂] = 0.45M and [H₂O] = 0.37M. Is the reaction at equilibrium? (show number) If not which way will it shift?

Fe₂O_3(s) + 3H_2(g)< > 2Fe_(s) + 3H₂O_(g)

0.55 shift to the reactants / left

LeChatelier's Principle

100

What would happen if gaseous water was added to the reaction?

CH_4(g) + H₂O_(g)< >CO_(g) + 3H_2(g)

shifts to the products / right

200

What would happen if the following reaction were heated?

H_2(g) + I_2(g) < > 2HI_(g) +heat

shift to reactants / left

300

What would increasing the pressure do to the following reaction:

CH_4(g) + H₂O_(g)< >CO_(g) + 3H_2(g)

Shift to the reactants / left

400

What would happen if you removed chlorine gas?

P_4(s) + 6Cl_2(g) < > 4PCl_3(l)

shift to the reactants / left

500

What would increasing the pressure do to the following reaction:

SnO_2(s) + 2CO_(g) < > Sn_(s) + 2CO_2(g)

Nothing

Challenge

100

Label EACH reaction as either homogenous or heterogeneous. 

a. H_2(g) + I_2(g) < > 2HI_(g)

b. CH_4(g) + H₂O_(g)< >CO_(g) + 3H_2(g)

c. 3O_2(g) 2H₂S_(g)< > 2SO_2(s) + 2H₂O_(g)

d. P_4(s) + 6Cl_2(g) < > 4PCl_3(l)

a. homogenous

b. homogenous

c. heterogenous

d. heterogenous

200

Given the reaction below and the fact that the change in enthalpy is positive. What would happen if you heated this reaction? 

CH_4(g) + H₂O_(g)< >CO_(g) + 3H_2(g)     

Shift to the to products / right

300

Given the following reaction what would happen if you remove phosphorus trichloride? Be very specific about the concentration and equilibrium shift.

P_4(s) + 6Cl_2(g) < > 4PCl_3(l)

The concentration would decrease, but the equilibrium would be unaffected.

400

The solubility of AgBr in water is very low. Write the solubility equilibrium equation and determine its solubility given Ksp=5.0×10−13

 7.07x10^-7

500

Given the reaction below, what is the concentration of [H⁺] given that the Keq 1.8x10^-5, CH₃COOH is 0.46 moles in 0.5 L and CH₃COO^- 8.1x10^-3 moles in the same 0.500L. 

CH₃COOH_(aq) <  >  CH₃COO^-_(aq)    + H⁺_(aq)

[H⁺] = 1.0x10^-3M