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Le Châtelier's Principle
Equilibrium Expressions
Calculations
Q versus K
Kp verus Kc
100
The direction of the equation shifts THIS WAY, when products are added to the equilibrium expression.
What is shift to the left?
100
K = ([C]^l[D]^m) / ([A]^j[B]^k)
What is the equilibrium expression?
100
An equilibrium mixture is analyzed and found to contain 0.62M N2, 0.50M H2, and 0.24M NH3. What is Kc for the reaction, N2(g) + 3H2(g) <--> 2NH3(g)
Kc= 0.74
100
Expresses the relative ratio of products to reactants at a given instant. Uses the initial concentration.
What is Reaction Quotient, Q?
100
The equation relating Kc and Kp.
What is Kp = Kc(RT)^delta n
200
The direction of the equation shifts THIS WAY, when reactants are added to the equilibrium expression.
What is shifts right?
200
The equilibrium constant used for identifying expressions with molar solutions.
What is Kc?
200
What is the molar solubility of calcium fluoride in pure water? Ksp of calcium fluoride= 3.2x10^-11
2.0x10^-4 M
200
The relation between Q and K when the system is at equilibrium.
What is Q=K?
200
When is Kc = Kp?
When delta n equals 0
300
Speeds up the reaction but does not change the equilibrium constant.
What is a catalyst?
300

NH4SH (s) <-->NH3 (g) + H2S (g) Write the equilibrium expression.

What is Kc = [NH3] [H2S] **solids not included in equilibrium expression

300

PCl3 + Cl2 <--> PCl5 [PCl3] is 0.5 M, [Cl2] is 0.07 M. If K = 96.2 what is [PCl5]?

[PCl5] = 3.4 M

300

The relation between Q and K where there are more products than reactants. Causes a shift to the left to compensate.

What is Q > K?

300
What is delta n in this equation? N2 + 3H2 <--> 2NH3
delta n = -2
400

N2 + 3 H2 ⇌ 2 NH3 ΔH = -92kJ mol-1 Equilibrium shifts THIS WAY when heat is added.

What is shifts left?

400

2SO2 + O2 <-> 2SO3 The initial pressure for SO3 is 3 atm. What is the final pressure for SO3 and what is the Kp expression?

SO3= 3-2x  atm Kp=3 (x-3)^2/(x)^2*(x)

400

At a given temperature, an equilibrium mixture of the reaction 2NO(g) + O2(g) <--> 2NO2(g) contains 0.090 moles NO, 0.120 moles of O2, and 0.060 moles of NO2 in a 3.00 liter container. The value of Kc is...

Kc= 11

400

2CH4(g) <-> C2H2 (g) + 3H2 (g) Kc=.154 at 2000K Starts of with 4.00 M CH4, 2.00 M C2H2, and 3.00 M H2 which direction will the reactin progress to reach equilibrium?

Q>K, so a net reaction occurs to the left. Q=[C2H2][H2]^3/[CH4]^2 Q=3.38 3.38>.154 Q>K

400
2NO + Cl2 <--> 2NOCl Kp = 50.8 at 500 K find Kc
Kc = 2083
500

N2 + 3 H2 ⇌ 2 NH3 Shifts the equilibrium system THIS WAY when pressure is increased.

What is shifts right?

500

N2(g)+3H2(g)<-> 2NH3(g) Kp=1.45x10^-5 at 500 degrees Celcius partial pressure of H2 is 0.928 atm, N2 is 0.432atm. What is the partial pressure of NH3?

2.24x10^-3atm NH3

500

What is the molar solubility of Ag3PO4 in 0.050 M AgNO3? Ksp of Ag3PO4= 2.6x10^-18

2.1X10^-14 M

500

H2(g)+I2(g)<-> 2HI Kc= 50.5 Predict in which direction the reaction will proceed, if there is 2.0x10^-2 mol of HI, 1.0x10^-2 mol H2 and 3.0x10^-2 mol I2 in a 2.0 L container.

K>Q proceeds to right

500

SO2 + Cl2 <--> SO2Cl2 Kp = 34.5 at 303 K what is Kc?

Kc = 858