2004 A

(a) Place the products in equilibrium expression. Remember the number of moles of Ag is the exponent in the equilibrium expression.

(a) Reading the question should immediately strike you. You should apply Le Chatelier’s principle. Adding Ag+ into the solution will make Q greater than K. And Le Chatelier’s principle states that when Q is greater than K, the reaction will shift left to reestablish equilibrium.

(b) When this solid is placed in the solution, the cations and anions will ionize.

(c) First, the equation for Ksp should come to mind. You simply have to find the concentrations of Ag+ and PO43-. Then you plug them in into the equation. Don't forget the exponents.

2004

a) First formulate the pressure equilibrium expression in your mind. Then plug in the products as the numerator and plug in the reactants as the denominator. Don't forget to include the exponents.

b) I) Plug in the given partial pressure values to obtain Q.

ii) First try to recall Le Chatelier’s principle. Since Q is greater than K, then the reaction must proceed to the left to establish equilibrium.

d) I) Take notice that the reaction is reversed. Solving for Kp is then simple because you simply flip the original equation. The reactants are placed in the place of products and vise versa. A quick way to do it would be simply using 1 to divide the first KP value.

ii) Break up the equation and solve for the KP of each of the components. And try to obtain something that looks like the original equation. At last, place the solved values into the equation.

2003 B

a) Write an equilibrium expression by placing the reactants on the bottom and products on top. Include the exponents. Don't get confused by the graph, you can derive the answer from the equation.

b) You can see that when the concentration of HI reaches 0.80M, it no longer decreases. This means it has reached an equilibrium where the forward reaction and the reverse reaction are at equal rates

c) Plug in the concentration values into the equilibrium constant equation.

ii) The answer might not strike you immediately, but if you write the equation for KP and solve it, youw will realize Kp = KC

f) Use the given information. Remember to underline key terms. Solve for Q so you can compare the value of Q to the value of K. It turns out Q is greater than K, so to establish equilibrium, Q must become smaller. So [HI] should increase. Think of this in terms of math. When

2002 A

i) You must know the basics of order. The order is the sum of the components in the rate law. So therefore it is 1 plus 1.

ii) Find K by dividing the rate by the concentration of O3 and Cl. You must know the rate determining step is the slowest step. Step 1 is the rate determining step because the coefficients in step 1 corresponds to the exponents in the rate law.

2001

ii) You must know the concentration of Pb2+ equals K over the concentration of Cl- squared. Plug in the values of the concentration.

2000

a) The equilibrium constant equation is simply plugging in the products on top and the reactants on the bottom.

b) Pay close attention to the coefficients of the reactants and products. Then divide them by the volume.

c) To solve for KC, you plug the values of the concentration of H2 and S2 in the numerator, and put all that under the concentration of H2S just because that's how a equilibrium constant equation works. Then simplify and solve.

1999

a) Simply put the products on top and the reactants on the bottom to form the equilibrium equation.