# Worksheet: Equilibrium Constants and Concentrations

In this worksheet, we will practice converting between equilibrium constant expressions and the concentrations of reactants and products.

Q1:

Consider the equilibrium of the ion acting as a weak base. What is the equilibrium constant for this reaction under these conditions?

• = M,
• = 0.042 M,
• = 0.341 M.
• A
• B
• C
• D
• E

Q2:

Consider the shown equilibrium.

Analysis of the gases in a sealed reaction vessel containing , , and at equilibrium at established the concentration of to be 1.2 M and the concentration of to be 0.24 M. What is the equilibrium molar concentration of ?

• A0.14 M
• B0.38 M
• C M
• D10 M
• E M

Q3:

Cobalt metal can be prepared by reducing cobalt(II) oxide with carbon monoxide, as shown in the equation. What concentration of remains in an equilibrium mixture with = 0.100 M?

• A M
• B M
• C M
• D M
• E M

Q4:

Carbon is reacted with water vapor at , establishing the shown equilibrium. What is the concentration of in the equilibrium mixture if = 0.750 M?

Q5:

Consider the shown equilibrium.

What is the equilibrium concentration of in 1.00 L of a solution prepared from 0.129 mol of with chloroform as the solvent? Assume that the change in concentration of is small enough to be neglected.

• A M
• B M
• C M
• D M
• E M

Q6:

Pure decomposes reversibly into and , as shown. The initial concentration of is 2.00 M. Calculate the equilibrium concentration of .

Q7:

What is the concentration of in an equilibrium mixture at that results from the reaction of 0.20 M   and 0.10 M, as shown?

• A0.0070 M
• B0.0044 M
• C0.012 M
• D0.0035 M
• E0.0056 M

Q8:

Consider the shown equilibrium.

How many grams of are present in an equilibrium mixture containing 1.25 mol of and 63.5 g of at ?

Q9:

Consider the shown equilibrium.

What is the minimum mass of required to establish equilibrium at a certain temperature in a 6.50 L container if the equilibrium constant () is 0.050 for the decomposition reaction of at that temperature?

Q10:

Carbon monoxide and water react at high temperature according to the shown equation. Under certain conditions, the equilibrium constant for this reaction () is 5.0.

An equilibrium mixture of the substances was found to contain 0.20 mol of , 0.30 mol of water vapor, and 0.90 mol of per liter of gas. How many moles of were present in the equilibrium mixture?

Additional was added to the system at the same temperature, and some water vapor was removed by drying. A new equilibrium mixture was thereby established containing 0.40 mol of , 0.30 mol of water vapor, and 1.2 mol of per liter of gas. How many moles of were there in the new equilibrium mixture?

Q11:

Antimony pentachloride decomposes according to the following equation. An equilibrium mixture in a 5.00 L flask at contains 3.85 g of , 9.14 g of , and 2.84 g of . How many grams of antimony pentachloride would be present if this mixture were transferred into a 2.00 L flask at the same temperature?

Q12:

Sucrose is hydrolyzed to fructose and glucose according to the equation.

This reaction follows a first-order rate law. The products are structural isomers, exhibiting the same structural formula .

In neutral solution, = s−1 at . In the human body, the rate of this reaction is catalyzed by an enzyme, increasing the rate constant to at . What is the concentration of fructose after a 0.150 M aqueous solution of sucrose has reached equilibrium?

Q13:

Gaseous nitrogen dioxide forms dinitrogen tetroxide according to the following equation. When 0.10 mol is added to a 1.0 L flask at , the concentration changes so that, at equilibrium, and .

What is the value of the reaction quotient before any reaction occurs?

What is the value of the equilibrium constant for the reaction?

• A0.38
• B2.6
• C
• D
• E4.2

Q14:

Consider the shown reaction. For this reaction, the concentrations at equilibrium are = 0.90 M, = 0.35 M, and = 1.1 M. What is the value of the equilibrium constant, ?

Q15:

Iodine molecules react reversibly with iodide ions to produce triiodide ions, as shown. Before a reaction, the concentrations of and in a solution are both equal to M. At equilibrium, the concentration of is M. If the concentrations of all species are 1.000 M under standard conditions, calculate the equilibrium constant for this reaction.

Q16:

Ethanol and acetic acid react to form water and ethyl acetate, the solvent responsible for the odor of some nail polish removers, as shown. When 1.00 mol of each of and are allowed to react in 1.00 L of the solvent dioxane, equilibrium is established when mol of each of the reactants remains. What is the equilibrium constant, , for the reaction?

Q17:

The equilibrium constant for the reaction of nitrogen and hydrogen to produce ammonia at a certain temperature is . What is the equilibrium concentration of ammonia if the equilibrium concentrations of nitrogen and hydrogen are 4.26 M and 2.09 M respectively?

Q18:

Under certain conditions, the equilibrium constant for the decomposition of into and is 0.0211. What is the equilibrium concentration of if its initial concentration is 1.00 M?

Q19:

Acetic acid, , reacts with ethanol, , to form water and ethyl acetate, , as shown. The equilibrium constant for this reaction in dioxane is 4.0. A dioxane solution contains 0.15 M acetic acid, 0.15 M ethanol, 0.40 M ethyl acetate, and 0.40 M water when initially prepared. Calculate the concentration of ethyl acetate at equilibrium.

Q20:

Consider the shown equilibrium.

A 1.00 L flask is filled with 1.00 mole of and 2.00 moles of . The value of the equilibrium constant for the reaction of hydrogen and iodine reacting to form hydrogen iodide is 50.5 under the given conditions. Calculate the equilibrium concentration of in the 1.00 L flask.

Q21:

Consider the shown equilibrium.

What is the approximate concentration of at equilibrium for a 0.15 M solution of ?

• A M
• B M
• C M
• D M
• E M

Q22:

Consider the shown equilibrium.

What is the equilibrium concentration of in a 0.25 M aqueous solution of ?

• A M
• B M
• C M
• D M
• E M

Q23:

Copper(II) ions form a complex ion in the presence of ammonia, as shown. If 0.010 mol   is added to 1.00 L of a 1.00 M   solution, what is the concentration of when the system comes to equilibrium?

• A M
• B M
• C M
• D M
• E M

Q24:

Consider the shown equilibrium.

What is the approximate equilibrium concentration of when 0.25 mol is added to 1.00 L of a 2.00 M solution?

• A M
• B M
• C M
• D M
• E M

Q25:

The equilibrium constant, , of a process may change if it is calculated relative to different standard conditions. For which process does the choice of standard conditions have no effect on ?

• A
• B
• C
• D
• E