# Worksheet: Concentrations from Equilibrium Constants

Q1:

Gaseous nitrogen dioxide forms dinitrogen tetroxide according to this equation: When 0.10 mol is added to a 1.0 L flask at , the concentration changes so that at equilibrium, = 0.016 M and = 0.042 M.

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

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

• A
• B
• C0.38
• D2.6
• E4.2

Q2:

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

Q3:

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, = sβ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?

Q4:

Carbon monoxide and water react at high temperature according to the 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?

Q5:

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 0.100 M
• B M
• C 490 M
• D M
• ENot enough information is provided.

Q6:

Iodine molecules react reversibly with iodide ions to produce triiodide ions: 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.

Q7:

Antimony pentachloride decomposes according to this 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?

Q8:

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

Q9:

What is the concentration of in an equilibrium mixture at that results from the reaction of 0.20 Mβ and 0.10 Mβ?

• A 0.0035 M
• B 0.0056 M
• C 0.012 M
• D 0.0070 M
• E 0.0044 M

Q10:

Consider the equilibrium of the ion acting as a weak base: A solution containing a mixture of and at equilibrium has the following concentrations:

• = M,
• = 0.042 M,
• = 0.341 M.

What is the equilibrium constant for this reaction under these conditions?

• A
• B
• C
• D

Q11:

Consider the equilibrium

What is the approximate equilibrium concentration of when is added to 1.00 L of a solution?

• A M
• B M
• C M
• D M
• E M

Q12:

Consider the equilibrium

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

• A M
• B 0.15 M
• C M
• D M
• E M

Q13:

Consider the 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

Q14:

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?

Q15:

Consider the 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.

Q16:

Consider the 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?

Q17:

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

Q18:

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

Q19:

Consider the equilibrium

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

Q20:

Acetic acid, , reacts with ethanol, , to form water and ethyl acetate, : 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.

• A 0.22 M
• B 0.15 M
• C 0.45 M
• D 0.37 M
• E 0.60 M

Q21:

Ethanol and acetic acid react to form water and ethyl acetate, the solvent responsible for the odor of some nail polish removers: When 1.00 mol 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?

Q22:

Consider the 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

Q23:

Consider the 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 ?

• A 0.14 M
• B 0.38 M
• C M
• D M
• E 10 M

Q24:

Copper(II) ions form a complex ion in the presence of ammonia: If 0.010 molβ is added to 1.00 L of a 1.00 Mβ solution, what is the concentration of when the system comes to equilibrium?

• A M
• B M
• C M
• D M
• E M

Q25:

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