<< Chapter < Page Chapter >> Page >

Key concepts and summary

The ratios of the rate of change in concentrations of a reaction are equal to the ratios of the coefficients in the balanced chemical equation. The sign of the coefficient of X is positive when the concentration increases and negative when it decreases. We learned to approach three basic types of equilibrium problems. When given the concentrations of the reactants and products at equilibrium, we can solve for the equilibrium constant; when given the equilibrium constant and some of the concentrations involved, we can solve for the missing concentrations; and when given the equilibrium constant and the initial concentrations, we can solve for the concentrations at equilibrium.

Chemistry end of chapter exercises

A reaction is represented by this equation: A ( a q ) + 2 B ( a q ) 2 C ( a q ) K c = 1 × 10 3

(a) Write the mathematical expression for the equilibrium constant.

(b) Using concentrations ≤1 M , make up two sets of concentrations that describe a mixture of A, B, and C at equilibrium.

K c = [ C ] 2 [ A ] [ B ] 2 . [A] = 0.1 M , [B] = 0.1 M , [C] = 1 M ; and [A] = 0.01, [B]= 0.250, [C] = 0.791.

Got questions? Get instant answers now!

A reaction is represented by this equation: 2 W ( a q ) X ( a q ) + 2 Y ( a q ) K c = 5 × 10 −4

(a) Write the mathematical expression for the equilibrium constant.

(b) Using concentrations of ≤1 M , make up two sets of concentrations that describe a mixture of W, X, and Y at equilibrium.

Got questions? Get instant answers now!

What is the value of the equilibrium constant at 500 °C for the formation of NH 3 according to the following equation?

N 2 ( g ) + 3 H 2 ( g ) 2 NH 3 ( g )

An equilibrium mixture of NH 3 ( g ), H 2 ( g ), and N 2 ( g ) at 500 °C was found to contain 1.35 M H 2 , 1.15 M N 2 , and 4.12 × 10 −1 M NH 3 .

K c = 6.00 × 10 −2

Got questions? Get instant answers now!

Hydrogen is prepared commercially by the reaction of methane and water vapor at elevated temperatures.

CH 4 ( g ) + H 2 O ( g ) 3 H 2 ( g ) + CO ( g )

What is the equilibrium constant for the reaction if a mixture at equilibrium contains gases with the following concentrations: CH 4 , 0.126 M ; H 2 O, 0.242 M ; CO, 0.126 M ; H 2 1.15 M , at a temperature of 760 °C?

Got questions? Get instant answers now!

A 0.72-mol sample of PCl 5 is put into a 1.00-L vessel and heated. At equilibrium, the vessel contains 0.40 mol of PCl 3 ( g ) and 0.40 mol of Cl 2 ( g ). Calculate the value of the equilibrium constant for the decomposition of PCl 5 to PCl 3 and Cl 2 at this temperature.

K c = 0.50

Got questions? Get instant answers now!

At 1 atm and 25 °C, NO 2 with an initial concentration of 1.00 M is 3.3 × 10 −3 % decomposed into NO and O 2 . Calculate the value of the equilibrium constant for the reaction.

2 NO 2 ( g ) 2 NO ( g ) + O 2 ( g )

Got questions? Get instant answers now!

Calculate the value of the equilibrium constant K P for the reaction 2 NO ( g ) + Cl 2 ( g ) 2 NOCl ( g ) from these equilibrium pressures: NO, 0.050 atm; Cl 2 , 0.30 atm; NOCl, 1.2 atm.

The equilibrium equation is
K P = 1.9 × 10 3

Got questions? Get instant answers now!

When heated, iodine vapor dissociates according to this equation:

I 2 ( g ) 2 I ( g )

At 1274 K, a sample exhibits a partial pressure of I 2 of 0.1122 atm and a partial pressure due to I atoms of 0.1378 atm. Determine the value of the equilibrium constant, K P , for the decomposition at 1274 K.

Got questions? Get instant answers now!

A sample of ammonium chloride was heated in a closed container.

NH 4 Cl ( s ) NH 3 ( g ) + HCl ( g )

At equilibrium, the pressure of NH 3 ( g ) was found to be 1.75 atm. What is the value of the equilibrium constant K P for the decomposition at this temperature?

K P = 3.06

Got questions? Get instant answers now!

Get Jobilize Job Search Mobile App in your pocket Now!

Get it on Google Play Download on the App Store Now




Source:  OpenStax, Chemistry. OpenStax CNX. May 20, 2015 Download for free at http://legacy.cnx.org/content/col11760/1.9
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Chemistry' conversation and receive update notifications?

Ask