± Adding Equilibrium Reactions Learning Goal: To understand how to calculate the

Question

± Adding Equilibrium Reactions

Learning Goal:

To understand how to calculate the equilibrium constants for chemical equations that can be produced by the addition of other chemical equations with known equilibrium constants.

For a chemical reaction equation with the general form

aA+bBcC+dD

K1=[C]c[D]d[A]a[B]b

Thus, for a chemical reaction equation with the general form

cC+dDeE+fF

K2=[E]e[F]f[C]c[D]d

aA+bBeE+fF

K3=[E]e[F]f[A]a[B]b=[C]c[D]d[A]a[B]b[E]e[F]f[C]c[D]d

K3=K1K2

Thus, when a chemical equation is the sum of two chemical equations for which equilibrium constants are already known, the equilibrium constant for the reaction is the product of the equilibrium constants for the individual reactions. Keep in mind that equilibrium equations do not include expressions for any pure solids or liquids that may be involved in the reaction.

Part A

H2SHS+H+,   K1 = 9.86×108, and

HSS2+H+,   K2 = 1.25×1019,

S2+2H+H2S

Enter your answer numerically.

7.14•1025

SubmitHintsMy AnswersGive UpReview Part

Incorrect; Try Again; 4 attempts remaining

Part B

PbCl2Pb2++2Cl,   K3 = 1.76×1010, and

AgClAg++Cl,   K4 = 1.13×104,

PbCl2+2Ag+2AgCl+Pb2+

Express your answer numerically.

SubmitHintsMy AnswersGive UpReview Part

± Adding Equilibrium Reactions

Learning Goal:

To understand how to calculate the equilibrium constants for chemical equations that can be produced by the addition of other chemical equations with known equilibrium constants.

For a chemical reaction equation with the general form

aA+bBcC+dD

the equilibrium equation is given by

K1=[C]c[D]d[A]a[B]b

Thus, for a chemical reaction equation with the general form

cC+dDeE+fF

the equilibrium equation is given by

K2=[E]e[F]f[C]c[D]d

If the first two equations are added together such that

aA+bBeE+fF

then the equilibrium equation is given by

K3=[E]e[F]f[A]a[B]b=[C]c[D]d[A]a[B]b[E]e[F]f[C]c[D]d

or

K3=K1K2

Thus, when a chemical equation is the sum of two chemical equations for which equilibrium constants are already known, the equilibrium constant for the reaction is the product of the equilibrium constants for the individual reactions. Keep in mind that equilibrium equations do not include expressions for any pure solids or liquids that may be involved in the reaction.

Part A

Given the two reactions

H2SHS+H+,   K1 = 9.86×108, and

HSS2+H+,   K2 = 1.25×1019,

what is the equilibrium constant Kfinal for the following reaction?

S2+2H+H2S

Enter your answer numerically.

Kfinal =

7.14•1025

SubmitHintsMy AnswersGive UpReview Part

Incorrect; Try Again; 4 attempts remaining

Part B

Given the two reactions

PbCl2Pb2++2Cl,   K3 = 1.76×1010, and

AgClAg++Cl,   K4 = 1.13×104,

what is the equilibrium constant Kfinal for the following reaction?

PbCl2+2Ag+2AgCl+Pb2+

Express your answer numerically.

Kfinal =

SubmitHintsMy AnswersGive UpReview Part

Explanation / Answer

H2SHS+H+,   K1 = 9.86×108,

K1=[HS-][H+]/[H2S]

HSS2+H+,   K2 = 1.25×1019

K2=[S2-][H+]/[HS]

S2+2H+H2S

Kfinal=[H2S]/[S2-][H+]2 = 1/k1k2=1/( 9.86×108x 1.25×1019)=8.1136x10^25.

pure solids are not included in equilibrium expressions

PbCl2Pb2++2Cl,   K3 = 1.76×1010, and

K3=[Pb2+][Cl]2 = 1.76×1010

AgClAg++Cl,   K4 = 1.13×104,

K4=[Ag+][Cl-]=1.13×104

PbCl2+2Ag+2AgCl+Pb2+

Kfinal=[Pb2+]/[Ag+]2 =K3/K42=1.76×1010/(1.13×104)2=0.01378

Related Questions

Navigate

• Browse (All)
• Browse #
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.