Chapter 15, Problem 40GQ

### Chemistry & Chemical Reactivity

10th Edition
John C. Kotz + 3 others
ISBN: 9781337399074

Chapter
Section

### Chemistry & Chemical Reactivity

10th Edition
John C. Kotz + 3 others
ISBN: 9781337399074
Textbook Problem

# Consider the following equilibrium:COBr2(g) ⇄ CO(g) + Br2(g)    Kc = 0.190 at 73 °C (a) A 0.50 mol sample of COBr2 is transferred to a 9.50-L flask and heated until equilibrium is attained. Calculate the equilibrium concentrations of each species. (b) The volume of the container is decreased to 4.5 L and the system allowed to return to equilibrium. Calculate the new equilibrium concentrations. (Hint: The calculation will be easier if you view this as a new problem with 0.5 mol of COBr2 transferred to a 4.5-L flask.) (c) What is the effect of decreasing the container volume from 9.50 L to 4.50 L?

(a)

Interpretation Introduction

Interpretation:

The equilibrium concentration of each species in the reaction COBr2(g)CO(g)+Br2(g) in a 9.50L flask and the new equilibrium concentration when the volume changes to 4.5L and the effect of decreasing volume is to be given.

Concept Introduction:

Equilibrium constant in terms of concentration[KC]: Equilibrium constant can be expressed in terms of concentration.

aA(g)+bB(g)cC(g)+dD(g)Kc=[C]c×[D]d[A]a×[B]b

Molarity=NumberofmolesVolumeofsolution(L)

Le Chatelier’s principle: If an equilibrium is disturbed by changing conditions, the system will moves the equilibrium to reverse the change.

Factor’s that effect chemical equilibria:

Concentration – Equilibrium will be affected by changing the concentration of reactant or product. If we increase the concentration of reactant system will try to reverse the change by favouring forward reaction and thus increase the concentration of products. Like wise adding products increase yield of reactants.

Temperature – When the temperature increases equilibrium will shift in the endothermic direction, in the direction that absorbs heat. When the temperature decreases equilibrium will shift in the exothermic direction, in the direction that releases heat.

Pressure – If the reaction consists of only liquid and solid reactants and products, pressure has no effect in the equilibrium.

In gas reactions if the number of moles has no change then there will be no effect by pressure on equilibrium.

If pressure increases (volume decreases) then equilibrium will shift to the direction having less number of molecules and if pressure decreases (volume increases) system will shift to the direction having more number of molecules.

Explanation

To determine:

The equilibrium concentration of each species in the reaction COBr2â€‰â€‰â€‰â€‰â€‰(g)â€‰â€‰â€‰â‡„â€‰â€‰â€‰â€‰COâ€‰â€‰â€‰(g)â€‰â€‰â€‰+â€‰â€‰Br2â€‰â€‰â€‰â€‰â€‰â€‰(g) when the volume is 9.50â€‰L.

Given:

COBr2â€‰â€‰â€‰â€‰â€‰(g)â€‰â€‰â€‰â‡„â€‰â€‰â€‰â€‰COâ€‰â€‰â€‰(g)â€‰â€‰â€‰+â€‰â€‰Br2â€‰â€‰â€‰â€‰â€‰â€‰(g)Kcâ€‰â€‰â€‰=â€‰â€‰0.190Tâ€‰â€‰â€‰â€‰â€‰â€‰=â€‰â€‰73Â°CÂ â€‰â€‰=â€‰â€‰346â€‰KNumberâ€‰ofâ€‰molesâ€‰ofâ€‰COBr2â€‰â€‰=â€‰0.50â€‰molVâ€‰â€‰â€‰â€‰â€‰=â€‰â€‰9.50â€‰L

Concentrationâ€‰ofâ€‰COBr2â€‰â€‰=â€‰â€‰Numberâ€‰ofâ€‰molesVolumeâ€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰=â€‰0.509.50â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰=â€‰0.0526â€‰M

â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰COBr2â€‰â€‰â€‰â€‰â€‰(g)â€‰â€‰â€‰â‡„â€‰â€‰â€‰â€‰COâ€‰â€‰â€‰(g)â€‰â€‰â€‰+â€‰â€‰Br2â€‰â€‰â€‰â€‰â€‰â€‰(g)Initialâ€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰â€‰0

(b)

Interpretation Introduction

Interpretation:

The equilibrium concentration of each species in the reaction COBr2(g)CO(g)+Br2(g) in a 9.50L flask and the new equilibrium concentration when the volume changes to 4.5L and the effect of decreasing volume is to be given.

Concept Introduction:

Equilibrium constant in terms of concentration[KC]: Equilibrium constant can be expressed in terms of concentration.

aA(g)+bB(g)cC(g)+dD(g)Kc=[C]c×[D]d[A]a×[B]b

Molarity=NumberofmolesVolumeofsolution(L)

Le Chatelier’s principle: If an equilibrium is disturbed by changing conditions, the system will moves the equilibrium to reverse the change.

Factor’s that effect chemical equilibria:

Concentration – Equilibrium will be affected by changing the concentration of reactant or product. If we increase the concentration of reactant system will try to reverse the change by favouring forward reaction and thus increase the concentration of products. Like wise adding products increase yield of reactants.

Temperature – When the temperature increases equilibrium will shift in the endothermic direction, in the direction that absorbs heat. When the temperature decreases equilibrium will shift in the exothermic direction, in the direction that releases heat.

Pressure – If the reaction consists of only liquid and solid reactants and products, pressure has no effect in the equilibrium.

In gas reactions if the number of moles has no change then there will be no effect by pressure on equilibrium.

If pressure increases (volume decreases) then equilibrium will shift to the direction having less number of molecules and if pressure decreases (volume increases) system will shift to the direction having more number of molecules.

(c)

Interpretation Introduction

Interpretation:

The equilibrium concentration of each species in the reaction COBr2(g)CO(g)+Br2(g) in a 9.50L flask and the new equilibrium concentration when the volume changes to 4.5L and the effect of decreasing volume is to be given.

Concept Introduction:

Equilibrium constant in terms of concentration[KC]: Equilibrium constant can be expressed in terms of concentration.

aA(g)+bB(g)cC(g)+dD(g)Kc=[C]c×[D]d[A]a×[B]b

Molarity=NumberofmolesVolumeofsolution(L)

Le Chatelier’s principle: If an equilibrium is disturbed by changing conditions, the system will moves the equilibrium to reverse the change.

Factor’s that effect chemical equilibria:

Concentration – Equilibrium will be affected by changing the concentration of reactant or product. If we increase the concentration of reactant system will try to reverse the change by favouring forward reaction and thus increase the concentration of products. Like wise adding products increase yield of reactants.

Temperature – When the temperature increases equilibrium will shift in the endothermic direction, in the direction that absorbs heat. When the temperature decreases equilibrium will shift in the exothermic direction, in the direction that releases heat.

Pressure – If the reaction consists of only liquid and solid reactants and products, pressure has no effect in the equilibrium.

In gas reactions if the number of moles has no change then there will be no effect by pressure on equilibrium.

If pressure increases (volume decreases) then equilibrium will shift to the direction having less number of molecules and if pressure decreases (volume increases) system will shift to the direction having more number of molecules.

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