Equilibrium Lab Report

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Unit 9: Lecture 1
The Concept of Equilibrium and the Equilibrium
Constant

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What is equilibrium?
A

state of balance

 It

can be static (like tug o war)

 It

can be dynamic, like cars moving across a bridge, and like most of the reactions we will be studying

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Chemical Equilibrium
 Occurs

when opposing reactions are proceeding at equal rates
 Rate

at which products form is equal to the rate at which reactants disappear
 Have

the illusion that the reaction has stopped +At equilibrium, the concentrations of the reactants and products are constant, but are not necessarily equal 

the reaction of iron(III) ions with thiocyanate

+Equilibrium and Rates
 The

equilibrium below is two reactions:
N2O4

 Forward

reaction:

 Reverse

reaction:
 Which

side of the equilibrium do you think is favored in the reaction below based on the value of Kp. Justify your response.
CO (g) + Cl2 (g) ⇌ COCl2 (g)
Kp = 4.56 x 109

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What can the equilibrium constant tell us?
A

large K indicates that there are more products than reactants at equilibrium

A

small K indicates that there are more reactants than products at equilibrium

 If
 If

K > 1, then it is products favored

K < 1, then it is reactants favored +
Example 3
 After

mixture of hydrogen and nitrogen gases in a reaction vessel are allowed to attain equilibrium at 472 oC, it is found to contain 7.38 atm H2, 2.46 atm N2, and
0.166 atm NH3.

 From

these data calculate the equilibrium constant, Kp, and state whether it is product or reactants favored.
N2 (g) + 3 H2 (g)

⇌

2 NH3 (g)

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Example 4
 An

aqueous solution of acetic acid is found to have the following equilibrium concentrations at 25 oC: [CH3COOH]