C.W. BAKER HIGH SCHOOL

 

Le Chatlier’s Principle

Prepared by J. Lerner

 

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The stress for each reaction is indicated.  Answer the questions below.

 

CaCO3(s) +         2HCl(aq)   ßà  CaCl2(aq) + H2CO3(aq)

 

1.        HCl is added to the above system in equilibrium

a)                            Which way does the reaction shift?

 

b)                            What occurs to the amount of CaCO3?

 

c)                             What occurs to the concentration of CaCl2?

 

d)                            What occurs to the concentration of H2CO3?

 

e)                            What happens to the rate of the forward reaction?

 

f) True or False:  You can determine which there is more of, products or reactants, once you understand which way a reaction has shifted.

 

 

O2(g) + N2(g)    ßà            2NO(g)

 

2.        NO is added to the above system in equilibrium

a)                            which way does the reaction shift?

 

b)                            What occurs to the concentration of N2?

 

c)                             What occurs to the concentration of O2?

 

A       +       B       ßà  C       +       D

 

 

3.        D is added to the above system in equilibrium

 

a)                            Which way does the reaction shift?

 

b)                            What occurs to the concentration of A?

 

c)                             What occurs to the concentration of B?

 

d)                            What occurs to the concentration of C?

 

Le Chatlier’s principle (Pressure &Temperature)

 

It helps to determine which way a reaction shifts before answering questions.

 

CaCO3(aq)  + heat     ßà   CaO(s) + CO2(g)

 

4.        Pressure is increased to the above system in equilibrium

a)                            What occurs to the concentration of CaCO3?

 

b)                            What occurs to the concentration of CaCl2?

 

c)                             What occurs to the concentration of H2CO3?

 

 

5.        Temperature is now decreased in the above reaction

a)                            What occurs to the concentration of CaCO3?

 

b)                            What occurs to the concentration of CaCl2?

 

e)                            What happens to the rate of the forward reaction?

 

f)                              What happens to the rate of the reverse reaction?

 

 

2A(g) +      2B(g)   +  101kJ/mol    ßà   4C(g) + D(s)

 

3. The pressure is increased on the system shown above

a)                                            What occurs to the concentration of A?

 

b)                                            Explain

 

4. The temperature is now increased.

a)                                            What occurs to the rate of the forward reaction?

 

b)                                            What occurs to the rate of the reverse reaction?

 

c)  Why does the equilibrium still shift?

 

d) What occurs to the concentration of C?

 

5. A catalyst is now added.

a)                                             How is the reaction’s equilibrium affected?

 

b)  When a new stress is added how long will it take to establish the new equilibrium compared to an uncatalyzed reaction?