– Le Chatelier’s Principle
Name _______________
Use the following equation to answer questions #1-6.
[Cu(H2O)4]2+ + 2NH3  [Cu(NH3)4]2+ + 4 H2O
1. Which way will the reaction shift if NH3 is added? ____________________
2. Which way will the reaction shift if water is added? _____________________
3. Which way will the reaction shift if [Cu(H2O)4]2+ is removed? _____________________
4. Which way will the reaction shift if [Cu(NH3)4]2+ is removed? ____________________
5. What information would you need to know to determine the effect of changing temperature on the reaction?
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6. What information would you need to know to determine the effect of pressure on the system?
_______________________________________________________________________________________
Use the following equation to answer questions #7-11.
C (g) + Y(g)  3B(g) + heat
In the reaction above C is colorless, Y is a bright yellow, and B is a bright blue. The system is initially at
equilibrium and has a green color.
7. Adding a large quantity of C will result in what color at equilibrium?
______________________
8. Cooling the system will result in what color?
______________________
9. Adding a catalyst gives what color?
_______________________
10. Increasing the pressure will result in what color?
_______________________
11. Removing B from the system will result in what color?
_______________________
12. Suppose you’re thinking about using the following reaction to produce hydrogen from hydrogen sulfide.
Keq for the equilibrium is 2.27 x 10-4
2 H2S(g) + heat  2 H2(g) + S2(g)
a. Would you expect a high yield of hydrogen? ____________
b. What could you do to the volume of the reaction vessel to produce more hydrogen? ____________________
c. How could you change the temperature to increase the yield of hydrogen? ____________________________
13. What effect would an increase in temperature have on these reactions at equilibrium?
a. Heat + H2(g) + I2(g)  2HI(g)
Shift LEFT or RIGHT or NO CHANGE
b. CH4(g) + 2O2(g)  CO(g) + 2H2O(g) + heat
Shift LEFT or RIGHT or NO CHANGE
c. N2(g) + 2H2(g)  2NH3(g) + heat
Shift LEFT or RIGHT or NO CHANGE
d. Heat + CH4(g)  C(s) + 2H2(g)
Shift LEFT or RIGHT or NO CHANGE
14. For each reaction, state whether increasing or decreasing the volume of the reaction vessel would yield
more product at equilibrium.
a. N2O4(g)  2NO2(g)
INCREASE or DECREASE Volume
b. 2SO3(g)  2SO2(g) + O2(g)
INCREASE or DECREASE Volume
c. CH4(g) + 2O2(g)  CO2(g) + 2H2O(g)
INCREASE or DECREASE Volume
d. 2CO(g) + O2(g)  2CO2(g)
INCREASE or DECREASE Volume
15. For a- f, fill in the blank with shift left, shift right, or no shift.
a) Which way will the equilibrium shift if more H2 is added to this reaction at equilibrium? _____________
N2 + 3 H2  2 NH3
b) Which way will the equilibrium shift if the system temperature goes up (heat is added)? ________________
2 SO2 + O2  2 SO3 + heat
c) The container holding the following reaction (already at equilibrium) has its volume suddenly reduced by
half. Which way will the equilibrium shift to compensate?
__________________
PCl3 + Cl2  PCl5
d) The container holding the following reaction (already at equilibrium) has its volume suddenly increased.
Which way will the equilibrium shift to compensate?
__________________
H2 + Cl2  2 HCl
e) The system below is already at equilibrium when some neon is added to the system. What happens to the
position of the equilibrium? Does it shift right, left, or no change?
__________________
H2 + Cl2  2 HCl
f) The system below is already at equilibrium when a catalyst is added to the system. What happens to the
position of the equilibrium? Does it shift right, left, or no change?
__________________
PCl3 + Cl2  PCl5