Quiz: le Châtelier – Temperature

Click to see a video of the effect of temperature on cobalt chloride solutions.
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Consider the following endothermic reaction (in solution CoCl42- is blue, and Co(H2O)62+ is pink):

CoCl42-  + 6H2O   Co(H2O)62+ + 4Cl- + energy

1. If you want to predict the effect of temperature, what should be the change you identify first?

CoCl42- + 6H2O Co(H2O)62+ + 4Cl- + energy

2. Which of the following is the expected response to a decrease in temperature?

Applied Stress Le Châtelier's Principle Prediction of Response to Stress
CoCl42- + 6H2O Co(H2O)62+ + 4Cl- + energy
Decrease T Increase Decrease Decrease Decrease Increase
Decrease T Decrease Decrease Increase Increase Increase
Decrease T Decrease Increase Decrease Increase Decrease
Decrease T Increase Increase Decrease Decrease Decrease

3.Which of the following is the expected response to an increase in temperature?

Applied Stress Le Châtelier's Principle Prediction of Response to Stress
CoCl42- + 6H2O Co(H2O)62+ + 4Cl- + energy
Increase T Increase Decrease Decrease Decrease Increase
Increase T Decrease Decrease Increase Increase Increase
Increase T Decrease Increase Decrease Increase Decrease
Increase T Increase Increase Decrease Decrease Decrease

 

Consider the following equation, and experimental results (in solution, Cu2+ is blue, and CuCl42- is green):
CuCl42-(aq) Cu2+(aq) + 4Cl-(aq)
0 deg C 100 deg C
As the temperature increases, the color shifts from blue to green.

CuCl2 solution
at 0 oC

CuCl2 solution
at 100 oC

4. What is the H for this reaction?
a)  negative (exothermic )
b)  zero (neither exothermic or endothermic)
c)  positive (endothermic)

Consider the following equilibrium reaction:

PCl5 (g) PCl3 (g) + Cl2 (g) H = 92.5 kJ

5. What is the effect on this reaction if the temperature is raised?
a)  the reaction will shift to the left
b)  the reaction will shift to the right
c)  the reaction will not change

The reaction between hydrogen and chlorine gases

H2 (g) + Cl2 (g) 2HCl (g)

is exothermic.

6. What is the effect on this reaction if the temperature is raised?
a)  the reaction will shift to the left
b)  the reaction will shift to the right
c)  the reaction will not change