Title: Le Chatelier's Principle and Determination of Ke
Pre-laboratory Assignment
Read the experiment and answer the following questions as directed by your instructor:
1. Use Le Chatelier's Principle to make the following predictions about the equilibrium reaction used in this lab experiment: Fe + SCN -> FeSCN (almost colorless) (red-orange)
a. Would you expect the red-orange color of the mixture to increase or decrease if additional Fe+3 is added? Explain your answer by describing how adding this reactant would shift the equilibrium.
b. Would you expect the red-orange color of the mixture to increase or decrease if additional SCN- is added?
c. If the reaction container was heated, and the red-orange color decreased, would this indicate that the reaction is exothermic or endothermic?
2. A student makes a reaction mixture that contains the following: 5.0 mL of 2.0x10M Fe, 2.0 mL of 2.0x10M SCN, and 3.0 mL of water.
a. What is the [Fe] and [SCN] in the mixture before equilibrium has been established?
b. If the equilibrium [FeSCN] is found to be 1.7x10^3, what are the [Fe] and [SCN] after equilibrium has been established?
c. Based on these values, what is Ke for this reaction?
