Equilibrium Problems

1. Draw a sketch of an energy vs. reaction path graph for an endothermic reaction. Identify the reactants, products, activation energy, heat of reaction, and where the transition state is.

2. What effect does a catalyst have on the rate of a reaction? How would it affect the activation energy and why?

3. A mixture at equilibrium at 827 °C contains 0.552 mol CO₂, 0.552 mol H₂, 0.448 mol CO, and 0.448 mol H₂O. CO₂   +   H₂   <-->   CO   +   H₂O
   1. What is the value for K_eq at this temperature?
   2. More CO₂ is added to the system, which direction will the reaction shift?
   3. What effect did part b) have on the equilibrium constant?
   4. What effect would adding a catalyst have on the equilibrium?
   5. Are the reactants or products favored in this reaction?

4. How does the equilibrium shift when
   1. the concentration of PCl₃ is increased at constant temperature and pressure?
   2. the pressure is decreased?
   3. the concentration of Cl₂ is decreased?
   PCl_5(g)   <-->   PCl_3(g)   +   Cl_2(g)

5. For the following equilibria, explain how the given stress affects the equilibrium point.
   1. N_2(g)   +   O_{2 (g)}   <-->   2 NO_(g)   Increase in pressure
   2. 2 SO_{3 (g)}   +   Heat   <-->   2 SO_{2 (g)}   + O_{2 (g)}   Increase in Temperature
   3. 2 SO_{3 (g)}   +   Heat   <-->   2 SO_{2 (g)}   + O_{2 (g)}   Increase in Pressure
   4. CaCO_3(s)   <-->   CaO_(s)   +   CO_2(g)   Removal of CO₂

6. Write the K_eq expressions for the following expressions.
   1. 2 C₂H_{6 (g)}   +   7 O_{2 (g)}   <-->   4 CO_{2 (g)}   +   6 H₂O_(g)
   2. 4 PH_{3 (g)}   <-->   P_{4 (g)}   +   6 H₂O_(g)
   3. 4 HCl_(g)   +   O_{2 (g)}   <-->   2 Cl_{2 (g)}   +   2 H₂O_(g)

7. At a high temperature the following system reaches equilibrium - N₂ + O₂   <-->   2 NO.
   An analysis of the mixture in a one liter container gives the following results: nitrogen = 0.50 moles, oxygen = 0.50 moles, nitrogen monoxide = 0.020 mol.
   1. Calculate K_eq for this system.
   2. At the same temperature, a new system is made with 0.70 moles of each of the reactants. Find the concentration of the NO. (Hint: you can use the same Keq from part a), why?)

8. If the K_eq for the following reaction is 8.2 x 10^-2, find the concentration of COCl_{2 (g)} if each product has a concentration of 1.2 x 10^-2 M?
   COCl_{2 (g)}   <-->   CO_(g)   +   Cl_{2 (g)}

9. Find the K_eq for the reaction if [H₂S] = 0.015 M, [H₂] = 0.010 M, and the [S₂] = 0.051 M.
   2 H₂S_(g)   <-->   2 H_{2 (g)}   +   S_{2 (g)}

10. In a 1.00 L container, 1 mole of SO₃ is decomposed. At equilibrium, 0.300 mole of O₂ is present. Calculate the concentrations of SO₂ and SO₃ at equilibrium, and calculate K_eq.
    2 SO_{3 (g)}   <-->   2 SO_{2 (g)}   + O_{2 (g)}
    
    
    
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