Le Châtelier s Principle ANSWERS

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Marjorie May
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1 Le Châtelier s Principle ANSWERS 1. When extra NH 3 is added to the following system at equilibrium: 2. When N 2 is removed from the following system at equilibrium: A. In order to restore equilibrium, the reaction shifts left, toward reactants 3. When H 2 is added to the following system at equilibrium: 4. When the pressure is increased on the following system at equilibrium: 1

2 5. When the pressure is decreased on the following system at equilibrium: A. In order to restore equilibrium, the reaction shifts left, toward reactants B. In order to restore equilibrium, the reaction shifts right, toward products 6. When the temperature is decreased on the following system at equilibrium: 7. When the temperature is increased on the following system at equilibrium: 8. When the temperature is decreased on the following system at equilibrium: B. In order to restore equilibrium, the reaction shifts right, toward products 2

3 9. When the temperature is increased on a closed system containing water and its A. In order to restore equilibrium, water vapor condenses to form liquid water 10. When the temperature is decreased on a closed system containing water and its C. In order to restore equilibrium, water vapor condenses to form liquid water 11. When the pressure is decreased on a closed system containing water and its A. In order to restore equilibrium, water vapor condenses to form liquid water 12. When the pressure is increased on a closed system containing water and its B. In order to restore equilibrium, water vapor condenses to form liquid water C. In order to restore equilibrium, more liquid water evaporates 3

4 13. The process of dissolving Na 2 SO 4 in water is known to be exothermic: Na 2 SO 4 (s) <--> 2 Na + (aq) + SO 4 2- (aq) + heat If the temperature of the solution is decreased, Na 2 SO 4 becomes: A. More soluble B. No change in solubility occurs C. Less soluble 14. In lab you studied the aqueous iron(iii) thiocyanate equilibrium: Fe 3+ (yellow) + SCN - (colorless) <--> [FeSCN] 2+ (dark red) If aqueous iron(iii) chloride is added to the solution at equilibrium: A. The solution turns darker red B. The solution becomes colorless C. No change in color occurs D. The solution becomes more yellow 15. In lab you studied the aqueous iron(iii) thiocyanate equilibrium: Fe 3+ (yellow) + SCN - (colorless) <--> [FeSCN] 2+ (dark red) If aqueous potassium thiocyanate is added to the solution at equilibrium: A. The solution becomes more yellow B. The solution turns darker red C. No change in color occurs D. The solution becomes colorless 16. A beaker with a mixture of ice and water is maintained at equilibrium: 4

5 H 2 O(s) + heat <--> H 2 O(l) If the temperature of the system is increased: B. Water freezes to form ice (shift to the left) C. Ice melts to form liquid water (shift to the right) 17. A beaker with a mixture of ice and water is maintained at equilibrium: H 2 O(s) + heat <--> H 2 O(l) If the temperature of the system is decreased: A. Water freezes to form ice (shift to the left) B. Ice melts to form liquid water (shift to the right) 18. A precipitation reaction achieves equilibrium: BaCl 2 (aq) + Na 2 SO 4 (aq) <--> 2 NaCl(aq) + BaSO 4 (s) If barium chloride (BaCl 2 ) is added to the system, which change occurs? A. The reaction shifts to the right, and more precipitate is produced C. The reaction shifts to the left, and some precipitate dissolves 5

Project: Chemical Equilibrium Lab

Project: Chemical Equilibrium Lab Potential Credits: /20 Name: Goal and Instructions: To observe the macroscopic properties of chemical systems at equilibrium and to explain the observations obtained by