Name Date Period Unit 8 Review

Transcription

1 Name Date Period Unit 8 Review Part one: Solutions 1. What is a solution? What are the parts of a solution? Define the parts. 2. Draw the process of dissolving below: 3. What are the solutes and solvents in the following solutions? a. Solid Acetic acid and water: b. Paint and paint thinner: c. Our atmosphere: 78% nitrogen gas (N2), 20.95% oxygen gas (O2), 0.93% argon gas (Ar), 0.038% carbon dioxide (CO2), and 0.082% water vapor (H2O). 4. What is solubility? 5. What two things affect the solubility of a substance? 6. What types of solutes will dissolve better in hotter solutes? What types of solutes dissolve better in colder solvents? 7. What is a saturated solution? Unsaturated? Supersaturated? a. If a soda is considered a solution of CO2 in water, in terms of saturation, what type of solution is an unopened soda? An opened soda? A flat soda? 8. Use the solubility curve below to answer the questions to the right: a. How many grams of KCl can be dissolved in 100 g of water at 65 o C to reach saturation? b. If you dissolved 80 g of NaNO3 in 100 g of water at 30 o C, would the solution be saturated, unsaturated and supersaturated? c. What makes the solubility curves of gases different from the solids? d. What happens to the solubility of solids as the temperature increases? e. What happens to the solubility of gases as they temperature increases?

2 9. What are three things that would affect the rate at which something dissolves? 10. What is concentration? 11. What is the equation for molarity? 12. What is the equation for molality? 13. How many moles of solute are in 250 ml a 0.5M solution? 14. What is the molality of a solution that contains 3.4 g of NaCl dissolved in 200 g of water? 15. There are g of caffeine in a 12 oz can (360 ml) of Red Bull. There are g of caffeine in one 16 oz can (480 ml) of Rockstar Energy Drink. The chemical formula for caffeine is C8H10N4O2. a. What is the solute they are focusing on in this information? b. What are the solutions in this question? c. What is the molar concentration of caffeine in each beverage? d. Which beverage delivers more caffeine per volume? 16. What does adding a solute do to the freezing point of the solvent? Why? 17. What does adding a solute do to the boiling point of the solvent? Why? 18. What is a Van t Hoff factor? 19. Which types of substances have a Van t Hoff factor of just one? 20. Which types of substance have a Van t Hoff factor of greater than one? 21. What is the increase in boiling point of a solution that contains 32.5 g of MgCl2 dissolve in 1.5 Kg of water? (Kb for water is 0.52 o C/m). a. What is the freezing point depression of the solution? (Kf of water is 1.86 o C/m)?

3 22. A water-based slushee solution contains 39.0 grams of sugar (C12H22O11) to every 360 g of water. What would be the freezing point depression of the solution? The Kf for water is 1.86 o C/m. a. The slushee machine doesn t seem to be freezing the solution correctly. It is checked and shown to be set at -0.3 o C. Is this low enough to freeze the slushee solution? Pure water freezes at 0.0 o C. Part Two: Equilibrium 1. What is equilibrium? 2. What is equal at equilibrium? 3. What remains constant at equilibrium? 4. What is changing at equilibrium? 5. For the reaction A B, at what time on the graph has the reaction reached equilibrium? a. What happens to the concentrations of the reactants (A) and products (B) at equilibrium? b. At equilibrium, do chemical reactions stop? 6. What is Le Chatelier s Principle? a. what are three things that will affect the equilibrium position (the side of the reaction that is favored at equilibrium?)

4 7. For the following reaction, write the two reactions that are happening in the reaction system. 3 Fe(s) + 4 H2O (g) Fe3O4 (s) + 4 H2 (g) 8. What does equilibrium position tell you about a reaction? 9. What does it mean to say that equilibrium lies to the right? 10. What does it mean to say that equilibrium shifts to the left? 11. Write the equilibrium expression for the equation in # List two ways in which the equilibrium position of the reaction in #7 can be shifted to the left. 13. Substances in which states of matter DO NOT affect (and are not affected by) the equilibrium of a reaction? 14. For the following reaction answer the questions that follow: 5CO(g) + I2O5(s) I2(g) + 5CO2(g) + Heat a. What would happen to the amount of CO if you added more I2 to the system? b. How would the system respond if you removed I2 from it (what would happen to the rates of c. How would the system respond if you removed I2O5 from it (what would happen to the rates of d. How would the system respond if you added more CO2 to it (what would happen to the rates of e. Name two ways you could shift the equilibrium position to the right. f. What would happen to the amount of CO2 if you decreased the volume of the container? g. What would happen to the amount of each of the substances if you put this reaction in the freezer?

5 15. Write equilibrium expressions for the following reaction: a) 3 O2 (g) 2 O3 (g) b) 5CO(g) + I2O5(s) I2(g) + 5CO2(g) c) 4NH 3 (g) + 3O 2 (g) 2N 2 (g) + 6H 2 O(g) 16. What is Keq? What does its value tell you about a reaction system? a. A system has a Keq of What side of the reaction is favored at equilibrium? b. A system has a Keq of 2.6. What side of the reaction is favored at equilibrium? c. A system has a Keq of 1. What side of the reaction is favored at equilibrium? 17. SO3(g) + H2O(g) H2SO4(g) At equilibrium, at 25 o C, [SO3] = 0.400M [H2O] = 0.480M [H2SO4] = 0.600M a) Calculate the value of the equilibrium constant. b) What side of the reaction is favored at this temperature? 18. What is a reaction quotient (Q)? 19. What information does a reaction quotient tell you? 20. If a system has a Keq of 0.11 and a reaction quotient of 0.33, is the system at equilibrium yet and if not, what direction does it need to proceed to get to equilibrium? 21. PCl5 (s) + H2O (g) 2HCl (g) + POCl3 (g) At equilibrium at 100 o C, Keq = 1.4 At some point during the reaction, the following quantities of each chemicals were found in the reaction flask which has a volume of 2.0L flask contains: M H2O 0.36M HCl 0.31 M POCl3 a) Calculate the Q for the reaction: b) Has this reaction reached equilibrium yet? How do you know? c) If it hasn t, what direction would it need to proceed to get there?