Chem Exam 3

8. If a solution is prepared by dissolving 15.6 g of lithium iodide, LiI, in enough water to make 400 mL of solution, what is the %(w/v) of LiI? A. 0.96% B. 1.9% C. 3.9% D. 7.7%

% (w/v) = 15.6 g x 100% = 3.9% (w/v) 400 mL C. 3.9%

3. 2.7 g NaCl dissolves in water to make 90 mL solution. What is the % w/v of the solution? A). 0.9 % w/v B). 1.8 % w/v C). 3.0 % w/v D). 4.1 % w/v

% (w/v) = 2.7g x 100 %= 3 % w/v 90 mL C. 3.0% w/v

17. Acetic acid is the active ingredient in vinegar. In a solution of acetic acid the following equilibrium is established. HC2H3O2(aq) H+(aq) + C2H3O2-(aq) The equilibrium constant for this reaction is 1.8 10-5. What is the equilibrium constant for the following reaction ? H+(aq) + C2H3O2-(aq) . HC2H3O2(aq) A. 1.8 10-5 B. 4.2 10-3 C. 5.6 104 D. 3.1 109

. K = K = [H+][ C2H3O2-]/[ HC2H3O2] = 1.8 x 10-5 K K = [ HC2H3O2]/[H+][ C2H3O2-] = 1/1.8 x 10-5 = 5.56 x 10-4 C. 5.56 x 10-4

12. A certain wine contains 0.02 M NaHSO3 as a preservative. What mass of NaHSO3 is in a 750 mL bottle of this wine? A. 0.39 g B. 0.70 g C. 0.78 g D. 1.56 g

0.02 M NaHSO3 0.02mole NaHSO3 750 mL x 1 L = 0.75 L 1 L solution 1000 mL 0.75 L x 0.02 mol NaHSO3 = 0.015 mole NaHCO3 1 L 1 mole NaHSO3 = 23 g + 1 g + 32 g + 3 x 16 g = 104 g NaHCO3 0.015 mole NaHSO3 x 104 g NaHCO3 = 1.56 g NaHSO3 1 mole NaSCO3 D)

7. Calculate the rate constant, , for the reaction 2H2O2(l) 2H2O(l) + O2(g) Using the rate, 0.02 mol/L.min H2O2, and the initial concentration, [H2O2] = 0.5 mol/L A. - 25/min B. 25/min C. - 0.04/min D. 0.04/min

0.02 mol/L.min = k x 0.5 mol/L 0.02 mol/L.min = k x 0.5 mol/L k = 0.04/min 0.5 mol/L 0.5 mol/L D)

8. How many moles of NaCl are contained in 2 L of 0.125 M KCl solution? A). 0.25 mole B). 0.50 mole C). 1.0 mole D). 1.5 moles

0.125 M = 0.125 mole 1 L 2 L x 0.125 mole = 0.25 mole 1 L A) O.25 mole

10. If we wish to prepare a 0.4 M solution of NaCl, how much water must be added to 1.0 mole of NaCl? A. 2.5 L B. Enough water to make 2.5 L of solution. C. 2.0 L D. Enough water to make 2.0 L of solution.

0.4 M NaCl = 0.4 mol NaCl and 1 L NaCl solution 1 L NaCl solution 0.4 mol NaCl 1 mol NaCl x 1 L NaCl solution = 2.5 L NaCl solution 0.4 mol NaCl 1 mol NaCl adds enough water to make 2.5 L solution B.Enough water to make 2.5 L of solution

6. Saline solutions (NaCl in water) used to deliver intravenous drugs are 0.89%(w/v). What mass of NaCl is found in 200 mL of such a solution? A.. 0.45 g B. 1.78 g C. 4.5 g D. 8.9 g

0.89% (w/v) = 0.89 g NaCl/100 mL saline solution 200 mL solution x 0.89 g NaCl = 1.78 g NaCl 100 mL saline B. 1.78 g

23. Isotonic saline is 0.89% NaCl (w/v). Suppose you wanted to make 0.5 L of isotonic solution of NH4Cl. What mass of NH4Cl would you need? A. 4.1 g B. 8.1 g C. 8.9 g D. 54 g

0.89%(w/v) = 0.89 g NaCl/100 mL solution 8.9 g NaCl/1000 mL (1 L) solution. 1 mole NaCl = 23 g + 35.5 g = 58.5 g NaCl; NaCl Na+ + Cl- = 2 particles 8.9 g NaCl x 1 mole NaCl = 0.152 mole NaCl Osmol = 0.152 x 2 = 0.304 Osmol 58.5 g NaCl NH4Cl NH4+ + Cl- = 2 particles. Isotonic = 0.304 Osmol 0.304 Osmol = M x 2 M of NH4Cl = 0.152 M NH4Cl 0.152 mole NH4Cl/1 L solution 0.5 L x 0.152 mole NH4Cl = 0.076 mole NH4Cl 1 L 1 mole NH4Cl = 14 g + 4 x 1 g + 35.5 g = 53.5 g NH4Cl 0.076 mol NH4Cl x 53.5 g NH4Cl = 4.066 g NH4Cl 1 mol NH4Cl A. 4.1 g

9. What is the mass of NaCl in a 2 L bottle of 1 M NaCl? A). 29.3 g B). 58.5 g C). 117 g D). 234 g

1 M = 1 mole NaCl 2 L x 1 mole NaCl = 2 mole NaCl 1 L 1 L 1 mole NaCl = 23 g + 35.5 g = 58.5 g 2 mole NaCl x 58.5 g NaCl = 117 g NaCl 1 mole NaCl C). 117 g

21. A solution is prepared by dissolving 208.3 grams of barium chloride, BaCl2 in 1000 grams of water? What is the boiling point of this solution? [The boiling point elevation constant for water is 0.512°C/mole solute in 1000g of water] A. 100.26°C B. 100.52°C C. 100.77°C D. 101.54°C

1 mole BaCl2 = 137.3 g + 2 x 35.5 g = 208.3 g BaCl2 208.3 g BaCl2 x 1 mol BaCl2 = 1 mol BaCl2 208.3 g BaCl2 BaCl2 Ba2+, 2 Cl- 3 particles Tb = 0.512 oC x 1 mol x 3 = 1.536 oC BP = 100 oC + 1.536 oC Mol = 101.536 oC D)

20. A solution is prepared by dissolving 107.5 grams of methanol, CH3OH, in 1000 grams of water. What is the freezing point of this solution? [The freezing point depression constant for water is 1.86°C/mole solute in 1000g of water] A. - 6.25°C B. - 12.5°C C. - 25.0°C D. - 40.3°C

1 mole CH3OH = 12 g + 4 x 1 g + 16 g = 32 g CH3OH 107.5 g CH3OH x 1 mole CH3OH = 3.36 moles CH3OH 32 g CH3OH Tf = -1.86oC x mole of particles Tf = - 1.86oC x 3.36 mol CH3OH Mol mol = - 6.25 oC A)

11. A solution is prepared by dissolving 4.40 g of KSCN in enough water to make 250 mL of solution. What is the concentration of the solution? A. 0.18 M B. 0.132 M C. 0.0543 M D. 0.0445 M

1 mole KSCN = 39.1 g + 32.1 g + 12 g + 14 g = 97.2 g KSCN 4.4 g KSCN x 1 mol KSCN = 0.045 mol KSCN 97.2 g KSCN Molarity = 0.045 mol KSCN (250 mL x 1 L = 0.25 L 0.25 L solution 1000 mL = 0.18 M A

7. 58.5g of NaCl dissolves in enough water to make 0.4 L of solution. What is the molarity of the NaCl solution? A). 0.25 M B). 0.5 M C). 2.0 M D). 2.5 M

1 mole NaCl = 23 g + 35.5 g =58.5 g Molarity = 1 mole = 2.5 M 0.4 L D. 2.5 M

13. A particular chemical reaction carried out at 10°C takes 4 hours. Approximately how long will it take to carry out the reaction at 40°C? A. 15 minutes B. 30 minutes C. 1 hours D. 2 hours

10oC 20oC 30oC 40oC 4 hr 2 hr 60 min 30 min B. 30 minutes

7. The label on a 300 mL bottle of wine states that its alcohol content is 15%(v/v). What volume alcohol is present in the bottle? A. 45 mL B. 90 mL C. 120 mL D. 180 mL

15%(v/v) = 15 mL alcohol 100 mL wine 300 mL wine x 15 mL alcohol = 45 mL alcohol 100 mL wine A. 45 mL

. For the reaction 2C A + B, 0.01 mol of A is formed during the first 20 seconds of the reaction. Assuming that the rate of reaction remains constant for two minutes, which of the following statements is true? A. After 2 minutes 0.08 moles of B were produced. B. After 2 minutes 0.12 moles of C were consumed. C. Both A and B D. Neither A nor B

2 min x 60 sec x 0.01 mole A x 2 moles C = 0.12 moles C 1 min 20 sec 1 mole A B. After 2 minutes 0.12 moles of C were consumed.

5. A salt water solution is 2.0% (w/w). How much salt is in 250 grams of salt water solution? A.. 1.5 grams B. 2.5 grams C. 5.0 grams D. 7.5 grams

2.0%(w/w) = 2 g salt/100 g solution 250 g solution x 2 g salt = 5 g salt 100 g solution C. 5.0 grams

22. What is the osmolarity of a 2.5 % (w/v) Na3PO4 solution? A. 0.20 osmolar B. 0.30 osmolar C. 0.60 osmolar D. 1.20 osmolar

2.5 %(w/v) Na3PO4 2.5 g Na3PO4/100 mL solution 25 g Na3PO4/1000 mL (1 L) solution 1 mole Na3PO4 = 3 x 23 g + 32 g + 4 x 16 g = 165 g Na3PO4 25 g Na3PO4 x 1 mol Na3PO4 = 0.15 mol Na3PO4 165 g Na3PO4 M = 0.15 mol Na3PO4 = 0.15 M 1 L solution Na3PO4 3 Na+ + PO43- 4 particles (i) Osmolarity = M x i = 0.15 x 4 = 0.6 osmol C. 0.60 osmolar

2. The solubility of KI is 50 g in 100 g of H2O at 20 °C. If 99 grams of KI are added to 200 grams of H20. A). All of the KI will dissolve completely. B). Some KI will be left on the bottom of the container. C). The solution will start boiling. D). A saturated solution will form.

200 g H2O x 50 g KI = 100 g KI 100gH2O 100 g KI can dissolve in 200 g H2O A). All of the KI will dissolve completely.

31. A particular chemical reaction carried out at 20°C takes 6 hours. Approximately how long will it take to carry out the reaction at 50°C? A.). 2 hours B). 1 hour C). 45 minutes D). 15 minutes

20oC 30oC 40oC 50oC 6 hr 3 hr 1.5 hr (90 min) 45 min C) 45 minutes

. If we wish to prepare 250 mL of 0.4 M BaCl2, how much solid is BaCl2 is needed? A. 4.17 g B. 5.21 g C. 10.4 g D. 20.8 g

250 mL x 1 L = 0.25 L 0.4 M = 0.4 mole BaCl2 1000 mL 1 L 0.25 L x 0.4 mol BaCl2 = 0.1 mol BaCl2 1 L 1 mol BaCl2 = 137.3 g + 2 x 35.5 g = 208.3 g 0.1 mol BaCl2 x 208.3 g BaCl2 = 20.8 g 1 mol BaCl2 D. 20.8 g

10. How many mL of 3 M HCl solution will provide 1.5 mole of HCl? A). 125 mL B). 250 mL C). 375 mL D). 500 mL

3 M = 3 mol/1L 1.5 mol x 1 L = 0. 5 L x 1000 mL = 500 mL 3 mol 1 L D). 500 mL

11. How many mL of 30 % w/v glucose solution is needed to prepare 600 mL of a 5 % w/v NaCl solution? A). 450 mL B). 100 mL C). 45 mL D). 9 mL

30 % w/v x V1 = 5 % w/v x 600 mL 30 % w/v x V1 = 5 % w/v x 600 mL 30% w/v 30 % w/v V1 = 100 mL B) 100 mL

4. What is the mass of NaCl in 200 mL of 4 % (w/v).NaCl solution? A). 50grams B). 8 grams C). 5 grams D). 4.5 grams

4 %(w/v) = 4 g NaCl/100 mL solution 200 mL solution x 4 g NaCl = 8 g NaCl 100 mL solution B. 8 grams

19. Compared to body fluids, both 0.9% (m/v) NaCl solution and 5% (m/v) glucose solution are isotonic. Red blood cells will undergo crenation in _____ solution. A). 0.5 % NaCl B). 2 % glucose C). 0.9 % NaCl D). 6 % glucose

6 % glucose is hypertonic D

17. A solution is prepared by dissolving 87.75 grams of sodium chloride, NaCl, in 1000 grams of water. What is the boiling point of this solution? A). 100.256°C B). 100.512°C C). 101.536°C D). 101.024°C

87.5 g NaClx 1 mole NaCl = 1.5 mole NaCl (Na+, Cl-) 58.5g NaCl Tb = 0.512 x 1.5 x 2 moles particles = 1.536 oC Boiling point = 100 oC + 1.536 oC = 101.536 oC C). 101.536°C

28. In an energy diagram for an exothermic chemical reaction which of the following is true? (see Fig. 7.4, in the reference sheet) A). The energy of the reactants is higher than that of the products. B). The energy of the reactants is lower than that of the products. C). Both A and B D). Neither A nor B

A). The energy of the reactants is higher than that of the products

22. The rate of reaction for the decomposition of hydrogen peroxide to yield water and oxygen, 2H2O2 2H2O + O2, is given by the equation: Rate = k[H2O2]. Which of the following is indicated by this equation? A). The rate of the reaction will increase with increasing concentration of H2O2. B). The rate of the reaction is unaffected by the concentration of H2O2. C). The rate of the reaction will decrease with increasing concentration of H2O2. D). None of the above

A). The rate of the reaction will increase with increasing concentration of H2O2.

36. What is the effect of increasing the temperature of an ENDOTHERMIC ( A + Heat B) reaction which has reached equilibrium? A). The reaction will shift to right (). B). The reaction will shift to left (). C). There will be no effect. D). Not sufficient information to predict the direction of the reaction.

A). The reaction will shift to right ().

15. The Tyndall effect is associated with which of the following? A). light scattering by colloidal particles B). keeping colloidal particles from settling C). both A and B D). neither A nor B

A). light scattering by colloidal particles

14. If drinking water is polluted with lead ions to the extent of 2 ppm (parts per million), it means that A. 2 mg of lead ions in 1 kg (1 L) of water B. 2 mg of lead ions in 1 g (1 mL) of water. C. 2g of lead ions in 1 kg (1 L) of water. D. 2g of lead ions in 1 g (1 mL) of water

A. 2 mg of lead ions in 1 kg (1 L) of water

6. Which of the following is true? A. Decreasing the activation energy increases the reaction rate. B. Increasing the activation energy increases the reaction rate. C. The activation energy of an exothermic reaction is negative. D. There is no relationship between activation energy and reaction rate.

A. Decreasing the activation energy increases the reaction rate.

1. Which of the following is the study of the rates of chemical reactions? A. kinetics B. stoichiometry C. thermodynamics D. All of the above

A. Kinetics

10. Which of the following is true of all multi-step reactions? A. The rate of reaction is determined by the slowest step. B. They involve more than two reactant molecules. C. They are endothermic. D. They are exothermic.

A. The rate of reaction is determined by the slowest step.

2. A beaker of salt water has some solid salt at the bottom. What type of solution is in the beaker? A. a saturated solution B. a supersaturated solution C. an unsaturated solution D. We cannot tell.

A. a saturated solution

19. The following reaction is endothermic: 3O2(g) 2O3(g) tell whether the equilibrium will shift to the right or the left if we increase the temperature. A. to the right B. to the left C. will go both direction D. None of the above

A. to the right

29. The temperature effect on reaction rate is the result of which of the following? A). At higher temperatures there are less collisions. B). At higher temperatures a larger fraction of the collisions are effective collisions. C). Neither A nor B D). Both A and B

B). At higher temperatures a larger fraction of the collisions are effective collisions.

20. For the reaction 2A + B 2 C, which of the following statements is true? A). A is consumed at the same rate that B is consumed. B). C is produced at the same rate that A is consumed. C). Neither A nor B D). Both A and B

B). C is produced at the same rate that A is consumed

26. Which of the following is true? A). Decreasing the activation energy decreases the reaction rate. B). Decreasing the activation energy increases the reaction rate. C). There is no relationship between activation energy and reaction rate. D). All of the above

B). Decreasing the activation energy increases the reaction rate

24. Many molecular collisions DO NOT result in chemical reaction. Why is this? A). The colliding molecules are the correct chemicals. B). The colliding molecules have incorrect orientations. C). The colliding molecules have sufficient energy. D). All of the above

B). The colliding molecules have incorrect orientations.

35. What is the effect of removing H2O(l) to a container in which the reaction has reached equilibrium? CH3COOH(l) + C2H5OH(l) CH3COOC2H5(l) + H2O(l) A). The reaction will shift to left (). B). The reaction will shift to right (). C). There will be no effect. D). What happens depends on the temperature

B). The reaction will shift to right ().

6. When considering the solubility of a solute in a particular solvent, the term "like dissolves like" generally refers to which of the following properties? A). formula weight B). molecular polarity C). molecular shape D). All of the above

B). molecular polarity

14. Because colloidal particles acquire the same kind of charge on their large surface areas and have large solvation layers, they ____. A). separate and settle down in solutions. B). remain stable dispersion in solutions without settling. C). both A and B D). neither A nor B

B). remain stable dispersion in solutions without settling.

16. Write the reaction to which the following equilibrium expression applies: K =[ HF3PF3] /[F2]3[ PH3] A. F2 + PH3 HF + PF3 B. 3F2 + PH3 3HF + PF3 C. HF + PF3 F2 + PH3 D. 3HF + PF3 3F2 + PH3

B. 3F2 + PH3 3HF + PF3

1. The following molecules can form hydrogen bonds between molecules EXCEPT A). H2O B). HCl C). NH3 D). HF

B. HCl

14. A catalyst speeds up a chemical reaction as a result of which of the following? A. It increases the number of collisions between reacting molecules. B. It provides an alternate pathway with a lower activation energy. C. It makes the reaction more endothermic. D. It makes the reaction more exothermic.

B. It provides an alternate pathway with a lower activation energy.

3. When considering the solubility of a particular solute in a particular solvent the term "like dissolves like" generally refers to which of the following properties? A. formula weight B. molecular polarity C. molecular shape D. All of the above

B. Molecular polarity

11. Which of the following accounts for the fact that reactions between ions in solution are usually very fast? A. Ionic bonds are weak. B. No covalent bonds need to be broken for reaction to occur. C. Reactions between ions are endothermic. D. Reactions between ions are exothermic.

B. No covalent bonds need to be broken for reaction to occur.

9. In an energy diagram for an endothermic chemical reaction which of the following is true? A. The energy of the products is lower than that of the reactants. B. The energy of the transition state is higher than that of the reactants. C. Both A and B D. Neither A nor B

B. The energy of the transition state is higher than that of the reactants.

2. For the reaction A + B 2 C, which of the following best describes how we can measure the reaction rate? A. The rate can be measured by measuring how fast A is produced. B. The rate can be measured by measuring how fast C is produced. C. Either of the above procedures can be used. D. Neither of the above procedures can be used.

B. The rate can be measured by measuring how fast C is produced.

25. Which of the following is associated with cells in a hypotonic solution? A. crenation B. hemolysis C. reverse osmosis D. None of the above

B. hemolysis

20. The following reaction is endothermic: 3O2(g) 2O3(g) tell whether the equilibrium will shift to the right or the left if we decrease the pressure. A. to the right B. to the left C. will go both direction D. None of the above

B. to the left

15. The term water of hydration is applied to which to which of the following? A. water molecules required to dissolve a solid B. water molecules associated with a salt in the solid state C. water molecules associated with ions in solution D. All of the above

B. water molecules associated with a salt in the solid state

25. Which of the following is true of a reaction which has reached equilibrium? A). The rate of the forward reaction is slower than the rate of the reverse reaction. B). The rate of the forward reaction is faster than the rate of the reverse reaction. C). The rate of the forward reaction is equal to the rate of the reverse reaction D). The reactants have been completely converted to products.

C). The rate of the forward reaction is equal to the rate of the reverse reaction

37. What is the effect of decreasing pressure to a container in which the reaction has reached equilibrium? 5A(g) + 2B(g) 7C(g) A). The reaction will shift to right (). B). The reaction will shift to left (). C). There will be no shift. D). What happens depends on the temperature.

C). There will be no shift.

13. Which of the following is a description of a hydrated salt? A). a solid salt which is insoluble in water B). a solid salt with no water incorporated in its crystal structure C). a solid salt with water incorporated in its crystal structure D). None of the above

C). a solid salt with water incorporated in its crystal structure

5. Water is likely to be a POOR solvent for which types of molecules? A). molecules which can form hydrogen bonds B). polar molecules C). nonpolar molecules D). None, water is considered a universal solvent for all solutes.

C). nonpolar molecules

16. Which of the following is true of a solid which is hygroscopic? A. It will gain weight when exposed to a damp environment. B. It may change its color upon being exposed to a damp environment. C. Both A and B D. Neither A nor B

C. Both A and B

18. Which of the following factors cause colloidal particles to remain in solution without settling? A. Colloidal particles acquire a charge on their large surface areas. B. Colloidal particles have large solvation layers. C. Both A and B D. Neither A nor B

C. Both A and B

12. The temperature effect on reaction rate is the result of which of the following? A. At higher temperatures there are more collisions. B. At higher temperatures a larger fraction of the collisions are effective collisions. C. Both A and B D. Neither A nor B

C. Both a and b

15. For the reaction, 2NH3(g) 3 H2(g) + N2(g), which of the following is the equilibrium constant expression? A. K = [H2][N2]/[NH3] B. K = [NH3]/[H2][N2] C. K = [H2]3[N2]/[NH3]2 D. K = [H2]2[O2]/[H2O]2

C. K = [H2]3[N2]/[NH3]2

1. A solution consists of 10 g NaCl and 100 g water (H2O). The solubility of water at 20oC is 36.09 g NaCl/100 g H2O. The following statements are correct EXCEPT A. NaCl is the solute B. H2O is the solvent C. This solution is a heterogenous mixture D. The solution is an unsaturated solution

C. This solution is a heterogenous mixture

13. What volume of 12 M HCl must be used to make 150 mL of 0.6 M HCl? A. 1.5 mL B. 7.5 mL C. 15 mL D. 24 mL

C1V1 = C2V2 12 M x V1 = 0.6 M x 150 mL 12 M x V1 = 0.6 M x 150 mL 12 M 12 M V1 = 7.5 mL B. 7.5 mL

32. For the reaction 2 H2(g) + O2(g) 2H2O(g), which of the following is the equilibrium constant expression? A). K = [H2][O2] B). K = [H2O] [H2O] [H2][O2] C). K = [H2]2[O2] D). K = [H2O]2 [H2O]2 [H2]2[O2]

D

34. Which of the following could be the equilibrium constant for a reaction to yield the MOST concentration of products? A). 1 x 10-12 B). 1 x 10-2 C). 1 x 10 2 D). 1 x 10 12

D). 1 x 10 12

12. A solution contains 7 ppb of arsenic ion (As3+). Which of the following is another way to describe the concentration of As3+ in this solution? A). 7 mg As3+ ions/ 1 g solution B). 7 mg As3+ ions/ 1 kg g solution C). 7 µg As3+ ions/ 1 g solution D). 7 g As3+ ions/ 1 kg solution

D). 7 g As3+ ions/ 1 kg solution ppb= 1 µg/kg

27. A catalyst speeds up a chemical reaction as a result of which of the following? A). It makes the reaction more endothermic. B). It makes the reaction more exothermic. C). It decreases the number of collisions between reacting molecules. D). It provides an alternate pathway with a lower activation energy.

D). It provides an alternate pathway with a lower activation energy.

30. Which of the following accounts for the fact that reactions between ions in solution are usually very fast? A). Ionic bonds are weak. B). Reactions between ions are exothermic. C). Reactions between ions are endothermic. D). No covalent bonds need to be broken for reaction to occur.

D). No covalent bonds need to be broken for reaction to occur.

19. Which of the following will have the lowest freezing point? A. 0.1 M glucose (C6H12O6) B. 0.1 M NaCl C. 0.1 M BaCl2 D. 0.1 M AlCl3

D. 0.1 M AlCl3 Glucose glucose (1 particle) NaCl Na+ + Cl- ( 2 particles) BaCl2 Ba2+ + 2 Cl- ( 3 particles) AlCl3 Al3+ + 3 Cl- (4 particles) Tf = -1.86oC x mole of particles Mol

4. Which of the following laws describes the relationship between pressure and the solubility of gases? A. Avogadro's B. Boyle's C. Dalton's D. Henry's

D. Henry's

5. Many molecular collisions do not result in chemical reaction. Why is this? A. The colliding molecules are not the correct chemicals. B. The colliding molecules do not have sufficient energy. C. The colliding molecules do not have the correct orientations. D. all of the above

D. all of the above

8. In an energy diagram for a chemical reaction what species represents the highest energy? A. the catalyst B. the products C. the reactants D. the transition state

D.The transition state

33. For the reaction A(g) + B(g) 2 C(g) at 100°C equilibrium is established when [A] =0.5 M, [B] = 0.1 M and [C] = 0.5M. What is the equilibrium constant for this reaction? A). 0.5 B). 0.4 C). 5 D). 4

K = (0.5)2 = 5 (0.5)(0.1)

18. When the following reaction reached equilibrium at 325 K , the equilibrium constant was found to be 172. When a sample was taken of the equilibrium concentration, it was found contain 0.2 M NO2. What was the equilibrium concentration of N2O4? 2NO2(g) N2O4(g) A. 0.877 B. 6.88 C. 2.41 x 103 D. 3.37 x 104

K = [ N2O4]/[NO2]2 172 = [ N2O4] [ N2O4] = 172 x (0.2)2 (0.2)2 = 6.88 M B. 6.88

17. Which of the following solutions will have the lowest electrical conductivity? (Hint: PO43-, HPO42-, H2PO4- ) A. 1 M Na3PO4 B. 1 M Na2HPO4 C. 1 M NaH2PO4 D. All have the same conductivity

Na3PO4 3 Na+ + 1 PO43- = 4 ions Na2HPO4 2 Na+ + 1HPO42- = 3 ions NaH2PO4 1 Na+ + 1H2PO4- = 2 ions C. 1 M NaH2PO4

16. Which of the following will have the lowest freezing point (reduce the freezing point the most)? a). 0.4 M NaCl B). 0.3 M AlCl3 C). 0.9 M glucose (C6H12O6) D). All have the same freezing point

NaCl Na+ + Cl- ( 2 particles); 0.4 x 2 = 0.8 AlCl3 Al3+ + 3 Cl- (4 particles); 0.3 x 4 = 1.2 C6H12O6 1 particle; 0.9 x1 = 0.9 Tf = -1.86oC x mole of particles mol B). 0.3 M AlCl3

24. Which of the following solutions of glucose (C6H12O6) is isotonic with a 0.1 M NaCl solution? A. 0.15%(w/v) B. 0.55%(w/v) C. 3.6 %(w/v) D. 5.4%(w/v)

NaCl Na+ + Cl- = 2 particles Osmol of 0.1 M NaCl = 0.1 x 2 = 0.2 Osmol NaCl Gulcose doesn't dissocate to particles so 0.2 Osmol glucose = 0.2 M glucose 0.2 M glucose = 0.2 mol glucose/1 L dolution 0.02 mol/100 mL 1 mol glucose (C6H12O6) = 6 x 12 g + 12 x 1 g + 6 x 16 g = 180 g glucose 0.02 mol glucose x 180 g glucose = 3.6 g glucose 3.6 g glucose/100 mL solution 1 mol gluose 3.6 %(w/v) glucose solution. C

18. What is the osmolarity of a 0.1 M of BaCl2 solution? A. 0.30 osmol B. 0.40 osmol C. 0.60 osmol D. 1.20 osmol

NaCl dissociates to Ba2+ and 2 Cl- (3 particles) Osmolarity = M x i = 0.1 x 3 = 0.3 Osmol A. 0.30 osmol

23. Calculate the rate for the reaction 2H2O2(l) 2H2O(l) + O2(g) , when the rate constant, k, is - 0.15 and the initial concentration of H2O2 is 1 mol/L. A). - 0.015 mol/min.L B). - 0.030 mole/min.L C). - 0.075 mole/min.L D). - 0.150 mole/min.L

Rate = - 0.15 x 1 mol = - 0.15 mol/min .L min L D) -0.150 mole/min.L

21. In the reaction Zn(s) + 2HCl(aq) ZnCl2(aq) + H2(g), we measure the evolution of H2 gas to determine the rate of reaction. At the beginning of the reaction (at 0 minutes), 0.0 L of H2 is present. After 30 seconds, the volume of H2 is 0.15 L. What is the rate of the reaction? A). 0.0015 L H2/sec B). 0.0020 L H2/sec C). 0.0050 L H2/sec D). 0.0045 L H2/sec

Rate = 0.15 L - 0.0 L= 0.005 L H2/sec 30 sec C). 0.0050 L H2/sec

4. In the reaction 2HgO(s) 2Hg(l) + O2(g) we measure the evolution of gas to determine the rate of reaction. At the beginning of the reaction (at 0 minutes), 0.02 L of O2 is present. After 10 minutes the volume of O2 is 0.36 L. What is the rate of reaction? A. 0.001 L/min B. 0.017 L/min C. 0.022 L/min D. 0.034 L/min

Rate = 0.36 L - 0.02 L = 0.034 L/min 10 min D. 0.034. L/min