3U-solns-prac-test



3U-Solutions -prac-test

Note: this sample test does not reflect length, weight and necessarily every topic and type of question that will be on the unit test. It should not be your only study tool, but rather used in conjunction with class notes, textbook and other resources.

Multiple Choice

Identify the choice that best completes the statement or answers the question.

____ 1. Which of the following is not an electrolyte?

|a. |sugar dissolved in water |d. |a basic solution |

|b. |salt dissolved in water |e. |Gatorade solution |

|c. |an acid solution |

____ 2. Which of the following mixtures is homogeneous?

|a. |orange juice from concentrate |d. |sand and rocks |

|b. |milk |e. |jello |

|c. |clay in water |

____ 3. Which of the following does not dissolve very well in water?

|a. |sodium chloride |d. |gasoline |

|b. |sugar |e. |lemon juice |

|c. |ethanol |

____ 4. The separation of ions that occur as ionic compounds dissolve in water is known as

|a. |dissociation |d. |dissolving |

|b. |separation |e. |deportation |

|c. |protonation |

____ 5. The dissociation equation K3PO4(s) → 3K+(aq) + PO4–3(aq) represents

|a. |soluble potassium phosphate |d. |soluble potassium phosphide |

|b. |insoluble sodium phosphate |e. |soluble potassium phosphite |

|c. |soluble potassium carbonate |

____ 6. Water is referred to as the "universal solvent" because

|a. |Water molecules are small in size. |

|b. |Water molecules are highly polar. |

|c. |Water molecules form hydrogen bonds. |

|d. |a, b, and c only |

|e. |a and c only |

____ 7. Vinegar is labelled with its concentration ratio measured in

|a. |mol/L |d. |ppm |

|b. |% by volume |e. |ppb |

|c. |% by mass |

____ 8. Which of the following is a common source of water contamination?

|a. |landfill leachate |

|b. |agricultural fertilizers and pesticides |

|c. |road salt runoff |

|d. |mining and mine tailings |

|e. |all of the above |

____ 9. The process of rapidly mixing chemicals with water to make small particles in the water clump together is

|a. |coagulation |d. |filtration |

|b. |flocculation |e. |mixing |

|c. |softening |

____ 10. Which of the following is not a disinfectant used in the treatment of water?

|a. |O3(g) |d. |KMnO4(aq) |

|b. |ClO2(g) |e. |NH3(aq) |

|c. |NaF |

____ 11. The contamination of Walkerton, Ontario's water supply in 2000 was caused by

|a. |lead |d. |E. coli bacteria |

|b. |mercury |e. |nitrates |

|c. |pesticides |

____ 12. A bottle contains 3 L of 12 mol/L H2SO4 solution. After half of the contents are used up, the remaining solution has a concentration of

|a. |18 mol/L |d. |3 mol/L |

|b. |12 mol/L |e. |none of the above |

|c. |6 mol/L |

____ 13. Water hardness is caused by which of the following ions?

|a. |Mn2+ |d. |both b and c |

|b. |Ca2+ |e. |Fe3+ |

|c. |Mg2+ |

____ 14. A hardness index of 500 ppm indicates that the water is

|a. |soft |d. |hard |

|b. |slightly hard |e. |very hard |

|c. |moderately hard |

____ 15. The soda-lime process is a water-softening process involving the chemicals

|a. |potassium nitrate and sodium chloride |

|b. |sodium carbonate and calcium hydroxide |

|c. |lithium carbonate and barium hydroxide |

|d. |all of the above |

|e. |none of the above |

____ 16. Which of the following solutions when mixed, would produce a PbI2(s) precipitate?

|a. |PbCl2 and AgI |d. |a and b only |

|b. |Pb(NO3)2 and KI |e. |b and c only |

|c. |Pb(C2H3O2)2 and NaI |

____ 17. Which of the following processes occur during the tertiary treatment of wastewater?

|a. |reverse osmosis |d. |all of the above |

|b. |steam distillation |e. |none of the above |

|c. |chemical precipitation |

____ 18. Which of the following cations in solution would precipitate the NO3– ion?

|a. |Na+ |d. |Cu2+ |

|b. |Ca2+ |e. |none of the above |

|c. |Fe3+ |

____ 19. Quantitative analysis of solutions is different from qualitative analysis because quantitative analysis involves

|a. |colour changes |

|b. |calculations of C, n, or V for solutions |

|c. |colourimetry |

|d. |use of a spectrophotometer |

|e. |none of the above |

____ 20. A company is recycling expensive silver metal from a concentrated silver nitrate solution. Consider the following skeleton equation: AgNO3(aq) + Cu(s) → Cu(NO3)2(aq) + Ag(s)

What are the coefficients required, in order from left to right, to make this equation balanced?

|a. |2, 1, 1, 2 |d. |3, 1, 1, 3 |

|b. |1, 2, 2, 1 |e. |equation is already balanced |

|c. |2, 2, 2, 2 |

____ 21. Based on the solubility curve, _____ KNO3/100 mL of water at _____ would be a supersaturated solution.

|a. |30 g , 10ºC |d. |100 g , 60ºC |

|b. |50 g , 40ºC |e. |100 g , 70ºC |

|c. |80 g , 50ºC |

____ 22. Breathalyzers can determine blood alcohol content indirectly by

|a. |aqueous dichromate ions (orange) + alcohol → chromium(III) ions (green) |

|b. |permanganate ions turning purple |

|c. |copper solution turning pink |

|d. |water + alcohol → red |

|e. |none of the above |

____ 23. Hydrogen chloride gas dissolves in water as follows: HCl(g) → H+(aq) + Cl–(aq)

This reaction is classified as

|a. |dissociation |d. |a and b only |

|b. |separation |e. |none of the above |

|c. |ionization |

____ 24. Nitric acid is classified as a strong acid because

|a. |it has high electrical conductivity |

|b. |it ionizes about 50% |

|c. |ionizes more than 99% |

|d. |both a and c |

|e. |it has a higher concentration than other acids |

____ 25. A dilute solution of a strong acid can be more dangerous than a concentrated solution of a weak acid because

|a. |there are still more H+(aq) ions in the dilute strong acid |

|b. |there are more molecules in the strong acid |

|c. |the amount of H+(aq) ions is the same for both |

|d. |the strong acid contains chloride ions |

|e. |the weak acid has fewer molecules than the strong acid |

____ 26. pH is an important factor in

|a. |consumer products |d. |soil in gardens and farms |

|b. |swimming pools |e. |all of the above |

|c. |human blood |

____ 27. An acid solution has a pH of 4.0. If water is added to this solution to increase its volume, which of the following will occur?

|a. |The pH will decrease. |d. |[H+(aq)] will decrease. |

|b. |The pH will increase. |e. |b and d only |

|c. |[H+(aq)] will increase. |

____ 28. Most antacids have a pH value of

|a. |7.0 |d. |5.0 |

|b. |8.0 |e. |4.0 |

|c. |10.0 |

____ 29. How much more acidic is vinegar (pH = 2.0) than coffee (pH = 5.0)?

|a. |3.0 |d. |2.5 |

|b. |1000 |e. |0.4 |

|c. |100 |

____ 30. According to Bronsted-Lowry an acid is

|a. |a substance that produces hydronium ions |

|b. |a substance that produces hydroxide ions |

|c. |a proton acceptor |

|d. |a proton donor |

|e. |really just neutral |

Completion

Complete each statement.

31. Sodium chloride and potassium iodide are ____________________ compounds that dissolve in water.

32. ____________________ is the process of decomposing ionic solids into their respective ions.

33. Concentrations of dissolved ions in bottled water are expressed in units of parts per ____________________.

34. A(n) ____________________ solution is one for which the precise concentration is known.

35. As the temperature of a solution decreases, the ____________________ of most solid solutes decreases.

36. A(n) ____________________ solution is one that cannot dissolve any more solute at the existing temperature.

37. Sodium and potassium are always soluble in precipitation reactions. Since they do not participate, they are called ____________________ ions.

38. Many fertilizers contain nitrate compounds because these compounds are ____________________ in water and can be easily absorbed by plants.

39. The first step in secondary treatment of wastewater involves ____________________ the water to support aerobic bacteria.

40. The point during a titration at which the indicator changes colour is called the ____________________.

Short Answer

41. Explain the difference between dilute and concentrated solutions.

42. Give an example of a solution with a solid solute dissolved in a solid solvent.

43. List three chemical substances that pollute water.

44. Briefly explain the most important step in water treatment.

45. Explain the approximate concentration criteria that distinguishes dilute and concentrated solutions.

46. Briefly explain how home water softeners work.

47. A chemist mixes aqueous potassium iodide with lead(II) acetate to produce a bright yellow precipitate for her chemistry magic show. Write the net ionic equation for this reaction.

48. Briefly describe two problems that would result from discharging untreated sewage into lakes.

49. State the approximate pH values for the following substances:

(a) vinegar

(b) distilled water

(c) swimming pool water

(d) normal rain

(e) seawater

50. A 0.1 mol/L solution of nitric acid has a pH of about 1 and a 0.1 mol/L solution of acetic acid has a pH of about 3.

(a) Account for this difference in pH.

(b) Explain which acid is more acidic and by how much.

51. List three empirical properties for acids and three empirical properties for bases.

52. Write the balanced chemical equation for the neutralization of aqueous phosphoric acid by potassium hydroxide.

Problem

53. Saline solutions are used in hospitals to replace lost body fluids and electrolyes. A normal saline solution is made by dissolving 0.9 g of NaCl in 100 mL of water. Calculate its concentration as % by mass.

54. The concentration of an HCl acid solution is initially 6.0 mol/L. What would the concentration of a new solution be if 200 mL of the original HCl solution is diluted to 1.0 L with water?

55. Standard solutions of sodium oxalate, Na2C2O4(aq), are required for certain types of chemical analyses. If 8.5 g of sodium oxalate is dissolved in 500 mL of distilled water, calculate the concentration of the sodium ion and the concentration of the oxalate ion dissolved in this solution.

56. Assume that laundry detergent is mostly sodium carbonate. Calculate the concentration of the sodium carbonate if a 95.0-g scoop of detergent is dissolved in 25.0 L of water in the washing machine?

57. A saturated solution of KClO3 is cooled from 50ºC to 5ºC when it is placed into a fridge. Calculate how much potassium chlorate will crystallize from a 1.0-L solution.

58. A student mixed 100.0 mL of a 0.100 mol/L solution of barium chloride with 100.0 mL of a 0.100 mol/L solution of iron(III) sulphate. The barium sulphate precipitate was filtered, dried, and was measured to have a mass of 2.0 g. Calculate the % yield of the barium sulphate.

59. Calculate the pH of vinegar which has a hydrogen ion concentration of 1 × 10–2 mol/L.

60. A swimming pool has a pH of 7.5. Calculate the hydrogen ion concentration in the pool.

61. Spinach leaves were boiled and 20.00 mL of the spinach juice was analyzed for its oxalic acid content. The spinach juice was titrated with a 0.50 mol/L calcium chloride solution and 5.25 mL of the calcium chloride was required to produce the calcium oxalate precipitate. Calculate the concentration of the oxalic acid in the spinach juice.

62. Cameco in Port Hope, Ontario uses hydrofluoric acid to make an uranium hexafluoride product which is used a fuel for nuclear reactors. A waste drum containing 85.0 L of 6.0 mol/L hydrofluoric acid needs to be neutralized so that it isn't hazardous. Calculate the mass of potassium hydroxide pellets that would be required to completely neutralize the acid.

63. A commercial rust remover contains 7.30 mol/L of phosphoric acid. Calculate the mass of calcium carbonate scale inside a coffeemaker that can be dissolved by 45.0 mL of this solution.

64. A student has accidentally spilled 100.0 mL of 3.0 mol/L nitric acid onto the lab bench. What mass of sodium bicarbonate would the teacher need to sprinkle on this spill to neutralize and clean it up?

Soln's-Prac-Test

Answer Section

MULTIPLE CHOICE

1. ANS: A PTS: 1 REF: K/U OBJ: 6.1

STA: SS2.01

2. ANS: A PTS: 1 REF: K/U OBJ: 6.1

STA: SS2.01

3. ANS: D PTS: 1 REF: K/U OBJ: 6.2

STA: SS1.01

4. ANS: A PTS: 1 REF: I OBJ: 6.2

STA: SS2.01

5. ANS: A PTS: 1 REF: K/U OBJ: 6.2

STA: SS1.02

6. ANS: D PTS: 1 REF: K/U OBJ: 6.2

STA: SS1.01

7. ANS: B PTS: 1 REF: I OBJ: 6.3

STA: SS2.02

8. ANS: E PTS: 1 REF: MC OBJ: 6.4

STA: SS3.03

9. ANS: A PTS: 1 REF: MC OBJ: 6.4

STA: SS3.04

10. ANS: C PTS: 1 REF: MC OBJ: 6.4

STA: SS3.04

11. ANS: D PTS: 1 REF: MC OBJ: 6.4

STA: SS3.03

12. ANS: B PTS: 1 REF: I OBJ: 6.3

STA: SS2.03

13. ANS: D PTS: 1 REF: MC OBJ: 7.2

STA: SS3.05

14. ANS: D PTS: 1 REF: MC OBJ: 7.2

STA: SS3.05

15. ANS: B PTS: 1 REF: MC OBJ: 7.2

STA: SS3.05

16. ANS: E PTS: 1 REF: K/U OBJ: 7.3

STA: SS1.04

17. ANS: D PTS: 1 REF: MC OBJ: 7.4

STA: SS3.04

18. ANS: E PTS: 1 REF: K/U OBJ: 7.5

STA: SS1.04

19. ANS: B PTS: 1 REF: C OBJ: 7.6 | 7.5

STA: SS2.08

20. ANS: A PTS: 1 REF: I OBJ: 7.6

STA: SS2.08

21. ANS: A PTS: 1 REF: I OBJ: 7.1

STA: SS2.04

22. ANS: A PTS: 1 REF: MC OBJ: 7.6

STA: SS3.02

23. ANS: C PTS: 1 REF: C OBJ: 8.1

STA: SS2.07

24. ANS: D PTS: 1 REF: K/U OBJ: 8.1

STA: SS1.06

25. ANS: A PTS: 1 REF: K/U OBJ: 8.1

STA: SS1.06

26. ANS: E PTS: 1 REF: K/U OBJ: 8.2

STA: SS1.07

27. ANS: E PTS: 1 REF: K/U OBJ: 8.2

STA: SS1.07

28. ANS: C PTS: 1 REF: K/U OBJ: 8.2

STA: SS1.07

29. ANS: B PTS: 1 REF: K/U OBJ: 8.2

STA: SS1.07

30. ANS: D PTS: 1 REF: K/U OBJ: 8.4

STA: SS1.05

COMPLETION

31. ANS: ionic

PTS: 1 REF: K/U OBJ: 6.2 STA: SS1.02

32. ANS: Dissociation

PTS: 1 REF: C OBJ: 6.2 STA: SS2.01

33. ANS: million

PTS: 1 REF: MC OBJ: 6.3 STA: SS3.02

34. ANS: standard

PTS: 1 REF: C OBJ: 6.5 STA: SS2.01

35. ANS: solubility

PTS: 1 REF: K/U OBJ: 7.1 STA: SS1.03

36. ANS: saturated

PTS: 1 REF: C OBJ: 7.1 STA: SS2.01

37. ANS: spectator

PTS: 1 REF: C OBJ: 7.3 STA: SS2.05

38. ANS: soluble

PTS: 1 REF: MC OBJ: 7.3 | 7.6 STA: SS3.02

39. ANS: aerating

PTS: 1 REF: MC OBJ: 7.4 STA: SS3.04

40. ANS: endpoint

PTS: 1 REF: I OBJ: 8.5 STA: SS2.09

SHORT ANSWER

41. ANS:

Dilute solutions contain very little dissolved solute in the solvent. Concentrated solutions contain a relatively large amount of dissolved solute in the solvent.

PTS: 1 REF: K/U OBJ: 6.3 STA: SS2.01

42. ANS:

metal alloy such as copper-nickel in coins.

PTS: 1 REF: K/U OBJ: 6.1 STA: SS3.01

43. ANS:

heavy metals, nitrates, and pesticides.

PTS: 1 REF: MC OBJ: 6.4 STA: SS3.03

44. ANS:

The most important step in water treatment is disinfection. Chlorine is added to the water to kill microorganisms that cause serious diseases.

PTS: 1 REF: MC OBJ: 6.4 STA: SS3.04

45. ANS:

Dilute solutions have molar concentrations less than 0.1 mol/L. Concentrated solutions have molar concentrations greater than 1 mol/L.

PTS: 1 REF: C OBJ: 6.5 STA: SS2.02

46. ANS:

Home water softeners use an ion exchange process. They contain resins which exchange two sodium ions for every one calcium ion removed from the water.

PTS: 1 REF: MC OBJ: 7.2 STA: SS3.05

47. ANS:

Pb2+(aq) + 2I–(aq) → PbI2(s)

PTS: 1 REF: I OBJ: 7.3 STA: SS2.05

48. ANS:

-Sewage contains fecal matter which can carry disease causing bacteria.

-Good bacteria in the water breaks down the organic matter in the sewage. To do this, they use up oxygen in the water.

-Fish can die from this lack of oxygen since they rely on it to breathe.

PTS: 1 REF: MC OBJ: 7.4 STA: SS3.04

49. ANS:

(a) pH = 2.0

(b) pH = 7.0

(c) pH = 7.5

(d) pH = 5.5

(e) pH = 8.0

PTS: 1 REF: K/U OBJ: 8.2 STA: SS1.07

50. ANS:

(a) Nitric acid is a strong acid and ionizes almost 100% into hydronium ions which makes it very acidic (lower pH). Acetic acid is a weak acid and only ionizes about 1% into hydronium ions which makes less acidic (higher pH).

(b) Nitric acid is about 100 times more acidic than acetic acid because nitric acid solution contains about 100 times the number of hydronium ions in solution than is found in acetic acid.

PTS: 1 REF: K/U OBJ: 8.2 STA: SS1.06

51. ANS:

Acids

-tastes sour

-turns blue litmus red

-reacts with active metals to produce hydrogen gas

Bases

-tastes bitter

-feels slippery

-has a pH higher than 7

-neutralizes acids

PTS: 1 REF: K/U OBJ: 8.4 STA: SS1.05

52. ANS:

H3PO4(aq) + 3KOH(aq) → K3PO4(aq) + 3H2O(l)

PTS: 1 REF: I OBJ: 8.5 STA: SS2.07

PROBLEM

53. ANS:

[pic]

[pic]

The % by mass of NaCl is 0.9%.

PTS: 1 REF: I OBJ: 6.3 STA: SS2.02

54. ANS:

[pic]

[pic]

The concentration of the diluted HCl solution is 1.2 mol/L.

PTS: 1 REF: I OBJ: 6.3 STA: SS2.02

55. ANS:

[pic]

[pic]

[pic]

[pic]

[pic]

The sodium ion concentration is 0.25 mol/L.

[pic]

The oxalate ion concentration is 0.13 mol/L.

PTS: 1 REF: I OBJ: 6.3 STA: SS2.02

56. ANS:

[pic]

[pic]

[pic]

The sodium carbonate concentration is 0.0358 mol/L.

PTS: 1 REF: I OBJ: 6.3 STA: SS2.02

57. ANS:

solubility of KClO3 at 50ºC = [pic]

solubility of KClO3 at 5ºC = [pic]

mass of KClO3 crystallizing = [pic]

[pic]

The mass of potassium chlorate that will crystallize from a 1.0-L solution is 150 g.

PTS: 1 REF: I OBJ: 7.1 STA: SS2.03

58. ANS:

3BaCl2(aq) + Fe2(SO4)3(aq) → 3BaSO4(s) + 2FeCl3(aq)

|100.0 mL |100.0 mL |m |

|0.100 mol/L |0.100 mol/L | |

[pic]

[pic]

The theoretical mass of barium sulphate is 2.3 g.

[pic]

The % yield of the barium sulphate precipitate was 87%.

PTS: 1 REF: I OBJ: 7.6 STA: SS2.08

59. ANS:

[pic]

The pH of vinegar solution is 2.0.

PTS: 1 REF: K/U OBJ: 8.2 STA: SS1.07

60. ANS:

[pic]

The hydrogen ion concentration of the swimming pool is 3.2 × 10–8 mol/L.

PTS: 1 REF: K/U OBJ: 8.2 STA: SS1.07

61. ANS:

H2C2O4(aq) + CaCl2(aq) → CaC2O4(s) + 2HCl(aq)

|20.00 mL |5.25 mL |

|C |0.50 mol/L |

[pic]

[pic]

[pic]

The concentration of oxalic acid in the spinach juice is 0.13 mol/L.

PTS: 1 REF: I OBJ: 8.5 STA: SS2.09

62. ANS:

HF(aq) + KOH(aq) → KF(aq) + H2O(l)

|85.0L |m |

|6.0 mol/L |56.11 g/mol |

[pic]

[pic]

[pic]

A 29 kg mass of potassium hydroxide pellets would neutralize the acid.

PTS: 1 REF: I OBJ: 8.5 STA: SS2.08

63. ANS:

2H3PO4(aq) + 3CaCO3(s) → Ca3(PO4)2(s) + 3CO2(g) + 3H2O(l)

|45.0 mL |m |

|7.30 mol/L |100.10 g/mol |

[pic]

[pic]

[pic]

The rust remover will dissolve 49.3 g of the scale.

PTS: 1 REF: I OBJ: 8.5 STA: SS2.08

64. ANS:

HNO3(aq) + NaHCO3(s) → CO2(g) + H2O(l) + NaNO3(aq)

|100.0 mL |84.01 g/mol |

|3.0 mol/L |m |

[pic]

[pic]

[pic]

The teacher would sprinkle 25.2 g of baking soda to neutralize the acid spill.

PTS: 1 REF: I OBJ: 8.5 STA: SS2.08

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