Chapter 7, Reactions and Solutions

Transcription

1 1. Classify the following reaction as precipitation, acid-base or oxidation-reduction: Ce4+(aq) + Fe2+(aq) Ce3+(aq) + Fe3+(aq) Ans. oxidation-reduction 2. Classify the following reaction as precipitation, acid-base or oxidation-reduction: H 2 SO 4 (aq) + 2KOH(aq) K 2 SO 4 (aq) + 2H 2 O(aq) Ans. acid-base 3. Classify the following reaction as precipitation, acid-base or oxidation-reduction: Na 2 S(aq) + CuSO 4 (aq) Na 2 SO 4 (aq) + CuS(s) Ans. precipitation 4. Complete the products and balance the following equation for an acidbase reaction: HCl(aq) + KOH(aq) Ans. HCl(aq) + KOH(aq) KCl(aq) + H 2 O(l) 5. Complete the products and balance the following equation for a precipitation reaction: FeSO 4 (aq) + NaOH(aq) eso 4 (aq) + 2NaOH(aq) Fe(OH) 2 (s) + Na 2 SO 4 (aq) 6. Write a balanced equation for the reaction between zinc metal and iron(iii) ions to form zinc(ii) ions and iron(ii) ions (Symbols: zinc = Zn; iron = Fe). Ans. Zn(s) + 2Fe3+(aq) Zn2+(aq) + 2Fe2+(aq) 7. Name the two products formed when octane (C 8 H 18 ) burns completely in excess oxygen gas. Ans. carbon dioxide and water 8. Classify the following reaction as decomposition, combination, singlereplacement or double-replacement: 2H 2 O(l) 2H 2 (g) + O 2 (g) Ans. decomposition 9. Classify the following reaction as decomposition, combination, singlereplacement or double-replacement: H 2 SO 4 (aq) Ba(OH) 2 (aq) BaSO 4 (s) + 2H 2 O(g) Ans. double-replacement 10. Classify the following reaction as decomposition, combination, singlereplacement or double-replacement: Mg(s) + 2HCl(aq) MgCl 2 (g) + H 2 (g) Ans. single-replacement General, Organic, and Biochemistry, 3/e Page 47

2 11. Classify the following reaction as decomposition, combination, singlereplacement or double-replacement: 2Na(s) + Cl 2 (g) 2NaCl(s) Ans. combination 12. What would you call a liquid that displayed the Tyndall effect? Ans. colloidal suspension 13. Outline a simple method to distinguish between a beaker containing a true solution and one containing a colloidal suspension. irect a narrow beam of light horizontally through the two beakers. The colloidal suspension will scatter light (the Tyndall effect) making the beam visible as it passes through; the true solution will show no scattering. 14. A solution contains 1.65 g of NaOH in a total volume of ml. What is its concentration expressed as % (W/V)? Ans. 1.10% (W/V) 15. How many grams of glucose are present in ml of a 5.00% (W/V) solution? Ans g 16. Define "molarity". Ans. It is the concentration of a solution expressed as the number of moles of solute per liter of solution. 17. How many moles of KNO 3 are contained in one liter of 0.2 M KNO 3 solution? Ans. 0.2 mol 18. How many moles of KCl are present in 50.0 ml of a M solution? Ans mol 19. How many grams of KCl are present in ml of a M solution? [Use formula weight: KCl, amu] Ans g 20. If 5.20 g of HCl is added to enough distilled water to form 3.00 L of solution, what is the molarity of the solution? [Use molecular weight: HCl, amu] Ans M 21. Calculate the molarity of a solution if ml of it contains 16.8 g of KNO 3. [Use formula weight: KNO 3, amu ] Ans M 22. What is the molarity of 50.0 ml of a M NaOH solution after it has been diluted to ml? Ans M General, Organic, and Biochemistry, 3/e Page 48

3 23. In one sentence, explain what is meant by a colligative property. Ans. It is a solution property which depends on the concentration of solute particles rather than on their identity. 24. An aqueous solution is warmed from 20 C to 30 C. Does this change in temperature affect either the molarity or the molality of the solution? Explain. he volume of the solution is likely to increase, causing a decrease in the molarity. Since mass is not affected by temperature, the molality will stay the same. 25. How much more will the freezing point of water be lowered by adding one mole of sodium chloride rather than one mole of glucose, C 6 H 12 O 6? Ans. twice as much 26. What type of membranes allow solvent molecules to pass through but do not allow solute molecules to pass through? Ans. semipermeable 27. What happens when a hypotonic solution is separated from a hypertonic solution by an osmotic membrane? Ans. water molecules move from the hypotonic solution to the hypertonic solution 28. What term do we use to describe a solution of lower osmolarity compared to one with a higher osmolarity? Ans. hypotonic 29. Describe what happens when red blood cells are placed in a hypertonic solution. Give the name of the process which occurs he cells lose water, by osmosis, to the hypertonic solution, and they collapse. The process is known as crenation. 30. What happens to red blood cells that are placed in an isotonic solution? Ans. they remain unchanged 31. Calculate the osmolarity of a M Na 3 PO 4 solution. Na 3 PO 4 is an ionic compound and produces an electrolytic solution. Ans Osm 32. Calculate the osmotic pressure of a M solution of NaCl at 20 C (293K). Ans. 2.9 atm 33. What liquid is referred to as the "universal solvent"? Ans. Water General, Organic, and Biochemistry, 3/e Page 49

4 34. In what way are dialysis and osmosis similar? In what way are they different? oth involve the selective movement of small molecules through a membrane, from a solution of high concentration of those molecules to one of lower concentration. They differ in that osmosis involves only movement of solvent (water) molecules, whereas in dialysis, solute molecules can also pass through the membrane. 35. Name two compounds which can move through the membrane used in hemodialysis. Ans. water, urea 36. Choose the best classification of the reaction represented by the following equation: C 6 H 12 O 6 (s) + 6O 2 (g) 6CO 2 (g) + 6H 2 O(l) A. combustion B. acid-base C. precipitation E. combination Ans. A 37. Choose the best classification of the reaction represented by the following equation: HNO 3 (aq) + KOH(aq) KNO 3 (aq) + H 2 O(l) A. combustion B. acid-base C. precipitation E. combination 38. Choose the best classification of the reaction represented by the following equation: Ans. E 2Fe 3+ (aq) + Fe(s) 3Fe 2+ (aq) A. combustion B. acid-base C. precipitation E. oxidation-reduction General, Organic, and Biochemistry, 3/e Page 50

5 39. Choose the best classification of the reaction represented by the following equation: Pb(NO 3 ) 2 (aq) + CaCl 2 (aq) PbCl 2 (s) + Ca(NO 3 ) 2 (aq) A. combustion B. acid-base C. decomposition D. precipitation E. oxidation-reduction 40. Choose the best classification of the reaction represented by the following equation: MgO(s) + CO 2 (g) MgCO 3 (s) A. single-replacement B. double-replacement C. combination E. precipitation Ans. C 41. Choose the best classification of the reaction represented by the following equation: CuSO 4 5H 2 O(s) CuSO 4 (s) + 5H 2 O(l) A. single-replacement B. double-replacement C. combination E. oxidation-reduction 42. Choose the best classification of the reaction represented by the following equation: Zn(s) + CuSO 4 (aq) ZnSO 4 (aq) + Cu(s) A. single-replacement B. double-replacement C. combination E. acid-base Ans. A 43. Choose the best classification of the reaction represented by the following equation: BaCl 2 (aq) + K 2 SO 4 (aq) BaSO 4 (s) + 2KCl(aq) A. single-replacement B. double-replacement C. combination E. oxidation-reduction General, Organic, and Biochemistry, 3/e Page 51

6 44. Which one of the following processes cannot separate solute from solvent in a true solution? A. chromatography B. filtration C. boiling D. adsorption E. evaporation 45. What term describes a solution in which the solute concentration exceeds its equilibrium concentration under the prevailing conditions? A. hypotonic B. hypertonic C. isotonic D. supersaturated E. saturated 46. What term describes a solution which is in equilibrium with undissolved solute? A. precipitating B. aqueous C. saturated D. unsaturated E. supersaturated Ans. C 47. The solubility of gases in liquids is highest at A. low temperature and low pressure B. low temperature and high pressure C. high temperature and low pressure D. high temperature and high pressure E. high pressure; temperature is immaterial 48. The number of moles of a gas dissolved in a liquid at a given temperature is proportional to the partial pressure of the gas. What is this law called? A. Dalton's Law B. Henry's Law C. The Tyndall Law D. Raoult's Law E. Boyle's Law General, Organic, and Biochemistry, 3/e Page 52

7 49. Calculate the concentration (% W/V) of NaCl solution that was made by dissolving 15.0 g of sodium chloride in enough water to make ml of solution. A. 50.0% (W/V) B % (W/V) C % (W/V) D. 35.6% (W/V) E. 5.00% (W/V) Ans. E 50. Calculate the mass in grams of NaCl that is present in ml of a 0.900% (W/V) solution. A g B g C g D g E g Ans. E 51. Assuming that air is a solution containing four molecules of N 2 for every one molecule O 2, what is the concentration of O 2 in this solution, expressed as % (W/V)? [Use formula weights: N 2, amu; O 2, amu] A. 22% (W/V) B. 47% (W/V) C. 53% (W/V) D. 78% (W/V) E. 114% (W/V) Ans. A 52. Calculate the molarity of 2.00 L of solution that contains g of NaOH. [Use formula weight: NaOH, 40.0 amu] A M B M C M D M E M 53. How many milliliters of M KCl solution contain g of KCl? [Use formula weight: KCl, amu] A ml B ml C ml D ml E ml Ans. E 54. How many milliliters of 12.0 M HCl are needed to prepare ml of 2.50 M HCl solution? Ans. C A ml B ml C ml D ml E ml General, Organic, and Biochemistry, 3/e Page 53

8 55. Which one of the following is NOT a colligative property of a solution? A. vapor pressure lowering B. density C. boiling point elevation D. freezing point depression E. osmotic pressure 56. What is the law which states that vapor pressure of the solvent decreases in proportion to the concentration of the solute? A. Dalton's Law B. Henry's Law C. the Tyndall Law D. Raoult's Law E. Boyle's Law 57. What concentration term is defined as the number of moles of solute per kilogram of solvent in a solution? A. normality B. osmolarity C. % (W/V) D. molarity E. molality Ans. E 58. What is the relationship among intracellular fluids, 0.9% (W/V) NaCl and 5.0% (W/V) glucose? A. they are saturated B. they are hypotonic C. they are hypertonic D. they are isotonic E. they are supersaturated 59. If the concentration of Mg2+ in solution is M, what is its concentration expressed in meq/l? A. 6.0 meq/l B. 3.0 meq/l C. 1.5 meq/l D meq/l E meq/l Ans. A 60. T F Sodium, potassium and ammonium compounds are generally insoluble. General, Organic, and Biochemistry, 3/e Page 54

9 61. T F Nitrates and acetates are generally soluble. 62. T F Some double-replacement reactions are also precipitation reactions. 63. T F The usual products of an acid-base reaction are a salt and water. 64. T F Complete combustion of a hydrocarbon compound in oxygen produces carbon dioxide and hydrogen. 65. T F An alloy, such as brass, is an example of a solution in the solid state. 66. T F A solution in equilibrium with undissolved solute is said to be unsaturated. 67. T F One liter of alcohol combined with one liter of water does NOT produce two liters of solution. 68. T F In normal room lighting, the eye cannot distinguish a true solution from a colloidal one. 69. T F If a solvent is colorless, all of its true solutions will also be colorless. 70. T F Change in pressure has very little effect on the solubility of solids in liquids. 71. T F The solid material that separates from solution when its solubility is exceeded, is called a precipitate. 72. T F The solubility of solids in water usually increases with increasing temperature. 73. T F The solubility of gases in liquids increases with increasing temperature. 74. T F Both molarity and molality are affected by change in temperature. General, Organic, and Biochemistry, 3/e Page 55

10 75. T F An aqueous solution containing a nonvolatile solute will boil above 100 C. 76. T F An aqueous solution containing a nonvolatile solute will have a freezing point above 0 C. 77. T F Colligative properties depend only on the concentration of solute particles, not on their identity. 78. T F The heavier the solute molecule is, the greater the effect on the freezing point of a solution. 79. T F Osmosis may be defined as the movement of a solvent through a semipermeable membrane from a region of higher solvent concentration to one of lower concentration. 80. T F Osmosis is the process that regulates the sodium/potassium ratio in living cells. General, Organic, and Biochemistry, 3/e Page 56