CHEM 1301 THIRD TEST REVIEW

CHEM 1301 THIRD TEST REVIEW Chemical Equations Express reactions as equations. These: a) must contain the symbols/formulas for substances involved in the reaction (things on left are reactants; things on right are products) b) must be balanced same number of each type of atoms on each side. Balance by placing COEFFICIENTS in front of formulas don t add molecules or change formulas. Also, don't use fractions for coefficients. 1. When the equation C 2 H 4 + O 2 CO 2 + H 2 O is balanced, what is the coefficient of O 2? (A) 1 (B) 2 (C) 3 (D) 4 (E) 5 2. When the following equation is balanced, what is the coefficient of O 2? C 3 H 8 + O 2 CO 2 + H 2 O (A) 1 (B) 2 (C) 3 (D) 5 (E) 7 3. Balance the following equation: B 2 O 3 (s) + HF(l) BF 3 (g) + H 2 O(l). What is the coefficient of water? (A) 3 (B) 1 (C) 4 (D) 2 (E) 5 4. Balance the following equation: UO 2 (s) + HF(l) UF 4 (s) + H 2 O(l). What is the coefficient of water? (A) 1 (B) 2 (C) 3 (D) 4 (E) 5 5. Balance the following equation: C 6 H 6 (l) + O 2 (g) H 2 O(g) + CO 2 (g). What is the coefficient of water? (A) 2 (B) 4 (C) 6 (D) 8 (E) 10 6. Balance the following equation: C 8 H 18 O 3 (l) + O 2 (g) H 2 O(g) + CO 2 (g). What is the coefficient of water? (A) 4 (B) 9 (C) 5 (D) 3 (E) 10 7. Balance the following equation: Ca 3 (PO 4 ) 2 (s) + SiO 2 (s) + C(s) CaSiO 3 (s) + CO + P 4. What is the coefficient of C? (A) 2 (B) 6 (C) 8 (D) 10 (E) 12 1

8. Balance the following equation: B 5 H 9 (l) + O 2 (g) B 2 O 3 (s) + H 2 O(g). What is the coefficient of water? (A) 10 (B) 9 (C) 6 (D) 8 (E) 14 Moles and Molar Mass A mole is 6.02 x 10 23. 1 mole of something has the relative mass of that thing in grams. When calculating moles from grams or grams from moles, use DIMENSIONAL ANALYSIS or equation: n = g /MM 9. Calcium fluoride, CaF 2, used to fluoridate drinking water. Calculate its molar mass in g/mol. (A) 118.15 (B) 99.15 (C) 78.07 (D) 59.08 10. Calculate the molar mass (in g/mol) of tetraphosphorus decaoxide, P 4 O 10. (A) 469.73 (B) 283.89 (C) 190.97 (D) 94.97 11. Calculate the molar mass (in g/mol) of rubidium carbonate, Rb 2 CO 3. (A) 340.43 (B) 255.00 (C) 230.94 (D) 113.48 12. Calculate the molar mass (in g/mol) of (NH 4 ) 3 AsO 4. (A) 417.80 (B) 193.03 (C) 165.02 (D) 156.96 13. Aluminum sulfate, A1 2 (SO 4 ) 3, is used in tanning leather, purifying water, and manufacture of antiperspirants. Calculate its molar mass (in g/mol). (A) 450.06 (B) 342.15 (C) 315.15 (D) 278.02 14. Calculate the mass in grams of 2.35 mol of sodium chloride, or common table salt. (A) 221 g (B) 137 g (C) 93.9 g (D) 58.4 g 15. Magnesium fluoride is used in the ceramics and glass industry. What is the mass of 1.72 mol of magnesium fluoride? (A) 107 g (B) 74.5 g (C) 62.3 g (D) 43.3 g 16. Sodium bromate (NaBrO 3 ) is used in a mixture which dissolves gold from its ores. Calculate the mass in grams of 4.68 mol of sodium bromate. (A) 706 g (B) 482 g (C) 32.2 g (D) 0.0310 g 2

17. What is the mass in grams of 0.250 mol of the common antacid calcium carbonate? (A) 4.00 10 2 g (B) 25.0 g (C) 4.00 10-2 g (D) 2.50 10-3 g 18. Calculate the number of moles in 17.8 g of the antacid magnesium hydroxide, Mg(OH) 2. (A) 3.28 mol (B) 2.32 mol (C) 0.431 mol (D) 0.305 mol 19. Calculate the number of moles in 38.7 g of PCl 5. (A) 5.38 mol (B) 3.55 mol (C) 0.282 mol (D) 0.186 mo1 20. Aluminum oxide, A1 2 O 3, is used as a filler for paints and varnishes as well as in the manufacture of electrical insulators. Calculate the number of moles in 47.51 g of A1 2 O 3. (A) 2.377 mol (B) 2.146 mo1 (C) 0.4660 mo1 (D) 0.4207 mol To go between moles of something and molecules of the thing: N = 6.02 x 10 23 x n (or use dimensional analysis) NOTE: atoms and molecules are NOT the same thing!!! 21. How many molecules are present in 2.45 moles of water? (A) 2.46 x 10 23 (B) 1.47 x 10 24 (C) 0.136 (D) 7.35 (E) 44.1 22. The number of hydrogen atoms in 0.050 mol of C 3 H 8 O 3 is (think about it!) (A) 3.0 10 22 (B) 1.2 10 23 (C) 2.4 10 23 (D) 4.8 10 23 Can use the coefficients in balanced equations to relate MOLES of one thing to MOLES of another: n B = (b / a) n A a and b are the coefficients of A and B in the equation 23. Sulfur dioxide reacts with chlorine to produce thionyl chloride and dichlorine oxide. SO 2 (g) + 2C1 2 (g) SOCl 2 (g) + Cl 2 O(g). If 0.400 mol of Cl 2 reacts with SO 2, how many moles of Cl 2 O are formed? (A) 0.800 mol (B) 0.400 mol (C) 0.200 mol (D) 0.100 mol 24. Aluminum will react with bromine to form aluminum bromide (used as an acid catalyst in organic synthesis). Al(s) + Br 2 (l) Al 2 Br 6 (s). How many moles of Al are needed to form 2.43 mol of Al 2 Br 6? (A) 7.29 mo1 (B) 4.86 mo1 (C) 2.43 mol (D) 1.62 mo1 3

25. Ammonia will react with fluorine to produce dinitrogen tetrafluoride and hydrogen fluoride (used in production of aluminum, in uranium processing, and in frosting of light bulbs). 2NH 3 (g) + 5F 2 (g) N 2 F 4 (g) + 6HF(g) How many moles of NH 3 are needed to react completely with 13.6 mol of F 2? (A) 34.0 mol (B) 6.80 mol (C) 5.44 mo1 (D) 2.27 mol 26. Titanium(IV) oxide (extensively used as a white pigment) reacts with bromine trifluoride to form titanium(iv) fluoride, bromine, and oxygen. 3TiO 2 + 4BrF 3 3TiF 4 + 2Br 2 + 3O 2 How many moles of bromine trifluoride are needed to react completely with 9.68 mol of titanium(iv) oxide? (A) 12.9 mol (B) 9.68 mol (C) 7.26 mol (D) 3.23 mol We can put them together to do more complex calculations. Two approaches to doing these: Dimensional analysis or the Roadmap: grams of A g grams of B g n = g / MM Particles N A N = 6.02 x 10 23 n Moles of A n A n B = (b/a)n A Moles of B n B N = 6.02 x 10 23 n Particles N B 27. Ammonia, an important source of fixed nitrogen that can be metabolized by plants, is produced using the Haber process: N 2 (g) + 3H 2 (g) 2NH 3 (g). How many grams of nitrogen are needed to produce 325 grams of ammonia? (A) 1070 g (B) 535 g (C) 267 g (D) 178 g 28. How many grams of sodium fluoride (used in water fluoridation and manufacture of insecticides) are needed to form 485 g of sulfur tetrafluoride? 3SCl 2 (l) + 4NaF(s) SF 4 (g) + S 2 Cl 2 (l) + 4NaCl(s) (A) 1510 g (B) 754 g (C) 205 g (D) 51.3 g 29. How many grams of oxygen are needed to react completely with 200.0 g of ammonia, NH 3? 4NH 3 (g) + 5O 2 (g) 4NO(g) + 6H 2 O(g) (A) 469.7 g (B) 300.6 g (C) 3.406 g (D) 2.180 g 4

30. How many grams of IO 2 F are needed to react completely with 150.0 g of BrF 3? 3 IO 2 F(s) + 4BrF 3 (l) 3IF 5 (l) + 2Br 2 (l) + 3O 2 (g) (A) 260.0 g (B) 146.2 g (C) 121.8 g (D) 64.98 g 31. Phosphine, an extremely poisonous and highly reactive gas, will react with oxygen to form tetraphosphorus decaoxide and water. PH 3 (g) + O 2 (g) P 4 O 10 (s) + H 2 O(g). Calculate the mass of P 4 O 10 (s) formed when 225 g of PH 3 reacts with oxygen. (A) 1880 g (B) 940 g (C) 470 g (D) 56.3 g 32. Calculate the mass of chromium(iii) chloride formed when 125 g of chlorine gas (used as bleach and as a disinfectant for water supplies) reacts with chromium. Cr(s) + Cl 2 (g) CrCl 3 (s) (A) 419 g (B) 186 g (C) 135 g (D) 59.9 g 33. Potassium chlorate (used in fireworks, flares and safety matches) forms oxygen and potassium chloride when heated. KClO 3 (s) KCl(s) + O 2 (g). How many grams of oxygen are formed when 26.4 g of potassium chlorate is heated? (A) 223 g (B) 99.1 g (C) 10.3 g (D) 4.60 g 34. Aluminum metal (Al) reacts with chlorine gas (Cl 2 ) to form solid aluminum trichloride, AlCl 3. What mass of chlorine gas is needed to react completely with 163 g of aluminum? (A) 643 g (B) 321 g (C) 245 g (D) 214 g 35. Barium hydroxide (used in corrosion inhibitors and lubricants) reacts with chloric acid (HClO 3 ) to form barium chlorate [Ba(ClO 3 ) 2 ] and water. What mass of water is formed when 138 g of barium hydroxide reacts with chloric acid? (A) 32.5 g (B) 29.0 g (C) 16.2 g (D) 7.31 g 36. Lead(II) sulfide (PbS) was once used in glazing earthenware. It will also react with hydrogen peroxide (H 2 O 2 ) to form lead(ii) sulfate and water. How many grams of hydrogen peroxide are needed to react completely with 265 g of lead(ii) sulfide? (A) 151 g (B) 123 g (C) 37.7 g (D) 9.41 g 37. Sulfur trioxide can react with atmospheric water vapor to form sulfuric acid that falls as acid rain. Calculate the mass in grams of 3.65 10 20 molecules of SO 3. (A) 6.06 10-4 g (B) 4.85 10-2 g (C) 20.6 g (D) 1650 g 38. Calculate the mass in grams of 8.35 10 22 molecules of CBr 4. (A) 46.0 g (B) 7.21 g (C) 0.139 g (D) 0.0217 g Some really nasty ones are as follows. The trick with these is to recognize what N stands for and what the formula involves. 5

39. Calculate the number of oxygen atoms in 29.34 g of sodium sulfate, Na 2 SO 4. (A) 1.244 10 23 O atoms (B) 4.976 10 23 O atoms (C) 2.915 10 24 O atoms (D) 1.166 10 25 O atoms 40. Potassium dichromate, K 2 Cr 2 O 7, is used in tanning leather, decorating porcelain and water proofing fabrics. Calculate the number of chromium atoms in 78.82 g of K 2 Cr 2 O 7. (A) 2.248 10 24 Cr atoms (B) 1.124 10 24 Cr atoms (C) 3.227 10 23 Cr atoms (D) 1.613 10 23 Cr atoms Moles and Molarity Sometimes, one doesn t do a reaction with PURE substances but one uses a solution [chapter 10]. If we use a solution, we can measure volume and work out how many moles are in it if we know the MOLARITY of the solution: We can include molarity in the Roadmap as well: Molarity = moles / liters of solution grams of A g grams of B g n = g / MM Particles N A N = 6.02 x 10 23 n Moles of A n A Moles of B n B N = 6.02 x 10 23 n Particles N B n B = (b/a)n A M = n / L Volume of Solution, L Volume of Solution, L 41. Hydrochloric acid is widely used as a laboratory reagent, in refining ore for the production of tin and tantalum, and as a catalyst in organic reactions. Calculate the number of moles of HCl in 0.06285 L of 0.453 M hydrochloric acid (A) 1.04 mol (B) 0.139 mol (C) 0.0285 mol (D) 0.00721 mol 6

42. Sodium hydroxide, also known as caustic soda, is used to neutralize acids and to treat cellulose in making of cellophane. Calculate the number of moles of solute in 1,875 ml of 1.356 M NaOH solution. (A) 2.543 mol (B) 1.383 mol (C) 0.7232 mol (D) 0.3932 mol 43. A 0.150 M sodium chloride solution is referred to as a physiological saline solution because it has the same concentration of salts as normal human blood Calculate the mass of solute needed to prepare 275.0 ml of a physiological saline solution. (A) 31.9 g (B) 16.1 g (C) 8.77 g (D) 2.41 g 44. Sodium chlorate is used as an oxidizer in the manufacture of dyes, explosives and matches. Calculate the mass of solute needed to prepare 1.575 L of 0.00250 M NaClO 3 (A) 419 g (B) 169 g (C) 0.419 g (D) 0.169 g 45. Lithium hydroxide is used in alkaline batteries. Calculate the molarity of a solution prepared by dissolving 35.8 g of LiOH in enough water to give a final volume of 750.0 ml. (A) 1.99 M (B) 1.50 M (C) 1.12 M (D) 0.502 M 46. Calculate the molarity of 1.25 L of a solution which contains 238.7 g of CoCl 2. (A) 2.30 M (B) 1.47 M (C) 0.435 M (D) 0.680 M 47. Calculate the molarity of a 23.55-mL solution which contains 28.24 mg of sodium sulfate (used in dyeing and printing textiles). (A) 1.199 M (B) 0.8339 M (C) 0.2031 M (D) 0.008445 M 48. When 2.61 g of solid Na 2 CO 3 is dissolved in sufficient water to make 250. ml of solution, the concentration of Na 2 CO 3 is: (A) 0.0246 M (B) 10.4 M (C) 0.205 M (D) 0.0985 M 49. What mass (in g) of solid CuSO 4 is needed to make up 250. ml of a 0.300 M solution of this salt? (A) 8.36 (B) 12.0 (C) 39.9 (D) 47.9 (E). 75.0 50. How many milliliters of 1.58 M HCl are needed to react completely with 23.2 g of NaHCO 3 HCl(aq) + NaHCO 3 (s) NaCl(s) + H 2 O(l) + CO 2 (g) (A) 638 ml (B) 572 ml (C) 536 ml (D) 175 ml 7

51. How many g of Mg are required to react with 250 ml of a 0.250 M solution of HCl? Mg(s) + HCl(aq) MgCl 2 (aq) + H 2 (g) (A) 0.0625 (B) 0.759 (C) 1.52 (D) 3.04 (E) 62.5 52. Aqueous solutions of H 2 SO 4 and sodium hydroxide react to produce sodium sulfate and water. How many ml of 0.350 M NaOH will react with 50.0 ml of 0.25 M H 2 SO 4? (A) 0.0357 (B) 12.5 (C) 17.9 (D) 35.7 (E) 71.4 Reaction Types: Different types of reactions. Combination or Synthesis Decomposition Single displacement Double displacement (metathesis) Combustion A + B C A (sometimes + heat) B + C A + BC AC + B AB + CD AD + CB Reaction with oxygen (usually with generation of heat) make OXIDES of the elements in the original compound Describe the following reactions as: (A) Combination (synthesis) (B) Decomposition (C) Single displacement (D) Double displacement (E) Combustion 53. H 2 + Cl 2 2 HCl 54. CaCl 2.2 H 2 O + heat CaCl 2 + H 2 O 55. H 2 CO 3 H 2 O + CO 2 56. 2 Na + H 2 O 2 NaOH + H 2 57. Zn + FeCl 2 ZnCl 2 + Fe 58. BaCl 2 + K 2 SO 4 BaSO 4 + 2 KCl 59. H 2 SO 4 + 2 KOH H 2 O + K 2 SO 4 60. CH 4 + 2 O 2 CO 2 + 2 H 2 O ANSWERS: 1-30 C D A B C B D B C B C B B B A A B D D C B C C B C A C B A B 31-60 C B C A B A B A B C C A D C A B D D B D B E A B B C C D D E 8