EXAM 3 CHEM 1310 WS09 Key Version #1 1. (p. 87) 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. 1940 g b. 1510 g c. 205 g d. 51.3 g E. 754 g Silberberg - 003 Stoichiometry... #40 2. (p. 77) A compound containing chromium and silicon contains 73.52 mass percent chromium. Determine its empirical formula. a. Cr 3 Si b. CrSi 3 c. Cr 2 S d. Cr 2 Si 3 E. Cr 3 Si 2 Silberberg - 003 Stoichiometry... #25
3. (p. 119) Select the net ionic equation for the reaction between lithium hydroxide and hydrobromic acid. LiOH(aq) + HBr(aq) H 2 O(l) + LiBr(aq) a. LiOH(aq) Li + (aq) + OH - (aq) b. Li + (aq) + Br - (aq) LiBr(aq) C. H + (aq) + OH - (aq) H 2 O(l) d. Li + (aq) + OH - (aq) + H + (aq) + Br - (aq) H 2 O(l) + LiBr(aq) e. HBr(aq) H + (aq) + Br - (aq) Silberberg - 004 The... #29 4. (p. 125) Calculate the oxidation number of the chlorine in perchloric acid, HClO 4, a strong oxidizing agent. a. +4 b. None of these is the correct oxidation number. c. +5 d. -1 E. +7 Silberberg - 004 The... #34 5. (p. 112) Which of the following is most soluble in water? a. hexane, C 6 H 14 b. ethane, C 2 H 4 C. potassium nitrate, KNO 3 d. carbon tetrachloride, CCl 4 e. benzene, C 6 H 6 Silberberg - 004 The... #8
6. (p. 82) Balance the following equation: Ca 3 (PO 4 ) 2 (s) + SiO 2 (s) + C(s) CaSiO 3 (s) + CO(g) + P 4 (s) a. 2Ca 3 (PO 4 ) 2 (s) + 6SiO 2 (s) + 10C(s) 6CaSiO 3 (s) + 10CO(g) + 4P 4 (s) B. 2Ca 3 (PO 4 ) 2 (s) + 6SiO 2 (s) + 10C(s) 6CaSiO 3 (s) + 10CO(g) + P 4 (s) c. Ca 3 (PO 4 ) 2 (s) + 3SiO 2 (s) + 8C(s) 3CaSiO 3 (s) + 8CO(g) + P 4 (s) d. Ca 3 (PO 4 ) 2 (s) + 3SiO 2 (s) + 14C(s) 3CaSiO 3 (s) + 14CO(g) + P 4 (s) e. Ca 3 (PO 4 ) 2 (s) + 3SiO 2 (s) + 8C(s) 3CaSiO 3 (s) + 8CO(g) + 2P 4 (s) Silberberg - 003 Stoichiometry... #35 7. (p. 116) Select the precipitate that forms when aqueous ammonium sulfide reacts with aqueous copper(ii) nitrate. a. NH 4 NO 3 b. NH 4 (NO 3 ) 2 C. CuS d. CuSO 4 e. Cu 2 S Silberberg - 004 The... #18 8. (p. 111) How many sodium ions are present in 325 ml of 0.850 M Na 2 SO 4? a. 1.57 10 24 Na ions b. 1.66 10 23 Na ions c. 4.99 10 23 Na ions d. 6.20 10 23 Na ions E. 3.33 10 23 Na ions Silberberg - 004 The... #7
9. (p. 120) A 0.00100 mol sample of Ca(OH) 2 requires 25.00 ml of aqueous HCl for neutralization according to the reaction below. What is the concentration of the HCl? Equation: Ca(OH) 2 (s) + 2HCl(aq) CaCl 2 (aq) + H 2 O(l) a. None of these choices is correct. b. 4.00 10-5 M c. 0.0200 M d. 0.0400 M E. 0.0800 M Silberberg - 004 The... #33 10. (p. 94) Tetraphosphorus hexaoxide ( = 219.9 g/mol) is formed by the reaction of phosphorus with oxygen gas. P 4 (s) + 3O 2 (g) P 4 O 6 (s) If a mixture of 75.3 g of phosphorus and 38.7 g of oxygen produce 43.3 g of P 4 O 6, what is the percent yield for the reaction? a. 38.0% b. 16.3% C. 48.8% d. 57.5% e. 32.4% Silberberg - 003 Stoichiometry... #51 11. (p. 125) Which one of the following is a redox reaction? a. Na 2 CO 3 (s) + 2HCl(aq) 2NaCl(aq) + CO 2 (g) + H 2 O(l) b. Ba 2+ (aq) + SO 4 2- (aq) BaSO 4 (s) c. H 2 O(l) H + (aq) + OH - (aq) D. 2Na(g) + Cl 2 (g) 2NaCl(s) e. K 2 Cr 2 O 7 (aq) + 2KOH(aq) 2K 2 CrO 4 (aq) + H 2 O(l) Silberberg - 004 The... #43
12. (p. 114) In the following reaction, what ions, if any, are spectator ions? Pb(NO 3 ) 2 (aq) + 2NaCl(aq) PbCl 2 (s) + 2NaNO 3 (aq) A. Na + (aq), NO 3 - (aq) b. Pb 2+ (aq), NO 3 - (aq) c. There are no spectator ions d. Pb 2+ (aq), Cl - (aq) e. Na + (aq), Cl - (aq) Silberberg - 004 The... #15 13. (p. 120) Automobile batteries use 3.0 M H 2 SO 4 as an electrolyte. How much 1.20 M NaOH will be needed to neutralize 225 ml of battery acid? H 2 SO 4 (aq) + 2NaOH(aq) 2H 2 O(l) + Na 2 SO 4 (aq) a. 0.28 L b. 0.90 L c. 0.56 L D. 1.1 L e. 0.045 L Silberberg - 004 The... #31 14. (p. 77) Hydroxylamine hydrochloride is a powerful reducing agent which is used as a polymerization catalyst. It contains 5.80 mass % H, 20.16 mass % N, 23.02 mass % O, and 51.02 mass % Cl. What is its empirical formula? a. H 4 NOCl 2 B. H 4 NOCl c. H 2 N 7 O 8 Cl 18 d. HN 3 O 4 Cl 9 e. H 2 N 2 O 2 Cl Silberberg - 003 Stoichiometry... #29
15. (p. 125) Identify the oxidizing agent in the following redox reaction. Hg 2+ (aq) + Cu(s) Cu 2+ (aq) + Hg(l) A. Hg 2+ (aq) b. Cu(s) c. Hg 2+ (aq) and Cu 2+ (aq) d. Hg(l) e. Cu 2+ (aq) Silberberg - 004 The... #39 16. (p. 116) Select the precipitate that forms when the following reactants are mixed. Na 2 CO 3 (aq) + BaCl 2 (aq) A. BaCO 3 b. NaCl 2 c. Ba 2 CO 3 d. NaCl e. BaO Silberberg - 004 The... #16 17. (p. 111) How many moles of ions are released when 0.27 mol of cobalt(ii) chloride, CoCl 2, is dissolved in water? a. 0.27 mol b. 0.090 mol c. 0.54 mol d. 0.18 mol E. 0.81 mol Silberberg - 004 The... #3
18. (p. 116) Select the correct name and chemical formula for the precipitate that forms when the following reactants are mixed. CuCl 2 (aq) + Na 2 CO 3 (aq) a. copper(i) carbonate, Cu 2 CO 3 b. copper(ii) carbonate, Cu 2 CO 3 c. copper(i) carbonate, CuCO 3 D. copper(ii) carbonate, CuCO 3 e. sodium chloride, NaCl Silberberg - 004 The... #20 19. (p. 111) How many moles of H + (aq) ions are present in 750 ml of 0.65 M hydrochloric acid? a. 0.98 mol b. 1.2 mol C. 0.49 mol d. 0.87 mol e. 0.65 mol Silberberg - 004 The... #5 20. (p. 111) Potassium carbonate, K 2 CO 3, sodium iodide, NaI, magnesium oxide, MgO, methanol, CH 3 OH, and ammonium chloride, NH 4 Cl, are soluble in water. Which produces the largest number of dissolved particles per mole of dissolved solute? a. NH 4 Cl b. MgO c. NaI D. K 2 CO 3 e. CH 3 OH