Exam 3 - Answer Key

7. One mole of __________ contains the largest number of atoms.A) Al 2 (SO 4 ) 3B) Cl 2C) C 10 H 8D) S 8E) Na 3 PO 42 (Al) + 3 (S) + 12 (O) = 17 atoms2 (Cl) = 2 atoms10 (C) + 8 (H) = 18 atoms8 (S) = 8 atoms3 (Na) + 1 (P) + 4 (O) = 8 atoms8. There are __________ mol of carbon atoms in 4 mol of dimethylsulfoxide (C 2 H 6 SO).A) 6B) 4C) 3D) 2E) 82 mol. C4 mol. C2HSO 6x = 8 mol. C1 mol. CHSO2 69. What is the empirical formula of a compound that contains 27.0% S, 13.4% O, and 59.6% Cl by mass?A) SOCl 2B) SOClC) S 2 OClD) SO 2 ClE) ClSO 4S: 27g / 32 g/mol ~ 1O: 13.4 g / 16 g/mol. ~ 1Cl: 59.6 g / 35.5 g/mol. ~ 2therefore - SOCl 2more accurately:S: 27g / 32 g/mol = 0.84, 0.84 / 0.84 = 1O: 13.4 g / 16 g/mol. = 0.84, 0.84 / 0.84 = 1Cl: 59.6 g / 35.5 g/mol. = 1.64, 1.64 / 0.84 = 2therefore - SOCl 210. A 3.82-g sample of Mg 3 N 2 (MW=100.9 g/mol.) was combined with 7.73 g of water (MW=18.02 g/mol.) togive 3.60 g MgO (MW=40.30 g/mol.). What is the percent yield in the reaction?Mg 3 N 2 + 3 H 2 O ? 2NH 3 + 3MgOA) 94.5%B) 46.6%C) 78.8%D) 99.9%E) 49.4%1 mol. Mg N 3 mol. MgO 40.3 g MgO3 23.82 g Mg3N 2x x x = 4.58 g MgO100.9 g Mg3N2 1 mol. Mg3N21 mol. MgO1 mol. H O 3 mol. MgO 40.3 g MgO27.73 g H2O x x x = 17.3 g MgO100.9 g H2O 3 mol. H2O 1 mol. MgOThus Mg 3 N 2 is the limiting reagent.3.60 g% yield = x 100% = 78.8%4.58 g11. What is the maximum mass of SO 3 (MW=80.06 g/mol.) that can be produced by the reaction of 1.0 g ofS (MW=32.07 g/mol.) with 1.0 g of O 2 (MW=32.00 g/mol.) via the equation below?2 S (s) + 3 O 2 (g) ? 2 SO 3 (g)A) 0.27 gB) 3.8 gC) 1.7 gD) 2.0 gE) 2.5 gSince we start with equal masses of S and O 2 , and they have the same MW, thenO 2 must be the limiting reactant since the reaction requires 3 moles O 2 per mole S.1 mol. O22 mol. SO3 80.06 g SO31.0 g O2x x x = 1.7 g SO332.0 g O 3 mol. O 1 mol. SO2 2 312. What is the solvent in an aqueous solution of sodium chloride?a) sodiumb) chlorinec) waterd) NaCle) ethanol