1. Balance the following equation. What is the sum of the coefficients of the reactants and products?

Transcription

1 1. Balance the following equation. What is the sum of the coefficients of the reactants and products? 1 Fe 2 O 3 (s) + _3 C(s) 2 Fe(s) + _3 CO(g) a) 5 b) 6 c) 7 d) 8 e) 9 2. Which of the following equations represents an acid-base neutralization reaction? a) H 2 SO 4 + Zn ZnSO 4 + H 2 b) NaOH + HClO 3 NaClO 3 + H 2 O c) K 2 SO 4 + Ba(OH) 2 BaSO 4 + 2KOH d) HCl + AgNO 3 HNO 3 + AgCl e) WO H 2 W + 3 H 2 O 3. What is the oxidation number for nitrogen in KNO 2? +1 + #N +2(-2) = 0 #N = +3 a) -1 b) -3 c) +3 d) +5 e) Identify the oxidizing agent in the following oxidation-reduction reaction. Ag + reduced to Ag Cu reducing agent 2 AgNO 3 (aq) + Cu(s) Cu(NO 3 ) 2 (aq) + 2 Ag(s) Cu oxidized to Cu 2+ (+1) (0) (+2) (0) Ag + oxidizing agent a) Ag + b) NO 3 - c) Cu d) Cu 2+ e) Ag 5. To three significant figures, what is the percent of sulfur in Al 2 (SO 4 ) 3? 3 sulfur atoms (F.W. Al 2 (SO 4 ) 3 = amu) Al 2 (SO 4 ) 3 a) 28.1 b) x amu x 100 = 28.1 c) amu d) 38.9 e) A hospital patient is given a solution containing 9.00 x 10-9 g of iodine-131 (isotopic weight: 131). How many atoms of iodine are present? Avogadro s Number = 6.02 x a) 6.68 x b) 1.36 x 10 8 c) 1.36 x x 10-9 g x 1 mol x 6.02x10 23 atoms d) 4.14 x g 1 mol e) 4.14 x

2 7. In which of the following pairings of masses does the first listed mass contain more moles of substance than the second listed mass? calculate molar masses, then moles of each a) g H 2 O and g NH 3 b) 38.5 g CH 4 and 38.5 g CO 2 c) g CO 2 and g CO d) more than one correct response e) no correct response 8. In the following reaction, how many grams of H 2 O are produced if 6.13 g of N 2 H 4 react? N 2 H 4 + 3O 2 2NO 2 + 2H 2 O M.W M.W. = a) 6.89 g b) 3.45 g c) 12.3 g 6.13 g x 1 mol x 2 mol H 2 O x g d) 1.72 g g 1 mol N 2 H 4 1 mol e) 8.96 g 9. How many moles of carbon monoxide will be produced from the reaction of 4.5 moles of SiO 2 and 4.5 moles of carbon? (Hint: one reagent is limiting) SiO C SiC + 2 CO a) moles 4.5 moles b) c) 4.5 limiting reagent has lowest mole to coefficient ratio d) 6.0 e) moles C x 2 mol CO / 3 mol C = 3.0 mol CO 10. How many moles of nitrate ions are in g of Cu(NO 3 ) 2? F.W amu Atomic weights: Cu = 63.55, O = 16.00, N = a) b) g Cu(NO 3 ) 2 x 1 mol Cu(NO 3 ) 2 x 2 mol NO 3 c) g Cu(NO 3 ) 2 1 mol Cu(NO 3 ) 2 d) e) The mineral zircon contains 49.8% Zr, 15.3% Si and 34.9% O. What is the empirical formula? (Atomic weights: Zr = 91.2, Si = 28.1, O = 16.0) a) ZrSiO g Zr = 0.55 mol 0.55/0.54 = 1 b) ZrSi 2 O g Si = 0.54 mol 0.54/0.54 = 1 c) Zr 2 SiO g O = 2.18 mol 2.18/0.54 = 4 d) ZrSiO 4 e) ZrSiO 3 2

3 12. When a student reacted 17.5 g of MnO 2 with excess aluminum and obtained 11.2 g of Al 2 O 3, what was the % yield? (F.W. MnO 2 = 86.9 g/mol; F.W. Al 2 O 3 = 102 g/mol) 3 MnO Al 2 Al 2 O Mn a) g MnO 2 x 1 mol x 2 Al 2 O 3 x 102 g = 13.7 g b) g 3 MnO 2 1 mol theoretical yield c) 78.7 d) 81.8 actual yield 11.2 g x 100 = 81.8 % yield e) 92.6 theoretical yield 13.7 g 13. Which of the following statements concerning evaporation is correct? a) Molecules with energies below average are those that escape from the liquid. b) Evaporation is an exothermic process. c) Increasing the surface area of the liquid decreases the rate of evaporation. d) Increasing the temperature of the liquid decreases the rate of evaporation. e) Evaporation causes the temperature of the liquid to decrease. 14. Which conversion of units for pressure is CORRECT? a) 2.28 x 10 3 mm Hg = 3.51 atm b) 152 torr = atm c) 114 mm Hg = atm d) atm = 45.6 cm Hg e) 830 torr = 830 cm Hg 15. Which of the following is an indicator of STRONG intermolecular forces in liquids? a) Low Heat of Vaporization b) Low Boiling Point c) Low Surface Tension d) Low Vapor Pressure is an indication of Strong intermolecular forces in liquids. e) None of the above. 16. The pressure on a 14.4 L sample of oxygen at 748 mm Hg is increased to 1.31 x 10 3 mm Hg at constant temperature. What will be the new volume in L? a) 8.22 V 1 P 1 = V 2 P 2 b) 17.5 c) L x 748 mm Hg = V 2 x 1.31 x 10 3 mm Hg d) 25.2 e)

4 17. Gas evolved in the fermentation of sugar in wine making occupies a volume of 0.75 L at 20 o C at 720 mm Hg. What volume (L) would the gas occupy at 39 o C and 1.00 atm? a) 0.76 V 1 P 1 /T 1 = V 2 P 2 /T 2 b) 0.80 c) L x 720 mm Hg = V 2 x 760 mm Hg d) 0.67 ( ) K ( ) K e) What is the density of chlorine in g/l at STP? 1 mol of any gas = 22.4 L at STP mass = 2 x g/mol Cl 2 = 3.2 g/l density volume 22.4 L/mol a) 0.80 b) 3.2 c) 1.6 d) 6.4 e) Which of the following molecules exhibits hydrogen-bonding in the pure liquid? a) CH 4 b) Br 2 c) NH 3 d) H 2 e) CH 3 CH 2 CH 3 All of these molecules, except for NH 3, are nonpolar and exhibit only London Forces. 20. Assume g of dry ice (solid CO 2 ) is placed in an evacuated 50.0 L closed tank. What will be the pressure in the tank in atmospheres at a temperature of 45 o C? Assume that all the CO 2 has been converted into gas. M.W. CO 2 = 44.01; the universal gas constant is L atm mole -1 K -1 n = g x 1 mol/44.01 g = mol a) 7.25 b) 6.10 P x V = nrt c) 10.8 P x 50 L = mol x L atm mole -1 K -1 x ( )K d) 9.15 e) Which of the following is NOT a distinguishing characteristic of a gas? a) Indefinite shape. b) Indefinite volume. c) Low density. d) Small compressibility. e) Moderate thermal expansion. 22. Arrange the following molecules according to increasing strength of intermolecular attractive forces: NH 3 CH 3 CH 2 OH CH 3 CH 2 CH 3 CH 4 H 2 O a) NH 3 < CH 3 CH 2 OH < CH 3 CH 2 CH 3 < CH 4 < H 2 O b) CH 4 < CH 3 CH 2 CH 3 < NH 3 < CH 3 CH 2 OH < H 2 O c) NH 3 < CH 4 < CH 3 CH 2 CH 3 < CH 3 CH 2 OH < H 2 O d) CH 3 CH 2 CH 3 < CH 4 < CH 3 CH 2 OH < NH 3 < H 2 O e) CH 4 < CH 3 CH 2 CH 3 < NH 3 < H 2 O < CH 3 CH 2 OH 4

5 23. What is the partial pressure of oxygen (in atm) a scuba diver experiences at a depth of 75 ft? Assume that 20 % of the compressed air she is breathing is oxygen and that the pressure of the water is equal to 1 atm for every 33 ft of depth. a) 1.2 Total P T = P water + P air b) 0.45 c) 0.95 P T = 75 ft x 1 atm + 1 atm (air) = 3.27 atm d) ft e) % of air = P O2 = 3.27 atm x 0.20 = 0.65 atm 24. Which of the following is an exothermic process? a) Evaporation b) Melting c) Sublimation d) Boiling e) Freezing 25. The compounds CF 4 and CCl 4 are tetrahedral molecules. Neither is polar. What is the reason for the large difference in their boiling points of -129 o C (CF 4 ) and 76.8 o C (CCl 4 )? a) CCl 4 has higher London Forces due to its larger size and greater number of electrons; i.e. it has a greater polarizability than CF 4. b) CCl 4 has more Hydrogen Bonding. c) CCl 4 has stronger Dipole-Dipole Forces. d) CF 4 has higher London Forces. e) CF 4 has more Hydrogen Bonding. 26. Which of the following statements is NOT correct? a) Most solids become more soluble in water with increasing temperature. b) Gases become more soluble in water with increasing temperature. c) The solubility of a gas increases with increasing pressure. d) A supersaturated solution is an unstable solution. e) When salts dissolve in water, entropy increases. 27. Based on the generalization of like dissolves like, and the solubility rules listed on page 6, which of the following substances will NOT dissolve in water? a) KNO 3 b) CH 3 CH 2 OH c) CH 3 CH 2 CH 2 CH 2 CH 3 d) CaCl 2 e) NH 3 ionic & soluble polar, H-bonding nonpolar ionic & soluble polar, H-bonding 28. For which of the following will the solubility in water increase with increasing pressure? The solubility for gases increases with increasing pressure. a) NaCl b) CCl 4 c) alcohol d) MgCl 2 e) O 2 5

6 29. When an aqueous solution of sodium phosphate is mixed with an aqueous solution of iron (III) nitrate a precipitate is formed. Consult the solubility rules below and identify the spectator ions for this reaction? FePO 4 (s) is insoluble; precipitation drives the reaction. a) Na + 3- and PO 4 b) Fe and PO 4 c) Na + - and NO 3 Na + and NO - 3 are soluble and do not react = spectator ions d) Fe 3+ - and NO 3 e) none are spectator ions 30. Based on the solubility rules below, what will happen when aqueous solutions of CsBr and Ba(NO 3 ) 2 are mixed together? a) Barium bromide will precipitate. b) Cesium nitrate will precipitate. c) Barium nitrate will precipitate. d) Cesium bromide will precipitate. e) No reaction occurs because all combinations of these ions are soluble. Solubility Rules of Common Ionic Compounds All ionic compounds of Li, Na, K, Rb, Ce, and ammonium ions are soluble. All nitrates, chlorates, and perchlorates are soluble. The chlorides, bromides, and iodides of most metals are soluble. Principal exceptions are those of lead, silver, and mercury (I). Barium & cesium bromide are soluble (not an exception). All sulfates are soluble except those of strontium, barium, lead, and mercury (I). All carbonates, chromates, and phosphates are insoluble except those of lithium, sodium, potassium, rubidium, cesium, and ammonium. The hydroxides of Li +, Na +, K +, Rb +, Ce + are soluble. The hydroxides of Ca 2+, Sr 2+, and Ba 2+ are moderately soluble. The rest of the hydroxides are insoluble. The sulfides of all metals are insoluble except those of Li +, Na +, K +, Rb +, Ce + and NH 4 + 6