Name: _________________________ St. Philip’s College Chem 1411.004 - General Chemistry I Part 2 Practice for Exam 3 Summer 2013 MULTIPLE CHOICE: 1. A solution is composed of solute and solvent. Circle all that are correct for the solute a) It must be a solid b) It is the substance that gets dissolved c) It must be the only substance other than the solvent d) It is generally present in smaller amounts than the solvent e) It must be soluble in water for an aqueous solution 2. When aqueous solutions of potassium carbonate (K2CO3) and calcium chloride (CaCl2) are mixed, a reaction occurs, producing a precipitate as one of the products: K2CO3(aq) + CaCl2(aq) CaCO3(s) + 2KCl(aq) Which ions (if any) are spectator ions in this reaction? a) K+ and Ca2+ b) Ca2+ and Cl- c) K+ and CO32- d) K+ and Cl- e) There are no spectator ions in this reaction 3. Is there a net ionic equation for the reaction in problem 2, and if so, what is it? a) There is no net ionic equation for this reaction b) K+(aq) + Cl-(aq) c) Ca2+(aq) + CO32-(aq) d) 2K+(aq) + Ca2+(aq) KCl(aq) CaCO3(s) + CO32-(aq) + 2Cl-(aq) CaCO3(s) + 2KCl(aq) 4. Circle all that complete the statement correctly: The term Oxidation-Reduction reaction refers to: a. Two different types of chemical reactions that occur separately b. The processes by which electrons are transferred in a reaction c. The action of an oxidizing agent on a reducing agent and vice versa d. The gain and loss of electrons resulting in changes in charge or oxidation number 5. The oxidation number of N in NaNO3 is a) +6 b) +5 c) +3 d) –3 e) None of the above. 6. Circle all that complete the statement correctly: A Half-reaction indicates a) the change in oxidation number of one element b) the identity of the precipitated product c) electrons lost or gained d) both oxidizing agent and reducing agent in one line Choose the correct set of half reactions for this full Redox reaction: 8Fe + S8 8FeS a. Fe Fe 2+ and S8 8S2b. 2e - + Fe Fe 2+ and S8 8S2- + 16e c. Fe Fe 2+ + 2e - and S8 16e - + 8S2d. 8Fe 8Fe 2+ + 16e - and S8 16e - + 8S2e. 8Fe 8Fe 2+ and S8 8S2In the above reaction, the substance oxidized is ___Fe______ In the above reaction, the substance reduced is ___S8_______ The reducing agent is _____ Fe ______ The oxidizing agent is _____S8_______ 7. Circle all that complete the statement correctly: The term Molarity refers to a. A measure of concentration of solute in a given amount of solvent b. the number of moles solute per volume in liters of solution c. the number of grams solution per volume in liters d. mass divided by the molar mass of the solute e. the volume of a solution at specific conditions 8. What is the molarity of an NaI solution that contains 3.00 g of NaI in 40.0 mL of solution? Molar mass NaI = 149.89 g/mol a. 0.100 M b. 0.500 M c. 1.00 M d. 2.00 M e. 5.00 M 9. What volume of 18.0 M sulfuric acid, H2 SO4, must be used to prepare 15.5 L of 0.195 M H2 SO4 by dilution? a. 168 mL b. 0.336 L c. 92.3 mL d. 226 mL e. none of these 10. How many moles of nitrogen gas are needed to react with 2 moles hydrogen gas to form ammonia, NH3? 3H2(g) + N2(g) 2NH3(l) a) 0.7moles N2 b) 6.0 moles N2 c) 12.0 moles N2 d) 1.7 moles N2 11. According to the following balanced reaction, how many moles of NO are formed from 8.44 moles of NO2 if there is plenty of water present? 3 NO2(g) + H2O(l) → 2 HNO3(aq) + NO(g) A) 2.81 moles NO B) 25.3 moles NO C) 8.44 moles NO D) 5.63 moles NO E) 1.83 moles NO 12. How many grams of oxygen are formed when 6.21 moles of KOH are formed? 4 KO(s) + 2 H2O(l) → 4 KOH(s) + O2(g) A) 19.9 g O2 B) 27.9 g O2 C) 49.7 g O2 D) 3.59 g O2 E) 11.7 g O2 13. A 14.01 g sample of N2 reacts with 3.02 g of H2 to form ammonia (NH3). If ammonia is the only product, what mass of ammonia is formed? A) 17.04 g B) 1.10 g C) 14.01 g D) 3.02 g E) 23.07 g 14. How many molecules of H2S are required to form 79.0 g of sulfur according to the following reaction? Assume excess SO2. 2 H2S(g) + SO2(g) → 3 S(s) + 2H2O(l) A) 1.48 × 1024 molecules H2S B) 9.89 × 1023 molecules H2S C) 5.06 × 1025 molecules H2S D) 3.17 × 1025 molecules H2S E) 2.44 × 1023 molecules H2S 15. A 12.39 g sample of phosphorus reacts with 42.54 g of chlorine to form only phosphorus trichloride (PCl3). If it is the only product, what mass of PCl3 is formed? A) 30.15 g B) 54.93 g C) 140.01 g D) 79.71 g E) 91.86 g 16. Determine the limiting reactant (LR) and the mass (in g) of nitrogen that can be formed from 50.0 g N2O4 and 45.0 g N2H4. Some possibly useful molar masses are as follows: N2O4 = 92.02 g/mol, N2H4 = 32.05 g/mol. N2O4(l) + 2 N2H4(l) → 3 N2(g) + 4 H2O(g) A) LR = N2H4, 59.0 g N2 formed B) LR = N2O4, 105 g N2 formed C) LR = N2O4, 45.7 g N2 formed D) LR = N2H4, 13.3 g N2 formed E) No LR, 45.0 g N2 formed 17. According to the following reaction, what amount of Al2S3 remains when 20.00 g of Al2S3 and 2.00 g of H2O are reacted? A few of the molar masses are as follows: Al2S3 = 150.17 g/mol, H2O = 18.02 g/mol. Al2S3(s) + 6 H2O(l) → 2 Al(OH)3(s) + 3 H2S(g) A) 28.33 g B) 14.00 g C) 8.33 g D) 19.78 g E) 17.22 g 18. Determine the percent yield of a reaction that produces 28.65 g of Fe when 50.00 g of Fe2O3 react with excess Al according to the following reaction. Fe2O3(s) + 2 Al(s) → Al2O3(s) + 2 Fe(s) A) 61.03 % B) 28.65 % C) 57.30 % D) 20.02 % E) 81.93 % 19. Which of the following solutions will have the highest concentration of chloride ions? A) 0.10 M NaCl B) 0.10 M MgCl2 C) 0.10 M AlCl3 D) 0.05 M CaCl2 E) All of these solutions have the same concentration of chloride ions. 20. How many milliliters of a 0.184 M NaNO3 solution contain 0.113 moles of NaNO3? A) 543 mL B) 163 mL C) 614 mL D) 885 mL E) 326 mL 21) How many liters of a 0.0550 M KCl solution contain 0.163 moles of KCl? A) 3.37 L B) 1.48 L C) 8.97 L D) 2.96 L E) 1.12 L 22) How many moles of LiI are contained in 258.6 mL of 0.0296 M LiI solution? A) 1.31 × 10-3 mol B) 8.74 × 10-3 molvdvv vbb b D) 3.67 × 10-3 mol E) 7.65 × 10-3 mol 23) What is the concentration of nitrate ions in a 0.125 M Mg(NO3)2 solution? A) 0.125 M B) 0.0625 M C) 0.375 M D) 0.250 M E) 0.160 M 24) What is the concentration of magnesium ions in a 0.125 M Mg(NO3)2 solution? A) 0.125 M B) 0.0625 M C) 0.375 M D) 0.250 M E) 0.160 M 25) What volume (in mL) of 0.0887 M MgF2 solution is needed to make 275.0 mL of 0.0224 M MgF2 solution? A) 72.3 mL B) 91.8 mL C) 10.9 mL D) 69.4 mL E) 14.4 mL 26) How many molecules of sucrose (C12H22O11, molar mass = 342.30 g/mol) are contained in 14.3 mL of 0.140 M sucrose solution? A) 8.29 × 1022 molecules C12H22O11 B) 1.21 × 1021 molecules C12H22O11 C) 6.15 × 1022 molecules C12H22O11 D) 1.63 × 1023 molecules C12H22O11 E) 5.90 × 1024 molecules C12H22O11 27) How many chloride ions are present in 65.5 mL of 0.210 M AlCl3 solution? A) 4.02 × 1023 chloride ions B) 5.79 × 1024 chloride ions C) 2.48 × 1022 chloride ions D) 8.28 × 1021 chloride ions E) 1.21 × 1022 chloride ions 28) According to the following reaction, what volume of 0.244 M KCl solution is required to react exactly with 50.0 mL of 0.210 M Pb(NO3)2 solution? 2 KCl(aq) + Pb(NO3)2 (aq) → PbCl2(s) + 2 KNO3(aq) A) 97.4 mL B) 116 mL C) 43.0 mL D) 86.1 mL E) 58.1 mL 29) According to the following reaction, what mass of PbCl2 can form from 235 mL of 0.110 M KCl solution? Assume that there is excess Pb(NO3)2. 2 KCl(aq) + Pb(NO3)2 (aq) → PbCl2(s) + 2 KNO3(aq) A) 7.19 g B) 3.59 g C) 1.80 g D) 5.94 g E) 1.30 g 30) Which of the following compounds is soluble in water? A) CaS B) MgCO3 C) PbCl2 D) BaSO4 E) None of these compounds is soluble in water. 31) Which of the following compounds is insoluble in water? A) Hg2I2 B) MgSO4 C) (NH4)2CO3 D) BaS E) All of these compounds are soluble in water. 32) Which of the following is a precipitation reaction? A) Zn(s) + 2 AgNO3(aq) → 2 Ag(s) + Zn(NO3)2(aq) B) NaCl(aq) + LiI(aq) → NaI(aq) + LiCl(aq) C) 2 LiI(aq) + Hg2(NO3)2(aq) → Hg2I2(s) + 2 LiNO3(aq) D) HCl(aq) + KOH(aq) → KCl(aq) + H2O(l) E) None of the above are precipitation reactions. 33) Identify the spectator ions in the following molecular equation. KBr(aq) + AgNO3(aq) → AgBr(s) + KNO3(aq) A) Ag+ and BrB) K+ and NO3C) K+ and BrD) Ag+ and NO3E) There are no spectator ions in this reaction. 34) Give the complete ionic equation for the reaction (if any) that occurs when aqueous solutions of lithium sulfide and copper (II) nitrate are mixed. A) Li+ (aq) + SO42-(aq) + Cu+(aq) + NO3-(aq) → CuS(s) + Li+(aq) + NO3-(aq) B) Li+ (aq) + S-(aq) + Cu+(aq) + NO3-(aq) → CuS(s) + LiNO3(aq) C) 2 Li+(aq) + S2-(aq) + Cu2+(aq) + 2 NO3-(aq) → Cu2+(aq) + S2-(aq) + 2 LiNO3(s) D) 2 Li+(aq) + S2-(aq) + Cu2+(aq) + 2 NO3-(aq) → CuS(s) + 2 Li+(aq) + 2 NO3-(aq) E) No reaction occurs. 35) Which of the following is an acid base reaction? A) C(s) + O2(g) → CO2(g) B) 2 HClO4(aq) + Ca(OH)2(aq) → 2 H2O(l) + Ca(ClO4)2(aq) C) Fe(s) + 2 AgNO3(aq) → 2 Ag(s) + Fe(NO3)2(aq) D) MgSO4(aq) + Ba(NO3)2(aq) → Mg(NO3)2(aq) + BaSO4(s) E) None of the above are acid base reactions. 36) Which of the following is a gas-evolution reaction? A) 2 C2H6(l) + 7 O2(g) → 4 CO2(g) + 6 H2O(g) B) 2 H2(g) + O2(g) → 2 H2O(g) C) LiCl(aq) + NaNO3(aq) → LiNO3(aq) + NaCl(g) D) NH4Cl(aq) + KOH(aq) → KCl(aq) + NH3(g) + H2O(l) E) None of the above are gas-evolution reactions. 37) The titration of 25.0 mL of an unknown concentration H2SO4 solution requires 83.6 mL of 0.12 M LiOH solution. What is the concentration of the H2SO4 solution (in M)? A) 0.20 M B) 0.40 M C) 0.10 M D) 0.36 M E) 0.25 M 38) The titration of 80.0 mL of an unknown concentration H3PO4 solution requires 126 mL of 0.218 M KOH solution. What is the concentration of the H3PO4 solution (in M)? A) 1.03 M B) 0.343 M C) 0.114 M D) 0.138 M E) 0.0461 M 39) Choose the reaction that represents the combustion of C6H12O2. A) C6H12O2(l) + 8 O2(g) → 6 CO2(g) + 6 H2O(g) B) Mg(s) + C6H12O2(l) → MgC6H12O2(aq) C) 6 C(s) + 6 H2(g) + O2(g) → C6H12O2(l) D) C6H12O2(l) → 6 C(s) + 6 H2(g) + O2(g) E) None of the above represent the combustion of C6H12O2. 40) Determine the oxidation state of P in PO33-. A) +3 B) +6 C) +2 D) 0 E) -3 41) What element is undergoing oxidation (if any) in the following reaction? CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(g) A) O B) H C) C D) both C and H E) None of the elements is undergoing oxidation. 42) What element is undergoing reduction (if any) in the following reaction? Zn(s) + 2 AgNO3(aq) → Zn(NO3)2(aq) + 2 Ag(s) A) Zn B) N C) O D) Ag E) This is not an oxidation-reduction reaction. 43) Determine the reducing agent in the following reaction. 2 Li(s) + Fe(C2H3O2)2(aq) → 2 LiC2H3O2(aq) + Fe(s) A) O B) H C) C D) Fe E) Li 44) Determine the oxidizing agent in the following reaction. Ni(s) + 2 AgClO4(aq) → Ni(ClO4)2(aq) + 2 Ag(s) A) Ag B) Ni C) Cl D) O E) This is not an oxidation-reduction reaction. 45) If the percent yield for the following reaction is 75.0%, and 45.0 g of NO2 are consumed in the reaction, how many grams of nitric acid, HNO3(aq) are produced? 3 NO2(g) + H2O(l) → 2 HNO3(aq) + NO(g) A) 30.8 g B) 41.1 g C) 54.8 g D) 69.3 g 46) How many H+ ions can the acid, H2SO4 , donate per molecule? A) 0 B) 1 C) 2 D) 3 SHOW THE WORK for THESE problems and circle or box-in your final answer: 1. Zinc reacts with 0.075 L of a 0.1 M Hydrochloric Acid solution, HCl, to produce Zinc chloride. How many liters of Hydrogen gas are produced at STP? The unbalanced reaction is: __Zn(s) + __HCl(aq) __ ZnCl2(aq) + __H2(g) 2. Write a balanced equation to show the reaction of gaseous ethane with gaseous oxygen to form carbon monoxide gas and water vapor. 3. Write a balanced equation to show the reaction of aqueous aluminum acetate with aqueous ammonium phosphate to form solid aluminum phosphate and aqueous ammonium acetate. 4. Aluminum metal reacts with aqueous iron( II) chloride to form aqueous aluminum chloride and iron metal. What is the stoichiometric coefficient for aluminum when the chemical equation is balanced using the lowest, whole-number stoichiometric coefficients?