Chemistry: A Molecular Approach (Tro) Chapter 4. Chemical Quantities and Aqueous Reactions

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1 Chemistry: A Molecular Approach (Tro) Chapter 4 Chemical Quantities and Aqueous Reactions 1) According to the following balanced reaction, how many moles of NO are formed from 8.44 moles of NO 2 if there is plenty of water present? 3 NO2(g) + H2O(l) 2 HNO3(aq) + NO(g) 2.81 moles NO 25.3 moles NO 8.44 moles NO 5.50 moles NO 1.83 moles NO A 2) Consider the following reaction. How many moles of oxygen are required to produce 2.33 moles of water? Assume that there is excess C3H7SH present. C3H7SH(l) + 6 O2(g) 3 CO2(g) + SO2(g) + 4 H2O (g) 1.55 moles O moles O moles O2 1

2 4.14 moles O moles O2 B 3) According to the following balanced reaction, how many moles of KO are required to exactly react with 5.44 moles of H2O? 4 KO(s) + 2 H2O(l) 4 KOH(s) + O2(g) 2.72 moles H2O 16.7 moles H2O 10.9 moles H2O 8.33 moles H2O 4.87 moles H2O C 2

3 4) Consider the following balanced reaction. How many grams of water are required to form 75.9 g of HNO 3? Assume that there is excess NO2 present. The molar masses are as follows: H2O = g/mol, HNO3 = g/mol. 3 NO2(g) + H2O(l) 2 HNO3(aq) + NO(g) 38.0 g H2O 21.7 g H2O 43.4 g H2O 10.9 g H2O 26.5 g H2O D 5) Consider the following balanced reaction. What mass (in g) of CO2 can be formed from 288 mg of O2? Assume that there is excess C3H7SH present. C3H7SH(l) + 6 O2(g) 3 CO2(g) + SO2(g) + 4 H2O (g) g CO g CO g CO g CO2 3

4 0.198 g CO2 E 6) According to the following reaction, how many grams of sulfur are formed when 37.4 g of water are formed? 2 H2S(g) + SO2(g) 3 S(s) + 2H2O(l) 99.8 g S 66.6 g S 56.1 g S 44.4 g S 14.0 g S A 7) How many grams of Li3N can be formed from 1.75 moles of Li? Assume an excess of nitrogen. 6 Li(s) + N2(g) 2 Li3N(s) 18.3 g Li3N 20.3 g Li3N 58.3 g Li3N 61.0 g Li3N 4

5 15.1 g Li3N B 5

6 8) 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) 19.9 g O g O g O g O g O2 C 9) How many moles of oxygen are formed when 58.6 g of KNO3 decomposes according to the following reaction? The molar mass of KNO3 is g/mol. 4 KNO3(s) 2 K2O(s) + 2 N2(g) + 5 O2(g) 23.2 mol O mol O mol O mol O mol O2 6

7 D 10) How many molecules of HCl are formed when 50.0 g of water reacts according to the following balanced reaction? Assume excess ICl3. 2 ICl3 + 3 H2O ICl + HIO3 + 5 HCl molecules HCl molecules HCl molecules HCl molecules HCl molecules HCl A 11) 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) molecules H2S molecules H2S molecules H2S molecules H2S 7

8 molecules H2S B 8

9 12) 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 = g/mol, N2H4 = g/mol. N2O4(l) + 2 N2H4(l) 3 N2(g) + 4 H2O(g) LR = N2H4, 59.0 g N2 formed LR = N2O4, 105 g N2 formed LR = N2O4, 45.7 g N2 formed LR = N2H4, 13.3 g N2 formed No LR, 45.0 g N2 formed C 13) Determine the theoretical yield of HCl if 60.0 g of BCl3 and 37.5 g of H2O are reacted according to the following balanced reaction. A possibly useful molar mass is BCl3 = g/mol. BCl3(g) + 3 H2O(l) H3BO3(s) + 3 HCl(g) 75.9 g HCl 132 g HCl 187 g HCl 56.0 g HCl 25.3 g HCl 9

10 D 14) Determine the theoretical yield of H2S (in moles) if 4.0 mol Al2S3 and 4.0 mol H2O are reacted according to the following balanced reaction. A possibly useful molar mass is Al2S3 = g/mol. Al2S3 (s) + 6 H2O(l) 2 Al(OH)3 (s) + 3 H2S(g) 12 mol H2S 4.0 mol H2S 18 mol H2S 6.0 mol H2S 2.0 mol H2S E 15) Determine the percent yield of a reaction that produces g of Fe when g of Fe2O3 react with excess Al according to the following reaction. Fe2O3(s) + 2 Al(s) Al2O3(s) + 2 Fe(s) % % % % 10

11 81.93 % E 11

12 16) Determine the molarity of a solution formed by dissolving 97.7 g LiBr in enough water to yield ml of solution M 1.18 M M M 2.30 M A 17) Determine the molarity of a solution formed by dissolving 468 mg of MgI 2 in enough water to yield 50.0 ml of solution M M M M M B 18) How many milliliters of a M NaNO3 solution contain moles of NaNO3? 12

13 543 ml 163 ml 614 ml 885 ml 326 ml C 19) How many liters of a M KCl solution contain moles of KCl? 3.37 L 1.48 L 8.97 L 2.96 L 1.12 L D 20) How many moles of LiI are contained in ml of M LiI solution? mol mol 13

14 mol mol mol E 21) How many moles of CH3CH2OH are contained in 548 ml of M CH3CH2OH solution? mol mol mol mol mol A 14

15 22) How many molecules of sucrose (C12H22O11, molar mass = g/mol) are contained in 14.3 ml of M sucrose solution? molecules C12H22O molecules C12H22O molecules C12H22O molecules C12H22O molecules C12H22O11 B 23) How many chloride ions are present in 65.5 ml of M AlCl3 solution? chloride ions chloride ions chloride ions chloride ions chloride ions C 24) What is the concentration of nitrate ions in a M Mg(NO3)2 solution? 15

16 0.125 M M M M M D 25) Which of the following solutions will have the highest concentration of chloride ions? 0.10 M NaCl 0.10 M MgCl MAlCl M CaCl2 All of these solutions have the same concentration of chloride ions. C 26) Which of the following solutions will have the highest electrical conductivity? M Al2(SO4)3 16

17 0.050 M (NH4)2CO M LiBr 0.10 M NaI 0.10 M KF A 27) How many milliliters of a M LiNO3 solution are required to make ml of M LiNO3 solution? 53.2 ml 42.3 ml 18.8 ml 23.6 ml 35.1 ml B 28) What volume (in L) of M MgF2 solution is needed to make ml of M MgF2 solution? 72.3 ml 91.8 ml 10.9 ml 17

18 69.4 ml 14.4 ml D 29) Determine the concentration of a solution prepared by diluting 25.0 ml of a stock M Ca(NO 3)2 solution to ml M M M M M C 30) Which of the following is NOT a strong electrolyte? LiOH CaCl2 MgCO3 NaC2H3O2 Li2SO4 18

19 C 31) Which of the following is considered a STRONG electrolyte? NH4NO3 C12H22O11 PbCl2 HC2H3O2 CH3OH A 32) According to the following reaction, what volume of M KCl solution is required to react exactly with 50.0 ml of M Pb(NO3)2 solution? 2 KCl(aq) + Pb(NO3)2 (aq) PbCl2(s) + 2 KNO3(aq) 97.4 ml 116 ml 43.0 ml 86.1 ml 58.1 ml D 19

20 20

21 33) What volume of M AgNO3 is required to react exactly with ml of M Na2SO4 solution? Hint: You will want to write a balanced reaction. 581 ml 173 ml 345 ml 139 ml 278 ml E 34) What mass (in g) of AgCl is formed from the reaction of 75.0 ml of a M AgC2H3O2 solution with 55.0 ml of M MgCl2 solution? 2 AgC2H3O2(aq) + MgCl2(aq) 2 AgCl(s) + Mg(C2H3O2)2(aq) g 1.72 g g 2.56 g 1.70 g A 35) 21

22 According to the following reaction, what mass of PbCl2 can form from 235 ml of M KCl solution? Assume that there is excess Pb(NO3)2. 2 KCl(aq) + Pb(NO3)2 (aq) PbCl2(s) + 2 KNO3(aq) 7.19 g 3.59 g 1.80 g 5.94 g 1.30 g B 36) According to the following reaction, how many moles of Fe(OH)2 can form from ml of M LiOH solution? Assume that there is excess FeCl2. FeCl2(aq) + 2 LiOH(aq) Fe(OH)2(s) + 2 LiCl(aq) moles moles moles moles moles 22

23 C 23

24 37) How many of the following compounds are soluble in water? Cu(OH)2 LiNO3 NH4Br K2S D 38) Which of the following compounds is soluble in water? CaS MgCO3 PbCl2 BaSO4 None of these compounds is soluble in water. A 39) How many of the following compounds are insoluble in water? 24

25 KC2H3O2 CaSO4 SrS AlPO C 40) Which of the following compounds is insoluble in water? Hg2I2 MgSO4 (NH4)2CO3 BaS All of these compounds are soluble in water. A 41) Which of the following pairs of aqueous solutions will react when mixed? 25

26 NH4NO3 + Li2CO3 Hg2(NO3)2 + LiI NaCl + Li3PO4 AgC2H3O2 + Cu(NO3)2 None of the above solution pairs will produce a reaction. B 26

27 42) Which of the following pairs of aqueous solutions will react when mixed? LiOH + Na2S (NH4)2SO4 + LiCl Sr(C2H3O2)2 + Na2SO4 KNO3 + NaOH None of the above solution pairs will produce a reaction. C 43) Which of the following pairs of aqueous solutions will react when mixed? HCl + LiOH Li2S + HCl K2CO3 + HNO3 MgCl2 + KOH All of these solution pairs will produce reactions. E 44) Give the complete ionic equation for the reaction (if any) that occurs when aqueous solutions of lithium sulfide and copper (II) nitrate are mixed. (the superscripts below aren't really acceptable on most of the ions, I don't know how to make it any better) 27

28 Li+ (aq) + SO42-(aq) + Cu+(aq) + NO3-(aq) CuS(s) + Li+(aq) + NO3-(aq) Li+ (aq) + S-(aq) + Cu+(aq) + NO3-(aq) CuS(s) + LiNO3(aq) 2 Li+(aq) + S2-(aq) + Cu2+(aq) + 2 NO3-(aq) Cu2+(aq) + S2-(aq) + 2 LiNO3(s) 2 Li+(aq) + S2-(aq) + Cu2+(aq) + 2 NO3-(aq) CuS(s) + 2 Li+(aq) + 2 NO3-(aq) No reaction occurs. D 45) Give the net ionic equation for the reaction (if any) that occurs when aqueous solutions of K2S and Fe(NO3)2 are mixed. K+(aq) + NO3-(aq) KNO3(s) Fe2+(aq) + S2-(aq) + 2 K+(aq) + 2 NO3-(aq) FeS(s) + 2 K+(aq) + 2 NO3-(aq) Fe2+(aq) + S2-(aq) + 2 K+(aq) + 2 NO3-(aq) Fe2+(aq) + S2-(aq) + 2 KNO3(s) Fe2+(aq) + S2-(aq) FeS(s) No reaction occurs. D 46) Give the net ionic equation for the reaction (if any) that occurs when aqueous solutions of H2SO4 and KOH are mixed. H+(aq) + OH-(aq) H2O(l) 28

29 2 K+(aq) + SO42-(aq) K2SO4(s) H+(aq) + OH-(aq) + 2 K+(aq) + SO42-(aq) H2O(l) + K2SO4(s) H22+(aq) + OH-(aq) H2(OH)2(l) No reaction occurs. A 29

30 47) Give the net ionic equation for the reaction (if any) that occurs when aqueous solutions of Al(C2H3O2)3 and LiNO3 are mixed. Al3+(aq) + 3 NO3-(aq) Al(NO3)3(s) Li+(aq) + C2H3O2-(aq) LiC2H3O2(s) Al3+(aq) + 3 NO3-(aq) + Li+(aq) + C2H3O2-(aq) Al(NO3)3(aq) + LiC2H3O2(s) 3 Li+(aq) + (C2H3O2)33-(aq) Li3(C2H3O2)3 (s) No reaction occurs. E 48) Give the net ionic equation for the reaction (if any) that occurs when aqueous solutions of Na2CO3 and HCl are mixed. 2 H+(aq) + CO32-(aq) H2CO3(s) 2 Na+(aq) + CO32-(aq) + 2 H+(aq) + 2 Cl-(aq) H2CO3(s) + 2 NaCl(aq) 2 H+(aq) + CO32-(aq) H2O(l) + CO2(g) 2 Na+(aq) + CO32-(aq) + 2 H+(aq) + 2 Cl-(aq) H2CO3(s) + 2 Na+(aq) + 2 Cl-(aq) No reaction occurs. C 49) Give the complete ionic equation for the reaction (if any) that occurs when aqueous solutions of MgSO3 and HI are mixed. 30

31 2 H+(aq) + SO32-(aq) H2SO3(s) Mg2+(aq) + 2 I-(aq) MgI2(s) 2 H+(aq) + SO32-(aq) + Mg2+(aq) + 2 I-(aq) H2SO3(s) + MgI2(aq) 2 H+(aq) + SO32-(aq) H2O(l) + SO2(g) No reaction occurs. D 50) Identify the spectator ions in the following molecular equation. KBr(aq) + AgNO3(aq) AgBr(s) + KNO3(aq) Ag+ & Br- K+ & NO3 K+ & Br Ag+ & NO3 There are no spectator ions in this reaction. B 51) Choose the statement below that is TRUE. 31

32 A weak acid solution consists of mostly nonionized acid molecules. The term "strong electrolyte" means that the substance is extremely reactive. A strong acid solution consists of only partially ionized acid molecules. The term "weak electrolyte" means that the substance is inert. A molecular compound that does not ionize in solution is considered a strong electrolyte. A 32

33 52) Which of the following is an acid base reaction? C(s) + O2(g) CO2(g) 2 HClO4(aq) + Ca(OH)2(aq) 2 H2O(l) + Ca(ClO4)2(aq) Fe(s) + 2 AgNO3(aq) 2 Ag(s) + Fe(NO3)2(aq) MgSO4(aq) + Ba(NO3)2(aq) Mg(NO3)2(aq) + BaSO4(s) None of the above are acid base reactions. B 53) Which of the following is a precipitation reaction? Zn(s) + 2 AgNO3(aq) 2 Ag(s) + Zn(NO3)2(aq) NaCl(aq) + LiI(aq) NaI(aq) + LiCl(aq) 2 LiI(aq) + Hg2(NO3)2(aq) Hg2I2(s) + 2 LiNO3(aq) HCl(aq) + KOH(aq) KCl(aq) + H2O(l) None of the above are precipitation reactions. C 54) Which of the following is a gas-evolution reaction? 33

34 2 C2H6(l) + 7 O2(g) 4 CO2(g) + 6 H2O(g) 2 H2(g) + O2(g) 2 H2O(g) LiCl(aq) + NaNO3(aq) LiNO3(aq) + NaCl(g) NH4Cl(aq) + KOH(aq) KCl(aq) + NH3(g) + H2O(l) None of the above are gas-evolution reactions. D 55) Which of the following is an oxidation-reduction reaction? HCl(aq) + LiOH(aq) LiCl(aq) + H2O(l) NaI(aq) + AgNO3(aq) AgI(s) + NaNO3(aq) Pb(C2H3O2)2(aq) + 2 NaCl(aq) PbCl2(s) + 2 NaC2H3O2(aq) Mg(s) + 2 HCl(aq) MgCl2(aq) + H2(g) All of the above are oxidation-reduction reactions. D 56) Determine the oxidation state of P in PO

35 A 57) Determine the oxidation state of Sn in Sn(SO4) B 35

36 58) What element is undergoing oxidation (if any) in the following reaction? CH4(g) + 2 O2(g) CO2(g) + 2 H2O(g) O H C both C and H None of the elements is undergoing oxidation. C 59) What element is undergoing reduction (if any) in the following reaction? Zn(s) + 2 AgNO3(aq) Zn(NO3)2(aq) + 2 Ag(s) Zn N O Ag This is not an oxidation-reduction reaction. D 36

37 60) Determine the reducing agent in the following reaction. 2 Li(s) + Fe(C2H3O2)2(aq) 2 LiC2H3O2(aq) + Fe(s) O H C Fe Li E 61) Determine the oxidizing agent in the following reaction. Ni(s) + 2 AgClO4(aq) Ni(ClO4)2(aq) + 2 Ag(s) Ag Ni Cl O This is not an oxidation-reduction reaction. A 37

38 62) 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)? 0.20 M 0.40 M 0.10 M 0.36 M 0.25 M A 63) The titration of 80.0 ml of an unknown concentration H3PO4 solution requires 126 ml of M KOH solution. What is the concentration of the H3PO4 solution (in M)? 1.03 M M M M M C 64) Chose the reaction that represents the combustion of C6H12O2. 38

39 C6H12O2(l) + 9 O2(g) 6 CO2(g) + 6 H2O(g) Mg(s) + C6H12O2(l) MgC6H12O2(aq) 6 C(s) + 6 H2(g) + O2(g) C6H12O2(l) C6H12O2(l) 6 C(s) + 6 H2(g) + O2(g) None of the above represent the combustion of C6H12O2. A 65) Determine the number of grams H2 formed when ml of M HCl solution reacts with 3.41 x 1023 atoms of Fe according to the following reaction. 2 HCl(aq) + Fe(s) H2(g) + FeCl2(aq) g 1.33 g 1.14 g g 1.51 g D 66) According to the following reaction, what amount of Al2O3 remains when g of Al2O3 and 2.00 g of H2O are reacted? A few of the molar masses are as follows: Al2S3 = g/mol, H2O = g/mol. Al2S3(s) + 6 H2O(l) 2 Al(OH)3(s) + 3 H2S(g) 39

40 28.33 g g 8.33 g g g E 67) Describe the difference between complete ionic and net ionic equations. A complete ionic equation shows all of the substances present in the reaction mixture. A net ionic equation only shows the substances that are participating in the reaction. The spectator ions are absent in the net ionic equation. 68) Explain the difference between a strong and weak electrolyte. Give an example of each. A strong electrolyte is either an ionic compound that is soluble in water or a molecular compound that ionizes completely in water. Possible examples are NaCl or HCl. A weak electrolyte is only slightly soluble or does not ionize to any great extent in water. Possible examples are AgCl or HC2H3O2. 40

41 69) What causes a precipitation reaction to occur between two soluble compounds? A precipitate, or insoluble compound, forms from a pair of the ions present. This "traps" some of the ions into a newly formed compound causing reaction. 70) How can you tell if a reaction is an oxidation-reduction reaction? At least one species is losing electrons while at least one other species is gaining electrons. This can be evaluated by assigning oxidation numbers to each element present and looking to see if these change from reactant to product. 71) How would the concentration change if a1.0 L flask of 1.0 M NaCl were left uncapped on a laboratory bench for several days. Why? The concentration would slowly increase as water from the solution evaporated. This is because the amount of NaCl in the flask would remain constant while the amount of water decreases. Match the following. 72) CH4(g) + 2 O2(g) CO2(g) + 2 H2O(g) Precipitation Acid Base 73) H2SO4(aq) + 2 LiOH(aq) 2 H2O(l) + Li2SO4(aq) Combustion 74) Mg(s) + Cu(NO3)2(aq) Mg(NO3)2(aq) + Cu(s) Gas Evolution Oxidation Reduction 75) HCl(aq) + (NH4)2S(aq) H2S(g) + 2NH4Cl(aq) 41

42 76) NaCl(aq) + AgNO3(aq) AgCl(s) + NaNO3(aq) 72) C 73) B 74) E 75) D 76) A 42