Q&A Hero

Q: A 50.00-mL sample of a weak acid is titrated with 0.0955M NaOH. At the endpoint, it is found that 32.56mL of titrant was used. What was the concentration of the weak acid?A) 0.0622 MB) 3.11 MC) 0.0955 MD) 5.87 x10-5ME) 0.147 M

Q: In a volumetric analysis experiment, an acidic aqueous solution of methanol (CH3OH) is titrated with a solution of potassium dichromate (K2Cr2O7) according to the following balanced chemical equation:2K2Cr2O7(aq) + 8H2SO4(aq) + 3CH3OH(aq) →2Cr2(SO4)3(aq) + 11H2O(l) + 3HCOOH(aq) + 2K2SO4(aq)What volume of 0.00389M K2Cr2O7is required to titrate 1.77g of CH3OH dissolved in 20.0mL of solution?A) 21.3 mLB) 683 mLC) 9.47 mLD) 20.0 mLE) 303 mL

Q: In a volumetric analysis experiment, a solution of sodium oxalate (Na2C2O4) in acidic solution is titrated with a solution of potassium permanganate (KMnO4) according to the following balanced chemical equation:2KMnO4(aq) + 8H2SO4(aq) + 5Na2C2O4(aq) →2MnSO4(aq) + 8H2O(l) + 10CO2(g) + 5Na2SO4(aq) + K2SO4(aq)What volume of 0.0388M KMnO4is required to titrate 0.134g of Na2C2O4dissolved in 20.0mL of solution?A) 1.38 mLB) 3.45 mLC) 10.3 mLD) 25.8 mLE) 20.0 mL

Q: The reaction of H2SO4with NaOH is represented by the equationH2SO4(aq)+2NaOH(aq)→Na2SO4(aq)+2H2O(l)What volume of 0.587MH2SO4is required to neutralize 12.7mL of 0.302M NaOH?A) 3.27 mLB) 1.70 mLC) 6.53 mLD) 12.7 mLE) 24.7 mL

Q: The reaction of HCl with NaOH is represented by the equationHCl(aq)+NaOH(aq)→NaCl(aq)+H2O(l)What volume of 0.631MHCl is required to titrate 15.8mL of 0.321M NaOH?A) 3.20 mLB) 1.58 mLC) 8.04 mLD) 15.8 mLE) 31.1 mL

Q: What minimum mass of copper (II) nitrate must be added to 30.0mL of a 0.0387Mphosphate solution in order to completely precipitate all of the phosphate as solid copper (II) phosphate?2PO43-(aq)+3Cu(NO3)2(aq)→Cu3(PO4)2(s) + 6NO3-(aq)A) 0.218 gB) 0.653 gC) 0.145 gD) 0.0726 gE) 0.327 g

Q: The concentration of Pb2+in a sample of wastewater is to be determined by using gravimetric analysis. To a 100.0-mL sample of the wastewater is added an excess of sodium carbonate, forming the insoluble lead (II) carbonate (267.2092g/mol) according to the balanced equation given below. The solid lead (II) carbonate is dried, and its mass is measured to be 0.4078g. What was the concentration of Pb2+in the original wastewater sample?Pb2+(aq)+Na2CO3(aq)→PbCO3(s)+2Na+(aq)A) 0.01526 MB) 0.001526 MC) 1.090 MD) 0.004078 ME) 65.52 M

Q: The concentration of sulfate in a sample of wastewater is to be determined by using gravimetric analysis. To a 100.0-mL sample of the wastewater is added an excess of calcium nitrate, forming the insoluble calcium sulfate (136.1g/mol) according to the balanced equation given below. The solid calcium sulfate is dried, and its mass is measured to be 0.7272g. What was the concentration of sulfate in the original wastewater sample?SO42-(aq)+Ca(NO3)2(aq)→CaSO4(s)+2NO3-(aq)A) 0.05343 MB) 0.9897 MC) 18.72 MD) 1.872 ME) 9.897 M

Q: In order to determine the amount of chloride ion in a solution by using gravimetric analysis, which of the following should you add to the solution? A) NaNO3(aq) B) Al(NO3)3(aq) C) NaCl(aq) D) AgNO3(aq) E) Mg(NO3)2(aq)

Q: A dilute solution is prepared by transferring 45.00 mL of a 0.5616 M stock solution to a 400.0 mL volumetric flask and diluting to mark. What is the molarity of this dilute solution?A) 0.06318 MB) 0.1264 MC) 0.04992 MD) 0.01580 ME) 0.2808 M

Q: What volume of 2.52M HCl is required to prepare 176.5mL of 0.449M HCl?A) 9.91 x102mLB) 1.56 x102mLC) 31.4 mLD) 0.0318 mLE) 2.00 x102mL

Q: In order to dilute 35.5mL of 0.533M HCl to 0.100 M, the volume of water that must be added isA) 28.8 mL.B) 6.66 mL.C) 1.89 x102mL.D) 1.50 x10-3mL.E) 1.54 x102mL.

Q: What is the final concentration of HCl in a solution prepared by addition of 930.0mL of 8.77M HCl to 468.0mL of 3.22M HCl? Assume volumes are additive.A) 6.00 MB) 0.00858 MC) 12.0 MD) 6.91 ME) 5.08 M

Q: To dilute 1.00 L of a 0.600 Mcto 0.100 M, the final volume must beA) 60 L.B) 0.7 L.C) 1/6 the original volume.D) More information is needed to answer this question.E) 6 times the original volume.

Q: What volume of 0.76M sodium bromide, NaBr, contains 8.8x10-4mol of bromide ions?A) 0.58 mLB) 0.67 LC) 1.2 mLD) 0.86 LE) 0.67 mL

Q: Calculate the molarity of a solution that contains 32.5g of NaOH (40.0 g/mol) in 469mL of solution.A) 0.381 MB) 2.77 x103MC) 0.577 MD) 3.81 x105ME) 1.73 M

Q: What mass of H3PO4(98.0 g/mol) is present in 36.2L of a 0.0827M solution of H3PO4?A) 0.0305 gB) 0.00341 gC) 2.93 x102gD) 4.29 x104gE) 4.47 g

Q: How many moles of KOH are present in 25.4mL of 0.965M KOH?A) molB) 26.3 molC) molD) 24.5 molE) 0.965 mol

Q: Which substance would produce 2 mol of particles per mole of solute when dissolved in water? A) NH4CH3COO B) CH2O C) CO2 D) SO2 E) Al(NO3)3

Q: Which of the following solutions contains the largest number of moles of dissolved particles? A) 25. mL of 5.0 Msodium chloride B) 25. mL of 2.0 Msulfuric acid C) 200. mL of 0.10 Msodium hydroxide D) 50. mL of 1.0 Mhydrochloric acid E) 100. mL of 0.5 Mnitric acid

Q: What volume of 0.745M Na2CO3(106g/mol) solution contains 50.3g of Na2CO3?A) 0.354 LB) 7.16 x103LC) 0.637 LD) 3.97 x103LE) 1.57 L

Q: How many moles of sulfate ions are there in a 0.545-L solution of 0.489M Al2(SO4)3?A) 0.267 molB) 0.800 molC) 3.34 molD) 0.0888 molE) 2.69 mol

Q: How many grams of lithium nitrate, LiNO3(68.9 g/mol), are required to prepare 342.6mL of a 0.783M LiNO3solution?A) 0.00389 gB) 18.5 gC) 0.0541 gD) 30.1 gE) 0.00635 g

Q: What mass of oxalic acid dihydrate, H2C2O42H2O, is required to prepare 250.0mL of a 1.32M solution of oxalic acid?A) 126 gB) 41.6 gC) 119 gD) 166 gE) 29.7 g

Q: What is the molarity of hydrochloric acid in a solution containing 88.5g of HCl in 215mL of solution? A) 0.412 M B) 0.00243 M C) 2.43 M D) 412 M E) 11.3 M

Q: A 29.0-g sample of NaOH is dissolved in water, and the solution is diluted to give a final volume of 1.60L. The molarity of the final solution is A) 18.1 M. B) 0.453 M. C) 0.725 M. D) 0.0552 M. E) 0.862 M.

Q: In order to prepare a standard 1.00M solution of oxalic acid from H2C2O42H2O (126.07g/mol), 7.564g of oxalic acid dihydrate should be dissolved inA) enough water to make 60.0 g of solution.B) 52.436 g of water.C) 60.0 g of water.D) enough water to make 60.0 mL of solution.E) 60.0 cm3of water.

Q: What is the molarity of an NaI solution that contains 7.3g of NaI in 28.0mL of solution? A) 1.7 M B) 0.049 M C) 0.0038 M D) 0.00019 M E) 0.26 M

Q: What mass of Na2CO3is present in 0.650L of a 0.505M Na2CO3solution?A) 34.8 gB) 68.9 gC) 53.5 gD) 136 gE) 82.3 g

Q: A student must prepare 5.00L of 0.100 M Na2CO3(106 g/mol). Which is the best procedure for preparing this solution?A) Measure 53.0 g Na2CO3and add 5.00 kg of H2O.B) Measure 10.6 g Na2CO3and add 5.00 kg of H2O.C) Measure 53.0 g Na2CO3and add H2O until the final homogeneous solution has a volume of 5.00 L.D) Measure 10.6 g Na2CO3and add H2O until the final homogeneous solution has a volume of 5.00 L.E) Measure 53.0 g Na2CO3and add 5.00 L of H2O.

Q: Each of the following containers illustrates a solution in which the black spheres represent solute. Which is the most concentrated solution? A) A B) All have the same concentration. C) B D) C E) D

Q: Which of the following do you need to know to be able to calculate the molarity of a salt solution? I. the mass of salt added II. the molar mass of the salt III. the volume of water added IV. the total volume of the solution A) II and III only B) I, II, and IV only C) I, II, and III only D) I and III only E) You need all of the information.

Q: The following change occurs in acidic solution:____ S2-(aq) + ____ Cr2O72-(aq) →____ S(s) + ____ Cr3+(aq)In the balanced equation, for every mole of Cr2O72- that reacts, _____ mol of H+are consumed.A) 7B) 10C) 5D) 14E) 8

Q: In basic solution, H2O2oxidizes Cr3+to CrO42-and is reduced to OH-. What is the lowest whole-number coefficient for OH-in the balanced net ionic equation?A) 6B) 10C) 4D) 16E) 8

Q: The following reaction occurs in basic solution. What is the sum of the lowest whole-number coefficients in the balanced equation?____ MnO4-(aq) + ____ NH3(aq) →____ NO3-(aq) + ____ MnO2(s)A) 9B) 18C) 12D) 29E) 23

Q: When the following equation is balanced, what is the lowest whole-number coefficient for SO2?____HBrO3(aq) + ____ SO2(g) + ____ H2O(l) →____ Br2(aq) + ____ H2SO4(aq)A) 7B) 10C) 8D) 4E) 5

Q: The following reaction occurs in basic solution:_ H2O(aq) + _ MnO4-(aq) + _ ClO-(aq) →_ MnO2(s) + _ ClO4-(aq) + _ OH-(aq)When the equation is properly balanced, what is the sum of the lowest whole-number coefficients?A) 20B) 9C) 10D) 6E) 12

Q: What is the balanced reduction half-reaction for the reaction3Mg(s) + N2(g) →Mg3N2(s)A) Mg2++ 2e-→MgB) Mg →Mg2++ 2e-C) Mg2+→Mg + 2e-D) N2+ 6e-→2N3-E) N2→2N3-+ 6e-

Q: All of the following half-reactions are balanced exceptA) NO3-(aq) + 4H+(aq) + 3e-→NO(g) + 2H2O(l).B) H3PO3(aq) + H2O(l) →H3PO4(aq) + 2H+(aq) + 2e-.C) 2Ta(s) + 5H2O(l) →Ta2O5(s) + 10H+(aq) + 10e-.D) 2H2O(l) + 2e-→H2(g) + 2OH-(aq).E) H2O2(aq) →2OH-(aq) + 2e-.

Q: What is the balanced oxidation half-reaction provided below?Zn(s) + 2H+(aq) →Zn2+(aq) + H2(g)A) Zn2+(aq) + 2e-→Zn(s)B) Zn2+(aq) + e-→Zn(s)C) Zn(s) →Zn2+(aq) + 2e-D) 2H+(aq) + 2e-→H2(g)E) 2H+(aq) →H2(g) + 2e-

Q: A 5.0-g sample of a white, powdery solid is heated in the presence of air. The solid remaining after heating now has a mass of 3.2 g. The reaction that took place must have been a(an) A) acid"base reaction. B) decomposition reaction. C) combination reaction. D) precipitation reaction. E) displacement reaction.

Q: All of the following reactions are described as decomposition reactions exceptA) PCl5(g) →PCl3(g) + Cl2(g).B) 2H2O(g) →2H2(g) + O2(g).C) BaCl2 + 2H2O(s) →BaCl2(s) + 2H2O(g).D) CH4(g) + Cl2(g) →CH3Cl(g) + HCl(g).E) CaCO3(s) →CaO(s) + CO2(g).

Q: All of the following reactions can be described as displacement reactions exceptA) CuSO4(aq) + Ni(s) →NiSO4(aq) + Cu(s).B) 3CuCl2(aq) + 2Al(s) →3Cu(s) + 2AlCl3(aq).C) Fe(s) + 2HCl(aq) →FeCl2(g) + H2(g).D) CH4(g) + Br2(g) →CH3Br(g) + HBr(g).E) Mg(s) + Hg(NO3)2(aq) →Mg(NO3)2(aq) + Hg(l).

Q: All of the following reactions are described as decomposition reactions exceptA) PCl5(l) →PCl3(g) + Cl2(g).B) 2CH3OH(l) + 3O2(g) →2CO2(g) + 4H2O(g).C) NH4HS(s) →NH3(g) + H2S(g).D) (NH4)2Cr2O7(s) →N2(g) + 4H2O(g) + Cr2O3(s).E) 2CO2(g) →2CO(g) + O2(g).

Q: All of the following reactions are called combination reactions exceptA) BaO(s) + SO2(g) →BaSO3(s).B) C6H10(l) + Br2(l) →C6H10Br2(l).C) Br2(l) + H2O(l) →HOBr(aq) + HBr(aq).D) CaCl2(s) + 6H2O(l) →CaCl2- 6H2O(s).E) 3H2(g) + N2(g) →2NH3(g).

Q: All of the following reactions can be described as displacement reactions exceptA) Zn(s) + FeCl2(aq) →ZnCl2(aq) + Fe(s).B) C6H6(l) + Cl2(g) →C6H5Cl(l) + HCl(g).C) 2Na(s) + 2H2O(l) →2NaOH(aq) + H2(g).D) Cu(s) + 2AgNO3(aq)→Cu(NO3)2(aq) + 2Ag(s).E) CuSO4(aq) + Fe(s) →Cu(s) + FeSO4(aq).

Q: All of the following reactions are described as decomposition reactions exceptA) CuSO4- 5H2O(s) CuSO4(s) + 5H2O(g).B) 2PbO2(s) 2PbO(s) + O2(g).C) Fe(CO)5(l) Fe(s) + 5CO(g).D) H2SO3(aq) SO2(g) + H2O(l).E) NO2(g) + H2O(l) NO(g) + 2HNO3(aq).

Q: Which of the following species would be expected to function as a reducing agent?A) Ba2+B) Zn2+C) ClO4-D) Cs+E) V2+

Q: In the following reaction,2H2O2(l) →2H2O(l) + O2(g)hydrogen peroxide functions asA) an acid.B) a reducing agent.C) an oxidizing agent.D) both an oxidizing agent and a reducing agent.E) neither an oxidizing agent nor a reducing agent.

Q: Besides its ability to function as an acid, hydrosulfuric acid, H2S, is able to act as a reducing agent. Which one of the following equations illustrates this property of H2S?A) H2S(aq) + 2OH-(aq) →S2-(aq) + 2H2O(l)B) H2S(aq) + 2Na(s) →H2(g) + 2Na+(aq) + S2-(aq)C) H2S(aq) + 2AgI(s) →Ag2S(s) + 2H+(aq) + 2I-(aq)D) H2S(aq) + Cu2+(aq) →CuS(s) + 2H+(aq)E) 3H2S(aq) + 2H+(aq) + 2NO3-(aq) →3S(s) + 2NO(g) + 4H2O(l)

Q: In the following oxidation"reduction reaction,8H+(aq) + 6Cl-(aq) + Sn(s) + 4NO3-(aq)→SnCl62-(aq) + 4NO2(g) + 4H2O(l)what is the oxidizing agent?A) SnB) NO3-C) H+D) Cl-E) SnCl62-

Q: In the balanced equation3Na+(aq) + 3OH-(aq) + P4(s) + 3H2O(l) →3Na+(aq) + 3H2PO2-(aq) + PH3(g)what is the reducing agent?A) OH-B) Na+C) H2OD) P4E) PH3

Q: For the reaction that occurs in a lead storage battery,Pb(s) + PbO2(s) + 2H+(aq) + 2HSO4"(aq) →2PbSO4(s) + 2H2O(l)the oxidizing agent isA) HSO4-.B) PbSO4.C) Pb.D) PbO2.E) H+.

Q: In the following reaction, which species is oxidized?3Na2S(s)+8H+(aq)+2NO3-(aq)→6Na+(aq)+3S(s)+2NO(g)+4H2O(l)A) NO3-B) Na2SC) Na+D) NOE) H+

Q: Consider the reaction of sulfur dioxide and water, which is represented by the following equation:2SO2(g) + 2H2O(g) →2H2S(g) + 3O2(g)How many moles of electrons are transferred according to the equation that is written?A) 2B) 6C) 4D) 12E) 8

Q: What is the balanced oxidation half-reaction for the following reaction?Cu2+(aq) + Fe(s) →Cu(s) + Fe2+(aq)A) Cu(s) + 2e-→Cu(s)B) Cu2+(aq) + 2e-→Cu(s)C) Fe2+(aq) + 2e-→Fe(s)D) Cu(s) →Cu2+(aq) + 2e-E) Fe(s) →Fe2+(aq) + 2e-

Q: What is the reduction half-reaction for the reaction between iron(II) sulfate and potassium permanganate in a sulfuric acid solution?5Fe2+(aq) + MnO4"(aq) + 8H+(aq) →5Fe3+(aq) + Mn2+(aq) + 4H2O(l)A) MnO4-(aq) + 3e-→Mn2+(aq) + 4H2O(l)B) MnO4-(aq) + 8H+(aq) + 5e-→Mn2+(aq) + 4H2O(l)C) 5Fe2+(aq) →5Fe3+(aq) + 5e-D) Fe2+(aq) + 2e-→Fe(s)E) MnO4-(aq) + 5e-→Mn2+(aq) + SO42-(aq)

Q: What is the reduction half-reaction for the reaction of zinc with hydrochloric acid?Zn(s) + 2H+(aq) + 2Cl-(aq) →Zn2+(aq) + 2Cl-(aq) + H2(g)A) Zn(s) →Zn2+(aq) + 2e-B) 2H+(aq) + 2e-→ H2(g)C) 2H+(aq) + 2e-(aq) →H2(g) + 2Cl-(aq)D) 2H+(aq) + 2Cl-(aq) →H2(g) + 2e-+ 2Cl-(aq)E) Zn(s) →Zn2+(aq) + 2Cl-(aq) + 2e-

Q: In basic solution the chromate ion, CrO42-, can be converted to the chromite, CrO2-, ion. The number of electrons gained or lost by the chromium atom isA) 0.B) 3 electrons lost.C) 2 electrons lost.D) 3 electrons gained.E) 2 electrons gained.

Q: Assign oxidation numbers to each atom in nitrous acid.A) H = +1, N = +5, O = -1B) H = +1, N = +5, O = -2C) H = +1, N = +3, O = -1D) H = +1, N = +3, O = 0E) H = +1, N = +3, O = -2

Q: Which of the following is a correct set of oxidation numbers for the atoms in calcium dihydrogen phosphate, Ca(H2PO4)2?A) Ca = +2, H = +1, P = +5, O = -2B) Ca = +2, H = 0, P = +7, O = -8C) Ca = +2, H = -1, P = +4, O = -2D) Ca2+= +2, H2PO4-= -1E) Ca = +2, H = +1, P = +3, O = -2

Q: In which of the following molecules or ions does the underlined element have an oxidation number of -3?A) NO2B) PH4+C) CrO2Cl2D) HNO2E) Zn(OH)42-

Q: The oxidation number of chromium in sodium chromite, NaCrO2, isA) -1.B) -2.C) +2.D) +1.E) +3.

Q: The oxidation number of barium in BaO isA) +1.B) +4.C) -1/2.D) +2.E) -2.

Q: The sum of all the oxidation numbers in cysteine, , isA) -1.B) +4.C) 0.D) -2.E) +2.

Q: The oxidation numbers of nitrogen in N2O and N2F4 are, respectively,A) -2 and +2.B) -2 and -3.C) +1 and +2.D) +1 and -1.E) +1 and -3.

Q: The oxidation number of carbon in the formate ion, HCOO-, isA) 0.B) -2.C) +2.D) -1.E) +1.

Q: What is the average oxidation number of C in C6H12O6?A) -2B) 0C) +1D) +2E) -1

Q: In which one of the following is the oxidation number of nitrogen given incorrectly?A) N2H4 (-2)B) NaN3 (-1)C) HNO2 (+3)D) N2O3 (+3)E) H2N2O2 (+1)

Q: The oxidation number of nitrogen given for all the following species is correct exceptA) N2H4 (-2).B) N2O (+1).C) NH2OH (-1).D) HNO2 (+3).E) HN3 (-1).

Q: What is the oxidation number of each H in NH4(H2PO4)? A) -3 B) -2 C) +1 D) +5 E) 0

Q: Which of the following species cannot function as an oxidizing agent?A) Co3+B) O2C) Cr2O72-D) MnO4-E) O2-

Q: What is the oxidation number of each O in BaFeO4? A) +6 B) +2 C) -2 D) +3 E) 0

Q: Which of the following species cannot function as an oxidizing agent?A) SB) Br-C) H+D) MnO4-E) Mn2+

Q: All the following species can be reduced exceptA) ClO2.B) F-.C) NO3-.D) H+.E) Fe3+.

Q: Which of the following conversions is not an oxidation"reduction reaction?A) conversion of Mn2O3to MnO2B) conversion of K to KClC) conversion of NaBr to Br2D) conversion of CaCO3to CaOE) conversion of VO2+to VO2+

Q: Which of the following reactions involves neither oxidation nor reduction?A) N2(g) + 3H2(g)→2NH3(g)B) NH4NO2(s) →N2(g) + 2H2O(l)C) Cu(s) + 2Ag+(aq) →Cu2+(aq) + 2Ag(s)D) 2CrO42-(aq) + 2H+(aq) →Cr2O72"(aq) + H2O(l)E) C2H4(g) + H2(g) →C2H6(g)

Q: Which of the following is best described as an oxidation-reduction reaction?A) SO2(g) + H2O(l) →H2SO3(aq)B) 2Cl(g) →Cl2(g)C) 3O2(g) →2O3(g)D) 2NO2(g) →N2O4(g)E) SO2(g) + O2(g) →SO3(g)

Q: Which of the following chemical reactions is an oxidation-reduction reaction?A) Mg(s) + CO2(g) → MgO(s) + CO(g)B) H2SO4(aq) + Ba(OH)2(aq) →BaSO4(s) + 2H2O(l)C) Pb(NO3)2(aq) + 2HCl(aq) →PbCl2(s) + 2HNO3(aq)D) CO2(aq) + H2O(l) →H2CO3(aq)E) NH3(g) + HCl(g) →NH4Cl(s)

Q: Which of the following reactions is an oxidation"reduction reaction?A) CaCO3(s) + 2HCl(aq) → CaCl2(aq) + H2O(l) + CO2(g)B) NH4NO3(aq) → N2O(g) + 2H2O(l)C) AgNO3(aq) + KI(aq) → AgI(s) + KNO3(aq)D) CaO(s) + SO3(g) → CaSO4(s)E) H2SO4(aq) + 2NaOH(s) → Na2SO4(aq) + 2H2O(l)