Classify each half-reaction occurring in acidic aqueous solution as an oxidation or a reduction and balance the half-reaction.
a.
b.
c.
d.
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Introductory Chemistry (6th Edition)
- The Toliens test for the presence of reducing sugars (say, in a urine sample) involves treating the sample with silver ions in aqueous ammonia. The result is the formation of a silver mirror within the reaction vessel if a reducing sugar is present. Using glucose, C6H12O6, to illustrate this test, the oxidation-reduction reaction occurring is C6H12O6 (aq) + 2 Ag+(aq) + 2OH(aq) C6H12O7(aq) + 2 Ag(s) + H2O() What has been oxidized, and what has been reduced? What is the oxidizing agent, and what is the reducing agent? Tolien's test. The reaction of silver ions with a sugar such as glucose produces metallic silver. (a) The set-up for the reaction. (b) The silvered test tubearrow_forwardThe blood alcohol (C2H5OH) level can be determined by titrating a sample of blood plasma with an acidic potassium di-chromate solution, resulting in the production of Cr3+ (aq) and carbon dioxide. The reaction can be monitored because the dichromate ion (Cr2O72) is orange in solution, and the Cr3+ ion is green. The balanced equations is 16H+(aq) + 2Cr2O72(aq) + C2H5OH(aq) 4Cr4+(aq) + 2CO2(g) + 11H2O(l) This reaction is an oxidationreduction reaction. What species is reduced, and what species is oxidized? How many electrons are transferred in the balanced equation above?arrow_forwardWhich two of the following reactions are oxidation-reduction reactions? Explain your answer briefly. Classify the remaining reaction. (a) CdC12(aq) + Na2S(aq) CdS(s) + 2 NaCl(aq) (b) 2 Ca(s) + O2(g) 2 CaO(s) (c) 4 Fe(OH)2(s) + 2 H2O() + O2(g) 4 Fe(OH)3(s)arrow_forward
- The iron content of hemoglobin is determined by destroying the hemoglobin molecule and producing small water-soluble ions and molecules. The iron in the aqueous solution is reduced to iron(II) ion and then titrated against potassium permanganate. In the titration, iron(ll) is oxidized to iron(III) and permanganate is reduced to manganese(II) ion. A 5.00-g sample of hemoglobin requires 32.3 mL of a 0.002100 M solution of potassium permanganate. The reaction with permanganate ion is MnO4(aq)+8H+(aq)+5Fe2+(aq)Mn2+(aq)+5Fe3+(aq)+4H2O What is the mass percent of iron in hemoglobin?arrow_forwardFour metals, A, B, C, and D, exhibit the following properties: (a) Only A and C react with 1.0 M hydrochloric acid to give H2(g). (b) When C is added to solutions of the ions of the other metals, metallic B, D, and A are formed. (c) Metal D reduces Bn+ to give metallic B and Dn+. Based on this information, arrange the four metals in order of increasing ability to act as reducing agents.arrow_forwardChromium has been investigated as a coating for steel cans. The thickness of the chromium film is determined by dissolving a sample of a can in acid and oxidizing the resulting Cr3+ to Cr2O72 with the peroxydisulfate ion: S2O82(aq) + Cr3+(aq) + H2O(l) Cr2O72(aq) + SO42(aq) + H+(aq) (Unbalanced) After removal of unreacted S2O82 an excess of ferrous ammonium sulfate [Fe(NH4)2(SO4)26H2O] is added, reacting with Cr2O72 produced from the first reaction. The unreacted Fe2+ from the excess ferrous ammonium sulfate is titrated with a separate K2Cr2O7 solution. The reaction is: H+(aq) + Fe2+(aq) + Cr2O72(aq) Fe3+(aq) + Cr3+(aq) + H2O(l) (Unbalanced) a. Write balanced chemical equations for the two reactions. b. In one analysis, a 40.0-cm2 sample of a chromium-plated can was treated according to this procedure. After dissolution and removal of excess S2O82, 3.000 g of Fe(NH4)2(SO4)26H2O was added. It took 8.58 mL of 0.0520 M K2Cr2O7 solution to completely react with the excess Fe2+. Calculate the thickness of the chromium film on the can. (The density of chromium is 7.19 g/cm3)arrow_forward
- Triiodide ions are generated in solution by the following (unbalanced) reaction in acidic solution: IO3(aq) + I(aq) I3(aq) Triiodide ion concentration is determined by titration with a sodium thiosulfate (Na2S2O3) solution. The products are iodide ion and tetrathionate ion (S4O6). a. Balance the equation for the reaction of IO3 with I ions. b. A sample of 0.6013 g of potassium iodate was dissolved in water. Hydrochloric acid and solid potassium iodide were then added. What is the minimum mass of solid KI and the minimum volume of 3.00 M HQ required to convert all of the IO3 ions to I ions? c. Write and balance the equation for the reaction of S2O32 with I3 in acidic solution. d. A 25.00-mL sample of a 0.0100 M solution of KIO. is reacted with an excess of KI. It requires 32.04 mL of Na2S2O3 solution to titrate the I3 ions present. What is the molarity of the Na2S2O3 solution? e. How would you prepare 500.0 mL of the KIO3 solution in part d using solid KIO3?arrow_forwardBromine is obtained from sea water by the following redox reaction: Cl2(g) + 2 NaBr(aq) 2 NaCl(aq) + Br2() (a) What has been oxidized? What has been reduced? (b) Identify the oxidizing and reducing agents.arrow_forwardBalance each of the following oxidationreduction reactions by using the oxidation states method. a.Cl2(g) + Al(s) Al3+(aq) + Cl(aq) b.O2(g) + H2O(l) + Pb(s) Pb(OH)2(s) c.H+(aq)+MnO4(aq)+Fe2+(aq)Mn2+(aq)+Fe3+(aq)+H2O(l)arrow_forward
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