. In each of the following reactions, identify which element is oxidized and which is reduced by assigning oxidation states.
a.
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Chapter 18 Solutions
Introductory Chemistry: A Foundation
- 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_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_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_forward
- Complete and balance the following oxidation-reduction reactions, which give the highest possible oxidation state for the oxidized atoms. (a) Al(s)+F2(g) (b) Al(s)+CuBr2(aq) (single displacement) (c) P4(s)+O2(g) (d) Ca(s)+H2O(l) (products are a strong base and a diatomic gas)arrow_forwardThe 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_forwardThe Ostwald process for the commercial production of nitric acid involves the Following three steps: 4NH3(g)+5O2(g)4NO(g)+6H2O(s)2NO(g)+O2(g)2NO2(g)3NO2(g)+H2O(l)2HNO3(aq)+NO(g) a. Which reaction in the Ostwald process are oxidation-reduction reactions? b. Identify each oxidizing agent and reducing agent.arrow_forward
- Which 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_forward4.112 A metallurgical firm wishes to dispose of 1300 gallons of waste sulfuric acid whose molarity is 1.37 M. Before disposal, it will be reacted with calcium hydroxide (slaked lime), which costs $0.23 per pound. (a) Write the balanced chemical equation for this process. (b) Determine the cost that the firm will incur from this use of slaked lime.arrow_forwardDetermine the oxidation states of the elements in the following compounds: (a) Nal (b) GdCl3 (c) LiNO3 (d) H2Se (e) Mg2Si (f) RbO2, rubidium superoxide (g) HFarrow_forward
- One of the few industrial-scale processes that produce organic compounds electrochemically is used by the Monsanto Company to produce1,4-dicyanobutane. The reduction reaction is 2CH2CHCH+2H++2eNC(CH2)4CN The NC(CH2)4CN is then chemically reduced using hydrogen gas to H2N(CH2)6NH2, which is used in the production of nylon. What current must be used to produce 150.kg NC(CH2)4CN per hour?arrow_forwardYou have two 500.0-mL aqueous solutions. Solution A is a solution of a metal nitrate that is 8.246% nitrogen by mass. The ionic compound in solution B consists of potassium, chromium, and oxygen; chromium has an oxidation state of + 6 and there are 2 potassiums and 1 chromium in the formula. The masses of the solutes in each of the solutions are the same. When the solutions are added together, a blood-red precipitate forms. After the reaction bas gone to completion, you dry the solid and find that it has a mass of 331.8 g. a. Identify the ionic compounds in solution A and solution B. b. Identify the blood-red precipitate. c. Calculate the concentration (molarity) of all ions in the original solutions. d. Calculate the concentration (molarity) of all ions in the final solution.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_forward
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