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Copper metal can reduce silver ions to metallic silver. The copper is oxidized to copper ions according to the reaction
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Chapter 4 Solutions
Chemistry: Principles and Reactions
- Gold can be dissolved from gold-bearing rock by treating the rock with sodium cyanide in the presence of oxygen. 4 Au(s) + 8 NaCN(aq) + O2(g) + 2 H2O() 4 NaAu(CN)2(aq) + 4 NaOH(aq) (a) Name the oxidizing and reducing agents in this reaction. What has been oxidized, and what has been reduced? (b) If you have exactly one metric ton (1 metric ton = 1000 kg) of gold-bearing rock, what volume of 0.075 M NaCN, in liters, do you need to extract the gold if the rock is 0.019% gold?arrow_forwardYou wish to determine the weight percent of copper in a copper-containing alloy. After dissolving a 0.251 -g sample of the alloy in acid, an excess of KI is added, and the Cu2+ and I ions undergo the reaction 2 Cu2+(aq) + 5 I(aq) 2 CuI(s) + I3(aq) The liberated I3 is titrated with sodium thiosulfate according to the equation I3 (aq) + 2 S2O32(aq) S4O62(aq) + 3 I (aq) (a) Designate the oxidizing and reducing agents in the two reactions above. (b) If 26.32 mL of 0.101 M Na2S2O3 is required for titration to the equivalence point, what is the weight percent of Cu in the alloy?arrow_forwardTo analyze an iron-containing compound, you convert all the iron to Fe2+ in aqueous solution and then titrate the solution with standardized KMnO4. The balanced, net ionic equation is MnO4(aq) + 5 Fe2(aq) + 8 H3O+(aq) Mn2(aq) + 5 Fe3+(aq) + 12 H2O(l) A 0.598-g sample of the iron-containing compound requires 22.25 mL of 0.0123 M KMnO4 for titration to the equivalence point. What is the mass percent of iron in the sample?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_forwardSodium thiosulfate, Na2S2O3, is used as a fixer in black-and-white photography. Suppose you have a bottle of sodium thiosulfate and want to determine its purity. The thiosulfate ion can be oxidized with I2 according to the balanced, net ionic equation I2(aq) + 2 S2O32(aq) 2 I(aq) + S4O62 (aq) If you use 40.21 mL of 0.246 M I2 in a titration, what is the weight percent of Na2S2O3 in a 3.232-g sample of impure material?arrow_forwardPotassium permanganate (KMnO4) solutions are used for the determination of Fe2+ in samples of unknown concentration. As a laboratory assistant, you are supposed to prepare 500 mL of a 0.1000 M KMnO4 solution. What mass of KMnO4, in grams, do you need?arrow_forward
- Write the net ionic equation for the reaction, if any, that occurs on mixing (a) solutions of sodium hydroxide and magnesium chloride. (b) solutions of sodium nitrate and magnesium bromide. (c) magnesium metal and a solution of hydrochloric acid to produce magnesium chloride and hydrogen. Magnesium metal reacting with HCl.arrow_forwardThe mineral dolomite contains magnesium carbon-ate. This reacts with hydrochloric add. MgCO3(s) + 2 HCl(aq) CO2(g) + MgCl2(aq) + H2O() (a) Write the net ionic equation for this reaction and identify the spectator ions. (b) What type of reaction is this?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_forward
- The 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_forwardChlorine gas was first prepared in 1774 by C. W. Scheele by oxidizing sodium chloride with manganese(IV) oxide. The reaction is NaCl(aq) + H2SO4(aq) + MnO2(s) Na2SO4(aq) + MnCl2(aq) + H2O(l) + Cl2 (g) Balance this equation.arrow_forwardThe 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_forward
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