The amount of sodium hypochlorite in a bleach solution can be determined by using a given volume of bleach to oxidize excess iodide ion to iodine, because the reaction goes to completion. The amount of iodine produced is then determined by titration with sodium thiosulfate, Na2S2O3, which is oxidized to sodium tetrathionate, Na2S4O6. Potassium iodide was added in excess to 5.00 mL of bleach (density = 1.00 g/mL). This solution, containing the iodine released in the reaction, was titrated with 0.100 M Na2S2O3. If 34.6 mL of sodium thiosulfate was required to reach the endpoint (detected by disappearance of the blue color of the starch iodine complex), what was the mass percentage of NaClO in the bleach?
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General Chemistry - Standalone book (MindTap Course List)
- The amount of sodium hypochlorite in a bleach solution can be determined by using a given volume of bleach to oxidize excess iodide ion to iodine; ClO- is reduced to Cl-. The amount of iodine produced by the redox reaction is determined by titration with sodium thiosulfate, Na2S2O3; I2 is reduced to I-. The sodium thiosulfate is oxidized to sodium tetrathionate, Na2S4O6. In this analysis, potassium iodide was added in excess to 5.00 mL of bleach (d=1.00g/cm3) . If 25.00 mL of 0.0700 M Na2S2O3 was required to reduce all the iodine produced by the bleach back to iodide, what is the mass percent of NaClO in the bleach?arrow_forwardAluminum is produced commercially by the electrolysis of Al2O3 in the presence of a molten salt. If a plant has a continuous capacity of 1.00 million A, what mass of aluminum can be produced in 2.00 h?arrow_forwardThree reactions very important to the semiconductor industry are The reduction of silicon dioxide to crude silicon, SiO2(s) + 2 C(s) → Si(s) + 2 CO(g) ΔrH° = 689.9 kJ/mol The formation of silicon tetrachloride from crude silicon, Si(s) + 2 Cl2(g) → SiCl4(g) ΔrH° = −657.01 kJ/mol The reduction of silicon tetrachloride to pure silicon with magnesium, SiCl4(g) + 2 Mg(s) → 2 MgCl2(s) + Si(s) ΔrH° = −625.6 kJ/mol Calculate the overall enthalpy change when 1.00 mol sand, SiO2, changes into very pure silicon by this series of reactions.arrow_forward
- In an analytical determination of arsenic, a solution containing arsenious acid, H3AsO3, potassium iodide, and a small amount of starch is electrolyzed. The electrolysis produces free iodine from iodide ion, and the iodine immediately oxidizes the arsenious acid to hydrogen arsenate ion, HAsO42. I2(aq)+H3AsO3(aq)+H2O(l)2I(aq)+HAsO42(aq)+4H+(aq) When the oxidation of arsenic is complete, the free iodine combines with the starch to give a deep blue color. If, during a particular run, it takes 65.4 s for a current of 10.5 mA to give an endpoint (indicated by the blue color), how many grams of arsenic are present in the solution?arrow_forward4.48 Elemental phosphorous is used in the semiconductor industry. It can be obtained from an ore called fluoroapatite via reaction with SiO2 and C: 4Ca5( PO4)3F+18SiO2+30C3P4+30CO+18CaSiO3+2CaF2 Suppose a particular semiconductor production plant requires 1500 kg of P4. If the recovery of P4 from this reaction is 73% efficient, what mass of fluoroapatite is needed?arrow_forwardWrite balanced net ionic equations for the following reactions in acid solution. (a) Liquid hydrazine reacts with an aqueous solution of sodium bromate. Nitrogen gas and bromide ions are formed. (b) Solid phosphorus (P4) reacts with an aqueous solution of nitrate to form nitrogen oxide gas and dihydrogen phosphate (H2PO4-) ions. (c) Aqueous solutions of potassium sulfite and potassium permanganate react. Sulfate and manganese(II) ions are formed.arrow_forward
- Sodium perchlorate, NaClO4, is produced by electrolysis of sodium chlorate, NaClO3. If a current of 2.50 103 A passes through an electrolytic cell, how many kilograms of sodium perchlorate are produced per hour?arrow_forwardPhosphorus occurs naturally in the form of fluorapatite, CaF2 3Ca3(PO4)2. The dot indicates 1 part CaF2 to 3 parts Ca3(PO4)2. This mineral is reacted with an aqueous solution of H2SO4 in the preparation of a fertilizer. The products are phosphoric acid, hydrogen fluoride, and gypsum, CaSO4 2H2O. Write the balanced equation describing this process.arrow_forwardIn the commercial preparation of aluminum, aluminum oxide, Al2O3, is electrolyzed at 1000C. (The mineral cryolite is added as a solvent.) Assume that the cathode reaction is Al3+3eAl How many coulombs of electricity are required to give 3.9 kg of aluminum?arrow_forward
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