11.4. The reactions of chlorine
A subsection of Chemistry, 9701, through 11. Group 17
Listing 10 of 290 questions
Chlorine is manufactured by the electrolysis of brine, NaCl. At the cathode, H2and OH–are produced, but the product at the anode depends on the in the solution. Either O2or Cl2is produced. The equation for the cathode reaction is 2H2O+ 2e– H2+ 2OH–. Starting from neutral NaCl, write equations for the production at the anode of O2, Cl2. For electrolysis to occur, the voltage applied to the cell must be at least as large as the E o–– cell, as calculated from standard electrode potentials. Use the Data Booklet to calculate E o–– cell for the production at the anode of O2, Cl2. By using one of the phrases more positive, less positive or no change, use the equations you wrote in to deduce the effect of increasing [Cl –] on • the Eanode for the production of O2, • the Eanode for the production of Cl2. Hence explain why the Cl2: O2ratio increases as increases. Sodium chlorate(is prepared commercially by electrolysing NaClin a cell which allows the cathode and anode electrolytes to mix. The cathode reaction is the same as that described in . The equation for the anode reaction is Cl –+ 6OH–– 6e– ClO3 –+ 3H2OConstruct an ionic equation for the overall reaction. Calculate the mass of NaClO3 that is produced when a current of 250 A is passed through the cell for 60 minutes. mass of NaCl O3 = g
9701_w10_qp_43
THEORY
2010
Paper 4, Variant 3
View
Write down what you would see, and write equations for the reactions that occur, when magnesium chloride, aluminium chloride and silicon tetrachloride are separately mixed with water. magnesium chloride aluminium chloride silicon tetrachloride Sodium chloride is traditionally added to a particular meat product. In response to the evidence that sodium chloride can lead to high blood pressure, the manufacturers have replaced the sodium chloride with a mixture of sodium and potassium chlorides. 100 g of the meat product usually contains about 2 g of the chloride mixture. A particular meat product contains 1.10 g of sodium chloride and 0.90 g potassium chloride in 100 g. Calculate the number of moles of chloride ions in 100 g of this meat product. The amount of chloride in the meat product can be found by titration with silver nitrate solution. Write the ionic equation, including state symbols, for the reaction between aqueous sodium chloride and aqueous silver nitrate. The chlorides from 100 g meat product are extracted into water and the solution made up to 1000 cm3 in a volumetric fl ask. A 10.0 cm3 portion of this solution is then titrated with 0.0200 mol dm–3 silver nitrate solution to precipitate the chloride. Calculate the volume of 0.0200 mol dm–3 silver nitrate solution that would be required if this titration were carried out on 100 g of the particular meat product described above. The iodination of benzene requires the presence of nitric acid. Using bond enthalpies from the Data Booklet, calculate the enthalpy change for the following reaction. + I2 + HI I → Nitric acid reacts with hydrogen iodide according to the following unbalanced equation. HI + HNO3 → I2 + N2O3 + H2O Balance this equation, and describe how the oxidation numbers of nitrogen and iodine have changed during the reaction. nitrogen iodine
9701_w12_qp_43
THEORY
2012
Paper 4, Variant 3
View
Questions Discovered
290