This chemistry question involves key chemical concepts and calculations. The detailed solution below walks through each step, from identifying the reaction type to computing the final answer.
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a) The positive ions present in aqueous sodium chloride are formed from the dissociation of sodium chloride and the autoionization of water. The positive ions are Sodium ions (Na^+), Hydrogen ions (H^+). b) Step 1: Identify the electrodes. The long line of the power supply is the positive terminal (anode), and the short line is the negative terminal (cathode). Gas C is collected at the cathode, and gas D is collected at the anode. Step 2: Determine the species discharged at the cathode (negative electrode). At the cathode, positive ions (Na^+ and H^+ from water) are attracted. Hydrogen ions are preferentially discharged over sodium ions because hydrogen is less reactive. 2H^+(aq) + 2e^- H_2(g) Therefore, gas C is hydrogen. Step 3: Determine the species discharged at the anode (positive electrode). At the anode, negative ions (Cl^- and OH^- from water) are attracted. In concentrated sodium chloride solution, chloride ions are preferentially discharged over hydroxide ions. 2Cl^-(aq) Cl_2(g) + 2e^- Therefore, gas D is chlorine. C: Hydrogen D: Chlorine c) Step 1: Identify the ions remaining in the solution. During the electrolysis, hydrogen ions (H^+) are discharged at the cathode and chloride ions (Cl^-) are discharged at the anode. This leaves sodium ions (Na^+) and hydroxide ions (OH^-) in the solution. Step 2: Explain the formation of hydroxide ions. As H^+ ions are removed from the solution at the cathode, the equilibrium of water dissociation (H_2O H^+ + OH^-) shifts to the right to replenish the H^+ ions. This leads to an increase in the concentration of OH^- ions. Step 3: Conclude why the solution is alkaline. The accumulation of OH^- ions (along with Na^+ ions, forming sodium hydroxide) makes the solution alkaline. That's 2 down. 3 left today — send the next one.