Question detail
Explain why hydrogen is produced at the cathode during the electrolysis of an aqueous solution of potassium sulfate.
Try the question, check the answer, then read the explanation to understand the curriculum point.
At a glance
Question
Type
exam_style
Style
Topic
Electrolysis
Question
Explain why hydrogen is produced at the cathode during the electrolysis of an aqueous solution of potassium sulfate.
Answer
Hydrogen is produced at the cathode during the electrolysis of an aqueous solution of potassium sulfate because potassium is more reactive than hydrogen. Therefore, instead of potassium ions being discharged, hydrogen ions from water gain electrons to form hydrogen gas.
Explanation
This question assesses the student's understanding of reactivity series and the principles governing the discharge of ions during electrolysis. It requires an explanation of why certain ions are preferentially discharged based on their reactivity.
Common mistake
Misidentifying the anode product
Students often think that oxygen is always produced at the anode in aqueous electrolysis, even when halide ions are present.
Explain that if halide ions (Cl⁻, Br⁻, I⁻) are present, the anode reaction will produce the corresponding halogen (Cl₂, Br₂, I₂) because the halide oxidation potential is lower than that of water. Use the reactivity series and ion potentials to predict the correct anode product, and remind students to test the gas with appropriate chemical tests (e.g., sodium hydroxide for chlorine, silver nitrate for bromine).
Related flashcards
Flashcard 1 of 5
Related practice questions
Question 1 of 5
Choose an answer, get feedback, then move sideways through the set.