lesson
Ions move towards opposite electrodes
1 · Learn
Electrolysis uses an electrical supply to drive chemical change in a suitable ionic liquid. In a molten binary ionic compound, positive ions move to the negative electrode and gain electrons; negative ions move to the positive electrode and lose electrons.
Aqueous solutions can have competing products involving water, so the simple molten rule is not enough for every solution. Practical electrolysis needs specialist safety controls.
2 · Worked example
In a conceptual molten sodium chloride example, sodium ions gain electrons and chloride ions lose electrons. This is not an instruction to melt or electrolyse salt.
3 · Your turn
At which electrode do positive ions gain electrons in this model?
Check your answer
The negative electrode, the cathode.
4 · Apply your learning
Track charge and particle changes on a supplied diagram and distinguish ion movement from electron movement in wires.
Adult guidance and safety
Use supplied data and approved diagrams. Laboratory work requires qualified supervision, suitable equipment and a risk assessment. No independent chemical, electrical, heating, radiation or biological-culture experiments. Human biology is general education, not personal diagnosis or treatment.
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Check a calculation · Year 5 onward
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Powers, roots and trigonometry · Year 7 onward
Use only when the task allows a calculator. Choose one operation at a time and record your working. Trigonometry here always uses degrees (DEG), not radians. Inverse sine, cosine and tangent return an angle, not a reciprocal. Keep exact fractions and π in answers when requested.
Approximate numerical results use up to 12 significant digits. Inverse sine returns −90° to 90°, inverse cosine 0° to 180°, and inverse tangent −90° to 90°; these are principal values, not every possible solution of a trigonometric equation.
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