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State and explain the colour observed at the negative electrode in the electrolysis of aqueous potassium iodide, containing a little phenolphthalein indicator, using inert electrodes. - Leaving Cert Chemistry - Question i - 2004
Question i
State and explain the colour observed at the negative electrode in the electrolysis of aqueous potassium iodide, containing a little phenolphthalein indicator, using... show full transcript
Worked Solution & Example Answer:State and explain the colour observed at the negative electrode in the electrolysis of aqueous potassium iodide, containing a little phenolphthalein indicator, using inert electrodes. - Leaving Cert Chemistry - Question i - 2004
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Explain the observed colour
Answer
The purple colour indicates that hydroxyl ions ( ext{OH}^-) are being produced at the cathode. This increase in hydroxyl ions raises the pH near the electrode, creating a more alkaline environment, which is detectable due to the phenolphthalein indicator turning purple in alkaline conditions.