Question

Why are OH- ions used to identify cations?

Answer 1

Because most hydroxides are insoluble........

Explanation:

Most metal hydroxides are quite insoluble. Most schemes of qualitative inorganic analysis use `pH>10` as a preliminary means to separate the insoluble hydroxides.........Anyway, of course, subsequent tests and separations have to be performed on the ions in the filtrate, and the ions that have precipitated as their hydroxide salts.

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