Calcium forms Ca2+ ions and the hydroxide ion is OH-. What is the correct formula of calcium hydroxide?
Question 1 Report
Calcium forms Ca2+ ions and the hydroxide ion is OH-. What is the correct formula of calcium hydroxide?
Answer Details
Calcium hydroxide must be neutral overall. Calcium forms Ca2+ with a 2+ charge, while each hydroxide ion OH- carries only 1-, so two hydroxide ions are needed to cancel one calcium ion. Because hydroxide is a group of two atoms, it is enclosed in a bracket before the subscript is added: Ca(OH)2.
CaOH leaves an overall charge of 1+ and Ca(OH)3 leaves 1-, so neither is a neutral compound. Ca2OH suggests two calcium ions to one hydroxide, which is even further out of balance.
Bracket any polyatomic ion you need more than one of, otherwise the subscript wrongly changes the ion itself.
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