Simplify the following text for a Grade 7 native English-speaking person.
Original: If excess sodium hydroxide is added , the precipitate of zinc hydroxide will dissolve , forming a colorless solution of zincate ion : Zn ( OH ) 2 + 2OH - â ' Zn ( OH ) 42 - .
Simplified: Its chemical formula is Zn ( OH ) 2 . It contains zinc and hydroxide ions .