Which formula represents lead(II) hydroxide? Pb(OH)2
The correct answer and explanation is:
The correct formula for lead(II) hydroxide is Pb(OH)₂.
Explanation:
Lead(II) hydroxide is an inorganic compound composed of lead, oxygen, and hydrogen atoms. To understand why its formula is Pb(OH)₂, consider the charges of the ions involved.
Lead in this compound is in the +2 oxidation state, indicated by the Roman numeral II in lead(II). This means the lead ion is Pb²⁺. The hydroxide ion is OH⁻, a polyatomic ion with a charge of -1.
Since the compound must be electrically neutral, the total positive charge must balance the total negative charge. One Pb²⁺ ion requires two OH⁻ ions to balance the charge:
+2 from Pb²⁺ and 2 × (-1) from OH⁻ ions = 0 net charge.
Therefore, the chemical formula combines one lead ion with two hydroxide ions, producing Pb(OH)₂.
This type of compound is classified as a hydroxide and is generally considered a base in chemistry. Lead(II) hydroxide is a solid under standard conditions and has limited solubility in water, often forming a precipitate when lead salts react with hydroxide ions in solution.
Understanding the formula also involves knowledge of ionic bonding. The Pb²⁺ and OH⁻ ions attract each other electrostatically, forming an ionic compound. The parentheses around the OH indicate that the hydroxide group remains intact as a unit, and the subscript 2 applies to the whole hydroxide ion, meaning there are two hydroxide groups for every one lead ion.
In summary, Pb(OH)₂ correctly represents lead(II) hydroxide because the lead ion’s +2 charge is balanced by two hydroxide ions, each with a -1 charge. This chemical formula is consistent with the rules of ionic compound formation and charge neutrality.