What is the correct chemical formula for strontium hydroxide? Select one: Sr(OH)2
The correct answer and explanation is:
The correct chemical formula for strontium hydroxide is Sr(OH)₂.
Explanation:
Strontium hydroxide is an ionic compound made up of strontium ions and hydroxide ions. To understand why the formula is Sr(OH)₂, let’s break down the components:
- Strontium (Sr) is an alkaline earth metal found in Group 2 of the periodic table. Elements in this group typically form ions with a +2 charge because they lose two electrons to achieve a stable electron configuration. Therefore, the strontium ion is Sr²⁺.
- Hydroxide (OH⁻) is a polyatomic ion consisting of one oxygen and one hydrogen atom, carrying a -1 charge.
To form a neutral compound, the total positive charge must balance the total negative charge. Since strontium has a +2 charge (Sr²⁺) and hydroxide has a -1 charge (OH⁻), two hydroxide ions are needed to balance one strontium ion:
- 1 × Sr²⁺ = +2 charge
- 2 × OH⁻ = 2 × (-1) = -2 charge
Adding these charges together:
+2 + (-2) = 0 (neutral compound)
Hence, the formula is Sr(OH)₂, indicating one strontium ion combined with two hydroxide ions.
Additional notes:
- The parentheses around (OH) indicate that the hydroxide ion acts as a single polyatomic group. The subscript ₂ applies to the entire hydroxide ion, not just to hydrogen or oxygen separately.
- Strontium hydroxide is commonly used in chemical synthesis and industrial applications, such as in water treatment and as a precursor to other strontium compounds.
- The compound is typically found as a hydrate in nature, often as Sr(OH)₂·8H₂O, but the basic formula remains Sr(OH)₂.
In summary, the correct chemical formula for strontium hydroxide is Sr(OH)₂, reflecting the ionic charges and the need for charge neutrality in the compound.