Which ions are present in SrSO4?
The correct answer and explanation is:
Correct Answer: The ions present in SrSO₄ are Sr²⁺ (strontium ion) and SO₄²⁻ (sulfate ion).
Explanation:
Strontium sulfate (SrSO₄) is an ionic compound formed by the combination of a metal cation and a polyatomic anion. Strontium (Sr) is an alkaline earth metal found in Group 2 of the periodic table. Elements in this group typically lose two electrons to form Sr²⁺ ions, which are positively charged with a +2 oxidation state.
The sulfate ion (SO₄²⁻) is a polyatomic anion composed of one sulfur atom bonded to four oxygen atoms. The overall charge of the sulfate ion is -2. This charge arises because sulfur forms double bonds with two oxygen atoms and single bonds with the other two oxygen atoms, which each carry a negative charge. The total negative charge is therefore -2, giving the sulfate ion the formula SO₄²⁻.
To form a neutral compound, the total positive and negative charges must balance. Since strontium has a +2 charge and sulfate has a -2 charge, they combine in a 1:1 ratio to form SrSO₄ with no overall charge. The formula does not require any subscripts or parentheses because one Sr²⁺ ion balances one SO₄²⁻ ion perfectly.
In solid form, SrSO₄ exists as a crystalline lattice, where Sr²⁺ and SO₄²⁻ ions are held together by strong electrostatic forces called ionic bonds. These interactions give the compound high melting and boiling points and make it generally insoluble in water.
When attempting to dissolve in water, SrSO₄ does not fully dissociate due to its low solubility, meaning only a small amount breaks into Sr²⁺ and SO₄²⁻ ions in solution. This insolubility is typical for many sulfate salts of Group 2 metals, especially barium, lead, and strontium.