How many of the following compounds are insoluble in water? NaC2H3O2 , SrSO4, SrS, AlPO4
The Correct Answer and Explanation is:
To determine how many of the following compounds are insoluble in water, evaluate each compound using standard solubility rules.
Given compounds:
- NaC₂H₃O₂ (Sodium acetate)
- SrSO₄ (Strontium sulfate)
- SrS (Strontium sulfide)
- AlPO₄ (Aluminum phosphate)
1. NaC₂H₃O₂ (Sodium acetate)
Solubility: Soluble
Explanation: All salts containing alkali metals (like sodium) and acetates (C₂H₃O₂⁻) are soluble in water. Sodium acetate dissolves readily.
2. SrSO₄ (Strontium sulfate)
Solubility: Insoluble (slightly)
Explanation: Most sulfates are soluble, but exceptions include sulfates of Ba²⁺, Pb²⁺, Hg₂²⁺, and Sr²⁺. Strontium sulfate is only sparingly soluble, often considered insoluble in qualitative terms.
3. SrS (Strontium sulfide)
Solubility: Soluble
Explanation: Sulfides of group 2 elements like Sr²⁺ are generally soluble in water due to their ability to produce basic solutions by forming hydroxides (Sr²⁺ + S²⁻ → Sr(OH)₂). While some sulfides are insoluble, SrS is considered soluble in water.
4. AlPO₄ (Aluminum phosphate)
Solubility: Insoluble
Explanation: Most phosphates are insoluble in water, especially those not involving alkali metals or ammonium. Aluminum phosphate falls into this category and does not dissolve readily in water.
Final Tally:
- Insoluble Compounds: SrSO₄, AlPO₄
- Soluble Compounds: NaC₂H₃O₂, SrS
Correct Answer: 2 compounds are insoluble in water
These are SrSO₄ and AlPO₄. Their low solubility arises from the poor ability of water to overcome the strong ionic bonds present in these specific salts.
