Solubility Guidelines

Usually Soluble Compounds

• Acetates: Generally soluble except AgCH₃COO (moderately soluble)
• Ammonium salts: NH₄⁺ compounds are soluble
• Chlorates & Perchlorates: ClO₃⁻ and ClO₄⁻ compounds are soluble
• Group 1 Cations: Na⁺, K⁺, Rb⁺, Cs⁺ salts are soluble
• Halides:
  • Cl⁻, Br⁻, I⁻ are generally soluble
  • Exceptions: AgX, Hg₂X₂, PbX₂ are insoluble
  • F⁻: MgF₂, CaF₂, SrF₂, BaF₂, PbF₂ are insoluble
• Nitrates & Nitrites: NO₃⁻ and NO₂⁻ compounds are soluble
• Sulfates: SO₄²⁻ compounds usually soluble
  • Exceptions: BaSO₄, PbSO₄, HgSO₄ (insoluble)
  • Moderately soluble: CaSO₄, SrSO₄, Ag₂SO₄

Usually Insoluble Compounds

• Carbonates (CO₃²⁻): Generally insoluble
  • Exceptions: (NH₄)₂CO₃, Na₂CO₃, K₂CO₃
• Hydroxides (OH⁻): Generally insoluble
  • Soluble: LiOH, NaOH, KOH, Ba(OH)₂
  • Moderately soluble: Ca(OH)₂, Sr(OH)₂
• Phosphates (PO₄³⁻): Generally insoluble
  • Soluble: (NH₄)₃PO₄, Na₃PO₄, K₃PO₄
• Sulfides (S²⁻): Generally insoluble
  • Soluble: (NH₄)₂S, Na₂S, K₂S, MgS, CaS