According to general solubility rules, which statement best describes the solubility of Na3PO4 in water at 40°C?

• A. Na3PO4 is moderately soluble in water at 40°C.
• B. Na3PO4 is only slightly soluble in water at 40°C.
• C. Na3PO4 is highly soluble in water at 40°C.
• D. Na3PO4 is insoluble in water at 40°C.

Answer: (B)

Verified step by step guidance

1. Recall the general solubility rules for ionic compounds in water, which state that most sodium (Na⁺) salts are soluble regardless of the anion.
2. Identify the compound Na₃PO₄ as sodium phosphate, which contains sodium ions (Na⁺) and phosphate ions (PO₄³⁻).
3. According to the solubility rules, all sodium salts are highly soluble in water at typical temperatures, including 40°C.
4. Understand that phosphate salts of other cations may be less soluble, but sodium phosphate remains highly soluble due to the presence of sodium ions.
5. Conclude that Na₃PO₄ is highly soluble in water at 40°C based on these general solubility principles.