Which compound is commonly used to prevent encrustation by sequestering metal ions?

Which compound is commonly used to prevent encrustation by sequestering metal ions?

• A. citric acid
• B. sodium hexametaphosphate
• C. muriatic acid
• D. sodium chloride

Answer: (B)

When you want to prevent encrustation, you use a sequestrant to keep metal ions like calcium and magnesium in solution instead of letting them form solid deposits. Sodium hexametaphosphate is a polyphosphate sequestrant that binds these ions, creating stable, soluble complexes. By keeping hardness ions dissolved, it stops crystals from forming on pipes and equipment, reducing scale buildup. That strong ion-sequestering action is why it’s commonly used for this purpose in water treatment. Other substances either don’t bind metal ions as effectively, or they serve different roles (like dissolving deposits or adjusting pH) rather than preventing encrustation through sequestration.

When you want to prevent encrustation, you use a sequestrant to keep metal ions like calcium and magnesium in solution instead of letting them form solid deposits. Sodium hexametaphosphate is a polyphosphate sequestrant that binds these ions, creating stable, soluble complexes. By keeping hardness ions dissolved, it stops crystals from forming on pipes and equipment, reducing scale buildup. That strong ion-sequestering action is why it’s commonly used for this purpose in water treatment. Other substances either don’t bind metal ions as effectively, or they serve different roles (like dissolving deposits or adjusting pH) rather than preventing encrustation through sequestration.