Which chemical is commonly used to increase alkalinity in feedwater?

• A. Sodium chloride
• B. Sodium hydroxide
• C. Calcium carbonate
• D. Magnesium sulfate

Answer: (B)

Sodium hydroxide is commonly used to increase alkalinity in feedwater due to its strong alkaline properties. When added to water, it dissociates into sodium ions and hydroxide ions, effectively raising the pH level and enhancing the alkalinity. This is essential in various industrial processes, especially in water treatment and boiler operations, where maintaining proper alkalinity is crucial to prevent corrosion and scaling.

Other chemicals may serve different functions. For instance, sodium chloride is primarily used for salting or as a source of sodium ions, while calcium carbonate can moderate pH levels but may not raise alkalinity as effectively as sodium hydroxide. Magnesium sulfate is typically used for other purposes, such as nutrient supply or softening water, rather than specifically increasing alkalinity.