What is a typical product used to adjust the pH of water upwards?

Sodium hydroxide is a strong base used to increase the pH of water, thereby making it more alkaline. When added to water, it dissociates completely into sodium and hydroxide ions, resulting in a significant rise in pH levels. This property makes sodium hydroxide highly effective for applications where raising the pH is necessary, such as in water treatment processes to neutralize acidity or in industrial settings.

In contrast, other choices serve different purposes or have different effects on water chemistry. For example, potassium chloride is commonly used in water softening but does not alter pH significantly. Calcium carbonate, while it can increase pH over time as it dissolves, does so more slowly and is often considered a buffering agent rather than a direct pH adjuster. Aluminum sulfate is primarily used for coagulation in water treatment and does not raise pH; in fact, it can lower pH due to the formation of sulfuric acid in solution.

Therefore, sodium hydroxide stands out as the appropriate choice for directly adjusting the pH of water upwards.