What is the purpose of using soda ash during the softening process?

Soda ash, chemically known as sodium carbonate, plays a critical role in the water softening process by addressing non-carbonate hardness. Non-carbonate hardness primarily comes from divalent metal ions such as calcium and magnesium, which can cause scaling and other issues in water systems.

When soda ash is added to water that has non-carbonate hardness, it reacts with the calcium and magnesium ions present. This reaction results in the precipitation of insoluble compounds, effectively removing these hardness-causing ions from the water. This process not only softens the water but also helps to improve its overall quality, making it more suitable for various applications, such as drinking, irrigation, and industrial processes.

The other answer options, while they may touch on related aspects of water chemistry, do not accurately capture the primary purpose of soda ash in the softening process. Options that suggest increasing carbonate hardness or enhancing taste do not reflect the chemical reactions that are central to water softening. Additionally, while stabilizing pH levels is a benefit that can arise from various treatments, it is not the primary function of soda ash in the context of removing non-carbonate hardness.