Why is a slightly alkaline mixture used in relation to boiler feed water?

Using a slightly alkaline mixture in boiler feed water primarily aids in corrosion prevention. When the pH of the water is slightly elevated, it helps to create a protective layer on the metal surfaces within the boiler system. This layer acts as a barrier, reducing the potential for corrosion by minimizing the chemical reactions that can lead to the degradation of metal over time.

Corrosion in boiler systems can lead to significant maintenance costs and operational issues; therefore, maintaining a slightly alkaline environment is essential in preserving the integrity of the boiler and extending its operational lifespan. In this context, balancing the water chemistry is crucial, as it helps maintain not only system efficiency but also safety and reliability.

While other options may relate to aspects of boiler operation, the primary role of a slightly alkaline mixture directly relates to preventing corrosion, making it the most appropriate answer.