How does flue gas desulfurization work?

Flue gas desulfurization is an important process used to remove sulfur dioxide from exhaust gases produced in power plants and industrial processes. The correct choice indicates that calcium oxide reacts with sulfur dioxide. In this process, calcium oxide (also known as quicklime) is used because it has a strong affinity for sulfur dioxide gas.

When sulfur dioxide comes into contact with calcium oxide, a reaction occurs that forms calcium sulfite. This is significant because it captures harmful sulfur emissions and converts them into a less harmful solid compound. The overall chemical reaction typically looks like this:

[ \text{CaO (s)} + \text{SO}_2 (g) \rightarrow \text{CaSO}_3 (s) ]

This calcium sulfite can be further processed or disposed of, reducing the environmental impact of sulfur emissions. The key to this method is the efficiency of calcium oxide in neutralizing sulfur dioxide, a toxic pollutant responsible for acid rain and other environmental issues.

Understanding the role of calcium oxide in this context highlights the chemical principles of acid-base reactions, as calcium oxide functions as a basic oxide reacting with the acidic sulfur dioxide to form a salt (calcium sulfite).