What type of steam is defined as having all water molecules in the gaseous state?

The type of steam defined as having all water molecules in the gaseous state is dry steam. This steam is completely vaporized and contains no liquid water, making it efficient for various applications in steam systems. In dry steam, the temperature and pressure are consistent, and it can be used to perform work effectively without the complications that arise from the presence of water droplets.

Understanding the nature of dry steam is critical in steam engineering, as it is essential for maximizing efficiency and preventing issues like corrosion or fouling that can occur when liquid water is present. This aspect of dry steam distinguishes it from other types, such as saturated steam, which is a mixture of water and steam, and wet steam, which contains both vapor and liquid water. Superheated steam is also distinct but involves heating the steam beyond its saturation point at a given pressure, which means it does not have the same characteristics as dry steam, as it can exist at temperatures higher than the boiling point without becoming liquid.