what is it called when a solid turns directly into a gas?

Sublimation is the process where a solid transforms directly into a gas, skipping the liquid phase entirely.

Core Definition

This phase change, known as sublimation, occurs when substances like dry ice (solid carbon dioxide) vaporize at room temperature and normal pressure due to their vapor pressure exceeding atmospheric levels. Unlike melting followed by boiling, sublimation happens below the substance's triple point, where solid and gas phases coexist stably. It's an endothermic process, absorbing heat from the surroundings.

Everyday Examples

• Dry ice : Famous for creating foggy effects at parties, it sublimes into CO2 gas, leaving no liquid residue.

• Frost on cold mornings : Water vapor in air deposits as ice overnight (reverse process, deposition), but exposed frost can sublimate in sunlight.

• Mothballs : Naphthalene crystals slowly turn to gas, releasing their scent over time.

• Freeze-drying : Used in food preservation, like instant coffee, where ice sublimes under vacuum.

Science Behind It

Sublimation relies on molecular kinetic energy overcoming intermolecular forces without a liquid intermediate, common in volatile solids with high vapor pressure. The reverse, deposition, forms snowflakes from vapor. In labs, it's harnessed for purification, separating sublimable compounds from impurities.

Real-World Applications

Chemists use it to isolate iodine or arsenic; in nature, it explains disappearing snowfields. As of early 2026, trending discussions on platforms like Reddit highlight sublimation in climate contexts, such as Arctic ice loss bypassing melt stages amid warming.

Phase Transition| From → To| Common Example
---|---|---
Sublimation 1| Solid → Gas| Dry ice fog 3
Deposition 3| Gas → Solid| Frost formation 3
Melting 1| Solid → Liquid| Ice to water
Vaporization 1| Liquid → Gas| Boiling water

TL;DR : Sublimation turns solids straight to gas—think dry ice vanishing into mist.

Information gathered from public forums or data available on the internet and portrayed here.