A change of state directly from solid to gas without changing into liquid state is called
Sublimation
Understanding Change of State: Solid to Gas
The question asks about a specific change of state where a substance transitions directly from the solid phase to the gaseous phase without passing through the liquid phase. This process has a unique name in chemistry and physics.
Analyzing the Options for Change of State
Let's look at the provided options to determine which one correctly describes the direct transition from solid to gas:
- Fusion: Fusion is the process where a solid changes into a liquid upon heating. This is commonly known as melting. An example is ice changing into water. So, this option describes solid to liquid change, not solid to gas directly.
- Sublimation: Sublimation is indeed the process where a substance changes directly from the solid state to the gaseous state, skipping the liquid state entirely. A common example is dry ice (solid carbon dioxide) turning directly into carbon dioxide gas at room temperature and atmospheric pressure. Another example is the disappearance of naphthalene balls over time. This definition perfectly matches the description in the question.
- Diffusion: Diffusion is the movement of particles from an area of higher concentration to an area of lower concentration. This process occurs in gases, liquids, and even solids over long periods, but it is related to the mixing and spread of substances, not a change of state from solid to gas.
- Emulsion: An emulsion is a mixture of two or more liquids that are normally immiscible (unmixable or unblendable), like oil and water. One liquid is dispersed in the other in the form of small droplets. This term describes a type of mixture, not a change of state from solid to gas.
Based on the analysis, the term that describes the direct change of state from solid to gas without changing into a liquid state is sublimation.
Conclusion: Identifying the Correct Term
The change of state directly from solid to gas is known as sublimation. This is distinct from melting (solid to liquid), boiling (liquid to gas), or condensation (gas to liquid), and deposition (gas to solid).
Revision Table: Common Changes of State
| Process | Change of State | Description |
|---|---|---|
| Melting (Fusion) | Solid to Liquid | Heat energy breaks down the forces holding solid particles together. |
| Boiling (Vaporization) | Liquid to Gas | Liquid particles gain enough energy to overcome intermolecular forces and escape as gas. |
| Condensation | Gas to Liquid | Gas particles lose energy and come closer to form a liquid. |
| Freezing (Solidification) | Liquid to Solid | Liquid particles lose energy and arrange into a fixed solid structure. |
| Sublimation | Solid to Gas | Solid particles gain enough energy to directly escape into the gaseous phase. |
| Deposition (Desublimation) | Gas to Solid | Gas particles lose energy and directly form a solid, skipping the liquid phase. |
Additional Information: Examples and Factors Affecting Sublimation
Sublimation occurs when the vapor pressure of the solid is higher than the partial pressure of the substance in the surrounding atmosphere at a specific temperature. Some substances that sublime easily include:
- Dry ice (solid \(\text{CO}_2\))
- Naphthalene (used in mothballs)
- Iodine
- Camphor
Factors like temperature and pressure can affect whether a substance sublimes or melts.
Important Questions from States of Matter
Which is correct statement ?
According to Charle's Law, which of the following is constant?
Which of the following statements is/are correct?
I. Mass vapor is obtained in the air by evaporation and transpiration.
II. Water circulation between the oceans and the water bodies is called the water cycle.
Which state of matter is characterized by a high-energy collection of ionized particles, where atoms have lost or gained electrons, making it electrically conductive, and is the most common state of matter in the universe?
Henry’s law is not applicable if:
