How can solid change into gas

When a liquid becomes a gas, the particles separate from each other, with each particle going its own way in space. This is how gases tend to fill their containers. Indeed, in the gas phase most of the volume is empty space; only about one one-thousandth of the volume is actually taken up by matter see Figure Under some circumstances, the solid phase can transition directly to the gas phase without going through a liquid phase, and a gas can directly become a solid.

The solid-to-gas change is called sublimation , while the reverse process is called deposition. Sublimation is isothermal, like the other phase changes. There are several common examples of sublimation.

A well-known product — dry ice — is actually solid CO 2. Dry ice is dry because it sublimes, with the solid bypassing the liquid phase and going straight to the gas phase. If you have ever noticed that ice cubes in a freezer tend to get smaller over time, it is because the solid water is very slowly subliming. The food is still good but looks unappetizing.

Reducing the temperature of a freezer will slow the sublimation of solid water. Chemical equations can be used to represent a phase change. In such cases, it is crucial to use phase labels on the substances. For example, the chemical equation for the melting of ice to make liquid water is as follows:.

A plot of the temperature versus the amount of heat added is known as a heating curve see Figure These are commonly used to visually show the relationship between phase changes and enthalpy for a given substance. In Figure At the melting point, the heat added is used to break the attractive intermolecular forces of the solid instead of increasing kinetic energy, and therefore the temperature remains constant.

After all the solid has melted, once again, the heat added goes to increasing the kinetic energy and temperature of the liquid molecules until the boiling point.

At the boiling point, once again, the heat added is used to break the attractive intermolecular forces instead of supplying kinetic energy, and the temperature remains constant until all liquid has been turned to gas. Skip to content Chapter Solids and Liquids. Describe what happens during a phase change. Calculate the energy change needed for a phase change. What is the energy change when Without a sign, the number is assumed to be positive.

The same water turns into a gas called water vapor if it is heated up. The changes only happen when the substance reaches a particular temperature. This is known as its freezing point. This is known as its boiling point. Boiling points and freezing points come at different temperatures for different substances. The metal gallium is a solid at room temperature, but melts in your hand if you pick it up. Sublimation is the process of transformation directly from the solid phase to the gaseous phase, without passing through an intermediate liquid phase.

At a given temperature, most chemical compounds and elements can possess one of the three different states of matter at different pressures.

In these cases, the transition from the solid to the gaseous state requires an intermediate liquid state. But at temperatures below that of the triple point, a decrease in pressure will result in a phase transition directly from the solid to the gaseous.

Also, at pressures below the triple point pressure, an increase in temperature will result in a solid being converted to gas without passing through the liquid region. For some substances, such as carbon and arsenic, sublimation is much easier than evaporation.

This is because the pressure of their triple point is very high and it is difficult to obtain them as liquids. The solid has such high vapor pressures that heating leads to a substantial amount of direct vaporization even before the melting point is reached.