How does pressure change the state of a substance?

Answer 1

For example, at a certain temperature a material is a solid - the atoms or molecules hold tight together. If the temperature is increased, the atoms or molecules move faster, and can eventually have enough energy to rip apart. In this case, the substance will change from solid to liquid (or directly to a gas, depending on the circumstances).With respect to pressure: basically, a high pressure changes the distance between the atoms or molecules; this, in turn, affects the forces between them.

Answer 2

A decrease in pressure will typically decrease the phase change temperature of a substance. For example, water will boil at a lower temperature (typically 100C at sea level) when at a higher elevation, due to the pressure change.

Impurities may affect the change of state temperature, but the answer and change will vary for material and impurity. For example Carbon impurities in Iron (a mixture of carbon and iron is called steel), will change the melting temperature depending on the concentration of carbon. (see Iron-Carbon phase diagram figure in the link below.)

Answer 3

Applying pressure to a substance can change its state by affecting the intermolecular forces between its particles. For example, increasing pressure can push particles closer together and overcome intermolecular forces, leading to a change in state. Conversely, decreasing pressure can cause particles to move farther apart and change state.

Answer 4

Increase in pressure decreases the distance between the particles of a gas allowing interparticular forces to become large enough to liquify the substance.