The question aims to find the state of the matter when the temperature is raised and pressure is reduced. The state of the matter highly depends on temperature and pressure. When thermal energy is added to matter, its temperature increases and the state of the matter also changes with it accordingly. When the temperature rises, solid changes to liquid, liquid to gas, or solid to gas directly.
Expert Answer
Generally, when the temperature is increased and pressure is reduced, matter would be in the gaseous state.
There are three states of matter that are commonly used.
Solid: Particles remain in contact with each other and vibrate in place, but do not move to each other and maintain the shape and volume of the solid.
Liquid: Particles remain in contact but can move to each other. In some containers, the liquid changes shape but retains its volume.
Gas: Particles can collide, but do not stay in contact. They move quickly against each other. The gas expands or contracts to fill the available space. That is, the gas does not maintain its shape or volume.
Effects of Temperature
When the temperature is lowered, molecular motion is reduced and the material’s internal energy is reduced. Atoms are in low energy states relative to each other and move very little. This is a solid feature.
As the temperature rises, additional thermal energy is given to the solid’s constituents, causing additional molecular motion. Molecules begin to collide with each other, increasing the total amount of substance. At this point, the substance is in a liquid state.
A gaseous state exists when molecules absorb a great deal of heat energy from high temperatures and are free to move around each other at high speeds.
Effects of Pressure
Solids and liquids are incompressible states of matter, so pressure does not affect them. However, it will break if pressure is applied to the solid.
On the other hand, applying pressure at low temperatures can cause the gas to liquefy. When pressure is reduced, the matter will mostly change into the gaseous state.
When the pressure increases, the state of the matter changes from gas to liquid and liquid to solid.
Numerical Result
Generally, when the temperature is increased and pressure is reduced, matter would be in the gaseous state.
Example
At normal temperatures and pressures, carbon dioxide is a gas. It can be liquefied at low pressure and at room temperature. It is converted to a solid-state under very high pressure. When the pressure drops to $1$ atmosphere, solid carbon dioxide bypasses the liquid state and is directly converted to the gaseous state. Therefore, solid carbon dioxide is also called dry ice.