Question

What are the instances the pressure decrease and increases

Answer 1

Temperature and pressure are directly proportional

to each other. This means that as the temperature

decreases, the pressure also decreases, and as the

temperature increases, the pressure increases. One

way to think of this is if you increase the speed of the

molecules –by increasing their temperature- the

force of the molecules hitting their container

increases and this increases the pressure. This

relationship is called Gay-Lussac’s Law and makes up part of the ideal gas law.

Theory

When the speed of a gas’s molecules increases, the gas molecules hit their container more often. The

more frequently the gas impacts the container walls, the higher the pressure. So, as temperature in-

creases, the pressure also increases. If the gas cools, the impacts are less frequent and the pressure decreases

This relationship can be described using mathematics as well. Mathematically, Gay-Lussac’s Law states

that

P/T = k

where k is any constant.

This relationship explains why race car tires are not filled with as much air as normal tires. At the high

speeds of race cars, the air inside the tires heats up, causing the pressure to increase. Tires with too high a

pressure have less contact with the road and are more easily damaged. So, the cold tire pressure for a

race car is lower than a normal car. As air sinks, it encounters higher pressures and the temperature in-

creases. This characteristic of gases leads to the definition of potential temperature. The potential tem-

perature is the temperature a parcel of air would have if it was moved to 100,000 Pa, although this defini-

tion does not require volume to be held constant.

This experiment shows how pressure changes under different temperatures.

Gay-Lussac's Law is one part of the ideal gas law and so explains how gases change when volume is held constant. As the temperature increases, the molecules in the gas move faster, impacting the gas's container more frequently and exerting a greater force. This increases the pressure.