Gases by Jimmy

Gas variables

Gas is arguably the most interesting state of matter. It changes both its shape and size according to what is around it. Gasses are also very difficult to measure effectively, because many of the gasses are lighter than normal air. There are a few things that make gases react in certain ways. Volume, heat, pressure, and the amount of particles are the things most commonly looked at in gasses. They are also very closely related.

The first variable is volume. Volume is the geometric area of the container of the gas.  The volume of gas is measured by the container it is in, because it is very difficult to isolate gas. Volume is measured in liters (L). The volume of a gas can either be fixed or variable, depending on its container. A rigid container, like glass or plastic, will have a fixed volume. The volume inside of the container will stay the same no matter what happens. A flexible container, like a balloon, will have a variable volume. The volume will change depending on the other variables. A balloon will expand when you blow into it and add more particles.

The next variable is heat. Heat is how much energy is in the particles. The unit for heat is Celsius (C). The temperature of the gas will affect both the volume and pressure of it. The amount of heat is directly proportional to the kinetic energy of the particles of the gas; as the heat increases, the particles will move faster and faster.

The variable that changes the most depending on the others is pressure. The pressure of a gas changes based upon the volume, heat or the amount of particles present. There are three main units for pressure: atmospheres (atm), millimeters of mercury (mmHg), and Pascal (Pa). Each unit has their own purpose and is used in different scenarios. At sea level, standard atmospheric pressure is 1 atm, 760 mmHg, and 101.325kPa.

The last variable is the amount of gas. This is usually expressed in moles. A mole is 6.022 * 10²³ particles. This is the only variable that is changed by only adding or subtracting more particles. Often the amount of particles in a substance will be notated as “n”.

The way these variables interact is predictable. For fixed volumes, as heat increases or decreases, the pressure will do the same and vice versa. If the amount of particles is increased, the pressure will increase. In a flexible container, more than one variable will change most likely. If you increase the amount of particles, the pressure inside will increase and the volume will expand.

Gas variables are used to help many things in today’s life. The most common and simplest is blowing up a balloon. As the amount of particles in the balloon increases, the elastic container expands increasing in volume. Because the container is elastic, it will push back on the air inside of the balloon, increasing pressure. These are also used in things such as tires, hair spray, and airplanes. Some of the properties of gasses will also apply to the other states of matter. How can we use the relationship of the properties of gas to help out many other things in our society?