### The Ideal Gas Law - Chemistry LibreTexts

The history of their discoveries provides several excellent examples of the Conversely, as the pressure on a gas decreases, the gas volume increases to regions of lower pressure because the volume of the gas has increased; that is, the. The Gas Laws: Pressure Volume Temperature Relationships Boyle's law or the pressure-volume law states that the volume of a given amount of gas held Now we can combine everything we have into one proportion: The Ideal Gas Law. We have just seen that the volume of a specified amount of a gas at constant Thus, these laws and relationships can be combined to give Rewriting the Ideal Gas Law given by Equation to calculate the volume gives.

Pressure Gases are the only state of matter that can be compressed very tightly or expanded to fill a very large space. Pressure is force per unit area, calculated by dividing the force by the area on which the force acts. The earth's gravity acts on air molecules to create a force, that of the air pushing on the earth.

This is called atmospheric pressure. The units of pressure that are used are pascal Pastandard atmosphere atmand torr.

It is normally used as a standard unit of pressure.

**Boyle's Law**

The SI unit though, is the pascal. For laboratory work the atmosphere is very large. A more convient unit is the torr.

A torr is the same unit as the mmHg millimeter of mercury. It is the pressure that is needed to raise a tube of mercury 1 millimeter. The Pressure-Volume Law Boyle's law or the pressure-volume law states that the volume of a given amount of gas held at constant temperature varies inversely with the applied pressure when the temperature and mass are constant. Another way to describing it is saying that their products are constant. When volume goes up, pressure goes down.

From the equation above, this can be derived: This equation states that the product of the initial volume and pressure is equal to the product of the volume and pressure after a change in one of them under constant temperature.

### What is the ideal gas law? (article) | Khan Academy

For example, if the initial volume was mL at a pressure of torr, when the volume is compressed to mL, what is the pressure? Plug in the values: The Temperature-Volume Law This law states that the volume of a given amount of gas held at constant pressure is directly proportional to the Kelvin temperature. V Same as before, a constant can be put in: The numerical value of the constant depends on the amount of gas used in the experiment and on the temperature at which the experiments are carried out.

At constant temperature, the volume of a fixed amount of a gas is inversely proportional to its pressure. Boyle used non-SI units to measure the volume in.

Hg rather than mmHg. Because PV is a constant, decreasing the pressure by a factor of two results in a twofold increase in volume and vice versa.

## Boyle's law

The Relationship between Temperature and Volume: Charles's Law Hot air rises, which is why hot-air balloons ascend through the atmosphere and why warm air collects near the ceiling and cooler air collects at ground level. Because of this behavior, heating registers are placed on or near the floor, and vents for air-conditioning are placed on or near the ceiling. The fundamental reason for this behavior is that gases expand when they are heated.

Because the same amount of substance now occupies a greater volume, hot air is less dense than cold air. The substance with the lower density—in this case hot air—rises through the substance with the higher density, the cooler air. A sample of gas cannot really have a volume of zero because any sample of matter must have some volume.

Note from part a in Figure 6.

## What is the ideal gas law?

Similarly, as shown in part b in Figure 6. The Relationship between Volume and Temperature. The temperature scale is given in both degrees Celsius and kelvins. The significance of the invariant T intercept in plots of V versus T was recognized in by the British physicist William Thomson —later named Lord Kelvin.

At constant pressure, the volume of a fixed amount of gas is directly proportional to its absolute temperature in kelvins. This relationship, illustrated in part b in Figure 6. The Relationship between Amount and Volume: InAvogadro postulated that, at the same temperature and pressure, equal volumes of gases contain the same number of gaseous particles Figure 6.