# Explain pressure and volume relationship

### Relationships among Pressure, Temperature, Volume, and Amount - Chemistry LibreTexts

The Relationship between Pressure and Volume . Use Boyle's law to explain why it is dangerous to heat even a small quantity of water in a sealed container. The relationship of a gas with pressure and volume was developed by the scientist Robert Boyle at The animation below gives and explanation of Boyle's law. Volume is the amount of space is taken up by an object or, in our case, a parcel of gas. Boyle's law describes the relationship between the pressure and volume.

## What is the relationship between pressure and volume?

Early scientists explored the relationships among the pressure of a gas P and its temperature Tvolume Vand amount n by holding two of the four variables constant amount and temperature, for examplevarying a third such as pressureand measuring the effect of the change on the fourth in this case, volume. The history of their discoveries provides several excellent examples of the scientific method.

**Boyle's Law (Physics - Thermodynamics - pressure - volume relationship)**

The Relationship between Pressure and Volume: Boyle's Law As the pressure on a gas increases, the volume of the gas decreases because the gas particles are forced closer together. Conversely, as the pressure on a gas decreases, the gas volume increases because the gas particles can now move farther apart.

Weather balloons get larger as they rise through the atmosphere to regions of lower pressure because the volume of the gas has increased; that is, the atmospheric gas exerts less pressure on the surface of the balloon, so the interior gas expands until the internal and external pressures are equal.

The Irish chemist Robert Boyle — carried out some of the earliest experiments that determined the quantitative relationship between the pressure and the volume of a gas. Boyle used a J-shaped tube partially filled with mercury, as shown in Figure 6. In these experiments, a small amount of a gas or air is trapped above the mercury column, and its volume is measured at atmospheric pressure and constant temperature. More mercury is then poured into the open arm to increase the pressure on the gas sample.

The pressure on the gas is atmospheric pressure plus the difference in the heights of the mercury columns, and the resulting volume is measured. This process is repeated until either there is no more room in the open arm or the volume of the gas is too small to be measured accurately.

### Relationships among Pressure, Temperature, Volume, and Amount

This relationship between the two quantities is described as follows: Dividing both sides of Equation 6. 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.

## Boyle's law

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.

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.

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.

### Boyle's law - Wikipedia

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: Also same as before, initial and final volumes and temperatures under constant pressure can be calculated. The Pressure Temperature Law This law states that the pressure of a given amount of gas held at constant volume is directly proportional to the Kelvin temperature.

P Same as before, a constant can be put in: The Volume Amount Law Amedeo Avogadro Gives the relationship between volume and amount when pressure and temperature are held constant. Remember amount is measured in moles. Also, since volume is one of the variables, that means the container holding the gas is flexible in some way and can expand or contract.

If the amount of gas in a container is increased, the volume increases. If the amount of gas in a container is decreased, the volume decreases. V As before, a constant can be put in: The Combined Gas Law Now we can combine everything we have into one proportion: The volume of a given amount of gas is proportional to the ratio of its Kelvin temperature and its pressure.

Same as before, a constant can be put in: The Ideal Gas Law The previous laws all assume that the gas being measured is an ideal gas, a gas that obeys them all exactly.

But over a wide range of temperature, pressure, and volume, real gases deviate slightly from ideal. Since, according to Avogadro, the same volumes of gas contain the same number of moles, chemists could now determine the formulas of gaseous elements and their formula masses.