The pressure of gas above a liquid affects the boiling point. In an open system this is called atmospheric pressure. The greater the pressure, the more energy required for liquids to boil, and the higher the boiling point.

You can see that at atmospheric pressure the freezing point of water is 273.2°Kelvin or 0°C or 32°F.

Or, from the CRC Handbook of Chemistry and Physics, P2=0.6920 atm , or 525.9208 torr , giving 0.59% error. (David R. Lide, ed. (2005).

Changes in pressure can raise or lower the freezing point of a substance. Generally, pressures lower than 1 atmosphere lower the temperature at which a substance freezes, but for water, a higher pressure gives a lower freezing point.

We know that with increasing atmospheric pressure, the freezing point of water slightly decreases. Because of increasing the pressure, which prevents water molecules properly arranging them. If water freezes, the mean forms a crystalline solid phase with a proper arrangement.

As ambient air pressure decreases, molecules evaporating from a boiling liquid meet less resistance from air molecules and enter the air more easily. Because the vapor pressure can be reduced, the temperature needed to boil the liquid is also reduced.

Decreasing Pressure The combined gas law states that the pressure of a gas is inversely related to the volume and directly related to the temperature. If temperature is held constant, the equation is reduced to Boyle’s law. Therefore, if you decrease the pressure of a fixed amount of gas, its volume will increase.

The pressure of a gas is inversely proportional to its volume when temperature is constant. The product of pressure and volume is constant when temperature is constant. This relationship is known as Boyle’s law or Mariotte’s law .

More collisions mean more force, so the pressure will increase. When the volume decreases, the pressure increases. This shows that the pressure of a gas is inversely proportional to its volume. This is shown by the following equation – which is often called Boyle’s law.

Boyle’s law states that pressure (P) and volume (V) are inversely proportional. Charles’ law states that volume (V) and temperature (T) are directly proportional. Gay-Lussac’s law states that pressure (P) and temperature (T) are directly proportional.

Avogadro’s law states that “equal volumes of all gases, at the same temperature and pressure, have the same number of molecules.” For a given mass of an ideal gas, the volume and amount (moles) of the gas are directly proportional if the temperature and pressure are constant.

Dilution is the prosess where a solution is added more of the solvent to decrease the concentration of the solute. In dilution, the amount of solute does not change, the number of moles are the same before and after dilution.

A plot of the effect of temperature on the volume of a gas at constant pressure shows that the volume of a gas is directly proportional to the number of moles of that gas. This is stated as Avogadro’s law.