Gases

Properties of Gases Fluidity - Gas particles move around freely with negligible attraction to fill the shape of their container. Fluidity - Gas particles move around freely with negligible attraction to fill the shape of their container. Molar Volume - Gases are over 99% empty space. As a result, the size of the particles does not affect the volume. Equal amounts of any gas will occupy almost the exact same volume. Molar Volume - Gases are over 99% empty space. As a result, the size of the particles does not affect the volume. Equal amounts of any gas will occupy almost the exact same volume.

Properties of Gases Compressibility - Gases can easily change volume by placing a force on its container. (Solids and liquids cannot) Compressibility - Gases can easily change volume by placing a force on its container. (Solids and liquids cannot) Diffusion - Mixing of 2 gases due to their random motion. All gases diffuse, but at different rates. Diffusion - Mixing of 2 gases due to their random motion. All gases diffuse, but at different rates.

Properties of Gases Pressure – Gas particles are moving very fast and when they collide with their surroundings, they exert an outward force. Pressure – Gas particles are moving very fast and when they collide with their surroundings, they exert an outward force. Due to expansion, gases will flow until pressure is equalized. (ex: if a plane loses cabin pressure, the air will rush out until the pressure is equalized)

Pressure Pressure is measured in: a. atmospheres (atm) b. millimeters of mercury (mm Hg) c. pascals (Pa) Atmospheric Pressure: 1.00 atm = 101.3kPa = 760 mm Hg

Pressure If you increase the amount of gas in a container, you will increase the pressure of the gas. (ex: adding air to your tires increases the pressure)

Pressure Dalton’s Law of partial pressures - The pressure of a mixture of gases is equal to the sum of their individual partial pressures. P total = P 1 + P 2 + P 3 …. P air = P nitrogen + P oxygen + P carbon dioxide + P water vapor …

Pressure Based on this table, if a chemical reaction done inside an enclosed container were to consume all of the oxygen, what would be the new pressure in kPa?

Pressure A vacuum is created when all of the gases are removed from a volume. Because there are no particles, there is no air pressure. (Empty space has been created.) A partial vacuum is any volume with less pressure than the surrounding air, but not a complete vacuum.

Pressure Total Vacuum = 0 atmospheres > 0 atm 1 atm > Partial Vacuum

In many gas equations, you will be given conditions of “STP.” STP = Standard Temperature and Pressure S PT Standard Temperature = 0 C or 273 K Standard Pressure = 1.00 atm kPa 760 mm Hg

Pressure and Volume Boyle's Law – At constant temperature, the pressure of a gas is inversely proportional to its volume.

Pressure and Volume Boyle's Law – At constant temperature, the pressure of a gas is inversely proportional to its volume. Inhaling – your lungs expand their volume creating low pressure. Air then rushes in to equalize the pressure. Exhaling – your diaphragm compresses your lungs into a smaller volume creating high pressure. Air then is expelled to equalize the pressure.

Pressure and Volume Boyle's Law – At constant temperature, the pressure of a gas is inversely proportional to its volume. P 1 V 1 = P 2 V 2 Graph