Gas Laws Chemistry

Obj: To describe the properties of gases. Do not have a definite volume or shape. Diffuse to the fill volume and shape of their container. Are compressible. Exert pressure on the walls of a container due to molecular collisions.

Obj: To describe the Kinetic Theory of Gases. Kinetic Theory of Gases – A description of an “Ideal” gas. The particles of an ideal gas have no volume. The particles of the gas move in straight lines until they collide with the wall of the container or another gas particle. There is no attraction between the gas molecules of an ideal gas. The collisions between ideal gas molecules are perfectly elastic (they lose no energy.) There is no “stickyness” between the particles when they collide. The average kinetic energy is proportional to the absolute temperature of the gas.

Obj: To describe when a gas does not behave as an ideal gas. When a gas does not fit the postulates of the Kinetic Theory of Gases, it does not behave exactly like the previous gas laws predict. For example when the temperature of the gas is reduced, the molecules slow down and their collisions become more sticky. At a low enough temperature the molecules will condense in to a liquid. Gases behave most ideal at high temperatures and low pressures.

Obj: To describe standard temperature and pressure conditions. Standard Temperature and Pressure (STP) Standard Temperature: 0o C = 273 K Standard Pressure: 1 atm = 760 mm Hg = 101.3 kPa

Obj: To understand the relationship between Temperature and Volume. Charles’ Law – At a constant pressure, Temperature and Volume are directly proportional. Temperature must be in an absolute scale, like Kelvin. oK = oC + 273

Obj: To understand the relationship between Temperature and Volume. Boyle’s Law – At a constant temperature, Volume and Pressure are inversely proportional.

Obj: To understand the relationship between Temperature and Pressure. Gay-Lussac’s Law – At a constant volume, Temperature and Pressure are directly proportional. Pressure

Obj: To understand the relationship between Volume, Temperature and Pressure. Combined Gas Law “At constant _____,” - cancel the variable. Will result in one of the three previous laws.

Obj: To understand the relationship between Volume, Temperature and Pressure, and number of moles of a gas. Ideal Gas Law n = number of moles of gas Temperature must be in Kelvin (oK = oC + 273) R = ideal gas law constant

Obj: To understand Dalton’s Law of partial pressures. Dalton’s Law – The total pressure of a gas mixture is the sum of each of the component gases’ partial pressures.

Obj: To understand Graham’s Law. Graham’s Law – The rate at which a gas diffuses is inversely proportional to the square root of its mass.