SECTION SUMMARY
13.1 The Nature of Gases Summary:
Particles in a gas are considered to be small, hard spheres with an insignificant volume. The motion of the particles in a gas is rapid, constant, and random. All collisions between particles in a gas are perfectly elastic. The kinetic theory describes the motion of particles in matter and the forces of attraction between them. The theory assumes that the volume occupied by a gas is mostly empty space, that the particles of gas are relatively far apart, move independently of each other, and are in constant random or rapid motion. The collisions between particles are perfectly elastic so that the total kinetic energy remains constant.
Gas pressure is the result of simultaneous collisions of billions of rapidly moving particles in a gas with an object. Barometers are used to measure the atmospheric pressure. It is true that at a given temperature, the particles of all substances, regardless of physical state, have the same average kinetic energy. For example, the ions in table salt, the molecules in water, and the atoms in helium gas all have the same average kinetic energy at room temperature even though the three substances are in different physical states.
The Kelvin temperature of a substance is directly proportional to the average kinetic energy of the particles of the substance.
Standard conditions are defined as a temperature of 0oC and a pressure of 101.3 kPa or 1atm.
13.1 The Nature of Gases Vocabulary Terms:
kinetic energy: the energy an object has because of its motion
kinetic theory: theory states that the volume occupied by a gas is mostly empty space, that the particles of gas are relatively far apart, move independently of each other, and are in constant random or rapid motion.
gas pressure: pressure that results from the force exerted by a gas per unit surface area of an object
vacuum a space where no particles of matter exist
atmospheric pressure: pressure results from the collisions of atoms and molecules in air with objects
barometer: a device used to measure atmospheric pressure
pascal (Pa): SI unit of pressure 1atm = 760 mm Hg = 101.3 kPa
The End of the Summary