Kinetic Model of Matter Flashcards
Shape of Solid
Fixed
Shape of Liquid
Not fixed
Shape of Gas
Not fixed
Volume of Solid
Fixed and incompressible
Volume of Liquid
Fixed and incompressible
Volume of Gas
Not fixed, compressible and occupies volume of container
Arrangement of molecules in solid
Closely together with little space, arranged in a regular pattern
Arrangement of molecules in liquid
Slightly further apart with little space in between molecules, arranged in a disorderly manner
Arrangement of molecules in gas
Far apart with mainly empty spaces between molecules
Motion of molecules in solid
Constantly and randomly vibrating about fixed position as it is held in place by strong attractive forces between the particles
Motion of molecules in liquid
Constantly and randomly moving to and fro within the liquid, sliding over each other.
Motion of molecules in gas
Moving constantly and randomly with high speed, colliding with each other and with the walls of the container due to the little attractive forces between the particles
Observation for Brownian Motion
Bright specks of light moving about in a constant, random motion.
The smaller air particles are in constant, random motion. The air particles collide unevenly with the larger smoke particles and exert a resultant force on the smoke particles. The smoke particles move in the direction of the resultant force due to Newton’s Second Law of Motion.
Effect of Temperature on Molecular Motion
At higher temperature, the air particles collide with the smoke particles with a larger force and more frequently. The motion of smoke particles is faster and more random.
Pressure of gas in terms of motion of its molecules
The gas particles are in a constant, random motion, moving freely within the container. They collide and rebound from the walls of the container. This is due to a resultant force acting on the gas particles by the walls of the container. Hence, since pressure is the force acting per unit area, gas pressure is thus caused due to collisions of the gas particles with the walls of the container.
Relationship between pressure and temperature of gas
For a fixed mass of gas at a constant volume, as the temperature increases, the average kinetic energy of the particles increases hence the speed of the particle increases, the particle will bombard the walls of the container with a larger force and more frequently, this results in the force per unit area exerted by the gas particles on the walls to increase, this cause the pressure of the gas to increase.
The temperature of the gas measured in kelvin is directly proportional to the pressure of the gas.
Relationship between volume and temperature of gas
For a fixed mass of a gas at constant pressure, as the temperature of the gas in the container increases, the average speed of the particles increases, and the particles bombard the walls more frequently and with a larger force. This causes the pressure of the gas to increase. However, as the gas pressure is larger than atmospheric pressure, a net force acts on the container causing the volume to increase. As the volume of gas increases, the gas pressure decreases until it is equal to the atmospheric pressure.
Relationship between pressure and volume of gas
For a fixed mass of a gas at constant temperature, the average speed of the gas particles is the same. If the volume of the container is increased, the number of gas particles per unit volume in the container will be decreased. The frequency of collisions with the walls of the container will also decrease due to the increase in volume. Hence the pressure exerted by the gas will decrease. The force of collisions remains the same as the average speed of the gas particles remains constant. Therefore, for a fixed mass of gas at constant temperature, the pressure of a gas is inversely proportional with its volume.
