Not compressible Not compressible Highly compressible
Hard and rigid
large force required to change its shape
Definite surface No surface
The kinetic theory of matter states that all matter is made up of a large number of tiny atoms or molecules which are in continuous motion. kinetic molecular model of matter states of matter
brownian motion dotted lines represent the path of smoke particles between collision kinetic molecular model of matter Using a microscope, smoke particles can be seen moving continuously and haphazardly, as a result of being hit by unseen fast-moving air molecules. Brownian motion provides evidence for the kinetic molecular model of matter (kinetic theory of matter).
When the air molecule collide with a smoke particle
The molecules exert a force on the smoke particle
Continuous random collisions produce a random resultant force on the smoke particle
Cause the smoke particle to move randomly and continuously.
Why is a microscope necessary in order to observe Brownian motion?
The points of light are too faint to be seen by an unaided eye
The small size particles are too small to be seen with the naked eye.
Explain how Brownian motion provides evidence for the kinetic molecular model of matter
Brownian motion is observed by suspending small sized particles in a fluid.
Points of light are light scattered by the small-sized particles.
The random, continuous and jerky movement of the smoke particles suggests that
the small sized particles are continuously bombarded by random and continuously moving air particles or molecules.
brownian motion If heat is supplied, the motion of the smoke particles becomes more vigorous. The smaller the smoke particles, the more rapid is their motion. Diffusion is a result of Brownian motion. smoke particles moving continuously and haphazardly (irregular or random motion) diffusion
Diffusion is the spreading of molecules of their own accord without any external aid. Gas molecules move randomly all the time and they move into any available space. Hence they stay mixed and do not separate out. brownian motion diffusion Rate of diffusion depends on
temperature of gases: higher temperature leads to faster diffusion
density of gases: greater density leads to slower diffusion
diffusion in air brownian motion If bromine vapour is released into a similar space full of air
bromine molecules keep hitting air molecules which get in the way
bromine vapour spreads quickly throughout the space but much slower than in vacuum
The pressure of a gas is causes by collisions of the molecules with the walls of the container.
The magnitude of the pressure is related to how hard and how often the molecules strike the wall.
The "hardness" of the impact of the molecules with the wall will be related to the velocity of the molecules times the mass of the molecules.
pressure exerted by a gas
pressure exerted by a gas Pressure exerted by gas molecules increases due to: relationship between the motion of molecules and pressure
a decrease in volume of a container, or (and)
an increase in temperature
pressure exerted by a gas pressure of a gas in terms of motion of its molecules 1. Number of gas molecules per cm 3 doubles half the volume of container 2. Number of collisions of molecules with the wall in one second doubles 3. Pressure doubles 1. Molecules move faster temperature of gas in container increases 2. Molecules hit the walls more frequently and more violently (with greater force) 3. Pressure increases
Relationship between Pressure, volume and Temperature
A syringe contains 80cm 3 of trapped air at room temperature. The piston is slowly pushed inwards, compressing the air. Some information about the air inside the syringe is given in the table below. Calculate the pressure P of the air after compression.
Before compression After compression Volume of air 80 cm 3 20 cm 3 Temperature of air 25 C 25 C Pressure of air 1.0 x 10 5 Pa P
The volume of air in the pump at the start of the stroke is 20 cm 3 , and the pressure of the air is 1.00 x 10 5 Pa. Calculate the pressure when the volume has been reduced to 8 cm 3 , assuming that no air has escaped from the pump and the temperature of the air is constant.
Matter Solid Gas (a) Properties of solids, liquids and gases (b) Relationship between the motion of molecules and temperature (c) Pressure of a gas Liquid
Kinetic theory of matter is based on evidence like consists of are discussed in used to explain