Particle theory Flashcards
Properties of a solid
Fixed shape and position
Fixed volume
Closely packed particles which are dense and difficult to compress
Strongest intermolecular forces
Properties of a liquid
Fixed volume
Takes the shape of its container
Closely packed particles which are dense and difficult to compress
Weaker intermolecular forces than solids
Properties of a gas
No fixed shape or volume
Particles spread out and fill container
Particles are far apart so easy to compress
Weakest intermolecular forces
Diffusion
The movement of particles from an area of higher concentration to lower concentration
Why does diffusion take place
Because of Brownian motion - the random movement of particles due to their kinetic energy
Only occurs in liquids and gases
What factors affect the rate of diffusion?
Heating increases the rate of diffusion
Gases have a faster rate of diffusion than liquids
Particles with a lower molecular mass diffuse faster
e.g. Cl (35.5) travels slower than Ammonia NH3 (17)
What is an experiment to show diffusion in water
Place Potassium Manganate VII crystals in water
This starts to diffuse and you can tell when it has stopped as the concentration of purple colour is the same throughout the container
What is an experiment to show how Mr affects the rate of diffusion
Air sealed glass tubing
On one side there is cotton wool soaked in ammonia solution and on the opposite end cotton wool soaked with hydrochloric acid
Smoke will form closer to the hydrochloric acid as the ammonia has a lower Mr meaning it can travel further in a shorter period of time
