This week, we saw diffusion happening in front of our own eyes!
Basically what is diffusion?
Diffusion is the movement of substances from a region of higher concentration to a region of lower concentration
The higher the temperature, the faster the rate of diffusion.
In the experiment, Mr Foo demonstrated diffusion by showing the spread of iodine vapor throughout the gas jar.
At the start of the experiment, the iodine vapor was at the bottom of the gas jar. There was a violet colouration at the bottom of the jar and over time, it faded. The purple colored vapor rose and spread throughout the jar.
We could then conclude that gaseous particles are in constant and random motion.
Relating it to matter...
Matter is made up of small particles which are in constant motion and random direction.
WHY DOES DIFFUSION ONLY HAPPEN IN LIQUIDS AND GASES?
The water and gas molecules are able to move freely and hence, diffusion is able to take place. In solids however, molecules are packed so tightly that a negligible amount of movement occurs and inhibits diffusion.
KINETIC PARTICLE THEORY
A solid
In the experiment, Mr Foo demonstrated diffusion by showing the spread of iodine vapor throughout the gas jar.
At the start of the experiment, the iodine vapor was at the bottom of the gas jar. There was a violet colouration at the bottom of the jar and over time, it faded. The purple colored vapor rose and spread throughout the jar.
We could then conclude that gaseous particles are in constant and random motion.
Relating it to matter...
Matter is made up of small particles which are in constant motion and random direction.
WHY DOES DIFFUSION ONLY HAPPEN IN LIQUIDS AND GASES?
The water and gas molecules are able to move freely and hence, diffusion is able to take place. In solids however, molecules are packed so tightly that a negligible amount of movement occurs and inhibits diffusion.
KINETIC PARTICLE THEORY
A solid
- cannot be compressed
- fixed volume
- fixed shape
- high density
- cannot be easily compressed
- no fixed shape
- fixed volume
- high density, but usually lower than solids
A gas
- can be easily compressed
- no fixed volume
- no fixed shape - take the shape of the whole container
- low density
Solid particles vibrate about fixed positions, held together by strong intermolecular bonds between them -> fixed shape and volume
Liquid particles are free to move about between clusters but confines within vessel containing it due to strong attractive forces between them -> fixed volume but take the shape of container holding it
Gas particles are always in high speed, independent motion in random manner with negligible attractive forces between them -> no fixed volume and shape, but highly compressible
BROWNIAN MOTION
We actually learnt this in physics. Pollen grains were ovine because the smaller and faster moving water particles were constantly colliding with them.
- Random motion of visible particles (pollen grains) caused by small, invisible ones
- Random motion of the smoke particles is caused by the bombardment of air molecules
- When temperature increases, smoke particles gets more agitated and change direction more often.
Boiling
- Liquid to gas
- Gain energy
- Move faster
- Further apart
- Completely overcome hydrogen bonding
- Far apart and away from each other
At boiling point, water molecules lose heat energy so as to bond with the molecules.
Thank you!
The reason why solid does not diffuse easily as compared to liquid or gas is because the particles in solid are closely packed together by the strong attractive forces held between them. This forces of attraction restrict the movement of particles to move throughout the substance as they are held in orderly or regularly or fixed and closely packed positions.
ReplyDeleteRemember in order for particles to move randomly and apart from each other, the forces of attraction have to be broken by external energy such as heat energy. In this case, the state of the substance will change as particles move apart with lesser forces of attraction between them .