Sunday, January 30, 2011

Difference between Osmosis and Diffusion

Diffusion is the movement of particles from an area of high concentration to an area of low concentration, while osmosis is the net movement of water molecules from an area of high concentration to a region of low concentration, through a partially permeable membrane.
 
Diffusion usually occurs in the gaseous state and the liquid state. It rarely happens in the solid state, but that does not mean that it would not happen at all. Furthermore, diffusion does not require water for the molecules to move.
 
On the other hand, osmosis requires water and usually happens with cells.When the liquid around the cell has a higher water concentration compared to the cell, the cell will gain water. This shows that osmosis requires water.

video explaining diffusion

Defination of diffusion

 Diffusion is a form of passive transport and it is the movement of molecules from a region of higher concentration to a region of lower concentration until both sides have an equal concentration.

Saturday, January 29, 2011

A conversation to help you understand better...

This is a conversation between a mother, her daughter and her son, based on our local slang, Singlish. We hope it will help you to understand the concept of diffusion and osmosis better, especially if you are familiar with this slang :) Enjoy!



Mother: So… what did you two learn in school today?

Sister: well, in science we learnt about diffusion.

Brother: What is deefeesion?

Sister: Its diffusion.

*brother farts*

Sister: Ew, what’s that horrible smell?

Brother: what smell? I don’t smell anything…

Sister: you farted right?

Brother: Huh. Like real lah. You anyhow accuse one. What is this?!

Sister: Okay lor… Hey! This is a perfect example of diffusion.

Mother: You’re right.

Brother: Can you tell me more about deefeesion?

Mother: Diffusion is the movement of particles from an area of high concentration to an area of low concentration. This works because everything is made up of very tiny particles. These particles are always moving and colliding with each other in the air as they move randomly. This is what causes diffusion. For example, when I cook dinner at home, you can smell my cooking from your room. This is because the smell is carried by particles that move around in the air from my food to your nose. When you farted just now, jie could smell it because the smell from your fart diffused in the air and travelled to her nose.

Brother: chey………

Sister: oh yeah hor! My teacher also talked about some other thing… Like got random particles from high dontknowwhat region to low also don’tknowwhat region! And the irritating thing is that it ISN’T diffusion! So confusing lah! What is it?

Mother: Oh and another thing that’s related to this is the process called osmosis! It’s *gets rudely interrupted*

Sister: CHEY! It’s osmosis sia! I remember now!

Mother: you prawn ah? Anyway, as I was saying before I was so rudely interrupted, osmosis is the process where water molecules move from a region of higher concentration to a region of lower concentration through a semi-permeable membrane. This usually occurs in cells.  See this plant here?

*gestures at a plant* 

Mother: when it photosynthesizes, water enters the plant cells by osmosis.

Sister: okay. Now I understand. Thanks mummy! Ohhhh I’m hungry, I smell food.

Brother: HAH. DIFEESEEEOONNNNN!! (:

Osmosis shown with a raw egg put in vinegar then in water

Video of osmosis shown in a Raw egg taken from: 



Raw egg after being put in Vinegar:

Taken From: k/S5HRny0XSJI/AAAAAAAAA4Y/p9noQ5PGkZM/s400/IMG_6650.JPG

Raw Egg after being put in the water:

Taken From: http://vcebiology.edublogs.org/files/2010/02/egg-with-shell-removed1.jpg



Picture taken from:http://api.ning.com/files/da-aYS2CiP2DgLfY80Z8bJsrSubBI4PPNmyC00koG7-idK2iu-YFVhjantfy1ZZKeqhTOK9DP*hFTx2fQidhCbSSlQxdN2dn/osmosis.gif

Link of Video taken from: http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_osmosis_works.html

Video on Osmosis (1)


Diagram on Osmosis


Taken From:http://www.chemprofessor.com/osmosis.jpg

Definition of Osmosis

Osmosis is the net movement of water molecules from a region of higher water potential to a region  of lower water potential through a partially permeable membrane.