1.3 Osmosis and Diffusion

Diffusion, Osmosis, and the Cell Membrane• Diffusion – is the movement of particles from an area of

higher concentration to an area of lower concentration (Ex. Perfume)• • Concentration – the amount of a substance in a given

space

• Osmosis – is the movement of water from an area of higher concentration to an area of lower concentration (Ex. Limp carrot in water) through a selectively permeable membrane

Movement across a Membrane• Cell membrane is selectively permeable = only some things in • Cell membrane can be compared to a coffee filter• Diffusion is one way that particles move across the cell

membrane• If one side of the membrane has a higher concentration of

particles they will move across the membrane until both sides have the same amount = this means an equilibrium is reached• Particles will continue to move back and forth but there will

be the same number on either side• Example: oxygen in our cells lungs to the blood cells

Reverse Osmosis• Reverse Osmosis – movement of water from a high to a low

concentration – backwards – this requires pressure to push the molecules

• Used for filtering water, purifying maple syrup and juice, and treating sewage

Your Turn

• Questions P. 49 #1-12•Make sure your lab write up is handed in