Osmosis and DiffusionOsmosis and Diffusion

Web LessonWeb Lesson

a. Hypotonica. Hypotonic

• Hypotonic refers to the solution Hypotonic refers to the solution in a concentration gradient in a concentration gradient having the lesser concentration having the lesser concentration (of solute ). (of solute ). – A hypotonic solution would have a A hypotonic solution would have a

greater concentration of solvent greater concentration of solvent but a lesser concentration of solute but a lesser concentration of solute than a hypertonic one. than a hypertonic one.

b. Hypertonicb. Hypertonic

• Hypertonic refers to the solution Hypertonic refers to the solution in a concentration gradient in a concentration gradient having the greater concentration having the greater concentration (of solute ). (of solute ). – A hypertonic solution would have a A hypertonic solution would have a

lesser concentration of solvent but lesser concentration of solvent but a greater concentration of solute a greater concentration of solute than a hypotonic one. than a hypotonic one.

c. Isotonicc. Isotonic

• Isotonic means having equal Isotonic means having equal concentration.concentration.

d. Diffusiond. Diffusion

• Diffusion is the movement of Diffusion is the movement of particles (ions or molecules) particles (ions or molecules) from an area of higher from an area of higher concentration to an area of lower concentration to an area of lower concentration.concentration.

e. Osmosise. Osmosis

• Osmosis is the diffusion of water Osmosis is the diffusion of water from a hypotonic solution into a from a hypotonic solution into a hypertonic solution across an hypertonic solution across an selectively permeable selectively permeable membrane.membrane.

f. Passive Transportf. Passive Transport

• Passive Transport is the Passive Transport is the movement of ions or molecules movement of ions or molecules across a membrane without the across a membrane without the expenditure of energy. Diffusion expenditure of energy. Diffusion and osmosis are examples of and osmosis are examples of passive transport.passive transport.

g. Thermal Motiong. Thermal Motion

• Thermal Motion is the constant Thermal Motion is the constant random movement of particles in random movement of particles in a liquid or gas resulting from the a liquid or gas resulting from the absorption of heat from the absorption of heat from the particles' surroundings. The particles' surroundings. The more heat absorbed the faster more heat absorbed the faster the speed of the particle.the speed of the particle.

h. Concentration Gradienth. Concentration Gradient

• Concentration Gradients - A Concentration Gradients - A concentration gradient exists concentration gradient exists when two or more solutions of when two or more solutions of differing concentrations are differing concentrations are separated by a membrane. separated by a membrane.

i. Solutioni. Solution

• Solution(s) is a homogeneous mixture Solution(s) is a homogeneous mixture of two (or more) forms of matter. of two (or more) forms of matter.

• The components of solutions are The components of solutions are called solute and solvent.called solute and solvent.

• In living systems the most common In living systems the most common types of solutions are a solid types of solutions are a solid dissolved in water (such as salt dissolved in water (such as salt water) or a gas dissolved in water (for water) or a gas dissolved in water (for example oxygen dissolved in water).example oxygen dissolved in water).

2.2. What happens to particles as temperature What happens to particles as temperature increases? Why? How does this influence increases? Why? How does this influence diffusion?diffusion?

• What happens to particles as What happens to particles as temperature increases?temperature increases?

• They move faster.They move faster.

• Why? Why?

• They absorb energy from their They absorb energy from their surroundings.surroundings.

• How does this influence diffusion? How does this influence diffusion?

• It increases the rate of diffusionIt increases the rate of diffusion

3.3. Thermal motion is random. True or false? Thermal motion is random. True or false? What causes a particle to change What causes a particle to change direction?direction?

• Thermal motion is random. True or Thermal motion is random. True or false?false?

• TrueTrue

• What causes a particle to change What causes a particle to change direction?direction?

• Bumping into other particles or Bumping into other particles or objects.objects.

3. What are the two consequences of 3. What are the two consequences of continuous random molecule movement?continuous random molecule movement?

1.1.molecules tend to move away molecules tend to move away (disperse) from centers of (disperse) from centers of concentrationconcentration

2.2.molecules of different types tend to molecules of different types tend to intermix.intermix.

4. What is the end result of dispersion of 4. What is the end result of dispersion of molecules (like perfume) from a point of molecules (like perfume) from a point of high concentration?high concentration?

• They eventually become evenly They eventually become evenly distributeddistributed

5. What is a homogeneous 5. What is a homogeneous mixture?mixture?

• A mixture that has an even A mixture that has an even distribution of all molecules.distribution of all molecules.

6 Name two properties of diffusion for like 6 Name two properties of diffusion for like and unlike particles.and unlike particles.

1.1.Unlike molecules will intermix to Unlike molecules will intermix to form a homogeneous solutionform a homogeneous solution

2.2. Like particles will spread from an Like particles will spread from an area of high concentration to an area of high concentration to an area of low concentrationarea of low concentration

7. In the example of NaCl in water, why do 7. In the example of NaCl in water, why do water and NaCl behave separately?water and NaCl behave separately?

They each follow concentration gradients high to low but they move in opposite directions

8. Why are the terms diffusion and osmosis 8. Why are the terms diffusion and osmosis used to describe the behaviour?used to describe the behaviour?

• Diffusion describes the movement of Diffusion describes the movement of NaCl particles from areas of high NaCl particles from areas of high concentration to areas of lower concentration to areas of lower concentration concentration

and and

• Osmosis describes the movement of Osmosis describes the movement of water from areas of high concentration water from areas of high concentration to areas of lower concentrationto areas of lower concentration

9 Define the term 9 Define the term permeable membrane.permeable membrane. Is cellophane permeable or impermeable?Is cellophane permeable or impermeable?

• A permeable membrane – a A permeable membrane – a membrane that allows molecules to membrane that allows molecules to pass through itpass through it

• Yes cellophane is permeable – to ions Yes cellophane is permeable – to ions and small moleculesand small molecules

10. For the example #3 given, describe the 10. For the example #3 given, describe the concentration gradients for the NaCl and concentration gradients for the NaCl and water. Which way will molecules move?water. Which way will molecules move?

• Water will move down its concentration gradient form high to low and will move from side A to side B•NaCl will also move down its concentration gradient from high to low and will move from side B to side A

11. When does diffusion stop? Does all 11. When does diffusion stop? Does all movement of particles stop at this point? movement of particles stop at this point? Why or why not?Why or why not?

• Diffusion stops when the Diffusion stops when the concentration on each side of the concentration on each side of the permeable membrane is equal.permeable membrane is equal.

• Movement still occurs but there is no Movement still occurs but there is no net movement of particles across the net movement of particles across the permeable membranepermeable membrane

12 In example #4, what causes the 12 In example #4, what causes the concentration gradient to occur? Identify concentration gradient to occur? Identify the hypertonic solution and the hypotonic the hypertonic solution and the hypotonic solution.solution.

13. What direction of particle diffusion 13. What direction of particle diffusion occurs when a concentration gradient exists occurs when a concentration gradient exists across a permeable membrane?across a permeable membrane?

• As long as the membrane is As long as the membrane is permeable to the solute, it will move permeable to the solute, it will move from high to low, and water (the from high to low, and water (the solvent) from high to low – in solvent) from high to low – in opposite directionopposite direction

14. What does the term isotonic mean? 14. What does the term isotonic mean? Why does it indicate the end of diffusion Why does it indicate the end of diffusion

• Isotonic means both solutions on Isotonic means both solutions on either side of the membrane have either side of the membrane have equal concentrations of soluteequal concentrations of solute

15. What is a selectively permeable 15. What is a selectively permeable membrane?membrane?

• A membrane that allows some A membrane that allows some particles to pass through it but not particles to pass through it but not othersothers

16. In example#5, why is osmosis the only 16. In example#5, why is osmosis the only type of diffusion? type of diffusion?

• The membrane is permeable to The membrane is permeable to water but not the other molecule, water but not the other molecule, therefore water is the only part of therefore water is the only part of the solution to move from an area of the solution to move from an area of high to an area of low concentrationhigh to an area of low concentration

17. Explain why the final result of 17. Explain why the final result of example#5 may not result in isotonic example#5 may not result in isotonic solutions on either side of the membrane.solutions on either side of the membrane.

Isotonic solutions will not occur Isotonic solutions will not occur because gravity will prevent the because gravity will prevent the water level on side A from rising, water level on side A from rising, thus preventing enough osmosis to thus preventing enough osmosis to create equal concentrations of solute create equal concentrations of solute on either side of the membraneon either side of the membrane