Water and its relation Water and its relation toto

Osmosis & DiffusionOsmosis & Diffusion

Living cells contain aqueous Living cells contain aqueous (water) solution and they are (water) solution and they are

surrounded by aqueous solutionssurrounded by aqueous solutions

If the concentration of dissolved If the concentration of dissolved substances (solutes) is not the same substances (solutes) is not the same inside and outside the cell –inside and outside the cell –

A process called A process called osmosisosmosis occurs occurs

OsmosisOsmosis: : the movement of the movement of water moleculeswater molecules from an from an

area with less solutes (low concentration) to area with less solutes (low concentration) to an area with more solutes in the solution an area with more solutes in the solution (high concentration)(high concentration)

The The waterwater passes through the semi-permeable passes through the semi-permeable membrane until the concentration of the membrane until the concentration of the solutes is the same on both sides.solutes is the same on both sides.

Osmosis is the Osmosis is the movement of water movement of water (red dots) through (red dots) through a semi permeable a semi permeable membrane to a membrane to a higher higher concentration of concentration of solutes (blue dots).solutes (blue dots).

What are semi-permeable What are semi-permeable membranes?membranes?

Those membranes that allow the solvent (liquid), Those membranes that allow the solvent (liquid), but not the solutes to pass from one side of the but not the solutes to pass from one side of the membrane to anothermembrane to another

EX: egg, cellophane, and cell membranesEX: egg, cellophane, and cell membranes

In these membranes the pores are large enough In these membranes the pores are large enough for water to pass through but too small for other for water to pass through but too small for other compounds to passcompounds to pass

ExamplesExamples

Sailor died from dehydration due to the Sailor died from dehydration due to the high concentration of salt in the seawater. high concentration of salt in the seawater.

After drinking the seawater the high After drinking the seawater the high concentration of salt caused the water to concentration of salt caused the water to travel out of his cells.travel out of his cells.

This caused the cells to dehydrate or This caused the cells to dehydrate or shrinkshrink

How do we How do we get pickles?get pickles?

Living cells contain aqueous solutions – Living cells contain aqueous solutions – intracellular fluidintracellular fluid

The cells are also surrounded by an The cells are also surrounded by an aqueous solution-aqueous solution-

intercellular fluidintercellular fluid Cells function and survive by keeping Cells function and survive by keeping

the concentration within and around the the concentration within and around the cell approximately the same.cell approximately the same.

If the concentration of solute in the fluid If the concentration of solute in the fluid surrounding the cell is higher than inside the surrounding the cell is higher than inside the cell the solution is cell the solution is hypertonichypertonic

Water will travel out of the cell through the Water will travel out of the cell through the membranemembrane - crenation - crenation

Red Blood Cells in a Hypertonic Red Blood Cells in a Hypertonic SolutionSolution

Hypertonic SolutionHypertonic Solution

The word "The word "HYPERHYPER" " means more, in this case means more, in this case there are more solute there are more solute (salt) molecules outside (salt) molecules outside the cell, which causes the cell, which causes the water to be sucked in the water to be sucked in that direction.that direction.

If the concentration of the solute outside the If the concentration of the solute outside the cell is less than inside the cell it is called a cell is less than inside the cell it is called a hypotonichypotonic solution. solution.

HemolysisHemolysis will occur – additional water will will occur – additional water will travel into the cell causing it to swell and travel into the cell causing it to swell and rupture.rupture.

Red Blood Cells in a Hypotonic Red Blood Cells in a Hypotonic SolutionSolution

Hypotonic SolutionHypotonic Solution

The word "The word "HYPOHYPO" " means less, in this means less, in this case there are less case there are less solute (salt) solute (salt) molecules outside the molecules outside the cell, so water will cell, so water will move into the cell.move into the cell.

When the fluids have the same concentrations When the fluids have the same concentrations they are called they are called isotonicisotonic

EX: when fluids are administered to a patientEX: when fluids are administered to a patient

Red Blood Cells in an Isotonic Red Blood Cells in an Isotonic SolutionSolution

Isotonic SolutionIsotonic Solution

If the concentration of If the concentration of solute (salt) is equal solute (salt) is equal on both sides, the on both sides, the water will move back water will move back in forth but it won't in forth but it won't have any result on the have any result on the overall amount of overall amount of water on either side.water on either side.

""ISOISO" means the " means the samesame

What is Diffusion?What is Diffusion?

Diffusion is the natural tendency of Diffusion is the natural tendency of molecules to flow from higher molecules to flow from higher concentrations to lower concentrations concentrations to lower concentrations

The rate of diffusion depends on the The rate of diffusion depends on the weight of the molecules—heavy molecules weight of the molecules—heavy molecules diffuse more slowly than light molecules. diffuse more slowly than light molecules.

Diffusion of GasesDiffusion of Gases A bottle of perfume opened in one A bottle of perfume opened in one

corner of a room would slowly fill the corner of a room would slowly fill the room room

Molecules disperse from a concentrated Molecules disperse from a concentrated source, the newly opened bottle, until source, the newly opened bottle, until they are evenly distributed throughout they are evenly distributed throughout the roomthe room

Smell of freshly baked cookiesSmell of freshly baked cookies

Diffusion of LiquidsDiffusion of Liquids

When two When two fluidsfluids mix together without any mix together without any help from us. help from us.

We can explain this using the idea that We can explain this using the idea that particles move. particles move.

Instead of the Instead of the particlesparticles moving around moving around and mingling with particles of the same and mingling with particles of the same material,material, they move around and mingle they move around and mingle with particles of the other material as wellwith particles of the other material as well

How Diffusion of Liquid in How Diffusion of Liquid in Liquid WorksLiquid Works

Add a drop of food coloring in a container Add a drop of food coloring in a container of water.of water.

The color will “diffuse” or disperse The color will “diffuse” or disperse throughout the entire sample until the throughout the entire sample until the sample is a uniform color.sample is a uniform color.

http://paer.rutgers.edu/pt3/movies/mixing2.mov

The solute (solid) dissolving in the solvent The solute (solid) dissolving in the solvent is also an example of diffusion.is also an example of diffusion.

The water “attacks” the solute which The water “attacks” the solute which eventually dissolve.eventually dissolve.

What are ways that this process in What are ways that this process in increased?increased?

How Diffusion of Solid in How Diffusion of Solid in Liquid WorksLiquid Works

How Diffusion of Solid in How Diffusion of Solid in Liquids WorksLiquids Works

Diffusion across a MembraneDiffusion across a Membrane

Selectively Permeable membranes – Selectively Permeable membranes –

Living membranes alter what may pass Living membranes alter what may pass through at any given time through at any given time

Diffusion of CODiffusion of CO22 and O and O22 in the Lung in the Lung

Kidney DialysisKidney Dialysis

ReviewReview

OsmosisOsmosis: the movement of : the movement of water water moleculesmolecules from an area of low solute from an area of low solute concentration to an area of high concentration to an area of high solute concentration. solute concentration.

The The waterwater passes through the semi- passes through the semi-permeable membrane until the permeable membrane until the concentration of the solutes is the concentration of the solutes is the same on both sides.same on both sides.

DiffusionDiffusion is the natural tendency of is the natural tendency of moleculesmolecules to flow from higher to flow from higher concentrations to lower concentrations concentrations to lower concentrations

Movement may be of molecules or ions Movement may be of molecules or ions across a semi-permeable membraneacross a semi-permeable membrane

Depends on molecular size, ionic Depends on molecular size, ionic charge, and molecular solubility (ability charge, and molecular solubility (ability of solute to dissolve in solvent)of solute to dissolve in solvent)

1% salt (low concentration) in the bag

10% salt (high concentration) surrounding the bag

Which way does the water move?

Diffusion or Osmosis?Diffusion or Osmosis?

Iodine solution in the bag

Starch solution surrounding the bag.

What do you predict will happen?

Diffusion or Osmosis?Diffusion or Osmosis?

Lab Set-upLab Set-up