Diffusion  Catalyst:  What is the function of the cell membrane?  It was hot last night, so Teyhones turned on the air conditioning in his house. But his sister, Perrinika, accidentally left the front door open. What happened to the temperature in Teyhones’ house, and why? Be specific! Write in complete sentences! Don’t talk during the Catalyst!

Objectives  By the end of the period, all SWBAT…  Predict the movement of molecules using diffusion

Definitions  Solution = a mixture of solute and solvent  Concentration = measurement of how much solute there is in the solvent  High concentration: lots of solute, compared to solvent  Low concentration: little solute, compared to solvent liquidstufffinal product

Can you give me some examples?  Fill in the blanks: in _______________, the _______________ is mixed into the _______________. SOLUTE SOLVENT SOLUTION

HIGHLOW Solutes What do you think would happen if we opened up a path between these two boxes? Concentration 75% Solute 5% Solute

Diffusion  Key Point #1: Diffusion is the net movement of molecules from an area of high concentration to an area of low concentration  Molecules are always moving  They bump into each other  This knocks molecules from the area of high concentration into the area of low concentration

Diffusion 75% Solute 25% Solute 65% Solute 35% Solute 50% Solute

Diffusion  Key Point #2: Diffusion continues until there is equilibrium  Equilibrium = The point at which two connected solutions have equal concentrations

Diffusion Diffusion moves toward equilibrium 75% Solute 25% Solute 65% Solute 35% Solute 50% Solute

Demonstration  In notes answer these two questions  I have a bottle of ink and a beaker of tap water.  Which has the higher concentration of ink?  Predict what will happen if I put a couple of drops of ink in the beaker of the water.  We will check in on this later on today…

 Solutes move even when concentration is equal “Net movement” of molecules 50% Solute

Demo!  LYSOL  Molecules move from HIGH concentration to LOW concentration

All this is great, but…  But what happens when you can’t just move from one area to another  Like there might be something that controls what goes in and out…  Like a cell membrane…

Cell Membranes  Key Point #3: Cell membranes are selectively permeable  Selectively permeable = only let certain things pass through

Selectively Permeable Cell Membrane  Cell membranes control what enters and what leaves the cell  Small things diffuse in, because they can fit between the gaps in the cell membrane  Big things are kept out, because they cannot

The diagram below shows a cells, surrounded by a semi-permeable membrane, in the bloodstream.  How will the solute move, according to diffusion? Example 10% Sugar Solution 80% Sugar Solution

Smelly Balloons! What is going on here!? Explain how this is diffusion  What does the balloon represent?  What about the vanilla?

Guided Practice  Provide your own example of a solution. Then, state what the solute and solvent in it are.  DO NOT USE HOT CHOCOLATE, OR ANY OTHER EXAMPLE WE HAVE DISCUSSED IN CLASS TODAY.

Guided Practice The diagram below shows two cells, separated by a semi-permeable membrane.  How will the solute move, according to diffusion?

The diagram below shows two cells, separated by a semi-permeable membrane.  How will the solute move, according to diffusion? Guided Practice 72% Sugar Solution 34% Sugar Solution

The diagram below shows two cells, separated by a semi-permeable membrane.  How will the solute move, according to diffusion? Guided Practice 55% solute 85% solute

The diagram below shows two cells, separated by a semi-permeable membrane.  Draw what this situation will look like after diffusion has FINISHED. Guided Practice 38% solute 41% solute

Guided Practice  “Diffusion causes solutions to move toward equilibrium.”  Describe what this means in your own words, and in complete sentences.

Exit Question The diagram below shows two cells, separated by a semi-permeable membrane.  How will the solute move, according to diffusion?  When will net movement of the solute stop? Use the vocabulary we learned today! Write in complete sentences! Don’t talk during the Exit Question!