Diffusion  Catalyst: 1. What is the function of the cell membrane? 2. It was cold last night, so Ms. S turned on the heater in her house. But her roommate accidentally left the front door open. Describe what happened to the temperature in Ms. S’s house and explain why. Be specific! FIRST FIVE.

Agenda  Catalyst  Solutions  What’s Diffusion? + Demos!  Guided Practice  Independent Practice  EQ

Objectives  By the end of the period, 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 food coloring and a beaker of tap water.  Which has the higher concentration of color?  Predict what will happen if I put a couple of drops of the food coloring 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!  It stinks in here.  AIRSPRAY  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 (“Semi- permeable”)

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

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 GATORADE, OR ANY OTHER EXAMPLE WE HAVE DISCUSSED IN CLASS TODAY.

Guided Practice – Ms. S’s Thinking The diagram to the right shows two cells, separated by a semi-permeable membrane.  How will the solute move, according to diffusion? This membrane is permeable to solution.

Guided Practice – Ms. S’s Thinking The diagram to the right shows two cells, separated by a semi-permeable membrane.  How will the solute move, according to diffusion? 72% Sugar Solution 34% Sugar Solution

Guided Practice – Ms. S’s Thinking The diagram to the right 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? 85% solute 55% solute

Guided Practice – Ms. S’s Thinking The diagram to the right shows two cells, separated by a semi-permeable membrane. 41% solute 38% solute  How will the solute move, according to diffusion?  When will net movement of the solute stop?

Guided Practice – Ms. S’s Thinking We know what will happen to the solutions in equilibrium…  Use words to DESCRIBE it.  When will net movement of the solute stop? 39.5% solute

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

Independent Practice  Complete the worksheet on your own.

SiLENT Exit Question The diagram to the right 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! This membrane is permeable to the solute.