Friday- 2/3/12

Homework: Short checkup on Monday on water movement and concentration.

Do you owe me logbook $$$??

Solute= stuff dissolved in a solution ex: sugar, salt

Solvent= liquid doing dissolving in a solutionex: water

Solute Solvent

Which side has a higher solute concentration?

In your own words:• What does concentration mean? (in

terms of solutions) The amount of Solute in a solution.

10 ml of water compared to 1 liter of the same water – which is more concentrated? They have the same concentration. We are not comparing the amount of solute.

Which is more concentrated? 10g of salt in a liter of water compared to 100g of salt in a liter of water.100g of salt is more concentrated because it has more solute.

Entry 2 :WATER ACROSS A MEMBRANE LAB2/3/12

• ON BACK OF EGG DEMO SHEET (write that under the title )

Design a controlled experiment…

…to investigate how a concentrated solution on one side of a membrane affects the movement of water through the membrane.

• Question: How does concentrated solution on one side of a membrane affect the movement of water?

• Hypothesis: (this should answer the question above) Water moves toward higher solute concentration.

We will perform an experiment that would have a concentration difference between two sides of a membrane.MATERIALS: Dialysis tubing (for a model of a cell), Beakers, Sugar solution (sugar and water), Water, String, Pipette, Labels, Scale

SUGAR WATER

WATER

WATER

SUGAR WATER

EXPERIMENTAL CONDITIONS

SUGAR WATER

SUGAR WATER

WATER

WATER

What would be the CONTROL setup?

PREDICTION: (How will you know your hypothesis is true?)

• “IF MY HYPOTHESIS IS SUPPORTED, THE TUBE CONTAINING SUGAR WATER WILL

GAIN MASS WHEN PLACED IN PURE WATER”

Procedure:

1) Tie one end of tubing.2) Place water/sugar water into dialysis tubing.3) Tie other end of tubing then rinse off bag.4) Measure the mass of the dialysis tubing.5) Place into beaker of water/sugar water. 6) Write mass on label and tape on beaker.

Take the mass of tubingThen put into beaker

Tie one end of tubing with string

BEFORE AFTER DIFF.

SUGAR INSIDE/WATER OUTBEFORE AFTER DIFF.

WATER INSIDE/SUGAR OUT

Procedure:

1) Tie one end of tubing.2) Place water/sugar water into dialysis tubing.3) Tie other end of tubing then rinse off bag.4) Measure the mass of the dialysis tubing.5) Place into beaker of water/sugar water. 6) Write mass on label and tape on beaker.

Take the mass of tubingThen put into beaker

Tie one end of tubing with string