Diffusion
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Introduction
What happens to the rate of diffusion as the concentration of salt is increased? Diffusion is the movement of particles from higher chemical concentration to lower chemical concentration. It is readily observed, for example, when dried food like spaghetti is cooked; water molecules diffuse into the spaghetti strings, making them thicker and more flexible. This lab is solely focused on the concentration of sucrose in a potato in relationship to the rate of diffusion.
Experimental Design
Equipment list:
3 15 cm lengths of dialysis tubing
3 400 mL beakers
1% NaCl solution, 10 mL
5% NaCl solution, 10 mL
10% NaCl solution; 10 mL
1 potato with 4 plugs taken out (approx 3cm each)
0.0M Sucrose, 5-10 mL
.33M Sucrose, 5-10 mL
.67M Sucrose, 5-10 mL
1.0M Sucrose, 5-10 mL
1 microscope slide
1 Coverslip
Scalpel
Forceps
Compound Microscope
LabPro
Computer with Logger Pro installed
Vernier Conductivity Probe
Vernier Gas Pressure Sensor
1 Graduated Cylinder; 10 mL
1 Funnel
1 Craft stick
1 Pipet, 1 mL
1 Thermometer
Plastic wrap
1 Onion
1 Cork Borer
Distilled Water
1 Balance
Paper Towels
1 Wash Bottle with dH2O
1 400 mL beaker for waste liquid
1 Beaker for dH2O
Procedure:
Open Lab Pro and set the conductivity probe for 2000 uS/cm
Get 3 400 mL beakers filled with 300 mL of dH2O; label 1%,5%, and 10%
Dry a piece of dialysis tubing and fill with 10 mL of 1% NaCl solution (repeat with 5% and 10%)
Place the tubing in the corresponding beaker and stir slowly for approximately 15 seconds
After stirring start your data collection let it run for 2 minutes
Use LabPro to calculate the rate of diffusion using the line function
Clean the area before proceeding to part 2
Part 2
Set up your Gas Pressure Sensor by connect it to channel 1 of the LabPro
Open the preset data collection table called “22 osmosis”
Cut a piece of string that when tied will still fit around your potato
Use a cork borer to make 4 well spaced hole in the potato 3 cm down
Save the plugs and mark the holes (0.0, .33, .67, and 1.0
Rinse the wells out then blot dry, be careful not to crack the well walls
Fill the 0.0 well with 0.0M sucrose and let it sit for 5 min
Empty the well and refill with fresh 0.0M sucrose
Place the stopper assembly