Lab Report

Topics: Molecular diffusion, Diffusion, Transport phenomena Pages: 2 (351 words) Published: September 19, 2013
Lab Report

Diffusion is
-One of two kinds of passive transport,
-Diffusion can transport ions from higher concentration to lower concentration region without any other forces. -A net movement of molecules in and out of cell membrane
-Diffusion can be affected by the steepness of the concentration gradient.

Lab question:
Is the rate of diffusion influenced by the presence of second molecule?

Prediction: the rate of diffusion is influenced by the presence of second molecule.

Material:
-Computer
-Vernier computer interface
-Logger Pro
-Vernier Conductivity Probe
-three 18×150 mm test tubes with rack
-1%, 5%, 10% salt water
-400mL beaker
-dialysis tubing, 2.5cm ×12 cm
-Dropper pipet or Beral pipet.
-Stirring rod
-Ring stand and utility clamp

Lab Procedure:
1. Connect the Conductivity Probe to the computer interface, and run Logger. 2. Put beaker on the Ring stand and pour 400ml water into beaker. 3. get 1%, 5%, 10% salt water in to three dialysis tubes

( -Obtain 15 mL of 1%, 5% and 10% salt-water solutions in each tube. -Soak three dialysis tubes into beaker one by one, and tie one end of the dialysis tubes. -Use a Beral pipet, transfer 15 mL of the 1%, 5% and 10% salt water into the dialysis tube -Tie off the other end of tube.)

4. put a weak magnet into the bottom of beaker.
5. wait for 20 sec
6. record by logger pro for 120 sec for 3 times (1%, 5% and 10% salt water each) 7. observe and compare all the data
8. get conclusion
9. Put every thing back and trash all three-dialysis tube.

Questions:

1.The more salt concentration, the higher rate of diffusion will have. 2.my conclusion proved my prediction is right. Almost no difference. 3. 5% to 1% ≈4.819 10% + 1% ≈ 8.886

Conclusions

The diffusion rate of a molecule is influenced by the presence of a second molecule. I proved this by using different salt concentrations and showing the...
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