Science Experiment - Diffusion Through a Membrane

[TheSasBreeze]

does the iodine go into the dialysis tubing because of a lower concentration in the starch or because it can fit through the spaces in the tubing and then bonds to the starch which are too big to fit through the tubing? some links would be good too!!! thanks for the video! :)

[TheMajorGator]

where were the starch molecules expected to move and why

[DarkAngelCullen]

Why Iodine..and not Bromine liquid?... ;D

[crazydude413968]

we did this in sciense but i forgot how so i googled it

[LMH1177]

horrible audio quality, i am quite disapionted in this outrageous video of science materials and i will not stand for this monstrosity which is this educational video apparatus.

[Narzonia]

That looks like a condom

[Edeferent]

Thanks for the video.

A good follow up would have been to test the starch solution and the iodine and water solution with Benedict's reagent afterwards to test for the reducing sugar.

[bigsbee]

Also the reason why the iodine solution in the jar did not turn purple as well is because the starch molecules are too large to pass through the semi permeable membrane whereas the iodine and water molecules are smaller and can easily pass through.

[Gabykaulitz49]

Is the plastic baggie selectively permeable?

[ThePooeater2]

Iodine helps you from the radioactivity from Japan.Drink it.

[PrabaniLiyaz]

omg this was soo helpful...

[millerhorses]

So is this a hypertonic solution or hypotonic??

[AutumnxDay]

Thanks for this video! I did this same experiment, but stupidly forgot to note down results and my prac is due on Monday soooooooooo.. I was desperate to find it.

[Mitch3lT0mas]

I did this in science class yesterday.

[PDiddyindie107]

@Mitch3lT0mas I did this in science class yesterday too! But you did this in science class yesterday a month ago, lol

[k1ngkung6]

i don't quite understand why the starch in the bag turned blue? did the iodine diffusion into the bag? I know that the starch molecules are too big to pass through the membrane so does the iodine diffuse into the bag because there is a greater concentration of iodine outside of the bag which causes the iodine to diffuse into the bag? sorry, im a noob

[aaronyanfan123]

@k1ngkung6 the iodine substance diffused into the bag because there is a higher concentration of iodine solution compared to the concentration of starch in the bag. Therefore, the starch turned blu in colour as starch reacts to iodine. Hope this helps! ^^

[YMTEAARMHNJ]

@aaronyanfan123

No, that's wrong. The iodine diffused into the bag because there is a higher concentration of iodine outside of the bag than the concentration of IODINE, not starch, within the bag. In fact, the bag contains no iodine potassium iodide at all to start off with! One may not apply a single case of high to low diffusion to two different solutes.

[YMTEAARMHNJ]

@YMTEAARMHNJ

Once inside the bag, the iodine does not leave because it bonds to starch, which is too large a molecule to exit the bag through dialysis tubing pores. The bonding causes the color inside the bag to change. Remember: diffusion means that for any one solute, movement will occur down its concentration gradient - solute will go from areas of high to low concentration. Also keep in mind that molecules that are too big will not pass through pores that are smaller.

[MrLembesis]

@aaronyanfan123 NO. The iodine diffused into the bag because iodine is small enough to pass through spaces in the tubing where as starch molecules are too large to fit through. If you reverse the experiment (put the iodine in the tubing and the starch on the outside) you will see the iodine once again pass through the tubing.

[cbuxt144]

@k1ngkung6

yes, the iodine diffused in. You are not a noob. You are a rock star.

[meganewbies]

Thanks for this experiment :)

[iPhoneanator]

Where did you get you semipermeable membrane? I am looking for one that will allow water to pass and not salt... Do you know where I can find one?

[hematitecrow]

@iPhoneanator any cellophane paper.

[brunojumbey]

hey, can you tell me what kind of starch is in the solution?

[lablover8]

@brunojumbey u dont need to.

[christean1830]

thx, i missed this lab, helped a lot :)