September 6, 2007 at 4:43 pm #8190tiger-napParticipant
I need to know the three factors which affect the process of diffusion.
So far, I understand that temperature does the whole kinetic energy thing, which gets particles really hyper so they spread faster through a solution or the atmosphere.
But can anyone help me with the other two?
September 6, 2007 at 4:57 pm #75838mithParticipant
Here’s a hint, just because you have energy doesn’t mean that diffusion is going to go on forever…eventually it "stops". Why?
September 7, 2007 at 3:10 am #75858DarbyParticipant
And are you being asked about "regular" diffusion or diffusion through a membrane?
September 7, 2007 at 4:36 pm #75879tiger-napParticipant
Well. Energy runs out because…
The molecules will lose their energy after passing it on or using it up, right?
September 7, 2007 at 7:37 pm #75884
You can’t use energy up – energy cannot be destroyed(first law of thermodynamics)
Google or wikipedia "electrochemical gradient"
September 7, 2007 at 8:49 pm #75886mithParticipant
Let’s say you’re doing laundry. It’s now the rinse cycle.
Your clothes are soapy.
The washer adds pure water.
Soap will diffuse into the water.
Now, why do you suppose additional rinse cycles might be used? Note that not all of the soap comes out, so you’re not getting soapy water and clean laundry. You’re getting soapy water and soapy laundry. You’re getting an equilibrium.
September 8, 2007 at 6:15 pm #75894
you would make a very fun professor to have in class dave
September 8, 2007 at 11:44 pm #75899MichaelXYParticipant
Are you saying I am wearing soapy clothes?
That explains this bubble on the front of my shirt. My wife kept saying it was a beer gut.
September 10, 2007 at 8:57 am #75921dr. dugmoreParticipantquote MrMistery:
comon! you knew wat he ment!
10/10 irrelevants points for you!
im disopointed in you….:(
September 10, 2007 at 9:11 am #75927
actually the important part of that post was the part with the electrochemical gradient.
Besides, I am allowed to post useless things. What are they gonna do, ban me? 😀
September 10, 2007 at 6:36 pm #75945blcr11Participant
So we’re talking simple diffusion of substances across a “standard” lipid bilayer, then. The factors, as I see them, would be temperature, concentration (or concentration gradient), and size. You could toss in solubility in lipids and/or charge, too. Temperature is sort of obvious—the higher the temperature, the faster the molecules move. Small molecules (especially lipophilic, small molecules) are more likely than larger molecules to move across a membrane by passive diffusion driven by a concentration gradient; also, the diffusion constant is inversely proportional to the square root of the molecular weight, so not only is it more difficult for them to enter the bilayer, but larger molecules just move more slowly than smaller ones do. Molecules in passive diffusion spontaneously move from areas of higher to areas of lower concentration until the concentrations in the two regions become equal and there is no longer any concentration gradient to drive the process. Because the interior of the bilayer is essentially hydrocarbon, charged molecules larger than a potassium ion are effectively barred from crossing the membrane passively. Larger charged or polar molecules almost always require some sort active or facilitated transport to get across.
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