Welcome Guest Search | Active Topics |

Tag as favorite
altius 2 covid Bio/biochem section question 10
#1 Posted : Sunday, July 05, 2020 10:38:21 PM
Rank: Newbie

Groups: Registered
Joined: 5/13/2020
Posts: 8

Thanks: 0 times
Was thanked: 0 time(s) in 0 post(s)
In this question I thought there would be a net flow of water (Since ions dont usually flow through physiological membranes). Bit the question used a formula that I have never heard of (P=iMRT) to calculate osmotic pressure to solve the question and found there was no net movement of ions. Is there another way to approach this question to get to the correct answer? Or will we be going over this formula in one of the classes?
#2 Posted : Monday, July 06, 2020 5:43:29 PM
Rank: Advanced Member

Groups: Registered
Joined: 6/24/2019
Posts: 250

Thanks: 0 times
Was thanked: 0 time(s) in 0 post(s)

Recall that the net flow of water requires a concentration gradient.

Here we have 100 nM of Na3PO4 and 200 nM of NaCl.

At first, this looks like a differential concentration gradient, but we have to keep in mind that these ions will dissociate which will account for how concentrated the solution is.

The dissociations are as follows:

Na3PO4 --> 3Na+ + PO43- (4 ions)

NaCl --> Na+ + Cl- (2 ions)

Therefore the effective concentrations are as follows:

100 nM x 4 ions = 400 nM

200 nM x 2 ions = 400 nM

Because these concentrations are the same, there will be no net water flow. The formula they have used for this account for this in the same way, I think it is covered at one point in the lessons. That being said, what I've done is essentially the same as the formula (i refers to the number of ion formed in solution, M is molarity and RT is a constant).

Please let me know if this is unclear.
Users browsing this topic
Tag as favorite
You cannot post new topics in this forum.
You cannot reply to topics in this forum.
You cannot delete your posts in this forum.
You cannot edit your posts in this forum.
You cannot create polls in this forum.
You cannot vote in polls in this forum.

Clean Slate theme by Jaben Cargman (Tiny Gecko)
Powered by YAF | YAF © 2003-2009, Yet Another Forum.NET
This page was generated in 0.106 seconds.