Why don't hydrogen ions have osmotic activity in living organisms?

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Discussion Overview

The discussion centers on the osmotic activity of hydrogen ions (H+) in living organisms, exploring why they may not exhibit osmotic behavior in aqueous solutions. Participants examine the implications of ion charge, membrane permeability, and the behavior of H+ in relation to water molecules.

Discussion Character

  • Debate/contested
  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • Some participants question why hydrogen ions cannot pass through semipermeable membranes, suggesting that their positive charge may prevent this.
  • Others propose that charged particles, including hydrogen ions, generally require transport mechanisms to cross membranes.
  • A participant raises the question of why only neutral atoms and molecules can pass membranes, indicating a lack of definitive knowledge on the topic.
  • Concerns are expressed about the osmotic activity of hydrogen ions in water solutions, with one participant questioning the pH range and related H+ concentrations.
  • One participant claims to have received an explanation from a professor, stating that H+ ions bind to water to form H3O+ ions, which do not increase the concentration of particles in water.
  • Another participant challenges this by suggesting that if H+ ions bind to water, they may lower the amount of free water, thus increasing the concentration of other substances.
  • There is speculation that H3O+ ions may behave similarly to water in terms of osmolality, potentially masking the osmotic effects of H+ ions in typical conditions.

Areas of Agreement / Disagreement

Participants express differing views on the osmotic activity of hydrogen ions and their behavior in solutions. There is no consensus on whether H+ ions are osmotically active or how their interactions with water affect osmotic pressure.

Contextual Notes

Participants note various assumptions regarding ion behavior, membrane permeability, and the conditions under which osmotic activity is evaluated, but these remain unresolved within the discussion.

Max123
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Why hydrogen ions dont have osmotic activity in living organisms?
 
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Though I am not good at chemistry, I think hydrogen ion, i.e. proton and proton-neutron core, pass the semipermeable membrane including ones in living organism. Why not ?
 
anuttarasammyak said:
Though I am not good at chemistry, I think hydrogen ion, i.e. proton and proton-neutron core, pass the semipermeable membrane including ones in living organism. Why not ?
Hydrogen ion is positevely charged so they can’t pass the membrane
 
Do you mean any positive charged ions cannot pass membrane or hydrogen ion only ?
 
I think any charged particles cant pass the membrane on its own without some mechanism of transport
 
So your question seems why only neutral atoms and molecules pass the membrane ? I say it in logic. I do not know the facts.
 
anuttarasammyak said:
So your question seems why only neutral atoms and molecules pass the membrane ? I say it in logic. I do not know the facts.
My question is why hydrogen ions arent osmotically active in water solutions
 
Max123 said:
My question is why hydrogen ions arent osmotically active in water solutions

Are you sure they aren't?

Also: what is the pH range of solutions involved? What are related H+ concentrations? What are osmotic pressures related to these concentrations?

And what are typical osmotic pressures related to other ions/substances?

Max123 said:
I think any charged particles cant pass the membrane on its own without some mechanism of transport

A bit too broad statement for my liking, as it depends on the ion and the membrane, but to some extent yes - cell walls are built to be mostly impenetrable.

To some extent that means you are asking "why cars don't get pass the roadblock put there to not allow cars to get through" :wink:
 
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Borek said:
Are you sure they aren't?

Also: what is the pH range of solutions involved? What are related H+ concentrations? What are osmotic pressures related to these concentrations?

And what are typical osmotic pressures related to other ions/substances?



A bit too broad statement for my liking, as it depends on the ion and the membrane, but to some extent yes - cell walls are built to be mostly impenetrable.

To some extent that means you are asking "why cars don't get pass the roadblock put there to not allow cars to get through" :wink:
Well I actually got my answer already from my professor st university and the reason H+ arents osmotically active is that they are immediately binding to water and comprise H3O+ ion and thus they dont increase a concentration of particles in water
 
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Max123 said:
Well I actually got my answer already from my professor st university and the reason H+ arents osmotically active is that they are immediately binding to water and comprise H3O+ ion and thus they dont increase a concentration of particles in water
Then have you known osmotic behaviour of H3O+ ion, which could cease your question ?
 
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  • #11
Max123 said:
Well I actually got my answer already from my professor st university and the reason H+ arents osmotically active is that they are immediately binding to water and comprise H3O+ ion and thus they dont increase a concentration of particles in water

Double-edged explanation, if they bind to water molecules, they lower amount of free water so the concentration of everything goes up.

As I was trying to suggest with my questions above: my bet is that they are osmotically active, just in typical conditions (pH somewhere between 5-8) this effect is masked by other ions/substances, present in much higher concentrations.
 
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  • #12
Borek said:
Double-edged explanation, if they bind to water molecules, they lower amount of free water so the concentration of everything goes up.

As I was trying to suggest with my questions above: my bet is that they are osmotically active, just in typical conditions (pH somewhere between 5-8) this effect is masked by other ions/substances, present in much higher concentrations.
 
  • #13
Well, my professor said thst H3O+ behaves exactly like water and doesnt increase osmolality
 
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