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Natural Buffer System (1 Viewer)
- Thread starter jackc91
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supanerd
New Member
Hello,
The carbonic acid/bicarbonate buffer system is so exciting because it's so important for your blood! Without it, your pH could change to a point where your enzymes don't function and you die from your own body's toxicity.
But that's besides the point, it's just exciting when what you learn in chem has a connection to something important in life =P
To answer your question, if you've learnt about buffer systems, you'll know that they involve a weak acid and it's conjugate base. You would have also learnt Le Chatelier's principle by now (a system in dynamic equilibrium, which is disturbed would shift to the side which would most minimise the disturbance). Thus, when we have the equilibrium of the weak acid and it's conjugate base (in this case, H2CO3 and HCO3), the decrease in pH (high conc. of Hydrogen protons) would cause the equilibrium to shift to the left, making more H2CO3, decreasing the amount of H+ and thus decreasing the acidity. If there is an increase in pH (low conc. of H+), the equilibrium would shift to the right to make more H+ ions, again minimising the disturbance and balancing the pH once again.
When it comes to blood, the increase in acidity would be caused by CO2 gas bonding with the water in your blood to form H2CO3. Too much of CO2 will make your blood acidic, which is why getting rid of carbon dioxide in your body is so important!
You might do an experiment with acetyl acid and it's conjugate base, adding acid and base to it. You'll see that the pH would hardly change compared to when you add the acid or base to other solutions. Which is really cool!
Remember, though, that the buffer system is not infinite, as in if you add HEAPS of acid/base, it wouldn't stabilise it. The large amount would be out of it's capacity and there would be a larger increase/decrease in pH.
Hope it helps!
The carbonic acid/bicarbonate buffer system is so exciting because it's so important for your blood! Without it, your pH could change to a point where your enzymes don't function and you die from your own body's toxicity.
But that's besides the point, it's just exciting when what you learn in chem has a connection to something important in life =P
To answer your question, if you've learnt about buffer systems, you'll know that they involve a weak acid and it's conjugate base. You would have also learnt Le Chatelier's principle by now (a system in dynamic equilibrium, which is disturbed would shift to the side which would most minimise the disturbance). Thus, when we have the equilibrium of the weak acid and it's conjugate base (in this case, H2CO3 and HCO3), the decrease in pH (high conc. of Hydrogen protons) would cause the equilibrium to shift to the left, making more H2CO3, decreasing the amount of H+ and thus decreasing the acidity. If there is an increase in pH (low conc. of H+), the equilibrium would shift to the right to make more H+ ions, again minimising the disturbance and balancing the pH once again.
When it comes to blood, the increase in acidity would be caused by CO2 gas bonding with the water in your blood to form H2CO3. Too much of CO2 will make your blood acidic, which is why getting rid of carbon dioxide in your body is so important!
You might do an experiment with acetyl acid and it's conjugate base, adding acid and base to it. You'll see that the pH would hardly change compared to when you add the acid or base to other solutions. Which is really cool!
Remember, though, that the buffer system is not infinite, as in if you add HEAPS of acid/base, it wouldn't stabilise it. The large amount would be out of it's capacity and there would be a larger increase/decrease in pH.
Hope it helps!
Thankyou very much,
ok so from what I understand, the equilibirium will shift to increase the amount of H2CO3 if the pH decreases. I am still a little confused as to increase the pH more H2CO3 is created, yet H2CO3 is an acid.
ok so from what I understand, the equilibirium will shift to increase the amount of H2CO3 if the pH decreases. I am still a little confused as to increase the pH more H2CO3 is created, yet H2CO3 is an acid.
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HCO3- + H+ <=> H2CO3
by shifting the equilibrium to the right (ie more carbonic acid) we reduce the concentration of H+ .'. increase the pH. Note that the bicarbonate is acting as a base. H2CO3 would usually decrease a solutions pH when it is added, as it donates hydrogen ions, but in this case it is not being introduced, it is being formed (a net reduction in hydrogen ions = increase of pH).
by shifting the equilibrium to the right (ie more carbonic acid) we reduce the concentration of H+ .'. increase the pH. Note that the bicarbonate is acting as a base. H2CO3 would usually decrease a solutions pH when it is added, as it donates hydrogen ions, but in this case it is not being introduced, it is being formed (a net reduction in hydrogen ions = increase of pH).
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supanerd
New Member
Yup, that's exactly it.
Remember that concentration of H+ is what affects the pH here. Acids decrease pH because of their ability to dissociate their ions, releasing H+ which decreases the pH =) Thus here, if you want to increase the pH, you want to shift the equilibrium to the side which uses up the H+, which is the carbonic acid side.
Remember that concentration of H+ is what affects the pH here. Acids decrease pH because of their ability to dissociate their ions, releasing H+ which decreases the pH =) Thus here, if you want to increase the pH, you want to shift the equilibrium to the side which uses up the H+, which is the carbonic acid side.
