ATAR Notes: Forum
HSC Stuff => HSC Science Stuff => HSC Subjects + Help => HSC Chemistry => Topic started by: infinityandbeyond on March 24, 2018, 07:17:10 pm
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Hey there,
I don't understand the way our blood maintains its pH. I don't know which equation to use when explaining the equilibrium. What is the name of the weak acid and conjugate base in the blood solution? Is CO2 the weak acid? So confused...
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Hey there,
I don't understand the way our blood maintains its pH. I don't know which equation to use when explaining the equilibrium. What is the name of the weak acid and conjugate base in the blood solution? Is CO2 the weak acid? So confused...
The buffer system in our blood is the conjugate acid base pair of carbonic acid (conjugate acid, it is formed in the blood when the CO2 made from respiration combines with the water in the blood) and the bicarbonate ion (conjugate base, formed when carbonic acid acts as a Bronsted acid and donates a hydrogen ion to water around). Because carbonic acid is a relatively weak acid, it exists in an equilibrium when added to water. The equation is basically carbonic acid + water is in equilibrium with (reversible arrows) hydronium ions and bicarbonate ions.
Using Le Chatelier's principle, when a base is added to this system, i.e. the surroundings become too basic, the equilibrium will shift to the left to produce more of the acid so as to counter the increase in basicity. Similarly, if acidity increases, the equilibrium shifts to the right to produce more of the conjugate base (bicarbonate ion) so as to increase alkalinity and counter the change in pH. Both of these techniques restore the pH to the original, suitable value in blood. It should be noted that they do only however resist small changes in pH. If you add a strong acid like HCl or a strong base like NaOH, the system is likely not to be able to resist the change. The buffer system helps our body in that it provides a consistent pH in the blood so the enzymes can be provided with an optimal pH surroundings and their function isn't interfered with.
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Thank you!! I understand better now. :)