The body\'s chemical buffer system consists of three individual buffers: the car
ID: 535086 • Letter: T
Question
The body's chemical buffer system consists of three individual buffers: the carbonate/carbonic acid buffer, the phosphate buffer and the buffering of plasma proteins.
In all multicellular organisms, the fluid within the cell and the fluids surrounding the cells have a characteristic and nearly constant pH. This pH is maintained in a number of ways, and one of the most important is through buffer systems.
The phosphate buffer system operates in the internal fluid of all cells.
Find the pH of this buffer after 0.070 mol of OH- was added to 1.00 l of this buffer containing 0.820 M is H2PO4- and 0.730 HPO42- (Ka1 = 7.2x10-3; Ka2 = 6.1x10-8; Ka3 = 4.2x10-13) assume no volume change due to the addition of OH-
Explanation / Answer
the henderson hasselbalch equation:
pH = pKa + Log [conjugate base]/[weak acid]
Here use Ka2 = 6.1x10-8
pKa 2= - log Ka2
= - log 6.1x10-8
= 7.2
If add 0.070 mol OH-
New moles of acids= 0.820 M is H2PO4- - 0.070 mole = 0.75 mole
New moles of base= 0.730 HPO42- + 0.070 = 0.80
Therefore;
pH = pKa + Log [conjugate base]/[weak acid]
pH = 7.2+ Log [0.80]/[0.75]
pH = 7.2+ 0.028
= 7.228
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