The body\'s chemical buffer system consists of three individual buffers: the car
ID: 535127 • 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 0.018 mol of H+ was added to 1.00 l of this buffer containing 0.361 M is H2PO4- and 0.568 HPO42- (Ka1 = 7.2x10-3; Ka2 = 6.1x10-8; Ka3 = 4.2x10-13) assume no volume change due to the addition of H+
Explanation / Answer
moles of H2PO4- = 0.361 x 1 = 0.361
moles of HPO42- = 0.568 x 1 = 0.568
moles of H+ added = 0.018 mol (C)
pKa2 = -log (6.1x10-8) = 7.21
pH = pKa + log [salt - C / acid + C]
= 7.21 + log [0.568 - 0.018 / 0.361 + 0.018]
= 7.37
pH = 7.37