Phosphate buffers are commonly used in biological research. If a small amount of
ID: 557203 • Letter: P
Question
Phosphate buffers are commonly used in biological research. If a small amount of strong acid is added to a buffer solution that is 0.700 M H3PO4 and 0.700 M KH2PO4, which of the following statements is true?
Choose one:
A) [H3PO4] will increase, [KH2PO4] will decrease, and pH will slightly decrease.
B) [H3PO4] will increase, [KH2PO4] will decrease, and pH will not change.
C) [H3PO4] will decrease, [KH2PO4] will increase, and pH will slightly decrease.
D) [H3PO4] will decrease, [KH2PO4] will increase, and pH will slightly increase.
E) [H3PO4] will increase, [KH2PO4] will decrease, and pH will slightly increase.
F) [H3PO4] will decrease, [KH2PO4] will increase, and pH will not change
Explanation / Answer
answer :
A) [H3PO4] will increase, [KH2PO4] will decrease, and pH will slightly decrease
explanation :
on addition of strong acid to the buffer . the acid concentration will increases and salt concentration will decreases
so the ratio of salt/ acid will decreases as a results pH decreases
pH = pKa + log [KH2PO4 -C / H3PO4 + C]
here C = acid concentration ( strong)