Question
A buffer solution of volume 100.0 mL is 0.150 M Na2HPO4(aq) and 0.100 M KH2PO4(aq). Refer to table 1.
(a) What are the pH and the pH change resulting from the addition of 80.0 mL of 0.0500 M NaOH(aq) to the buffer solution?
pH
pH change (include negative sign if appropriate)
(b) What are the pH and the pH change resulting from the addition of 10.0 mL of 1.0 M HNO3(aq) to the initial buffer solution?
pH
pH change (include negative sign if appropriate)
So I found the pH of the initial buffer solution to be 7.38 (using pka2=7.21). I am not sure how to set up this problem to add the NaOH to the buffer solution
(a) What are the pH and the pH change resulting from the addition of 80.0 mL of 0.0500 M NaOH(aq) to the buffer solution?
pH
pH change (include negative sign if appropriate)
(b) What are the pH and the pH change resulting from the addition of 10.0 mL of 1.0 M HNO3(aq) to the initial buffer solution?
pH
pH change (include negative sign if appropriate)
So I found the pH of the initial buffer solution to be 7.38 (using pka2=7.21). I am not sure how to set up this problem to add the NaOH to the buffer solution
Answers
for part a I tried using the HH equation, found moles of NaOH and used that for [base] and moles Na2HPO4 as [acid]...i used pKa 7.21...that was incorrect. For part b I used a similar method...plugging in HNO3 as the [acid] and Na2HPO4 moles as [base]
the other pka values for H3PO4 are:
Ka1 = 7.6E-3 ...... pKa1= 2.12
Ka2 = 6.2E-8 ...... pKa2= 7.21
Ka3 = 2.1E-13 .....pKa3= 12.68
the other pka values for H3PO4 are:
Ka1 = 7.6E-3 ...... pKa1= 2.12
Ka2 = 6.2E-8 ...... pKa2= 7.21
Ka3 = 2.1E-13 .....pKa3= 12.68
I figured out the correct new pH for each respective part, but apparently the initial pH i found for the buffer solution is incorrect. I just need help in figuring that so I can calculate the change.
I initially thought the buffer pH was 7.38. Thanks!
I initially thought the buffer pH was 7.38. Thanks!
NVM i was using the pKA instead of pH....i had it right afterall...guess it's just time for bed....
what's the answer then?
Related Questions
What is pH buffer of 0.1 mol L-1 Na2HPO4/O.15 mol L-1 KH2PO4?
KH2PO4?
Given Ka(H2PO4-) = 6.2 x 10...
Calculate the pH of a buffer solution obtained by dissolving 16.0 g of KH2PO4(s) and 27.0 g of Na2HP...
A buffer solution of volume 100.0 mL is 0.140 M Na2HPO4(aq) and 0.120 M KH2PO4(aq). What are the pH...
calculate the pH of a buffer solution obtained by dissolving 18.0g of KH2PO4 (s) and 34.0g of Na2HPO...