If you mix 44 mL of 0.05 M K2HPO4 with 24 mL of 0.05 M KH2PO4, what % of the PO4 buffer is in the K2HPO4 form?

1 answer

To determine the percentage of the PO4 buffer in the K2HPO4 form, we first need to calculate the moles of K2HPO4 and KH2PO4 in the given volumes.

The number of moles can be calculated using the formula:

moles = concentration * volume

Moles of K2HPO4:
0.05 M * 44 mL = 2.2 mmol

Moles of KH2PO4:
0.05 M * 24 mL = 1.2 mmol

To calculate the percentage of the PO4 buffer in the K2HPO4 form, we need to compare the moles of K2HPO4 to the total moles of phosphate buffer used.

Total moles of phosphate buffer = moles of K2HPO4 + moles of KH2PO4
Total moles of phosphate buffer = 2.2 mmol + 1.2 mmol = 3.4 mmol

Percentage of PO4 buffer in K2HPO4 form = (moles of K2HPO4 / total moles of phosphate buffer) * 100%
Percentage of PO4 buffer in K2HPO4 form = (2.2 mmol / 3.4 mmol) * 100%
Percentage of PO4 buffer in K2HPO4 form = 64.71%

Therefore, approximately 64.71% of the PO4 buffer is in the K2HPO4 form.