A buffer solution is prepared by dissolving 0.200 mol of NaH2PO4 and 0.100 mol of NaOH in enough water to make 1.00 L of solution. What is the pH of the H2PO4- / HPO42- buffer if the Ka2 = 6.2 * 10^-8
A) 7.71
B) 7.21
C) 7.51
D) 6.91
The correct answer is B) 7.21. Please explain how it is 7.21. I know pKa is 7.21, but I don't fully understand the steps of this question.