1. A buffer solution contains 0.476 M KH2PO4 and 0.202 M Na2HPO4. Determine the pH change when 0.050 mol HClO4 is added to 1.00 L of the buffer.
pH change = ______
2. Determine the pH change when 0.077 mol HClO4 is added to 1.00 L of a buffer solution that is 0.331 M in CH3COOH and 0.304 M in CH3COO-.
pH after addition − pH before addition = pH change =_____
1)
A buffer solution contains 0.476 M KH2PO4 and 0.202 M Na2HPO4. Determine the pH change when 0.050 mol HClO4 is added to 1.00 L of the buffer.
pKa of H2PO4- = 7.21
pH = pKa + log [Na2HPO4 / KH2PO4]
= 7.21 + log [0.202 / 0.476]
= 6.84
initial pH = 6.84
pH = pKa + log [salt - C / acid + C]
= 7.21 + log [0.202 - 0.05 / 0.476 + 0.05]
= 6.67
final pH = 6.67
pH change = 6.67 - 6.84 = -0.17
pH change = - 0.17
Get Answers For Free
Most questions answered within 1 hours.