A Buffer Is Prepared by Adding 150 ML of 1

Multiple Choice

A buffer is prepared by adding 150 mL of 1.0 M NaOH to 250 mL of 1.0 M NaH₂PO₄. How many moles of HCl must be added to this buffer solution to change the pH by 0.18 units? If necessary, assume the total volume remains unchanged at 400 mL.

A) 0.025 mol HCl
B) 0.063 mol HCl
C) 0.082 mol HCl
D) 0.50 mol HCl
E) 1.0 mol HCl