We need 1.00L of a formic acid/formate (Ka= 1.80×10-4) buffer with a starting pH of 3.500. It must be able to resist the addition of 20.00mL of 0.250M NaOH while remaining below pH 4.150. How many mL of 0.500M stock acid and 0.250M NaOH base solution must be used in preparation of this buffer?
