Finding volume needed for buffer (URGENT!!) 1. The problem statement, all variables and given/known data What volume of 0.50M NaClO must be added to 0.20M HClO in order to prepare 500mL of a NaClO/HClO buffer with pH=7.00. Ka(HClO)= 3.5e-8 2. Relevant equations I'm using the H-H equation pH=pKa + log ([A]/[HA]) NaClO being A and HClO being HA 3. The attempt at a solution I tried doing it by method mentioned in another thread but I still did not get the right answer (answer is supposed to be NaClO = 61mL) pKa= -log(3.5e-8) = 7.46 Using H-H found that [A]/[HA] = .35 mols A = mols HA (.35) (mols A + mols HA)/.5 = .2 (.35 mols HA + mols HA)/.5 = .2 1.35 mols HA / .5 =.2 mols of HA = 7.4e-2 mols mols A = (7.4e-2)(.35) = 2.58e-2 mols .5= 2.58e-2/ L L= 5.16e-2 mL = 51.6 Close but no cigar. What am I doing wrong? I have a midterm tomorrow and I've been trying to solve this problem for 5 hours now and I feel like crying I am so frustrated. Please help!