1. The problem statement, all variables and given/known data Q) Calculate the volume of 0.1M HCl you would need to add to 200ml of 0.15M sodium acetate solution to obtain a buffer of pH 4.2. Ka = 1.74 * 10^-5 moldm-3 2. Relevant equations pH = pKa + log [salt]/[acid] 3. The attempt at a solution Log[salt]/[acid] = pH - pKa [salt]/[acid] = 0.275 Equation: [salt] = 0.275 [acid] [salt] = 200*0.15/200+v [acid] = (0.1*V / 200+v) - (200*0.15/200+v) Substituting into above equation: 200*0.15/200+v = 0.275(0.1*V/200+v) - 0.275(200*0.15/200+v) 30 = 0.0275v - 8.25 38.25= 0.0275v V = 38.25/0.0275v V = 1390 cm^3 This is obviously wrong! Where did I go wrong?