Question

Determining the Concentration of an Unknown Acid 1) Dilution of the Stock 2M NaOH: Calculate the amount of stock NaOH solution required to prepare 200ml of 0. 1 M working NaOH solution. 2) Standardization of the Working NAOH Solution: Calculate the amount of Potassium hydrogen phthalate (KHP: 204.22g/mol) required to titrate with 15ml of -0.1M working NAOH solution.

Answer 1

1) Concentration of the stock NaOH solution, M = 2 M Volume of the stock NaOH solution = V Volume of the dilute NaOH solution, V = 200 mL Concentration of the dilute NaOH solution, M = 0.1M According to dilution principle, VM = VM, Volume of stock NaOH solution needed, V = 90122 M (200 mL)x(0.1M) 2M = 10 mL ------------------------------------- 1L 0.1 mol NaOH 2) No of moles of NaOH = 15 mL * 1000 mLiL = 0.0015 mol NaOH Potassium hydrogen pth al ate is simply called KHP and its molecular formula is KHC,H,OH The equation : KHP (aq) + NaOH (aq) – KPNa (aq) +H20 () No of moles of KHP = 0.0015 mol NaOH x 1 mol KHP 1 mol NaOH = 0.0015 mol KHP Mass of KHP = 0.0015 mol KHP- D 204.22 g 1 mol KHP = 0.306 g = 0.31 g * 0.3g