Question

a) If 42.1 mL of 1.02 M sodium hydroxide, measured using a graduated cylinder, is placed in a beaker filled with 300 mL of DI water, what is the concentration of the diluted NaOH solution?

b) Why does this calculation only provide an estimate of the NaOH concentration? In other words, why do we have to standardize the NaOH in this experiment to find its exact concentration? (Hint: think about the glassware

Answer 1

a) concentration of NaOH = 1.02 M

volume of NaOH = 42.1 mL

volume of DI water = 300 mL

concentration of diluted NaOH = concentration of NaOH / total volume

                                                  = 1.02 / (42.1 + 300)

                                                  = 0.00298 M

concentration of diluted NaOH = 0.00298 M

b)

because of NaOH hygroscopic nature. NaOH catches moisture from atmsphere. while preparing the particular concentration of NaOH we need to measure the weight of NaOH. but the measured weight is not accurate in fact. so the concentration is not correct. once you prepare the NaOH solution with particular concentration we need to conform agian whether it is correct or not . fot that we need to standardise with oxalic acid or HCl in order to know the exact concentration of NaOH.