Question

A chemistry student weighs out 0.140 g of sulfurous acid (H,SO2), a diprotic acid, into a 250. mL volumetric flask and dilutes to the mark with distilled water. He plans to titrate the acid with 0.1200 M NaOH solution. Calculate the volume of NaOH solution the student will need to add to reach the final equivalence point. Be sure your answer has the correct number of significant digits. 1 ml x s ?

Answer 1

H2SO4 + 2 NaOH ----> Na2SO4 + 2H2O

1 mol H2SO4 = 2 mol NaOH = 1 mol Na2SO4 = 2 mol H2O

No of mol of H2SO4 taken = w/Mwt = 0.14/98 = 0.00143 mol

No of mol of naOH required to reach final equivalence point = 2*0.00143

                                = 0.00286 mol

volume of naOH required = n/M

                        = 0.00286/0.12

           = 0.0238 L

                        = 23.8 ml