Look at the procedure section entitled Prepare these stock

) Look at the procedure section, entitled \'Prepare these stock solutions\'... For the solution listed as (1), you will measure out Na2S,03.5 H,O...determine the mass of this sodium thiosulfate pentahydrate that you\'ll need to create a 0.04 M solution in a 50 mL volumetric flask. a.

Solution

molarity of solution = 0.04M
volume of solution    = 50ml = 0.05L
gram molar mass of Na2S2O3.5H2O   = 158g/mole

no of moles of Na2S2O3.5H2O   = molarity * volume in L

                                                   = 0.04*0.05   = 0.002 moles

mass of Na2S2O3.5H2O   = no of moles * gram molar mass

                                           = 0.002*158   = 0.316g of Na2S2O3.5H2O