Question

Determine mass of Na2SO4.10H2O, required for preparing 250 mL of solution whose molarity is 0.45M.

Answer 1

number of miiliequivalents = 250*0.45*2 = 225
mass of Na2SO4.10H2O = 225*322/1000*2 = 36.225
 

Answer 2

36.225 grams (approx)

Here we need to first the no. of moles of solute(na2so4.10h2o)

Molarity = moles/ per litre

0.45 = moles ×1000 / 250 (as it is in ml I multiplied the numerator with 1000)

0.45×4=0.1125 moles

Mass=no.of moles× molecular mass

Molecular Mass of na2so4.10h2o=322 grams

Mass of na2so4.10h2o= 0.1125×322=36.225 grams