Calculate the mass in grams of sodium thiosulfate the chemist has added to the flask.

Question

A chemist adds 210.0mL

 of a 1.8

M sodium thiosulfate Na2S2O3

 solution to a reaction flask. Calculate the mass in grams of sodium thiosulfate the chemist has added to the flask. Be sure your answer has the correct number of significant digits.

Answer 1

molarity = no. of moles/ volume in liters

molarity given = 1.8 M

volume = 210mL = 0.21 L

no. of moles =1.8 M x 0.21 L = 0.378 moles

no. of moles = mass taken/ molar mass

molar mass of Na2S2O3 = 158.11g/mol

mass taken = 0.378 moles x 158.11 = 60 g (2 sig fig)