Question

A chemist prepares a solution of sodium thiosulfate by measuring out of sodium thiosulfate into a volumetric flask and filling the flask to the mark with water. calculate the concentration in of the chemist's sodium thiosulfate solution. round your answer to significant digits.

Answer 1

Mass of sodium thiosulfate $Na_{2}S_{2}O_{3}$ is 110. g

Volume of the solution is 350. mL

Calculating the moles of sodium thiosulfate:

$110. g Na_{2}S_{2}O_{3} * \frac{1 mol Na_{2}S_{2}O_{3}}{158.1 g Na_{2}S_{2}O_{3}}$ = 0.696 mol$Na_{2}S_{2}O_{3}$

Converting the volume of solution to L:

$350. mL * \frac{1 L}{1000 mL} = 0.350 L$

Finding out the concentration of solution in molarity:

$\frac{0.696 mol}{0.350 L} = 1.99 mol/L$