Question

A chemistry student must write down in her lab notebook the concentration of a solution of sodium thiosulfate. The concentration ofa solution equals the mass of what's dissolved divided by the total volume of the solution. Here's how the student prepared the solution: The label on the graduated cylinder says: empty weight: 3.25g She put some solid sodium thiosulfate into the graduated cylinder and weighed it. With the sodium thiosulfate added, the cylinder weighed 76.373 g. She added water to the graduated cylinder and dissolved the sodium thiosulfate completely. Then she read the total volume of the solution from the markings on the graduated cylinder. The total volume of the solution was 170.95 mL What concentration should the student write down in her lab notebook? Be sure your answer has the correct number of significant digits. -1 CP

Answer 1

Answer:-

Given:-

wt. of empty graduated cylinder = 3.25 g

wt. of empty graduated cylinder + wt. of sodium thiosulfate = 76.373 g

volume of water added to graduated cylinder (V) = 170.95 mL

As we know that

wt. of sodium thiosulfate (m) = (wt. of empty graduated cylinder + wt. of sodium thiosulfate) - (wt. of empty graduated cylinder)

wt. of sodium thiosulfate (m) = 76.373 g - 3.25 g

wt. of sodium thiosulfate (m) = 73.123‬ g

So the concentration of a solution of sodium thiosulfate is obtained by 73.123‬ g of solid sodium thiosulfate dissolved in 170.95 mL of water i.e total volume of solution.

therefore

the concentration of a solution of sodium thiosulfate (c) = wt. of sodium thiosulfate (m) / volume of water added to graduated cylinder (V)

the concentration of a solution of sodium thiosulfate (c) = 73.123‬ g / 170.95 mL

the concentration of a solution of sodium thiosulfate (c) = 0.43 g / mL (i.e the answer)

or

the concentration of a solution of sodium thiosulfate (c) = 0.43 g.mL^-1 (i.e the answer)