Question

A chemistry student must write down in her lab notebook the concentration of a solution of sodium thiosulfate. The concentration of a 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: She put some solid sodium thiosulfate into the graduated cylinder and weighed it. With the sodium thiosulfate added, the cylinder weighed . 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 . What concentration should the student write down in her lab notebook

Answer 1

9.92 M

Step-by-step explanation:

The complete question is shown in the image attached.

Now, the data in the question are as follows;

Mass of empty cylinder = 6.5 g

Mass of cylinder and thiosulphate = 62.41 g

Mass of thiosulphate solid = 62.41 - 6.5 = 55.91 g

volume of solution = 35.30 mL

Recall that;

n = CV

where;

n = number of moles

C = concentration of solution

V= volume of solution

n = mass/molar mass

molar mass of thiosulphate = 158.11 g/mol

n = 55.91 g/158.11 g/mol

n = 0.35 moles

Hence;

C= n/V

C= 0.35/35.30/1000

C= 0.35 * 1000/35.30

C= 9.92 M