Question

A chemistry student must write down in her lab notebook the concentration of a solution of potassium chloride. 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 potassium chloride into the graduated cylinder and weighed it. With the potassium chloride added, the cylinder weighed . She added water to the graduated cylinder and dissolved the potassium chloride 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? Be sure your answer has the correct number of significant digits

Answer 1

Answer:

3.65 g / ml correct to 3 sig. fig.

Explanation:

The computation of the concentration required is shown below:

As we know that

[A] = mass of solute ÷ volume of solution

Before that first find the mass of solute

Given that

Initial weight = 5.55g

And,

Final weight = 92.7 g

So,

Mass of KCl is

= 92.7 - 5.55

= 87.15 g ~ 87.2 g

Now the KCi is fully dissolved, so the volume is 23.9 ml

So,  concentration is

= 87.2 g ÷ 23.9 ml

= 3.65 g / ml correct to 3 sig. fig.