Adding or subtracting and multiplying or dividing measurements A chemistry stude

Question

Adding or subtracting and multiplying or dividing measurements A chemistry student must write down in her lab notebook the concentration of a solution of sodium hydroxide. 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: 9.050 & . She put some solid sodium hydroxide into the graduated cylinder and weighed it. With the sodium hydraxide added, the cylinder weighed 55.77g. . She added water to the graduated cylinder and dissolved the sodium hydraxide completely. Then she read the total volume of the solution from the markings on the graduated cylinder. The total volume of the solution was 115.1 mL What concentration should the student write down in her lab notebook? Be sure your answer has the correct number of significant digits 30 Deml 8-mL Chick

Explanation / Answer

Concentration of any soultion is the amount of solute present in the solution.

Solute is the substance which dissolves in the solution or the compound which is less in terms of amount in the solution. In the given question, solute is NaOH ( Sodium hydroxide)

Solvent: In which the solute dissolves. Usually, solvent is more in terms of amount in the soultion. In the given question, water is the solvent.

Solution = Solute + Solvent.

Here, the combined amount of NaOH and water is the solution.

Given,

Mass of the empty cylinder = 9.050 g

Mass of the cylinder after the addition of NaOH = 55.77 g

Therefore, mass of the solute = mass of NaOH = 55.77g - empty cylinder mass

= 55.77 - 9.050 = 46.72 g

==> Mass of the solute = 46.72 g

And the total volume of the solution is = 115.1 mL

Now,

Concentration = Mass of the solute / Volume of the solution

= 46.72 g/ 115.1 mL

= 0.4059 g/mL

Therefore, the answer is, Concentration = 0.4059 g/mL

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