Question

Calculate the concentration in mol/L, M, of an aqueous sugar solution with a concentration of 23.5% (w/w) and density of 1.005 g/mL at 25 °C. The molecular weight of sugar is 342.30 g/mol. Report your answer to three significant figures.

Answer 1

Answer:

The concentration in mol/L is 0.683M

Explanation:

23.5% (w/w)

This data means that in 100 g of solution, we have 23.5 grams of solute.

From this point, we can calculate the moles of sugar.

Moles = Mass / Molar mass

Moles = 23.5 g /342.30 g/m

Moles = 0.068 moles

Density data make us know, the volume of our solution.

solution δ = solution mass / solution volume

δ = 1.005 g/mL = 100 g /  solution volume

solution volume = 100g / 1.005 g/ml

solution volume = 99.5 mL

In conclusion, 0.068 moles are in 99.5 mL

Molarity (M) is mol/L

Let's convert 99.5 mL in L

99.5 mL / 1000 = 0.0995 L

0.068 m / 0.0995L = 0.683

If we convert moles in mmoles, we can also get Molarity (M)

mmoles / mL = M

0.068 moles . 1000 = 68 mmoles

68 mmmoles / 99.5mL = 0.683