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Otrada [13]
3 years ago
10

Calculate the number of moles of solute present in 55.0 mg of an aqueous solution that is 1.45 m NaCl. Assume that for dilute aq

ueous solutions, the mass of the solvent is the mass of solution.
Chemistry
1 answer:
Aloiza [94]3 years ago
8 0

Answer:

0.00007975 mole

Explanation:

Number of moles can be calculated as; mass of solute/volume of solvent or concentration of solution x volume of that solution.

In this case:

Concentration of solution = 1.45 M

Mass of solvent (water in this case) = 55.0 mg

55.0 mg of water is equivalent to 0.55 ml of water.

Therefore, volume of solution = 0.055 ml

Hence, number of moles of solute = molarity x volume

                                                           1.45 x 0.000055 = 0.00007975 mole

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Answer:

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Our strategy here is to use the definition of molarity and molality to solve this question.

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For the molarity what we need is to first calculate the kilograms of glycerine from the given density:

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m = mol sucrose/ kg solvent = 3.24 x 10⁻³ mol / 0.544 Kg = 0.0060 m

Note: In the calculation for  volume of solution we could have approximated it to that of just glycerine, but since the density of sucrose was given we calculated the total volume of solution to be more rigorous.

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