Question

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 aqueous solutions, the mass of the solvent is the mass of solution.

Answer 1

0.00007975 mole

Step-by-step 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