Question

An aqueous solution was created by placing 0.018 g of NaCl into a 50 mL volumetric flask and diluting to volume with deionized water. (Because the amount of solute is small, you may assume that the volume & density of the solution is equal to the volume & density of the solvent where appropriate.)Find the concentration in terms of the following units. Report your answers without scientific notation.Only input numbers. Your answers must be expressed to the correct number of significant figures. Any values less than one must have a zero in front of the decimal (e.g. 0.01 not .01)Molarity (M): Molality (m):Mole fraction of NaCl (X):Mass % of NaCl:

Answer 1

Answer:

Molarity: 6.2x10⁻³M NaCl

Molality: 6.2x10⁻³m NaCl

Mole Fraction: 1.1x10⁻⁴

Mass% NaCl: 0.036% (m/m NaCl)

Explanation:

Molarity -Moles NaCl / L-

Moles NaCl -Molar mass: 58.44g/mol-

0.018g * (1mol/58.44g) = 0.000308 moles NaCl

Liters water:

50mL * (1L/1000mL) = 0.050L

M = 0.000308 moles NaCl / 0.050L

M = 6.2x10⁻³M NaCl

Molality -Moles NaCl / kg water-

Moles NaCl = 0.000308 moles NaCl

kg water = 50mL * (1g/mL) * (1kg/1000g) = 0.050kg

m = 0.000308 moles NaCl / 0.050kg

m = 6.2x10⁻³m NaCl

Mole Fraction -Moles NaCl / Moles water+ Moles NaCl-

Moles water = 50g * (1mol/18.01g) = 2.776 moles

Moles fraction = 0.000308 moles NaCl / 0.000308 moles NaCl + 2.776moles water

Mole fraction = 1.1x10⁻⁴

Mass Percent -Mass NaCl / Mass NaCl+Mass Water * 100

0.018g / 50g+0.018g * 100

0.036% (m/m NaCl)