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
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
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
Mass Percent -Mass NaCl / Mass NaCl+Mass Water * 100
0.018g / 50g+0.018g * 100