Question

Suppose 10 mg of deprenyl is diluted in 10 mL of water. What is the a) mass fraction and b) mol fraction of deprenyl in the solution?

Answer 1

Answer:

(a) Mass fraction of deprenyl in the solution is 0.55

(b) Mole fraction of deprenyl in the solution is0.11

Explanation:

(a) Mass of deprenyl = 10mg = 10/1000 = 0.01g

Volume of water = 10mL = 10/1000 = 0.01L

1 mole of a substance contains 22.4L of the substance

0.01L of water = 0.01/22.4 = 0.00045mole of water

MW of water = 18g/mole

Mass of water = 0.00045mole × 18g/mole = 0.0081g

Mass of solution = mass of deprenyl + mass of water = 0.01g + 0.0081g = 0.0181g

Mass fraction of deprenyl = mass of deprenyl/mass of solution = 0.01g/0.0181g = 0.55

(b) Molecular weight (MW) of deprenyl (C13H17N) = 187g/mole

Number of moles of deprenyl = mass/MW = 0.01/187 = 0.000053mole

Total moles of solution = moles of deprenyl + moles of water = 0.0000053mole + 0.00045mole = 0.000503mole

Mole fraction of deprenyl in the solution = moles of deprenyl/moles of solution = 0.000053mole/0.000503mole = 0.11