Question

a throat spray is 1.40% by mass phenol, C6H5OH, in water. If the solution has a density of 0.9956g/ml, calculate the molarity of the solution.

Answer 1

Ans:

Phenol is 1.40% by mass in water means, of the 100 g of throat spray solution (in water) 1.40 g is phenol.

So, mass of phenol in the solution, w = 1.40 g

Molar mass of phenol, M = 94.11 g/mol

No. of moles of phenol in the throat spray, n = w/M = 1.40/94.11 = 0.0149 mol

Mass of solution = 100 g

Density of the solution, d = 0.9956 g/ml

Volume of the solution, V = mass/density = 100g/0.9956g/ml = 100.442 ml = 0.100442 L

Molarity of the solution = n/V = 0.0149/0.100442 = 0.1483 M