Question

22. Glycerol, C3H8O3, is a substance used extensively in the manufacture of cosmetics, foodstuffs, antifreeze, and plastics. Glycerol is a water-soluble liquid with a density of 1.2656 g/mL at 15 0C. Calculate the molarity of a solution of glycerol made by dissolving 50.000 mL glycerol at 15 0C in enough water to make 250.00 mL of solution. Show work.

Answer 1

Answer:

2.75M

Explanation:

Density = mass/volume

Density of glycerol (C3H8O3) at 15°C is given as 1.2656 g/mL.

Volume of glycerol at this same temperature before dissolving in water = 50mL

Hence, using Density = mass/volume

1.2656 = mass/50

mass = 1.2656g/mL × 50mL

mass = 63.28g

Molarity of solution = number of moles (n) ÷ volume (V)

Volume of glycerol dissolved in water = 250mL = 0.250L

number of moles = mass/molar mass

Molar mass of C3H8O3 = 12(3) + 1(8) + 16(3)

= 36 + 8 + 48

= 44 + 48

= 92g/mol

n = 63.28g ÷ 92g/mol

n = 0.688mol

* Molarity = n/V

Molarity = 0.688/0.250

Molarity = 2.75M