Question

Describe the preparation of
(a) 1.50 L of 21.0% (w/v) aqueous glycerol (C3H8O3, 92.1 g/mol).
(b) 1.50 kg of 21.0% (w/w) aqueous glycerol.
(c) 1.50 L of 21.0% (v/v) aqueous glycerol.

Answer 1

a)

The following data has been given:

Volume of the solution = 2.50 L

                                          = 2500 mL

 

Weight/volume percent concentration = 21.0%(w/v)

Weight/volume percent concentration is formulated as:

Weight/volume percent (w/v) = (weight solute, g/volume of the solution, mL) × 100

 

Thus, 21.0%(w/v) of 2500 mL ethanol solution = 21.0g/100 mL × 2500 mL

                                                                                   = 525 g

Therefore, 21.0% (w/v) solution of glycerol can be prepared by dissolving 525 g glycerol in water and then diluting to 2500 mL.

 

b)

The following data has been given:

Weight percent concentration = 21.0% (w/w)

Mass of the solution = 2.50 kt

                                     = 2500 g

Weight percent (w/w) = (mass of the solute,g/mass of the solution, g) × 100%

Thus, 21.0% (w/w) of 2500 g ethanol solution = 21.0/100g × 2500 g

                                                                                 = 525 g

 

Therefore, 21.0% (w/w) solution of glycerol can be prepared by dissolving 525 g glycerol in 2475 mL of water.

 

c)

The following data has been given:

Volume percent concentration = 21.0%(v/v)

Volume of the solution = 2.50 L

                                         = 2500 mL

Volume percent (v/v) = (volume of the solute, mL/volume of the solution, mL) × 100 %

 

Thus, 21.0% (v/v) of 2500 mL glycerol solution = 21.0 mL/100 mL × 2500 mL

                                                                                   = 525 mL

 

Therefore, 21.0% (v/v) of glycerol solution can be prepared by dissolving 525 mL of glycerol in water and then diluting to 2500 mL.

a) Therefore, 21.0% (w/v) solution of glycerol can be prepared by dissolving 525 g glycerol in water and then diluting to 2500 mL.

 

b) Therefore, 21.0% (w/w) solution of glycerol can be prepared by dissolving 525 g glycerol in 2475 mL of water.

 

c) Therefore, 21.0% (v/v) of glycerol solution can be prepared by dissolving 525 mL of glycerol in water and then diluting to 2500 mL.