Answer to Question #301794 in General Chemistry for Ken

Question

Calculate the molality of a solution prepared from 15.25 g of NaCl in 1.50 kg of water.

Answer 1

molality of the solution is 1.388 m.

Explanation:

Molality (

m

)

 is a way of indicating the concentration of a solute dissolved in a solution. It is calculated by dividing the moles of solute by the mass of the solvent in kg.

molality

=

moles solute

kg solvent

You have been given the masses of both the solute and the the solvent in grams. You will need to convert the mass of C

6

H

12

O

6

 to moles using its molar mass, and you will need to convert the mass of water from grams to kilograms.

Molar mass of C

6

H

12

O

6

 is 180.15588 g/mol

.

https://pubchem.ncbi.nlm.nih.gov/compound/5793#section=Top

Determine moles of C

6

H

12

O

6

:

mol solute

=

150.0

g C

6

H

12

O

6

×

1

mol C

6

H

12

O

6

180.15588

g C

6

H

12

O

6

=

0.8326 mol C

6

H

12

O

6

Convert mass of solvent from g to kg.

600.0

g H

2

O

×

1

kg H

2

O

1000

g H

2

O

=

0.6000 kg H

2

O

Calculate molality:

molality

=

moles solute

kg solvent

molality

=

0.8326

mol

0.6000

kg

=

1.388 mol/kg=1.388 m