Question

16. A solution is made by dissolving 25 g of NaCl in enough water to make 1.0 L of solution. Assume the density of the solution is 1.0 g/cm3. Calculate the molarity and molality of the solution.

Answer 1

Answer:

The molarity will be "0.43 M" and molality will be "0.43 m".

Explanation:

Given that:

mass of NaCl,

= 25 g

Volume of solution,

= 1 L

Density of solution,

= 1 gm/cm³

Now,

The weight of solvent will be:

= $Volume\times density$

= $1\times 1$

= $1 \ kg$

The mole of NaCl will be:

= $\frac{mass}{Molar \ mass}$

= $\frac{25}{58.44}$

= $0.43$

hence,

The molarity will be:

= $\frac{number \ of \ mole}{Volume \ of \ solution}$

= $\frac{0.43}{1}$

= $0.43 \ M$

The molality will be:

= $\frac{mole \ of \ solute}{Weight \ of \ solvent}$

= $\frac{0.43}{1}$

= $0.43 \ m$