# Concentration of a Solution: Calculating % (v/v)

When preparing a solution by dissolving a solute in a solvent, the concentration of the solution can be expressed in various ways. One common way is by calculating the percentage by volume (% v/v) of the solute in the solution.

In this case, we are given that 30 grams of sodium chloride is dissolved in 45ml of water. To determine the % (v/v) concentration of the solution, we need to calculate the ratio of the volume of sodium chloride to the total volume of the solution.

First, we need to convert the mass of sodium chloride from grams to milliliters. The density of sodium chloride is approximately 2.165 g/cm³. So, 30 grams of sodium chloride is equal to:

(30 grams) / (2.165 g/cm³) ≈ 13.87 ml

Now, we can calculate the % (v/v) concentration of the solution by following this formula:

**Concentration = (Volume of Solute / Volume of Solution) x 100**

Plugging in the values:

Concentration = (13.87 ml / 45 ml) x 100 ≈ 30.82%

Therefore, the concentration of the solution prepared by dissolving 30 grams of sodium chloride in 45ml of water is approximately 30.82% (v/v).