# Numerical: How will you prepare a 0.75% #Na_2CO_3# solution?

##### 1 Answer

#### Answer:

Here's a way you could do this.

#### Explanation:

The first thing you need to do is pick a volume for the target solution.

To make the calculations easier, I'll show you how to prepare a **0.75% w/v** solution that has a total volume of **100 mL**.

A solution's mass by volume percent concentration is defined as the mass of the solute, in your case sodium carbonate, divided by the total volume of the solution, and multiplied by 100.

You can isolate the mass of the solute to get

Since you want your target solution to have a volume of 100 mL and a mass by volume percent concentration of 0.75%, the mass of solute that would be needed is

So, if you dissolve **0.75 g** of sodium carbonate in enough water to make the total volume of the solution equal to **100 mL**, you'll get a **0.75% w/v** solution.

You can use this approach for any volume you may need the target solution to have.