# What do you divide the mass of to calculate the percent concentration of a solution?

##### 1 Answer

You divide by the mass of the solution.

Percent by mass is the mass of the solute divided by the mass of the solution, multiplied by 100.

% by mass =

**Example**:

You dissolve a 4.00 g sugar cube in 350 mL of tea at 80 °C. The density of water at 80 °C is 0.975 g/mL. What is the percent by mass of sugar in the solution?

**Solution**

*Step 1* — Determine mass of the solute.

The solute is the sugar cube. Mass of solute = 4.00 g.

*Step 2* — Determine mass of solvent.

The solvent is the 80 °C water. Use the density of the water to find the mass.

mass of solvent = 350 mL ×

*Step 3*— Determine the total mass of the solution

mass of solution = mass of solute + mass of solvent = 4.00 g + 341 g = 345 g

*Step 4* — Determine percent composition by mass of the sugar solution.

% by mass =

The percent composition by mass of the sugar solution is 1.159 %.