How can I find percent concentration from density?

Question

Olivia Anton · Accepted Answer

This typically appears in a problem where you are asked to convert between different sets of concentration units.

To convert from molarity to percent concentration, for instance, you need to know the density.

This is a common issue.

For a 13.0 mol/L solution of phosphoric acid with a density of 1.464 g/mL, what is the percent concentration?

Assume that the solution has a fixed volume.

Let's assume a volume of 1 L for convenience.

Determine H3O₃'s mass.

1 L soln × #(13.0"mol H₃PO₄")/(1"L soln") × (98.00"g H₃PO₄")/(1"mol H₃PO₄")# = 1274 g H₃PO₄ (3 significant figures + 1 guard digit)

Determine the mass of the solution using the density.

1000 mL soln × #(1.464"g soln")/(1"mL soln")# = 1464 g soln

Determine the concentration percentage.

% by mass = #"mass of [solute](https://tutor.hix.ai)"/"mass of solution"# × 100 % = #(1274"g")/(1464"g")# × 100 % = 87.0 % (3 significant figures)

By mass, the solution is 87.0% HPO₄.

Xavier Avery · Answer

undefined To find percent concentration from density, you need to know the density of the substance and the density of the solution. Then, you can use the formula:

$$ \text{Percent concentration} = \frac{\text{Density of substance}}{\text{Density of solution}} \times 100 $$

This formula helps you determine the percentage of the substance in the solution based on their densities.

Natalie Anton · Answer

undefined To find percent concentration from density, you need to know the density of the solution and the density of the pure solvent. Then, you can use the following formula:

$$ \text{Percent Concentration} = \left( \frac{\text{Density of Solution}}{\text{Density of Pure Solvent}} \right) \times 100 $$

Once you have the density values, divide the density of the solution by the density of the pure solvent, and then multiply the result by 100 to express the concentration as a percentage.