How do you convert between different concentration units?

To convert between different concentration units, you use conversion factors related to the units' definitions.

Concentration units are used to express the amount of solute in a given amount of solvent or solution. The most common units are molarity (M), molality (m), mass percent, volume percent, and parts per million (ppm). Each of these units has a specific definition that can be used as a conversion factor.

Molarity (M) is defined as the number of moles of solute per litre of solution. To convert from molarity to molality, you need to know the density of the solution. Molality (m) is defined as the number of moles of solute per kilogram of solvent. Therefore, you can convert from molarity to molality by multiplying the molarity by the density of the solution and dividing by the mass of the solvent in kilograms.

Mass percent is defined as the mass of the solute divided by the total mass of the solution, multiplied by 100. To convert from molarity to mass percent, you need to know the molar mass of the solute and the density of the solution. You can calculate the mass of the solute by multiplying the molarity by the molar mass, and then calculate the total mass of the solution by dividing the volume of the solution by its density. The mass percent is then the mass of the solute divided by the total mass of the solution, multiplied by 100.

Volume percent is similar to mass percent, but it involves the volume of the solute and solution instead of their masses. To convert from molarity to volume percent, you need to know the volume of the solute and the volume of the solution. The volume percent is then the volume of the solute divided by the total volume of the solution, multiplied by 100.

Parts per million (ppm) is defined as the number of parts of solute per million parts of solution. To convert from molarity to ppm, you need to know the molar mass of the solute and the density of the solution. You can calculate the mass of the solute by multiplying the molarity by the molar mass, and then calculate the total mass of the solution by dividing the volume of the solution by its density. The ppm is then the mass of the solute divided by the total mass of the solution, multiplied by 1,000,000.