What is the SI unit of molarity?

What is the SI unit of molarity?

• A. mol/kg
• B. mol/L
• C. g/L
• D. L/mol

Answer: (B)

Molarity is a measure of how many moles of solute are in a given volume of solution. By definition, it’s moles per liter, so the unit is mol/L. The liter is a convenient volume unit for solutions, and 1 L equals 1 dm^3, making mol/L equivalent to mol/dm^3. The other options don’t fit: mol/kg is molality (moles per kilogram of solvent), not per liter; g/L is a mass concentration (grams per liter) rather than a count of particles per volume; L/mol is the reciprocal of concentration, describing volume per mole rather than moles per volume. If you wanted a strictly SI expression, you could use mol/m^3, but mol/L is the conventional and equivalent way to express molarity.

Molarity is a measure of how many moles of solute are in a given volume of solution. By definition, it’s moles per liter, so the unit is mol/L. The liter is a convenient volume unit for solutions, and 1 L equals 1 dm^3, making mol/L equivalent to mol/dm^3.

The other options don’t fit: mol/kg is molality (moles per kilogram of solvent), not per liter; g/L is a mass concentration (grams per liter) rather than a count of particles per volume; L/mol is the reciprocal of concentration, describing volume per mole rather than moles per volume.

If you wanted a strictly SI expression, you could use mol/m^3, but mol/L is the conventional and equivalent way to express molarity.