What does molarity express in chemistry?

Molarity is a fundamental concept in chemistry that expresses the concentration of a solute in a solution. It is defined as the number of moles of the solute divided by the volume of the solution in liters. This relationship directly indicates how much solute is present in a given volume of solution, which is critical for understanding reactivity, stoichiometry, and other chemical properties.

For example, a molarity of 1 M (molar) means there is one mole of solute dissolved in one liter of solution. This measure is essential for calculations in chemical reactions, dilutions, and various laboratory preparations, enabling chemists to make precise adjustments based on concentration.

Other options do not accurately define molarity. The volume of a solution refers to how much space it occupies, while the amount of solvent in grams specifies the mass of the solvent rather than the concentration of the solute. Density measures how mass relates to volume in a substance, but it does not provide information about the concentration of solute in a solution. Thus, expressing molarity as the concentration of solute in moles per liter is the most accurate and relevant definition in the context of chemistry.