Normality is defined as:

Normality is defined as:

• A. the ratio of solute to solvent in a solution
• B. the number of moles of solute per liter of solution
• C. The mass of solute per liter of solution
• D. the number of equivalents of a substance dissolved in a liter of solution

Answer: (D)

Normality measures reactive capacity per liter of solution. It tells you how many equivalents of a solute are present in one liter, where an equivalent is the amount of substance that reacts to furnish or consume one mole of reactive units (such as H+, OH−, or electrons) in the specific chemical reaction you’re considering. So, normality is defined as the number of equivalents of solute per liter. It relates to molarity by the factor of how many reactive units each mole provides: Normality = Molarity × (equivalents per mole for that solute in the reaction). For example, a monoprotic acid like HCl has one reactive proton per molecule, so its normality equals its molarity. A diprotic acid like H2SO4 can furnish two protons per molecule, giving a normality twice its molarity for acid-base reactions. This is why normality focuses on the reaction’s stoichiometry rather than just the amount of solute or its mass. The other descriptions miss the essential reaction-based aspect: molarity is moles per liter, mass concentration is mass per liter, and simple solute-to-solvent ratios don’t account for how much reactive capacity is available in the solution.

Normality measures reactive capacity per liter of solution. It tells you how many equivalents of a solute are present in one liter, where an equivalent is the amount of substance that reacts to furnish or consume one mole of reactive units (such as H+, OH−, or electrons) in the specific chemical reaction you’re considering.

So, normality is defined as the number of equivalents of solute per liter. It relates to molarity by the factor of how many reactive units each mole provides: Normality = Molarity × (equivalents per mole for that solute in the reaction). For example, a monoprotic acid like HCl has one reactive proton per molecule, so its normality equals its molarity. A diprotic acid like H2SO4 can furnish two protons per molecule, giving a normality twice its molarity for acid-base reactions. This is why normality focuses on the reaction’s stoichiometry rather than just the amount of solute or its mass.

The other descriptions miss the essential reaction-based aspect: molarity is moles per liter, mass concentration is mass per liter, and simple solute-to-solvent ratios don’t account for how much reactive capacity is available in the solution.