Question

Molarity of a solution is defined as:

• A. Number of moles of solute per kilogram of solvent
• B. Number of gram equivalents of solute per liter of solution
• C. Number of moles of solute per liter of solution
• D. Number of grams of solute per liter of solvent

Hint:

Logic Tip: Remember the classic formula: $M = n/V$, where $n$ is Moles and $V$ is Volume in Liters. This instantly points you to "Moles per Liter"!

Answer 1

The Correct Option is C

Concept:
In chemistry, there are multiple standard ways to express the concentration of a solution. Molarity ($M$) is the most common volumetric measurement of concentration used in laboratory stoichiometry.

Step 1:
Molarity is based on the chemical amount of the dissolved substance. In chemistry, the standard unit for the amount of substance is the mole. Therefore, the numerator is the "number of moles of solute."

Step 2:
Molarity measures how densely those moles are packed into a physical space. Therefore, the denominator must be a unit of volume, not mass. The standard unit is the Liter (L).

Step 3:
Molarity measures the concentration of the *entire* completed mixture, not just the base liquid. Therefore, it is per liter of the total "solution", not per liter of the pure "solvent".

Step 4:
- Option (A) defines Molality ($m$). - Option (B) defines Normality ($N$). - Option (D) defines Mass Concentration.

Step 5:
Combining the parameters from the previous steps, Molarity is strictly defined as the number of moles of solute per liter of solution. This matches Option (C).