Question

Tell me the molarity on dilution concept in detail

Answer 1

The molarity on dilution concept explains that when a solution is diluted by adding more solvent, the number of moles of solute remains constant, but the total volume of the solution increases. This increase in volume, with a fixed amount of solute, leads to a decrease in the concentration (molarity) of the solution. The relationship is mathematically expressed by the dilution equation: $M_1V_1 = M_2V_2$, where $M_1$ and $V_1$ are the initial molarity and volume, and $M_2$ and $V_2$ are the final molarity and volume after dilution. This equation is derived from the principle that the moles of solute ($n = M \times V$) are conserved during the dilution process.

Answer 2

Explanation of Molarity on Dilution Concept

1. Definition of Molarity:

Molarity (M) is a measure of the concentration of a solute in a solution. It is defined as the number of moles of solute dissolved per liter of solution. $M = \frac{\text{Number of moles of solute (n)}}{\text{Volume of solution (V in Liters)}}$ From this definition, the number of moles of solute can be expressed as: $n = M \times V$

2. Concept of Dilution:

Dilution is the process of reducing the concentration of a solute in a solution by adding more solvent (typically water). When a solution is diluted:

• The amount (number of moles) of the solute remains constant. No solute is added or removed during the dilution process.

• The volume of the solution increases because more solvent is added.

3. Effect of Dilution on Molarity:

Since molarity is inversely proportional to the volume of the solution (for a fixed amount of solute), increasing the volume by adding more solvent will decrease the molarity of the solution. The solute particles become more spread out in a larger volume, leading to a lower concentration.

4. Derivation of the Dilution Formula:

Consider a solution with an initial molarity $M_1$ and an initial volume $V_1$. The number of moles of solute in this initial solution is: $n_1 = M_1V_1$ Now, suppose this solution is diluted by adding more solvent to a new total volume $V_2$. The new molarity of the solution becomes $M_2$. The number of moles of solute in the diluted solution is: $n_2 = M_2V_2$ As established, during dilution, the number of moles of solute remains constant. Therefore, the moles of solute before dilution must be equal to the moles of solute after dilution: $n_1 = n_2$ Substituting the expressions for $n_1$ and $n_2$: $M_1V_1 = M_2V_2$ This is the fundamental equation used for dilution calculations. It states that the product of molarity and volume remains constant before and after dilution.

Terms in $M_1V_1 = M_2V_2$:

• $M_1$: Initial molarity of the concentrated solution.

• $V_1$: Initial volume of the concentrated solution.

• $M_2$: Final molarity of the diluted solution.

• $V_2$: Final volume of the diluted solution.

Key Takeaway: The core principle of dilution is the conservation of the number of moles of solute. While the volume changes and the molarity decreases, the total amount of the substance dissolved remains unchanged.