Relative Lowering of Vapour Pressure given Number of Moles for Dilute Solution Calculator

Relative Lowering of Vapour Pressure Formula:

\[ \Delta p = \frac{n}{N} \]

Relative Lowering of Vapour Pressure:

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1. What is Relative Lowering of Vapour Pressure?

Definition: The Relative Lowering of Vapour Pressure is the lowering of vapour pressure of pure solvent on addition of solute.

Purpose: This calculation is important in colligative properties studies and helps determine how much a solute affects the solvent's vapour pressure.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ \Delta p = \frac{n}{N} \]

Where:

\( \Delta p \) — Relative Lowering of Vapour Pressure (dimensionless)
\( n \) — Number of Moles of Solute (mol)
\( N \) — Number of Moles of Solvent (mol)

Explanation: The ratio of solute moles to solvent moles gives the relative lowering of vapour pressure for a dilute solution.

3. Importance of This Calculation

Details: Understanding vapour pressure lowering is crucial for predicting solution behavior, designing distillation processes, and studying colligative properties.

4. Using the Calculator

Tips: Enter the number of moles of solute and solvent. The solvent moles must be greater than zero. For accurate results, ensure the solution is dilute.

5. Frequently Asked Questions (FAQ)

Q1: What is the physical significance of relative lowering of vapour pressure?
A: It measures how much the solute particles interfere with the solvent's ability to evaporate, indicating the strength of solute-solvent interactions.

Q2: Does this formula work for concentrated solutions?
A: No, this simple formula is accurate only for dilute solutions where solute-solute interactions are negligible.

Q3: What are typical values for relative lowering of vapour pressure?
A: For dilute solutions, values are typically between 0.001 and 0.1, depending on the solute concentration.

Q4: How does temperature affect this calculation?
A: Temperature affects absolute vapour pressure but not the relative lowering, which depends only on mole ratios (for ideal solutions).

Q5: Can I use mass instead of moles?
A: No, the formula requires moles because it's based on particle count (colligative property). Convert mass to moles using molecular weights.