Van't Hoff Factor for Relative Lowering of Vapour Pressure using Number of Moles Calculator

Van't Hoff Factor Formula:

\[ i = \frac{(p_o - p) \times N}{n \times p_o} \]

Vapour Pressure of Pure Solvent:

Vapour Pressure of Solvent in Solution:

Number of Moles of Solvent:

mol

Number of Moles of Solute:

mol

Van't Hoff Factor (i):

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1. What is Van't Hoff Factor for Relative Lowering of Vapour Pressure?

Definition: The Van't Hoff factor (i) is a measure of the effect of a solute on colligative properties, calculated from the relative lowering of vapour pressure.

Purpose: It helps determine how much a solute affects the vapour pressure of a solvent, important in chemistry and chemical engineering applications.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ i = \frac{(p_o - p) \times N}{n \times p_o} \]

Where:

\( i \) — Van't Hoff Factor (dimensionless)
\( p_o \) — Vapour pressure of pure solvent (Pa)
\( p \) — Vapour pressure of solvent in solution (Pa)
\( N \) — Number of moles of solvent (mol)
\( n \) — Number of moles of solute (mol)

Explanation: The formula compares the vapour pressure lowering to the mole fraction of solute, adjusted by the Van't Hoff factor.

3. Importance of Van't Hoff Factor Calculation

Details: Accurate calculation helps predict solution behavior, including boiling point elevation and freezing point depression, crucial for industrial processes and laboratory work.

4. Using the Calculator

Tips: Enter vapour pressures in Pascals (Pa) and mole quantities in moles (mol). All values must be > 0. The result is dimensionless.

5. Frequently Asked Questions (FAQ)

Q1: What does the Van't Hoff factor represent?
A: It indicates how many particles a solute dissociates into in solution, affecting colligative properties.

Q2: What's a typical value for i?
A: For non-electrolytes, i ≈ 1; for strong electrolytes, i ≈ number of ions produced (e.g., 2 for NaCl).

Q3: Why measure vapour pressure lowering?
A: It's one of the most accurate ways to determine solute effects on solvent properties.

Q4: How does temperature affect this calculation?
A: Temperature affects vapour pressures but not the Van't Hoff factor directly.

Q5: What if my solute is volatile?
A: This calculation assumes non-volatile solutes. For volatile solutes, more complex models are needed.