Weight of Solute given Relative Lowering of Vapour Pressure Calculator

Weight of Solute Formula:

\[ w = \frac{(p_o - p) \times W \times M_{solute}}{p_o \times M_{solvent}} \]

Vapour Pressure of Pure Solvent:

Vapour Pressure of Solvent in Solution:

Weight of Solvent:

Molecular Mass Solute:

Molecular Mass Solvent:

Weight of Solute: kg

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1. What is Weight of Solute given Relative Lowering of Vapour Pressure?

Definition: This calculator determines the weight of solute in a solution based on the relative lowering of vapour pressure.

Purpose: It's used in chemistry to calculate the amount of solute needed to achieve a specific vapour pressure lowering in a solution.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ w = \frac{(p_o - p) \times W \times M_{solute}}{p_o \times M_{solvent}} \]

Where:

\( w \) — Weight of solute (kg)
\( p_o \) — Vapour pressure of pure solvent (Pa)
\( p \) — Vapour pressure of solvent in solution (Pa)
\( W \) — Weight of solvent (kg)
\( M_{solute} \) — Molecular mass of solute (kg)
\( M_{solvent} \) — Molecular mass of solvent (kg)

Explanation: The formula relates the weight of solute to the observed lowering of vapour pressure in a solution.

3. Importance of This Calculation

Details: This calculation is fundamental in colligative properties studies and helps determine molecular weights of unknown solutes.

4. Using the Calculator

Tips: Enter all required values in consistent units (Pa for pressures, kg for weights and molecular masses). All values must be positive.

5. Frequently Asked Questions (FAQ)

Q1: What is relative lowering of vapour pressure?
A: It's the ratio of vapour pressure lowering (p₀-p) to the original vapour pressure (p₀) of the pure solvent.

Q2: Why does adding solute lower vapour pressure?
A: Solute particles reduce the solvent's escaping tendency from the solution surface, lowering vapour pressure.

Q3: What are typical units for molecular mass?
A: While kg is used here for consistency, molecular masses are often expressed in g/mol or kg/kmol.

Q4: Can this be used for volatile solutes?
A: No, this formula applies only to non-volatile solutes that don't contribute to vapour pressure.

Q5: How accurate is this calculation?
A: It's accurate for ideal, dilute solutions but may deviate for concentrated or non-ideal solutions.