Molecular Mass of Solute given Relative Lowering of Vapour Pressure Calculator

Molecular Mass Solute Formula:

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

Weight of Solute:

Molecular Mass Solvent:

Vapour Pressure of Pure Solvent:

Vapour Pressure of Solvent in Solution:

Weight of Solvent:

Molecular Mass Solute (kg):

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

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

Purpose: It helps chemists and researchers determine the molecular mass of unknown solutes by measuring vapour pressure changes.

2. How Does the Calculator Work?

The calculator uses the formula:

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

Where:

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

Explanation: The formula relates the molecular mass of the solute to the change in vapour pressure caused by its addition to the solvent.

3. Importance of Molecular Mass Determination

Details: Determining molecular mass is fundamental in chemistry for identifying substances, calculating concentrations, and understanding solution properties.

4. Using the Calculator

Tips: Enter all required values in appropriate units. Ensure vapour pressure of pure solvent is greater than in solution. Default values are provided for common solvents like water.

5. Frequently Asked Questions (FAQ)

Q1: Why does adding solute lower vapour pressure?
A: Solute particles occupy space at the surface, reducing solvent molecules that can escape into vapour phase (Raoult's Law).

Q2: What's a typical molecular mass for water as solvent?
A: Water has a molecular mass of approximately 0.018 kg/mol (18 g/mol).

Q3: What units should I use for this calculator?
A: Use consistent units (kg for masses, Pa for pressures) as shown in the input fields.

Q4: Can I use this for non-volatile solutes only?
A: Yes, this calculation is most accurate for non-volatile solutes that don't contribute to vapour pressure.

Q5: What if my vapour pressures are equal?
A: The formula requires \( p_o > p \). Equal pressures would mean no solute effect (infinite molecular mass).