1. What is Molality?

Molality (m) is a measure of the concentration of a solute in a solution, expressed as the number of moles of solute per kilogram of solvent. Unlike molarity, molality is temperature-independent because it's based on mass rather than volume.

2. How Does the Calculator Work?

The calculator uses the molality equation:

Where:

• \( m \) — Molality (mol/kg)
• \( n_{\text{solute}} \) — Amount of solute (moles)
• \( kg_{\text{solvent}} \) — Mass of solvent (kilograms)

Explanation: The equation calculates the concentration by dividing the number of moles of solute by the mass of solvent in kilograms.

3. Importance of Molality Calculation

Details: Molality is particularly important in colligative property calculations (boiling point elevation, freezing point depression) and in situations where temperature varies, as it remains constant regardless of temperature changes.

4. Using the Calculator

Tips: Enter the amount of solute in moles and the mass of solvent in kilograms. Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between molality and molarity?
A: Molality uses mass of solvent (mol/kg) while molarity uses volume of solution (mol/L). Molality is temperature-independent.

Q2: When should I use molality instead of molarity?
A: Use molality for precise work with temperature changes or colligative properties. Use molarity for general concentration measurements.

Q3: What are typical molality values?
A: Common solutions range from 0.1 to 10 mol/kg. Concentrated acids can be higher (e.g., 18 mol/kg for pure sulfuric acid).

Q4: Can molality be used for gaseous solutions?
A: No, molality is only meaningful for liquid solutions where a clear solvent can be identified.

Q5: How do I convert molarity to molality?
A: You need the solution density: m = M / (d - M × MW_solute), where d is density (kg/L) and MW is solute molecular weight.