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Molality Equation:
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Molality (m) is a measure of the concentration of a solute in a solution, defined as the number of moles of solute per kilogram of solvent. Unlike molarity, molality is not affected by temperature changes because it's based on mass rather than volume.
The calculator uses the molality equation:
Where:
Explanation: The equation calculates the concentration by dividing the number of moles of solute by the mass of the solvent in kilograms.
Details: Molality is particularly important in colligative property calculations (like boiling point elevation and freezing point depression) because these properties depend on the number of solute particles relative to the solvent molecules, not on the volume of solution.
Tips: Enter the amount of solute in moles and the mass of solvent in kilograms. Both values must be positive numbers. The calculator will compute the molality in mol/kg.
Q1: What's the difference between molality and molarity?
A: Molarity (M) is moles of solute per liter of solution, while molality (m) is moles of solute per kilogram of solvent. Molarity changes with temperature, molality doesn't.
Q2: When should I use molality instead of molarity?
A: Use molality when working with temperature-sensitive experiments or when calculating colligative properties. Use molarity for most general concentration needs.
Q3: Can molality be used for any solvent?
A: Yes, molality can be used with any solvent, though it's most commonly used with water as the solvent.
Q4: What are typical molality values?
A: Common aqueous solutions range from 0.1 m to 6 m, though very concentrated solutions can have higher molality.
Q5: How do I convert molality to molarity?
A: You need the density of the solution. Molarity = (molality × solvent density) / (1 + (molality × molar mass of solute/1000)).