Expressing Concentration of Solutions
Solution concentration is expressed as molarity, molality, mole fraction or mass percentage, each with a different denominator.
What is Expressing Concentration of Solutions?
Solution concentration is expressed as molarity, molality, mole fraction or mass percentage, each with a different denominator.
Key formula / rule: Molarity is moles of solute per litre of solution.
Key points
- Compute molarity, molality and mole fraction for a given solution.
- Compare molarity and molality with respect to temperature dependence.
Common exam trap
Using the mass of solvent as the volume of solution in molarity.
Definitions
- Term
Expressing Concentration of Solutions
- Meaning
Solution concentration is expressed as molarity, molality, mole fraction or mass percentage, each with a different denominator.
- Term
Expressing Concentration of Solutions — explanation
- Meaning
Molarity depends on volume and therefore on temperature, while molality depends on mass and does not. Choosing the right measure is essential for colligative property work.
Learning objectives
Compute molarity, molality and mole fraction for a given solution.
Compare molarity and molality with respect to temperature dependence.
Formulae
- Key point
Molarity is moles of solute per litre of solution.
- Key point
Molality is moles of solute per kilogram of solvent.
- Key point
Mole fractions of all components sum to one.
Prerequisites
CHE-U1-BC-T1-S1-C1
Common mistakes
Using the mass of solvent as the volume of solution in molarity.
Treating molarity as temperature independent.
Keywords
Expressing
Concentration
Solutions
Practice preview
The concentration term that expresses the number of moles of solute per kilogram of solvent is:…
easy
Calculate the molarity of a solution prepared by dissolving 4.9 g of H2SO4 in 250 mL of solution. (Molar mass of H2SO4 = 98 g/mol)…
medium
What is the molality of a solution containing 18 g of glucose (C6H12O6) dissolved in 500 g of water? (Molar mass of glucose = 180 g/mol)…
medium