Solution Concentration Quiz

Solution Concentration

• Molarity (M) is moles of solute per liter of solution.
• Molarity is not ideal for precise measurements because volume changes with temperature.
• Molality (m) is moles of solute per kilogram of solvent.
• Molality is temperature-independent.
• Mole fraction (X) is a direct measure of the number of molecules of a compound present.
• It's calculated by dividing the moles of a component by the total moles of all components in the solution.
• Parts by mass (m/m) is a quick way to compare different concentrations.
• It's calculated by dividing the mass of solute by the total mass of the solution.
• Parts by mass and mole fraction are different.
• Mole fraction is weighted by the number of molecules.
• Parts by mass is weighted by the mass of molecules.

Example Calculation

• Calculate molality, mole fraction, and mass fraction of a solution containing 80.9 g of HBr and 1.00 kg of H₂O.
• Molality: 1.00 mol HBr / 1.00 kg H₂O = 1.00 molal
• Mole fraction of HBr: 1.00 mol HBr / (1.00 mol HBr + 55.5 mol H₂O) = 0.0177
• Mass fraction of HBr: 80.9 g HBr / (80.9 g HBr + 1000 g H₂O) = 0.0749
• Percent mass: 7.49% or 74.900 ppm
• Different molal solutions of HF, HCl, or HBr in water will have the same mole fraction.
• However, their parts by mass will be different.

Test your understanding of solution concentration concepts, including molarity, molality, mole fraction, and parts by mass. This quiz features example calculations and helps reinforce the differences between these measures. Perfect for students in chemistry classes.