Concentration of Solutions Study Notes

Lesson Overview

• Involves concentration of solutions in General Chemistry.

Definition of Solution

• A solution is a homogeneous mixture of two or more substances.

  • Solute: Present in smaller amounts.

  • Solvent: Present in larger amounts.

Expressing Solution Concentration

• Concentrations can be expressed qualitatively and quantitatively:

  • Qualitative: dilute vs concentrated.

  • Quantitative:

  • Mass percentage (% w/w)

  • Parts per million (ppm)

  • Parts per billion (ppb)

  • Mole fraction

  • Molarity (M)

  • Molality (m)

Types of Solutions

• Saturated Solution: Maximum solute at a given temperature.

• Unsaturated Solution: Less solute than the solvent can dissolve.

• Supersaturated Solution: More solute than saturated; can precipitate upon disturbance.

Calculation of Concentration

• Mass Percentage:

  • Formula: ext{Mass ext{
    Percentage} } = rac{( ext{mass of solute})}{( ext{mass of solution})} imes 100

• Parts per Million (ppm):

  • Formula: ext{ppm} = rac{( ext{mass of solute})}{( ext{mass of solution})} imes 10^6

• Molarity:

  • Formula: M = rac{( ext{moles of solute})}{( ext{volume of solution in L})}

• Molality:

  • Formula: m = rac{( ext{moles of solute})}{( ext{mass of solvent in kg})}

Practical Examples and Applications

• Maximum allowable limits for drinking water parameters.

• Calculations in various scenarios for % mass, ppm, molarity, and molality based on given data.