Concentrations of Solutions

• Types:

  1. Unsaturated - A solution that can dissolve more of the solute. (A sugary drink with undissolved sugar crystals at the bottom)
  2. Saturated - has reached its maximum amount of dissolved material at a given temperature. ( A sugary drink that can dissolve more sugar)
  3. Supersaturated - Holds more solute than it normally could at a given temperature (unstable) ( A special ice cream that stays liquid at a colder temperature than usual until disturbed)
• A solute is a substance that is dissolved in another substance, called a solvent, to form a solution.
• A solvent is a substance that dissolves other substances, called solutes, to form a solution.
• Concentration - shows the relative amounts of solute and solvents in a solution. There are three common ways to express it, namely: molarity, mole fraction, and molality
• Molarity (M) is the amount of a substance in a certain volume of solution. It is defined as the moles of a solute per liters of a solution (mol/L). It is also known as the molar concentration of a solution.
• Molarity = moles of solute / liters of solution
• Mole Fraction (x) is a way of describing solution composition. It is the ratio of the number of moles of one component of a mixture to the total number of moles of all components.
• Mole Fraction:

  XA= moles of solute / total moles of solution
• Molality (m) is the ratio of the number of moles of solute per kilogram of solvent.
• molality (m) - moles of solute / mass of solvent (in kg)
• The difference of molality from molarity is that molality does not change with the solution’s temperature . In molarity, the volume of a solution can change with temperature due to expansion or contraction, while the mass of solvent in molality does not change with temperature.
• Saturation point is a stage of solution at which no more of a substance can be absorbed into a vapor or dissolved into it.