Concentration of solutions

• What is a solution?

  A mixture formed by a solute and a solvent.
• What is a solute?

  The dissolved substance in a solution.
• What happens when a substance dissolves?

  It breaks up and mixes completely with a solvent to produce a solution.
• What is a solvent?

  The liquid in which the solute dissolves to form a solution.
• How is the concentration of a solution defined?

  It is a measure of the mass or amount of solute dissolved in a given volume of solvent or solution.
• What does a higher concentration indicate about a solution?

  The more concentrated the solution, the more particles it contains in a given volume.
• What is the formula to calculate concentration?

  \(concentration~in~g/dm^3 = \frac{mass~of~solute~in~g}{volume~in~dm^3}\)
• If 8 g of sodium hydroxide is dissolved in 2 dm³ of water, what is the concentration?

  4 g/dm³
• What units are used to measure volume in concentration calculations?

  Volume must be in cubic decimetres (dm³).
• How do you convert from cm³ to dm³?

  Divide by 1000 to convert from cm³ to dm³.
• What is 250 cm³ in dm³?

  0.25 dm³
• If 100 cm³ of dilute hydrochloric acid contains 0.5 g of dissolved hydrogen chloride, what is the concentration in g/dm³?

  5 g/dm³
• How can the mass of solute be calculated from concentration?

  Mass of solute in g = concentration in g/dm³ × volume in dm³.
• If a solution has a concentration of 10 g/dm³, what mass of sodium chloride is dissolved in 2 dm³ of the solution?

  20 g
• How can the concentration of a solution be changed?

  • Increase concentration by dissolving more solute in a given volume.
  • Increase concentration by allowing some solvent to evaporate.
• What is the relationship between concentration and the mass of solute?

  Concentration can be increased by increasing the mass of the solute.
• What happens to the volume of a solution when some solvent evaporates?

  The volume of the solution decreases, increasing the concentration.