‘Fixed Volume’ Method

• 1. Accurately measure a known volume of water into a conical flask.
• 2. Add an excess of the solute to tge water - if all solute dissolves, keep adding solute until no more can dissolve.
• 3. Filter out the undissolved solid to obtain the saturated solution.
• 4. Place the saturated solution into a pre-weighed evaporating dish and leave it in a warm place to allow water to evaporate (can heat solution to speed up, but if heated to much risk losing some of the solute).
• 5. When all of the water has evaporated, place the solute in an oven at 100°C to ensure that all of the water has evaporated.
• 6. Weigh the evaporating dish and solute and then subtract the mass of the empty dish to calculate the mass of the solute.
• 7. Use the volume of water and mass of solute to calculate the solubility in g / 100g water - done easily using:

  • solubility = mass of solute / volume of water x 100