How can the concentration of water in solution be decreased?

2 Answers
Mar 16, 2014

The concentration can be decreased by 2 ways, by increasing the solute, or decreasing the water.

Increasing the solute will increase the solution's concentration. This can be done by simply adding more of your compound into the solution and dissolving it. It may not help if you are using an aqueous solution (already dissolved in water).

In that case, you can heat up the water if it is safe. Wear goggles and a mask to make sure that you aren't breathing in anything harmful. Keep the solution below boiling point, and slowly evaporate off the water.

If you want to be precise, measure the initial volume and calculate the molarity (concentration) of the substance after you have steamed off enough water

Molarity= moles (of substance) / volume of solution (liters)

You can use a process called dialysis to decrease the water in a solution.

  1. Place your solution in a dialysis bag. This bag should be made up of semipermeable substance.
  2. Place the bag in a solution that has a high concentration of an ion (salt for example)
  3. Water will leave the bag through the semi permeable membrane by rushing out of the bag to the solution.

Thus, our dialysis bag has now smaller amount of water.