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How to Adjust the Osmolarity

Osmolarity refers to the number of osmoles per liter of fluid. An osmole (abbreviated Osm) is a "piece" of a molecule. For example, when table salt -- sodium chloride -- is added to water, it dissolves into two pieces: a chloride ion and a sodium ion. So one molecule of salt breaks down into two osmoles. Osmolarity is an important measurement in medical science, where it's used to keep track of substances dissolved in body fluids such as blood and spinal fluid.

Instructions

- 1
  Increase the osmolarity by increasing the amount of solute. The simplest way to adjust osmolarity is to add more solute. If you're working with table salt as your solute, increasing the amount of salt will increase the osmolarity an equal amount (adding 20 percent more salt to the solution will increase the osmolarity by 20 percent; adding 50 percent more salt will increase the osmolarity by 50 percent and so on).
- 2
  Increase the osmolarity by decreasing the amount of fluid. Because osmolarity is a measure of osmoles per liter of fluid, decreasing the amount of fluid causes an increase in osmolarity. A solution with two osmoles of solute in one liter of fluid has an osmolarity of two. But a solution with two osmoles of solute in just half a liter of fluid has an osmolarity of four because 2 / 0.5 = 4.
- 3
  Decrease the osmolarity by increasing the amount of fluid. Again, because osmolarity is a measure of osmoles per liter, increasing the amount of fluid decreases the overall osmolarity. This is the simplest way to decrease osmolarity.
- 4
  Decrease the osmolarity by decreasing the amount of solute. This is not possible if your solution is already made, but you can change your "recipe" so that future solutions will have a lower osmolarity.

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