Re: How does the density of a solution effect the freezing point?

Hi Krista, I think that you would like to understand osmolarity. Osmolarity measures the effective gradient for water assuming that all the osmotic solute is completely impermeant. It is simply a count of the number of dissolved particles. Therefore a 300 millimolar solution of glucose, a 300 millimolar solution of urea, and a 150 millimolar solution of NaCl each have the same osmolarity. Try this site: http://physioweb.med.uvm.edu/bodyfluids/ A few points to remember about osmolarity: solution=one substance dissolved into another solvent=generally a liquid (larger part) solute= smaller part, usually a salt Changes in amount of solute affects: Increase in solute= decrease in freezing point, decrease in vapor pressure Increase in solute= increase in boiling point, increase in osmotic pressure These above changes are proportional to changes in true molal concentration, regardless of particle size, density or electrical charge. Molal solutions consist of one mole of solute dissolved in one kilogram of solvent, so a molal solution is slightly more dilute than a molar solution (one more liter) An osmometer measures freezing point depression Freezing point can be used to measure a solution's concentration One milliosmol per kilogram of water change in concentration will cause a change of 0.001858 degrees Celsius in the freezing point. I hope this helps, Sue Scotino MadSci Administration