# Calculate the osmolarity of a 0.9% wt/vol NaCl (mol wt 58.44). ?

The osmotic coefficient of NaCl is 0.93? How many osmoles (ions) does NaCl dissociate into?

Osmolarity is calculated from the sum of the molar concentration of each solute multiplied by the osmotic coefficient for that solute. The osmotic coefficient is determined by the degree to which a solute dissociates in solution.

### 2 Answers

- Ted KLv 72 months agoFavorite Answer
Osmolarity depends on the number of particles in solution. Theoretically, NaCl should fully dissociate into two particles, one of Na+ and one of Cl- --which would mean that osmolarity should be exactly equal to 2 x its molarity. That's if its osmotic coefficient was 1.0. But it's not. NaCl does NOT fully dissociate, which is why its osmotic coefficient is only 0.93--it means that for every mole of NaCl, only about 0.93 mol (93%) of NaCl molecules will be dissociated, on average.

So, if an osmotic coefficient of 1.0 would result in 2 particles, how many particles if the coefficient is 0.93?

Do you not know how to convert a wt % concentration into a molarity?? The equation to use is given to you, right there in the question. First, you have to convert wt % (g/100 ml) into g/L. This is just a matter of moving a decimal point over one place.

- Anonymous2 months ago
Do your own homework and this does not belong in personal finance. Move it or remove you it lazy cheater.

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Good job.