# Osmolarity calculations

1. Apr 14, 2015

### Nouranoura

• You have to show your attempts, this is a forum policy. Also, all homework like questions should go to homework forum.
I don't know how to get the oolarity from just the percentage
See this question:
Calculate the osmolarity of each solutions:
5% glucose solution
.89% NaCl solution
And 8% glucose solution
i=1.9

2. Apr 14, 2015

### Staff: Mentor

Convert percentages to molarities.

3. Apr 15, 2015

### Nouranoura

Yeah I know but how do I do that? Is it by using w/v %? How does the NaCl 0.89% become 8.9 g/l? That's the part that I don't get

4. Apr 15, 2015

### Staff: Mentor

Approximately: 1 L is 1 kg.

Precisely: take a density table, read the density for a given concentration, calculate mass of 1 L of the solution, follow from there.

5. Apr 15, 2015

### Nouranoura

I do not follow sir how is the density related to the percentage? Please forgive me I may have not understood you. English is not my first language

6. Apr 15, 2015

### Staff: Mentor

This is something that has to be measured. For many compounds there are ready density tables, some of them printed in chemistry handbooks, some of them available on the internet. You need to locate such a table and read the density for a given concentration.

7. Apr 15, 2015

### Nouranoura

Excuse me sir I did not ask what density is, I do know what it is but my question was that why would we need the density.You see the main question is part of a sample exam paper there won't be any density tables whatsoever

8. Apr 15, 2015