Which solution has the greatest osmolarity?
0.6 M NaCl
0.10 M KNO3
0.35 M AlCl3
0.2 M CaBr2
0.14 M KF

Explanation:

Osmolarity is the number of moles of particles that count to calculate the osmotic pressure, in one liter of solution.

In ionic compounds, your first calculate the molarity and then multiply it by the factor to calculate the number of particles product of the dissociation.

The factor is the number of ions produced per mole of compound.

Assuming 100% dissociation for the given solutions, the calculations are:

Solution                 Ionization     Factor            Osmolarity

0.6 M NaCl             Na⁺ + Cl⁻          2                 0.6 × 2 = 1.2          

0.10 M KNO₃           K⁺ + NO₃⁻        2                 0.10 × 2 = 0.20

0.35 M AlCl₃           Al⁺ + 3Cl⁻         4                 0.35 × 4 = 1.4

0.2 M CaBr₂           Ca²⁺ + 2Br⁻      3                  0.2 × 3 = 0.6

0.14 M KF                K⁺ + F⁻             2                  0.14 × 2 = 0.28