Calculate the osmolarity of a solution that contains 0.1 M urea, 0.2 M NaCl, and 0.5 M CaCl2. Assume urea does not ionize and NaCl and CaCl2 ionize completely

Answer 1

Osmolarity measures the number of particles in a solution. For ionized compounds, each ion counts as one.
For example,
NaCl=Na+ + Cl- counts as 2 particles

So the total osmolarity
=0.1*1 + 0.2*2 + 0.5*3
=2 osm/l.