Which solution has the higher osmotic pressure, 2 M NaCl or 2 M CaCl2?
pi = i*MRT.
i is the van't Hoff factor which "counts" the number of particles. For
CaCl2, it ionizes to Ca^+2 + 2Cl^- or three particles. NaCl ionizes NaCl ==> Na^+ + Cl^- or two particles. Since R and T are not given, we can call them K.
pi = 3*2K
pi = 2*2K.
For which is pi greater?
To determine which solution has a higher osmotic pressure between 2 M NaCl and 2 M CaCl2, we need to consider the number of particles each compound dissociates into when it dissolves in water.
NaCl dissociates into two particles when it dissolves: Na+ and Cl-. So a 2 M NaCl solution contains a total of 2 moles of particles per liter.
On the other hand, CaCl2 dissociates into three particles when it dissolves: Ca2+ and two Cl-. Therefore, a 2 M CaCl2 solution contains a total of 3 moles of particles per liter.
Since the osmotic pressure is directly proportional to the concentration of particles, a solution with a higher number of particles will have a higher osmotic pressure. In this case, the 2 M CaCl2 solution has a higher osmotic pressure because it contains 3 moles of particles, while the 2 M NaCl solution has only 2 moles of particles.