# How do solutes affect osmotic pressure?

Jun 20, 2014

The more solute added to a solvent, the higher the osmotic pressure. The formula for osmotic pressure is:
Π = iMRT

Where Π is osmotic pressure
i = the number of particles a solute breaks down into
M = molarity (moles/liter)
R = gas law constant (0.08206 L atm mol-1 K-1, or other values depending on the pressure units)
T = temperature in kelvin

So, the more concentrated a solute is, the higher the osmotic pressure. Also, the more particles it breaks into (i.e. NaCl has an i = 2 because it breaks into sodium and chloride particles whereas $M g C {l}_{2}$ breaks into 3 particles)