# What is the difference between osmotic potential and osmotic pressure?

Which term is used to calculate water potential? Does osmotic potential mean the same as solute potential?

• Welcome on biology.stackexhchange. This is a pretty broad question, so it would be nice if you could start on these topics yourself (either with a good biology book or the Wikipedia) and then ask specific questions. – Chris Sep 30 '14 at 13:05
• Please donot comment if u cannot help me .I know about these term but I need deeper explanation not your criticism . – Abdul Wajid Lakhani Sep 30 '14 at 14:20
• Then you need to edit your question so people can answer specific questions. There are certain rules about questions, if you choose to not pay attention to them, questions can be closed, as this has already happened here. You can still edit the question and it can be nominated for reopening. – Chris Sep 30 '14 at 14:26
• Does it meet the site rules now? – Abdul Wajid Lakhani Sep 30 '14 at 14:33
• sometimes a question is just a question – shigeta Sep 30 '14 at 17:38

Osmotic pressure: pressure applied by a solution to prevent the inward flow of water across a semi-permeable membrane.

Osmotic potential: the potential of water molecules to move from a hypotonic solution to a hypertonic solution across a semi-permeable membrane.

Osmotic pressure can be calculated using the following formula:

$$Π = iMRT$$

where $Π$ is the osmotic pressure in atm

$i$ = van 't Hoff factor of the solute.

$M$ = molar concentration in mol/L

$R$ = universal gas constant = 0.08206 L·atm/mol·K

$T$ = absolute temperature in K

The following page has a worked out example.

As for your question on solute potential vs osmotic potential, the answer is that they are indeed the same. You can compare the formula for $\Psi_{\pi}$ on the wikipedia page and the page of this pearson textbook. These formulas are the same:

$\Psi_{\pi} = -Π =-iMRT$

So there's a simple relationship between osmotic pressure and osmotic potential.