Science, Tech, Math › Science Calculate Osmotic Pressure Example Problem Share Flipboard Email Print PHOTO INSOLITE REALITE/SCIENCE PHOTO LIBRARY / Getty Images Science Chemistry Basics Chemical Laws Molecules Periodic Table Projects & Experiments Scientific Method Biochemistry Physical Chemistry Medical Chemistry Chemistry In Everyday Life Famous Chemists Activities for Kids Abbreviations & Acronyms Biology Physics Geology Astronomy Weather & Climate By Todd Helmenstine Todd Helmenstine is a science writer and illustrator who has taught physics and math at the college level. He holds bachelor's degrees in both physics and mathematics. our editorial process Todd Helmenstine Updated May 10, 2019 This example problem demonstrates how to calculate the amount of solute to add to create a specific osmotic pressure in a solution. Osmotic Pressure Example Problem How much glucose (C6H12O6) per liter should be used for an intravenous solution to match the 7.65 atm at 37 degrees Celsius osmotic pressure of blood?Solution:Osmosis is the flow of a solvent into a solution through a semipermeable membrane. Osmotic pressure is the pressure that stops the process of osmosis. Osmotic pressure is a colligative property of a substance since it depends on the concentration of the solute and not its chemical nature.Osmotic pressure is expressed by the 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, and T = absolute temperature in Kelvin.Step 1: Determine the van 't Hoff factor.Since glucose does not dissociate into ions in solution, the van 't Hoff factor = 1.Step 2: Find the absolute temperature.T = Degrees Celsius + 273T = 37 + 273T = 310 KelvinStep 3: Find the concentration of glucose.Π = iMRTM = Π/iRTM = 7.65 atm/(1)(0.08206 L·atm/mol·K)(310)M = 0.301 mol/LStep 4: Find the amount of sucrose per liter.M = mol/VolumeMol = M·VolumeMol = 0.301 mol/L x 1 LMol = 0.301 molFrom the periodic table:C = 12 g/molH = 1 g/molO = 16 g/molMolar mass of glucose = 6(12) + 12(1) + 6(16)Molar mass of glucose = 72 + 12 + 96Molar mass of glucose = 180 g/molMass of glucose = 0.301 mol x 180 g/1 molMass of glucose = 54.1 gramsAnswer:54.1 grams per liter of glucose should be used for an intravenous solution to match the 7.65 atm at 37 degrees Celsius osmotic pressure of blood. What Happens If You Get the Answer Wrong Osmotic pressure is critical when dealing with blood cells. If the solution is hypertonic to the cytoplasm of the red blood cells, the cells will shrink through a process called crenation. If the solution is hypotonic with respect to the osmotic pressure of the cytoplasm, water will rush into the cells to try to reach equilibrium. This may cause the red blood cells to burst. In an isotonic solution, red and white blood cells maintain their normal structure and function. It's important to remember that there may be other solutes in the solution that affect osmotic pressure. If a solution is isotonic with respect to glucose but contains more or less of an ionic species (sodium ions, potassium ions, and so on), these species may migrate into or out of a cell to try to reach equilibrium.