Converting Volume from Milliliters to Liters and Calculating Molarity

• Concentrated solutions have high concentrations of solute, while dilute solutions have a small amount of solute compared to solvent.

• Concentrating a solution involves adding more solute or removing solvent. Non-volatile solvents can be concentrated by evaporation or boiling off solvent.

• Dilutions are made by adding solvent to a more concentrated solution. Stock solutions are prepared for better precision in making dilutions.

• To calculate molarity, identify the volume and amount of solute (in moles or grams) of a solution. Convert the volume to liters if necessary.

• Determine the number of moles of solute by converting grams to moles using the solute's molar mass.

• Divide the number of moles of solute by the volume of the solution (in liters) to obtain the molarity.

• One osmole (Osmol) is one mole of particles that contribute to osmotic pressure. NaCl produces two osmoles per mole due to dissociation into ions.

• Blood contains solutes such as sodium ions (Na+), glucose, and blood urea nitrogen (BUN). Na+ contributes to osmolarity as NaX (where X is a negative ion), and glucose and BUN contribute based on their concentration.

• For the given example of a blood sample, the osmolarity calculation is: [Na+] = 0.140 mol/L * 2 (for NaX) + [glucose] = 180 mg/100 mL * (1/1801 g/mol) + [BUN] = 20 mg/100 mL * (1/0.022 g/mol) = 909.1 mOsm/kg (osmolarity is typically expressed as mOsm/kg)

• Molarity and osmolarity can be calculated from mass per unit volume by converting mass to moles using molar mass and dividing by the volume (in liters).

• For an ionic compound such as NaCl, each mole contributes 2 mol of osmotic particles, and the osmolarity is the molarity multiplied by the number of particles produced per mole.

• In the example, the NaCl solution has a molarity of 0.5 mol/L and an osmolarity of 1.2 mol/L (2 mol/L for NaCl).

• Molarity is the number of moles of solute per liter of solution. For calculating molarity, convert the volume to liters if it is given in milliliters, and determine the amount of solute in moles using the molar mass. Divide the number of moles of solute by the number of liters of the solution to obtain the molarity.

• Example: For an ammonia solution, the volume is 100 mL, and the mass of ammonia is 5.00 g. The molarity is 2.9 M.

• Osmolarity is the number of osmoles per liter of solution, which is the number of particles contributing to the osmotic pressure. One mole of an ionic compound generates two osmoles.

• For instance, a solution of 1 mol/L of sodium chloride (NaCl) has an osmolarity of 2 Osmol/L.

• To calculate osmolarity from molarity, multiply the molarity by the number of osmoles produced by one mole of solute.

• Example: Blood has a sodium concentration of 0.140 mol/L, glucose concentration of 180 mg/100 mL, and BUN (blood urea nitrogen) concentration of 20 mg/100 mL. The osmolarity of blood can be calculated by adding the contributions of Na+, glucose, and BUN.

• Molarity and osmolarity can be calculated from mass per unit volume. For example, a solution containing 40.0 g of sodium chloride (NaCl) in 1.00 L of solution has a molarity of 1.2 mol/L and an osmolarity of 3.6 mol/L.

• Ionic compounds dissociate into ions, contributing the number of moles of each ion to both molarity and osmolarity calculations. For example, 1 mol of NaCl generates 2 mol of osmotic particles (1 mol of Na+ and 1 mol of Cl-).

• Different solutions, such as calcium chloride, calcium gluconate, dextrose, magnesium sulfate, potassium acetate, potassium chloride, potassium phosphate, sodium acetate, and sodium bicarbonate, have various molarities and osmolarities depending on their chemical composition.

Learn about the steps involved in calculating molarity, including converting volume from milliliters to liters and determining the amount of solute present in moles from grams. Gain a better understanding of the process by practicing related problems.