Final answer:
The sodium chloride equivalent method is used to adjust isotonicity by calculating and comparing the osmotic pressure of a solution with cells, then adding solutes like NaCl or glycerol to achieve an osmotic balance.
Step-by-step explanation:
The sodium chloride equivalent method is utilized to adjust the isotonicity of a solution to ensure it is compatible with the body's natural fluids such as blood. When a solution is isotonic with red blood cells, it has the same osmotic pressure as the cells, preventing them from swelling or shrinking. The sodium chloride equivalent of a compound is a value that represents how much sodium chloride (NaCl) is needed to produce an isotonic solution. Adjusting isotonicity is critical, especially in intravenous (IV) solutions, to maintain the proper balance of fluids within the cells.
The process involves calculating the osmotic pressure of a solution and comparing it to the normal osmotic pressure of cells. Correction may require adding an appropriate amount of a sodium chloride solution or another agent like glycerol to achieve isotonicity. The concentration of sodium chloride needed is determined by the sodium chloride equivalent of the solute and the desired volume of the solution. For instance, NaCl produces two ions when it dissolves, therefore a 0.16 M NaCl solution has an osmolarity of 0.32 osmol/L because it dissociates into sodium and chloride ions.
After calculating the molarity of NaCl, we use the calculated osmolarity to correct the solution — if needed, by adding solutes such as glycerol whose molarity we calculate based on the additional osmotic pressure needed to achieve isotonicity with the cells.