Main Answer
The molarity of 0.9% NaCl is approximately 154 mM, and its osmolarity is approximately 308 mOsm/kg.
Explanation
To calculate the molarity and osmolarity of a solution, we need to know its concentration and the molar mass of its solutes. In this case, we have a 0.9% (W/V) solution of NaCl, which means that there are 0.9 grams of NaCl in every 100 milliliters of solution.
To convert this to molarity, we need to know the molar mass of NaCl, which is 58.443 grams per mole. Here's how we calculate the molarity:
Calculate the number of moles of NaCl in 100 milliliters of solution:
- Mass of NaCl = 0.9 grams
- Moles of NaCl = Mass / Molar mass = 0.9 g / 58.443 g/mol = 0.0158 mol
Calculate the volume of solution required to make up one mole:
- Volume required = Moles / Concentration = 0.0158 mol / 0.0154 mol/L = 1 L
Calculate the molarity:
- Molarity = Moles / Volume = 0.0158 mol / 1 L = approximately 154 mM
To calculate the osmolarity, we need to know the number of osmoles per kilogram (Osm/kg) in the solution. One osmole is equivalent to one mole of solute in one liter of solution, so we can calculate it as follows:
Calculate the number of osmoles in the solution:
- Osmoles = Moles / Liter = 0.0158 mol / (1 L / 1 kg) = approximately 308 mOsm/kg
Calculate the osmolarity:
- Osmolarity = Osmoles / Kilogram = approximately 308 mOsm/kg
So, our calculated values for both molarity and osmolarity are within the typical range for Normal Saline, which is commonly used in medical applications due to its similarity to human physiological fluids in terms of electrolyte balance and tonicity.