Question

What is the percent composition of sodium chloride in normal saline?

Answer 1

Saline solution, usually called normal saline, is a mixture of salt and water. The normal saline solution contains 0.9 percent (w/v) sodium chloride (salt), which is somewhat similar to the sodium concentration in blood serum.

Complete answer: Saline solution, also known as normal, physiological, or isotonic saline, is basically a solution of 0.9% (mass by volume – w/v) of NaCl. It is a solution formed by dissolving 9 grams of sodium chloride salt in water, to a total volume of 1000 mL.
Since the molar mass of sodium chloride is 58.5 grams per mole, therefore 58.5 grams NaCl is equal to its 1 mole. And we know normal saline contains 9 grams NaCl, so the concentration of normal saline in moles per liter will be 0.154 moles per liter.

& 58.5\text{ grams NaCl}\to \text{1 mole NaCl} \\\ & \therefore 9\text{ grams NaCl}\to \dfrac{9}{58.5}\text{ = 0}\text{.154 moles NaCl} \\\ & \text{Hence,} \\\ & \text{0}\text{.9 }\\!\\! \% \\!\\!\text{ (w/v) NaCl}\equiv \text{9 g/L NaCl}\equiv \text{0}\text{.154 mol/L NaCl} \\\ \end{aligned}$$ The normal saline has many applications in real life as well as in biological studies whereas higher and lower concentrations of saline solution are rarely used. It can either be applied topically or used intravenously. The uses of normal saline include – -To clean wounds. -To remove contact lenses. -To treat dehydration. -Used in eye and nose drops, etc. Thus, the percentage composition of sodium chloride in normal saline is 0.9% mass by volume. **Note:** Less commonly, this solution is also referred to as physiological saline or isotonic saline because it is isotonic to blood serum, which makes it a physiologically normal solution. However, it is not exactly similar to the blood serum.