Questions: Normal saline is a solution of aqueous sodium chloride with a concentration of 0.90 % (g / mL). Express this concentration in molarity. concentration: M

Solution Steps

The given concentration of normal saline is \(0.90\% \, (\mathrm{g/mL})\). This means there are 0.90 grams of sodium chloride (NaCl) in 100 mL of solution.

First, we need to convert the mass of NaCl to moles. The molar mass of NaCl is: \[ \text{Molar mass of NaCl} = 22.99 \, (\text{Na}) + 35.45 \, (\text{Cl}) = 58.44 \, \text{g/mol} \]

Using the given concentration, we have 0.90 grams of NaCl in 100 mL of solution. To find the number of moles: \[ \text{Moles of NaCl} = \frac{0.90 \, \text{g}}{58.44 \, \text{g/mol}} = 0.0154 \, \text{mol} \]

The volume of the solution is 100 mL, which is equivalent to 0.100 liters.

Molarity (M) is defined as the number of moles of solute per liter of solution: \[ \text{Molarity} = \frac{\text{Moles of NaCl}}{\text{Volume of solution in liters}} = \frac{0.0154 \, \text{mol}}{0.100 \, \text{L}} = 0.154 \, \text{M} \]

Final Answer