How to determine the molarity of a 1.8% NaCl solution.

To determine the molarity of a solution, you need to know the amount of solute (in moles) and the volume of the solution (in liters). In this case, you have a 1.8% NaCl solution, which means that there is 1.8 grams of NaCl in 100 mL of the solution.

To calculate the molarity, follow these steps:

1. Convert the percentage to grams:
Since you have 1.8% NaCl, it means you have 1.8 grams of NaCl in 100 mL of the solution.

2. Convert the volume from mL to liters:
There are 1000 mL in 1 L, so the volume is 100 mL ÷ 1000 mL/L = 0.1 L

3. Calculate the number of moles of NaCl:
The molar mass of NaCl is approximately 58.44 g/mol. Divide the mass (in grams) by the molar mass to get the moles:
Moles = Mass (in grams) / Molar mass
Moles = 1.8 g / 58.44 g/mol ≈ 0.0309 mol

4. Calculate the molarity:
Molarity (M) is defined as moles of solute per liter of solution. Divide the moles of NaCl by the volume of the solution (in liters) to get the molarity:
Molarity = Moles / Volume (in liters)
Molarity = 0.0309 mol / 0.1 L ≈ 0.309 M

Therefore, the molarity of the 1.8% NaCl solution is approximately 0.309 M.