SOLUTIONS

9.5 - Molarity

The concentration of a solution is a measure of the amount of solute in a specific quantity of solvent. Chemists express solution concentrations as molarity (abbreviation M). Molarity is defined as

Let's prepare a 500.0 mL of a 0.0540 M of NaOH.

Calculate how much NaOH is required:

Step 1: Convert 500.0 mL to liter. (show work)
Step 2: Convert liters to moles using molarity as the conversion factor. (show work)
Step 3: Convert moles of NaOH to mass of NaOH (in grams) using molar mass as the conversion factor. (show work)

From the above three steps, we need to weigh out 1.08 grams of NaOH.

Directions for preparing the solution:

Step 1: Weigh out 1.08 grams of NaOH	(Note: this is not the color of NaOH.)
Step 2: Transfer the solid to a 250 mL beaker that is partly filled with distilled water. Dissolve the solid in the beaker.
Step 3: Quantitatively transfer the solution in the beaker to the volumetric flask. Fill the flask with distilled water up to the mark. Stopper the volumetric flask and shake vigorously to ensure the solution is well mixed.

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Section 14.8
Molarity ..p377

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