How to Prepare a 10 Millimolar Solution
Preparing a 10 millimolar (mM) solution is a common task in laboratory settings, whether for scientific research, medical applications, or industrial processes. A 10 mM solution contains 10 moles of solute per liter of solution. This concentration is often used because it is suitable for various experiments and applications that require a moderate concentration of the solute. In this article, we will guide you through the steps to prepare a 10 mM solution accurately and efficiently.
Materials Needed
Before you begin, gather the following materials:
– Distilled water
– Weighing scale
– Volumetric flask (100 mL or larger, depending on the desired volume of the solution)
– Stirrer or magnetic stirrer
– Pipette or graduated cylinder
– Filter paper or a funnel (optional)
– Safety equipment (gloves, lab coat, safety goggles)
Step 1: Calculate the Amount of Solute Needed
To prepare a 10 mM solution, you first need to determine the amount of solute required. The formula for calculating the mass of solute needed is:
Mass of solute (g) = Molarity (M) × Molar mass of solute (g/mol) × Volume of solution (L)
For example, if you want to prepare 100 mL of a 10 mM NaCl solution, you would calculate the mass of NaCl needed as follows:
Mass of NaCl (g) = 10 mM × 58.44 g/mol × 0.1 L = 5.844 g
Step 2: Weigh the Solute
Using a weighing scale, accurately measure the calculated amount of solute. It is crucial to ensure that the scale is properly calibrated and that you are using the correct unit of measurement (grams).
Step 3: Dissolve the Solute in a Small Amount of Distilled Water
Transfer the weighed solute into a clean, dry beaker. Add a small amount of distilled water to the beaker and stir the mixture until the solute is completely dissolved. This step is important to ensure that the solute is fully dissolved before transferring it to the volumetric flask.
Step 4: Transfer the Solution to the Volumetric Flask
Using a funnel or pipette, transfer the dissolved solute into a volumetric flask. Be careful to avoid spilling any of the solution.
Step 5: Rinse the Beaker and Add the Rinsate to the Flask
To ensure that all of the solute is transferred to the volumetric flask, rinse the beaker with a small amount of distilled water and add the rinsate to the flask. Swirl the flask gently to mix the solution.
Step 6: Add Distilled Water to the Mark
Using a pipette or graduated cylinder, add distilled water to the volumetric flask until the solution reaches the mark on the neck of the flask. Be careful not to exceed the mark, as this would result in an inaccurate concentration.
Step 7: Stir the Solution
Attach a stirrer or use a magnetic stirrer to mix the solution thoroughly. Allow the solution to sit for a few minutes to ensure that the solute is evenly distributed throughout the solution.
Step 8: Label the Flask
Once the solution is prepared, label the volumetric flask with the following information: the concentration (10 mM), the solute name (e.g., NaCl), the date, and your initials.
Congratulations! You have successfully prepared a 10 millimolar solution. Remember to store the solution in a cool, dry place and use it within the recommended shelf life to maintain its stability and accuracy.
