Making a Molar Solution

Summary

This tutorial demonstrates how to prepare a 1 molar sodium chloride (NaCl) solution. The process involves measuring 5.84 grams of NaCl, transferring it into a 100 mL volumetric flask using a powder funnel, and dissolving it in distilled water. The solution is then carefully brought to the 100 mL mark, ensuring precise volume measurement. Finally, the prepared solution is labeled with essential details such as concentration, contents, and preparer’s name, and transferred to a reagent bottle to avoid contamination. This step-by-step guide ensures accuracy and proper handling in solution preparation.

Takeaways

• 😀 Weigh 5.84 grams of sodium chloride using an electronic balance and a weighing boat (WBO).
• 😀 Use a powder funnel to transfer the sodium chloride into a 100 mL volumetric flask.
• 😀 Rinse the WBO and funnel with distilled water to ensure all sodium chloride is transferred into the flask.
• 😀 Sodium chloride crystals may be hydrophobic, so be thorough when rinsing the WBO.
• 😀 Add distilled water to the flask until it is about half full, then swirl to dissolve the sodium chloride completely.
• 😀 Continue swirling until the solution is clear, indicating that all sodium chloride has dissolved.
• 😀 Add distilled water drop by drop near the meniscus to bring the solution up to exactly 100 mL.
• 😀 Use a dropper bottle or transfer pipet to carefully add the final drops of water to the etched line on the flask.
• 😀 Create a label with the concentration (1 Molar), contents (Sodium Chloride Solution), preparer's name, and the date.
• 😀 Fold the sides of the label for easier removal at a later date.
• 😀 When transferring the solution to a reagent bottle, hold the lid to avoid contamination.

Q & A

What is the target concentration and volume for the sodium chloride solution in this procedure?

The target concentration is 1 molar (1 M), and the total volume of the sodium chloride solution to be made is 100 milliliters.

How much sodium chloride is needed to prepare the solution?

You will need 5.84 grams of sodium chloride to prepare the 1 M solution.

Why is it important to use an electronic balance for measuring the sodium chloride?

An electronic balance is crucial for accurately measuring the mass of sodium chloride, ensuring the correct amount is used to achieve the desired molarity.

What equipment is used to dissolve the sodium chloride in water?

A 100 mL volumetric flask is used to dissolve the sodium chloride. A squirt bottle filled with distilled water is also used to rinse any remaining sodium chloride from the balance and funnel.

What should you do after transferring the sodium chloride into the volumetric flask?

After transferring the sodium chloride into the volumetric flask, you should rinse the WBO (weighing boat) with distilled water to ensure all sodium chloride is transferred into the flask.

Why is it necessary to swirl the flask while dissolving the sodium chloride?

Swirling the flask helps to dissolve the sodium chloride crystals completely and evenly, ensuring a clear solution without any undissolved solids.

How can you tell when the sodium chloride has completely dissolved in the water?

Once all of the sodium chloride crystals have dissolved, the solution will become clear, indicating complete dissolution.

What should be done when adding distilled water near the etched mark on the flask?

As you near the etched mark on the flask, use a dropper bottle or transfer pipet to add water drop by drop, ensuring precise filling to the correct volume.

What information should be included on the label for the prepared solution?

The label should include the concentration, contents of the solution, the name of the preparer, and the date of preparation.

Why is it recommended to fold the side of the label during preparation?

Folding the side of the label makes it easier to remove the label later, preventing any residue or interference when handling the solution.

How should the solution be transferred to the reagent bottle?

The solution should be carefully transferred to the reagent bottle, making sure to hold the lid while pouring to prevent contamination from touching surfaces.