How to Dilute a Solution

Summary

In this instructional video, Professor Jared Heyman from Elon University demonstrates the technique for diluting a concentrated sodium chloride solution. He outlines the necessary calculations to determine the moles required for a 250 mL solution at a 0.01 molarity, derived from a 250 M stock solution. The professor emphasizes laboratory safety by recommending the transfer of stock solution to a separate container before pipetting. Detailed steps are provided for accurately using a volumetric pipet and preparing the dilute solution, ensuring precise measurements and adherence to proper protocols. For more resources, viewers are directed to Carolina Chemistry.

Takeaways

• 😀 Diluting a solution is a common laboratory technique for preparing a more dilute solution from a concentrated stock solution.
• 📏 To prepare a 250 mL solution of 0.01 M, you need to calculate the exact number of moles required.
• 🧪 For a 0.01 M solution, you need 0.025 moles of sodium chloride.
• 💧 The stock solution concentration is 0.25 M, which means you can calculate the volume needed for dilution.
• 🔬 Use a 10 mL volumetric pipet to accurately measure the stock solution.
• ⚠️ Always pour the stock solution into another container before using the pipet to avoid contamination.
• 🖊️ Clearly label all flasks to adhere to proper laboratory safety protocols.
• 👌 When using the pipet, create a seal with your thumb to control the liquid flow precisely.
• 📊 After transferring the liquid, fill the volumetric flask with solvent to reach the exact volume using the meniscus.
• 🛠️ All necessary materials for this procedure can be found at Carolina.com.

Q & A

What is the main topic of the video?

The video focuses on the procedure and technique for diluting a solution in a laboratory setting.

What volume and concentration of the dilute solution are being prepared?

A 250 mL solution of 0.01 M (molar) sodium chloride is being prepared.

What is the concentration of the stock solution used for dilution?

The concentration of the stock solution is 0.25 M (molar).

How is the number of moles required for the dilute solution calculated?

The number of moles is calculated using the formula: moles = concentration × volume. Here, 0.01 M × 0.250 L = 0.025 moles.

What is the purpose of transferring the stock solution to another container before pipetting?

Transferring the stock solution prevents contamination of the stock by avoiding direct contact with the pipet.

What is the correct procedure for using a pipet to measure liquid?

To use a pipet, place it in the liquid, squeeze the bulb to fill it, seal the end with your thumb, and then carefully release the liquid to the meniscus line.

What is the significance of the meniscus in liquid measurement?

The meniscus is the curve of the liquid surface, and measurements should be taken at the bottom of the meniscus for accuracy.

Why should you never pipet by mouth?

Pipetting by mouth is unsafe and can lead to accidental ingestion of hazardous chemicals.

What should you do after transferring the correct volume from the pipet to the volumetric flask?

After transferring the liquid, fill the volumetric flask with solvent to the exact volume marked on the flask.

Where can you find more information or products related to this technique?

More information and products for this technique can be found at Carolina.com, specifically in their chemistry section.