How to Dilute a Solution

Carolina Biological
5 Nov 200903:36

Summary

TLDRIn 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.

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Related Tags
ChemistryLaboratory SkillsDilution TechniquesSodium ChlorideStock SolutionsEducational VideoScience InstructionLab SafetySolution PreparationElon University