Technique: Using Serological Pipette

ISU General Chemistry Laboratory Experiments
21 Sept 202004:39
EducationalLearning
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TLDRThis instructional script demonstrates the proper use of a pipette for precise liquid measurement. It begins with attaching the bulb and creating a vacuum by squeezing it partially. The user is then guided to submerge the pipette tip, release the pressure to draw liquid, and hold it vertically to read the volume. The process involves adjusting the liquid level by controlling pressure with a thumb and observing the meniscus to ensure accuracy. The demonstration concludes with transferring the measured liquid to a vial, adjusting the volume to the desired mark, and weighing the filled vial to confirm the accuracy of the measurement.

Takeaways
  • 💧 Proper placement of the bulb is crucial for creating a vacuum in the pipette.
  • 🫙 The bulb should be squeezed to expel air before drawing liquid.
  • 🔬 The pipette tip should be placed at the bottom of the container to draw liquid.
  • 👁️ Observing the meniscus is key to accurately measuring the volume.
  • 👍 Releasing the pressure gradually allows for precise volume control.
  • ✋ Thumb placement is used to stop the flow and adjust the volume.
  • 📏 It's important to align the meniscus with the desired volume marking.
  • 📉 Releasing pressure causes the liquid level to drop, which is monitored closely.
  • 🔄 The process may require adjusting the pressure to achieve the exact volume.
  • 💊 Transferring the liquid to a vial involves careful control of the pipette.
  • ⚖️ The final step involves weighing the vial to confirm the liquid's weight.
Q & A

  • What is the purpose of the bulb in a pipette?

    -The bulb in a pipette is used to create a vacuum. When you squeeze the bulb, it expels air, allowing you to draw up liquid into the pipette by releasing the pressure.

  • How should you insert the bulb into the pipette?

    -You should insert the bulb firmly into the pipette so that it doesn't fall out, but you should not push it all the way down. It needs to make contact to facilitate the vacuum.

  • What sound do you expect to hear when you squeeze the bulb of the pipette?

    -When you squeeze the bulb, you should hear a sound of air being pushed out, indicating that the vacuum is being created.

  • How do you transfer the liquid from the pipette to a beaker?

    -You put the tip of the pipette to the bottom of the beaker, slightly release the pressure on the bulb, and then quickly remove the bulb, replacing it with your thumb to push out the liquid.

  • What is the meniscus and why is it important to observe it?

    -The meniscus is the curved surface of the liquid in the pipette. It's important to observe the meniscus to accurately read the volume of the liquid and ensure that it reaches the desired measurement mark.

  • How do you adjust the volume of liquid in the pipette to the desired level?

    -You adjust the volume by releasing or applying pressure on the bulb or your thumb. You can control the flow of the liquid by carefully watching the meniscus and adjusting the pressure accordingly.

  • What is the correct way to fill the pipette to a specific volume, such as 10 mL?

    -You start by filling the pipette slightly above the desired volume, then kneel to get a better view of the meniscus. You release the pressure gradually until the meniscus reaches the 10 mL mark, and then stop.

  • How do you ensure accuracy when measuring liquid with a pipette?

    -Accuracy is ensured by carefully observing the meniscus and adjusting the pressure on the bulb or your thumb to make sure the liquid level aligns with the desired measurement mark without going over it.

  • What is the final step after filling the pipette to the desired volume?

    -The final step is to cap the vial containing the liquid, place it on a scale, and close the scale door to read the weight of the vial with the liquid.

  • Why is it important to use a scale to weigh the vial after transferring the liquid?

    -Using a scale to weigh the vial after transferring the liquid ensures that the correct volume has been transferred, especially when precise measurements are critical for the experiment or procedure.

  • How do you prevent spillage when transferring liquid from the pipette to a beaker or vial?

    -To prevent spillage, you should control the flow of the liquid by applying and releasing pressure on the bulb or your thumb, and ensure that the pipette tip is positioned correctly in the container.

  • What is the significance of the zero marking on the pipette?

    -The zero marking on the pipette is the reference point from which you start measuring the volume of the liquid. It's crucial for ensuring that you are measuring the correct amount of liquid.

Outlines
00:00
🧪 Pipette Usage and Measurement Technique

This paragraph demonstrates the correct method for using a pipette to measure liquids accurately. It begins with the proper placement of the bulb to create a vacuum and ensuring a firm but not overly tight fit. The user is instructed to squeeze the bulb to expel air, then submerge the pipette tip into the liquid and gradually release the pressure to draw up the liquid. The importance of observing the meniscus is highlighted, and the user is guided through adjusting the pipette to ensure the liquid level is at the zero mark. The process continues with measuring out a specific volume, such as 10 mL, by releasing the liquid slowly and monitoring the meniscus at the desired marking. The paragraph concludes with transferring the measured liquid into a vial, capping it, and weighing it to confirm the accuracy of the measurement.

Mindmap
Keywords
💡Pipette
A pipette is a laboratory tool used for the precise measurement and transfer of liquids. In the video, the pipette is central to the demonstration as it is used to accurately measure and dispense a specific volume of liquid. The script details the correct way to attach the bulb, create a vacuum, and control the release of liquid to achieve the desired volume.
💡Bulb
The bulb in the context of the video refers to the part of the pipette that is squeezed to create a vacuum, which allows the user to draw liquid into the pipette. It is crucial for the operation of the pipette, as it controls the suction and release of the liquid, as demonstrated when the script instructs to 'squeeze the bulb'.
💡Vacuum
A vacuum is a space devoid of matter, including air. In the script, creating a vacuum is essential for the pipette to function properly. When the bulb is squeezed, it expels air and creates a vacuum that enables the pipette to draw in liquid. The vacuum is maintained until the liquid is released by adjusting pressure on the bulb.
💡Meniscus
The meniscus is the curved surface of a liquid in a container, caused by surface tension. In the video, the meniscus is used as a visual aid to accurately measure the liquid level. The script describes how the presenter looks at the meniscus to ensure that the liquid level is at the correct marking, which is crucial for precise measurement.
💡Beaker
A beaker is a container used for mixing, stirring, and heating liquids in a laboratory. In the video, the beaker is mentioned as the initial container from which the liquid is drawn using the pipette. It is an essential piece of laboratory equipment that facilitates the process of transferring liquids.
💡Vial
A vial is a small container, often used to hold liquids or samples in a laboratory. In the script, the vial is the destination where the measured liquid is transferred to. The process of transferring the liquid to the vial is carefully controlled to ensure the accuracy of the measurement.
💡Scale
A scale in this context refers to a laboratory balance used to measure the weight of objects with precision. The script mentions using a scale to weigh the vial after transferring the liquid, which helps in verifying the accuracy of the liquid volume transferred to the vial.
💡Volume
Volume refers to the amount of space that a substance or object occupies. In the video, measuring volume is the main task, and the script provides a step-by-step guide on how to accurately measure the volume of liquid using a pipette. The term is repeatedly used to emphasize the importance of precise volume measurement.
💡Pressure
Pressure in this context refers to the force applied to the pipette's bulb, which controls the flow of liquid. The script describes how releasing or applying pressure on the bulb affects the liquid level inside the pipette, which is a key aspect of the liquid measurement process.
💡Marking
A marking, in this case, refers to the graduations or lines on the pipette that indicate the volume of liquid. The script mentions the zero marking and the 10 mL marking, which are used to ensure that the correct volume of liquid is measured and transferred.
💡Release
Release in the script refers to the action of letting go of the pressure on the pipette's bulb, which allows the liquid to flow out of the pipette. The term is used to describe the careful control needed to ensure that the liquid is dispensed accurately, as seen when the presenter releases the liquid into the vial.
Highlights

Introduction to using a pipette with a bulb

Proper placement of the bulb for creating a vacuum

Avoiding over-pushing the bulb to ensure proper contact

Explanation of the vacuum principle for liquid aspiration

Technique of squeezing the bulb to expel air

Positioning the pipette tip at the beaker's bottom

Releasing pressure to draw liquid into the pipette

Demonstration of vertical pipette positioning

Quick removal and replacement of the bulb with a thumb

Visual confirmation of volume level in the pipette

Adjusting pipette position for accurate volume measurement

Using the meniscus for precise volume alignment

Controlling liquid flow with thumb pressure

Releasing liquid into a vial until reaching the 10 mL mark

Approach to estimating volume before reaching the exact mark

Finalizing the volume measurement with careful observation

Transferring the remaining liquid to a beaker

Capping the vial and weighing it for accuracy

Final weight reading of the vial

Transcripts

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Pipette TechniqueLab EquipmentLiquid MeasurementScience TutorialVacuum CreationMeniscus ReadingVolume ControlLab SafetyBeaker UseScale ReadingAccuracy Tips