23.1.4 CIA Demonstration: Pipetting

Question 1

CIA Demonstration: Pipetting

Answer 1

• Volumetric pipettes are used to transfer one specific volume, such as 20.00 mL.
• Graduated pipettes are used to transfer varying volumes.

Question 2

note

Answer 2

• Pipettes are used to transfer a specific volume of a liquid from one container to another.
• Volumetric pipettes are used are used to transfer one specific volume, such as 20.00 mL. Volumetric pipettes must be filled to the point where the bottom of the meniscus of the liquid is at the fill line of the pipette. A pipette bulb is used to draw liquid into the pipette. After the pipette is filled, placing a finger on the pipette and wiggling it gently allows the liquid to drain slowly to the fill line.
• Once the pipette is filled to the fill line, the liquid can be transferred to a receiving flask. A small amount of liquid will remain in the tip of the pipette.
• Graduated pipettes are used to transfer varying volumes. Graduated pipettes are less precise and accurate than volumetric pipettes.
• Instead of filling to a fill line and delivering the total volume, graduated pipettes are filled to a zero line and drained to the mark of the desired volume. For example, to deliver 2.00 mL of liquid, fill the pipette to the 0.00 mL mark, and drain to the 2.00 mL mark.
• Mastering the technique of pipetting requires practice.