Volumetric pipette facts for kids
A volumetric pipette is a special tool used in science labs to measure a very exact amount of liquid. It's also sometimes called a bulb pipette or a belly pipette because of its unique shape.
This type of pipette is known for being super accurate. When scientists need to know the exact volume of a liquid, like when they are mixing chemicals or doing important experiments, they often choose a volumetric pipette.
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What is a Volumetric Pipette?
A volumetric pipette is a long, thin glass tube with a wider section in the middle, which looks like a bulb or belly. It has a single mark, called a calibration mark, usually a thin line around the neck of the pipette. This mark shows the exact volume the pipette is designed to hold or deliver.
Parts of a Volumetric Pipette
- Tip: The narrow end where the liquid goes in and out.
- Bulb: The wider, middle part that holds most of the liquid.
- Calibration Mark: A single line on the narrow neck above the bulb. This line indicates the precise volume (like 10 mL or 25 mL) when the bottom of the liquid's curve (meniscus) touches it.
- Top Opening: The end where a special pump or bulb is attached to draw liquid in.
How Does a Volumetric Pipette Work?
Using a volumetric pipette involves a few careful steps to make sure you get the right amount of liquid:
- Cleaning: First, the pipette must be very clean. Any dirt or leftover liquid can affect how accurate it is.
- Drawing Liquid: A special rubber bulb or pump is attached to the top. You squeeze the bulb to create a vacuum, then place the tip of the pipette into the liquid you want to measure. Slowly release the bulb to draw the liquid up past the calibration mark.
- Adjusting Volume: Once the liquid is above the mark, you carefully remove the bulb and quickly cover the top opening with your finger. Then, you slowly release your finger to let the liquid drain until the bottom of the liquid's curve (called the meniscus) lines up exactly with the calibration mark.
- Dispensing Liquid: Finally, you let the liquid flow out into another container. Volumetric pipettes are designed to deliver the exact volume when they are allowed to drain completely.
Why is Accuracy Important?
In science, especially in chemistry, getting the exact amount of a substance is often very important. If you use too much or too little of a chemical, your experiment might not work correctly, or your results could be wrong. Volumetric pipettes help scientists make sure their measurements are precise, leading to more reliable and accurate scientific discoveries.