Pipette

Definition

A pipette is a laboratory tool used to transport a measured volume of liquid from one place to another with precision and accuracy. It is essential in experiments that require exact measurements, especially during procedures like titrations and pH curve determinations, where small changes in volume can significantly affect results.

5 Must Know Facts For Your Next Test

1. Pipettes come in various types, including micropipettes for small volumes and serological pipettes for larger volumes.
2. Using a pipette correctly involves techniques like pre-wetting the tip and holding it vertically to ensure accurate measurements.
3. Calibration of pipettes is crucial for maintaining accuracy, as even small errors can lead to significant discrepancies in titration results.
4. Different pipettes can have varying levels of precision; for example, single-channel pipettes are common for routine lab work while multi-channel pipettes are useful for high-throughput applications.
5. Understanding how to read the meniscus accurately is key to obtaining precise measurements when using a pipette.

Review Questions

• How does the accuracy of a pipette impact the results obtained from titrations?
  • The accuracy of a pipette is crucial in titrations because even minor deviations in volume can lead to significant changes in the calculated concentration of the analyte. For example, if too much or too little titrant is added due to improper pipetting, it can skew the endpoint determination, resulting in incorrect conclusions about the solution's properties. Therefore, mastering pipetting techniques ensures reliable data during titration experiments.
• What are some common types of pipettes used in laboratories, and how do their functions differ?
  • Common types of pipettes include micropipettes, serological pipettes, and automatic pipettes. Micropipettes are designed for very small volumes (typically less than 1 mL) and allow for precise dispensing. Serological pipettes are used for larger volumes and can be graduated for more flexibility. Automatic pipettes facilitate rapid dispensing and often come with adjustable volume settings, making them ideal for repetitive tasks. Each type serves different purposes based on the volume needed and the level of precision required.
• Evaluate the importance of proper calibration and maintenance of pipettes in the context of experimental validity.
  • Proper calibration and maintenance of pipettes are essential for ensuring experimental validity because they directly affect measurement accuracy. Over time, pipettes can drift from their calibrated settings due to wear or contamination, leading to inconsistent results. Regular calibration checks allow researchers to identify discrepancies before conducting critical experiments like titrations. Ensuring that pipettes are well-maintained not only preserves accuracy but also enhances reproducibility across experiments, which is vital for drawing reliable conclusions in scientific research.

Related terms

Titration: A technique used to determine the concentration of a solution by adding a reactant of known concentration until the reaction reaches completion.

Meniscus: The curve at the surface of a liquid in a container, which is important for accurate measurement when using pipettes or other graduated cylinders.

Volumetric Flask: A type of laboratory glassware designed to contain a precise volume of liquid and used for preparing solutions.