Pipette

Definition

A pipette is a laboratory tool used to transport a measured volume of liquid. It is essential for precise liquid handling in various experiments, especially in titrations where accurate measurement of reagents is crucial for determining the concentration of solutions. Pipettes come in different types, such as volumetric and graduated, each serving specific purposes in experimental procedures.

5 Must Know Facts For Your Next Test

1. Pipettes can be either manual or electronic, with electronic pipettes providing more consistent and precise measurements.
2. Volumetric pipettes are designed for delivering a single, specific volume with high accuracy, making them ideal for titration procedures.
3. Graduated pipettes allow for variable volumes to be measured and are marked with graduation lines for easier reading.
4. When using a pipette, it’s important to always read the liquid level at the bottom of the meniscus to ensure accurate measurement.
5. Pipettes must be calibrated regularly to maintain precision and avoid errors during quantitative analysis.

Review Questions

• How does the use of a pipette enhance the accuracy of titration experiments?
  • Using a pipette enhances the accuracy of titration experiments by allowing for precise measurement and transfer of liquid reagents. This precision is critical since even small errors in volume can lead to significant discrepancies in calculating concentrations. A well-calibrated pipette ensures that the exact amount of titrant is added to the analyte, which directly affects the results of the titration.
• Discuss the differences between volumetric and graduated pipettes and their respective applications in lab settings.
  • Volumetric pipettes are designed to deliver one specific volume with high precision, making them ideal for tasks where accuracy is critical, such as preparing standard solutions. In contrast, graduated pipettes can deliver variable amounts and have multiple graduation marks, which allows them to be used for a range of applications requiring different volumes. While volumetric pipettes are more accurate for fixed volumes, graduated pipettes offer versatility in measurements.
• Evaluate how improper use or maintenance of pipettes could impact experimental outcomes in acid-base titrations.
  • Improper use or maintenance of pipettes can significantly skew experimental outcomes in acid-base titrations by introducing measurement errors. If a pipette is not calibrated correctly or if it has residual liquids from previous uses, this could lead to inaccurate volumes being dispensed. Such inaccuracies may result in incorrect endpoint determination, affecting calculations of molarity and potentially leading to flawed conclusions about solution concentrations. Therefore, ensuring proper handling and regular calibration is essential for reliable results.

Related terms

Titration: A technique used to determine the concentration of a solution by reacting it with a solution of known concentration.

Burette: A long, graduated glass tube with a stopcock at the bottom used to dispense precise volumes of liquid during titrations.

Meniscus: The curve at the surface of a liquid in a container, which is important to read accurately for measuring liquid volumes.