What is the uncertainty for a 15 mL pipette? What is the uncertainty for a 100 mL graduated cylinder? What is the uncertainty for a 50 mL beake
The Correct Answer and Explanation is:
The uncertainty in a measuring instrument refers to the degree of precision with which it can measure a given quantity. It typically depends on the smallest division on the instrument scale, or its tolerance, and can vary depending on the design and calibration of the instrument. Let’s analyze the uncertainty for each of the instruments mentioned:
1. 15 mL Pipette:
A typical 15 mL pipette is used for precise liquid measurements. The uncertainty is generally determined by the smallest graduation on the pipette, which is usually 0.01 mL. This means the uncertainty in measurements with this pipette is ±0.01 mL. The pipette is designed for high precision, so the uncertainty is relatively small. However, other factors, such as the pipette’s calibration and the user’s technique in reading the meniscus, may slightly contribute to the overall uncertainty.
2. 100 mL Graduated Cylinder:
For a 100 mL graduated cylinder, the uncertainty is typically determined by the smallest graduation visible on the scale. In many cases, this could be 1 mL, though higher-quality graduated cylinders may have smaller divisions, such as 0.2 mL or 0.5 mL. If the smallest division is 1 mL, the uncertainty in measurement would be ±1 mL. If it’s a more precise cylinder with smaller divisions, the uncertainty would be smaller, such as ±0.5 mL or ±0.2 mL, depending on the instrument.
3. 50 mL Beaker:
A 50 mL beaker typically has large divisions, often marked in 10 mL increments. This makes it suitable for rough measurements, but not highly precise ones. The uncertainty in a 50 mL beaker would typically be around ±5 mL, corresponding to the largest division. Beakers are often used for approximate measurements, so the uncertainty is larger compared to more precise instruments like pipettes or graduated cylinders.
Conclusion:
In summary, the uncertainty for each instrument depends on its scale and design. The pipette offers the smallest uncertainty (±0.01 mL), followed by the graduated cylinder (which can range from ±0.2 mL to ±1 mL), and the beaker, which has the largest uncertainty (±5 mL).
