How much water is present in each of the following graduated cylinders? Be sure to include units.
10 mm
B
µm
10
C
nm
The correct answer and explanation is :
Understanding Graduated Cylinders and Meniscus Reading
Graduated cylinders are essential laboratory instruments used to measure liquid volumes accurately. They come in various sizes, typically marked in milliliters (mL). The liquid inside a graduated cylinder forms a curve at the surface known as the meniscus. For most liquids, including water, the meniscus is concave, meaning it curves downward. Accurate measurement requires reading the volume at the bottom of the meniscus at eye level. citeturn0search1
Steps to Read a Graduated Cylinder Accurately
- Place the Cylinder on a Level Surface: Ensure the graduated cylinder is on a flat, stable surface to prevent any tilting that could affect the accuracy of the reading.
- Bring Your Eye to the Level of the Meniscus: Position yourself so that your line of sight is directly in line with the meniscus to avoid parallax errors, which occur when the measurement is read from an angle.
- Identify the Bottom of the Meniscus: For water and most liquids, locate the lowest point of the curved surface.
- Read the Measurement: Note the marking on the cylinder that aligns with the bottom of the meniscus. If the meniscus falls between two markings, estimate the volume accordingly. For example, if the meniscus is halfway between 21 mL and 22 mL, the volume is approximately 21.5 mL.
Precision and Accuracy
The precision of your measurement depends on the calibration of the graduated cylinder. Smaller cylinders, such as 10 mL ones, typically have finer graduations (e.g., 0.1 mL increments) compared to larger cylinders like 100 mL ones, which may have 1 mL increments. Therefore, using the smallest appropriate cylinder for your measurement enhances accuracy. citeturn0search3
Common Mistakes to Avoid
- Reading from Above or Below Eye Level: This can lead to inaccurate readings due to parallax error.
- Ignoring the Meniscus: Failing to read from the bottom of the meniscus can result in measurement errors.
- Using an Inappropriately Sized Cylinder: Measuring a small volume in a large cylinder can reduce measurement precision.
Conclusion
Accurate measurement of liquid volumes using a graduated cylinder is a fundamental skill in laboratory settings. By understanding the concept of the meniscus and following proper reading techniques, you can ensure precise and reliable measurements. If you provide the specific identifiers and measurements for each graduated cylinder in question, I can offer more detailed assistance.
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