What is a meniscus and how is it used to determine the volume of a liquid using a graduated cylinder?

What is a meniscus and how is it used to determine the volume of a liquid using a graduated cylinder?

When a liquid is placed into a graduated cylinder, the surface takes on a curved shape. This curve is known as a meniscus. The graduated cylinder is calibrated so that reading the bottom of the meniscus, when viewed at eye level, will give accurate results.

What part of the meniscus do you use to measure the volume?

The key to getting an accurate reading, is to measure the center of the meniscus whether it be concave or convex. E.g. with a concave meniscus, measure the bottom of the meniscus and for convex meniscus, take the reading from the top of the meniscus. (See diagram reading line in the diagram A and B).

How do you read the volume of a cylinder?

Determine the volume contained in a graduated cylinder by reading the bottom of the meniscus at eye level. Read the volume using all certain digits and one uncertain digit. Certain digits are determined from the calibration marks on the cylinder.

How do you read volume in a graduated cylinder?

Why do we read the bottom of the meniscus?

The location of the mark on the glass is where the bottom of the meniscus should be in order to have the “true” volume be what’s marked. So by measuring from the bottom of the meniscus, you’re synchronizing your measurement procedure with the procedure of the people who originally calibrated the markings on the glass.

Where do you read the meniscus inside a graduated cylinder?

To correctly read a graduated cylinder, the surface at the center of the meniscus must be read, not the top of the ring of liquid clinging to the wall of the graduated cylinder. For most liquids, this “center” will be the lowest point of the meniscus.

What tool can be used to measure volume?

Chemists use beakers, flasks, burets and pipets to measure the volume of liquids.

Which meniscus is read for water?

A concave meniscus, which is what you normally will see, occurs when the molecules of the liquid are attracted to those of the container. This occurs with water and a glass tube. A convex meniscus occurs when the molecules have a stronger attraction to each other than to the container, as with mercury and glass.

How do you read a meniscus in chemistry?

A meniscus occurs because of surface tension in the liquid and must be read at eye level. For a concave meniscus, the correct volume will be read at the bottom of the curve. For a convex meniscus, the opposite is true and the correct reading will be at the top of the curve. What is meniscus in laboratory?

Why is it important to account for the meniscus?

This makes taking measurements easy. When you read a scale on the side of a container with a meniscus, such as a graduated cylinder or volumetric flask, it’s important that the measurement accounts for the meniscus. Measure so that the line you are reading is even with the center of the meniscus.

What is the difference between a concave and convex meniscus?

A meniscus occurs because of surface tension in the liquid and must be read at eye level. For a concave meniscus, the correct volume will be read at the bottom of the curve. For a convex meniscus, the opposite is true and the correct reading will be at the top of the curve.

How do you measure a flat meniscus?

In either case, you are measuring based on the center of the meniscus. For a flat meniscus, make sure the liquid is level. Usually placing the container on a lab bench does the trick. You won’t be able to take an accurate reading looking up at the liquid level or down into it. Get eye level with the meniscus.