A: A meniscus is the curved surface at the top of a column of liquid. In a science class, this liquid is usually water or some sort of aqueous solution, and the column is usually a graduated cylinder or a pipet.
What is it called when water forms a dome?
Cohesion of water
Before it overflows, the water forms a dome-like shape above the rim of the glass. ... Cohesive forces are responsible for surface tension, a phenomenon that results in the tendency of a liquid’s surface to resist rupture when placed under tension or stress.
What is the top layer of water called?
Bodies of water are made up of layers, determined by temperature. The top surface layer is called the epipelagic zone , and is sometimes referred to as the “ocean skin” or “sunlight zone.” This layer interacts with the wind and waves, which mixes the water and distributes the warmth.
What is upper meniscus?
The meniscus (plural: menisci, from the Greek for “crescent”) is the curve in the upper surface of a liquid close to the surface of the container or another object , caused by surface tension. It can be either concave or convex, depending on the liquid and the surface.
Why water has a concave meniscus?
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 break the surface tension of water?
However, the surface tension of water can be broken by adding certain substances such as detergents . Soaps and detergents are useful for cleaning because when they break water’s surface tension, they are able to spread out onto dirty surfaces and soak into laundry, breaking up dirt and oil.
What is the skin of water called?
Surface tension could be defined as the property of the surface of a liquid that allows it to resist an external force, due to the cohesive nature of the water molecules.
What is the tendency of water to stick to other substances?
Essentially, cohesion and adhesion are the “stickiness” that water molecules have for each other and for other substances. A water drop is composed of water molecules that like to stick together-an example of the property of cohesion.
Why does water make a dome on a penny?
What allows us to get such a large dome of water on top of the penny? Water has a high surface tension . This happens because water molecules like to stick together. This property is called cohesion.
Is water concave or convex?
Water meniscus is convex , mercury menisucs is concave
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.
Do you read from the top of the meniscus?
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.
What is the correct level at which to read a 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.
When using aqueous solutions do we read at the bottom or top of the meniscus?
Measure so that the line you are reading is even with the center of the meniscus. For water and most liquids, this is the bottom of the meniscus . For mercury, take the measurement from the top of the meniscus. In either case, you are measuring based on the center of the meniscus.
What liquids have surface tension?
There is only one liquid having higher surface tension and that’s mercury which is a liquid metal with a surface tension of almost 500 mN/m.
Why does water curve in a graduated cylinder?
Since opposites attract, the positive sides attract the negative sides, and all of the molecules stick to one another. This is why water droplets can form. ... You can see this at the top of the graduated cylinder, where the water will slightly creep up the sides and form a curve, which is the meniscus.
What does a convex look like?
A convex shape is the opposite of a concave shape. It curves outward, and its middle is thicker than its edges . If you take a football or a rugby ball and place it as if you’re about to kick it, you’ll see that it has a convex shape—its ends are pointy, and it has a thick middle.
