A meniscus is a curve in the surface of a molecular problem (water, of course) when it touches another material. V water, you have the right to think of the as as soon as water sticks come the inside of a glass.
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What is a meniscus?
A meniscus is a curve in the surface ar of a molecular substance (water, of course) when it touches one more material. With water, you deserve to think of that as when water sticks to the within of a glass.
Why a meniscus occurs
Adhesion is responsible because that a meniscus and this needs to do in component with water"s relatively high surface tension. Water molecules space attracted to the molecule in the wall surface of the glass beaker. And also since water molecules like to stick together, once the molecules emotional the glass cling to it, various other water molecules cling come the molecules emotional the glass, creating the meniscus. They"ll take trip up the glass as far as water"s cohesive pressures will enable them, till gravity prevents them indigenous going further. Cohesion is one intermolecular attraction between like molecules (other water molecules in this case).
Sad story of a meniscus misread
Few people take the moment to take into consideration the prominence of water menisci in your lives. But, imagine this chilling scenario:
In her high-school chemistry last exam you mistakenly read a meniscus together 21.9 milliliters (ml) instead of the correct 21.7 ml (in this picture), and thus you gain an 89 ~ above the test instead of a 90. Her GPA falls from 4.00 to 3.99 and you don"t obtain into that design college regimen you wanted. Consequently, girlfriend don"t obtain that prestigious design job, where, 20 years later, friend would have actually invented a brand-new water-based chemistry to permit rubber come grip better. Sadly, 10 year later, a mother and her lover 4-year old daughter space leaving the ice cream cream store and also the tiny girl, who shoes don"t have actually your un-invented coating, slips on a napkin and drops her ice cream cream cone. She cries at she loss ... Because you misread the meniscus in the 12th grade.
The ethical of this fictional story is the it is crucial to read the measure correctly, and also yes, in the picture above, the true volume in the graduated cylinder is at the bottom the the water level—21.7 milliliters, no 21.9.
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"Upside down" meniscus
As this photo shows, a meniscus deserve to go increase or down. That all depends on if the molecules of the fluid are much more attracted come the exterior material or to themselves. A concave meniscus, i m sorry is what you generally will see, occurs when the molecule of the liquid space attracted to those that the container. This occurs v water and a glass tube. A convex meniscus occurs once the molecules have a more powerful attraction come each other than come the container, similar to mercury and also glass. A level meniscus occurs with water in some types of plastic tubes; tube made out of material that water does no stick to. In any type of case, you obtain the true volume of the liquid by reading the facility of the fluid in the tube, which will certainly the lowest vertical allude of the liquid.