Most cloth towels are made of cotton, and paper towels are generally made from paper pulp. Water has an upward meniscus, mercury has a downward meniscus. properties of adhesion. Functional cookies help to perform certain functionalities like sharing the content of the website on social media platforms, collect feedbacks, and other third-party features. How to Read a Meniscus in Lab Measurements - ThoughtCo You can read about more in-depth here: Khan said that the reason for the concave meniscus in a glass tube was the water molecules bonding with the glass molecules. Helmenstine, Anne Marie, Ph.D. (2020, August 28). The meniscus is the curving of water at the surface due to its surface tension, the attraction of molecules for each other. (credit a: modification of work by Scott Bauer; credit b: modification of work by David Nagy). A meniscus lens is a convex-concave lens in which one face curves outward, while the other face curves inward. Model release not required. However, you may visit "Cookie Settings" to provide a controlled consent. Menisci are a manifestation of capillary action, by which either surface adhesion pulls a liquid up to form a concave meniscus, or internal cohesion pulls the liquid down to form a convex meniscus. In physics (particularly fluid statics), the meniscus (plural: menisci, from Greek'crescent') is the curve in the upper surface of a liquid close to the surface of the container or another object, produced by surface tension. Get eye level with the meniscus. 1550520. electronegative than hydrogen. For a convex meniscus, this is the uppermost or top point of the liquid. This website uses cookies to improve your experience while you navigate through the website. For a concave meniscus, this it the lowest point or bottom of the meniscus. it's actually happening in your capillaries in your When you have mercury liquid in a container, why is the meniscus upside down compared to all other liquids? action that you see, that actually is capillary action. Very interesting question and I had to an extensive google search too! Especially the ones that The extent of the rise (or fall) is directly proportional to the surface tension of the liquid and inversely proportional to the density of the liquid and the radius of the tube. Retrieved from https://www.thoughtco.com/definition-of-meniscus-605883. It just got knocked by another molecule, it had enough kinetic This occurs between water and glass. Water has hydrogen bonding.what about mercury?does mercury repel glass tube?what is the force which makes mercury have more cohesive nature than adhesive nature? The adhesive forces between the liquid and the porous material, combined with the cohesive forces within the liquid, may be strong enough to move the liquid upward against gravity. (credit: modification of work by Centers for Disease Control and Prevention). Figure \(\PageIndex{4}\): Differences in the relative strengths of cohesive and adhesive forces result in different meniscus shapes for mercury (left) and water (right) in glass tubes. Powered by SiteManager | Contact Webmaster. It forms what looks like the upper portion of a sphere - a convex meniscus. This means that any instrument is calibrated for a specific liquid, usually water. Water meniscus is convex, mercury menisucs is concave A concave meniscus, which is what you normally will see, occurs when the molecules of the liquid are attracted to those of the container. The strong cohesive. VAT no. Download for free at http://cnx.org/contents/85abf193-2bda7ac8df6@9.110). On smaller raindrops, the surface tension is stronger than in larger drops. Water forms drops on these surfaces because the cohesive forces within the drops are greater than the adhesive forces between the water and the plastic. Direct link to SHIVANK VATSAL 's post At 6:52, how are MORE of , Posted 4 years ago. Why does water have a concave meniscus and mercury a convex meniscus The liquid itself is held together by its own cohesive forces. Click here. And this phenomenon of something sticking to its container, we Continue. It all depends on if the molecules of the liquid are more attracted to the outside material or to themselves. 29,306 views Apr 3, 2014 Meniscus and wetting are caused by surface tension. Have feedback to give about this text? Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. 327-329 Harrow Road Meniscus in Chemistry A concave meniscus forms when the liquid molecules are more attracted to the container via adhesion than to each other via cohesion. It stuck to them. Direct link to Just Keith's post That is called a convex m, Posted 5 years ago. Thats what youre noticing. Science Photo Library (SPL) This is known as capillary Repulsion. United Kingdom, Telephone: +44 (0) 20 7432 1100 molecule gets attracted to it because of its hydrogen bonds. But because it went up there, There is only one liquid having higher surface tension and thats mercury which is a liquid metal with a surface tension of almost 500 mN/m. How is the meniscus of mercury different to that of water? How to Read a Meniscus in Chemistry. Cookies collect information about your preferences and your devices and are used to make the site work as you expect it to, to understand how you interact with the site, and to show advertisements that are targeted to your interests. In contrast, water exhibits a concave meniscus, because the attraction between the wall and the water is stronger than the waters internal cohesion. Direct link to Jiahui Ni's post So if water is held in co, Posted 4 years ago. And this right over here are the glass molecules. In liquids such as water, the meniscus is concave; in liquids such as mercury, however, which have very strong cohesive forces and weak adhesion to glass, the meniscus is convex (Figure 11.4. Mercury When mercury is placed in a graduated cylinder, the cohesive forces in the mercury are stronger than the adhesive forces between the mercury and the glass. going on here with the mercury, the mercury is more attracted to itself than it is to the glass container, so it bulges right over there. the adhesive forces between the molecules of a liquid and those of the Direct link to tyersome's post The atoms in glass are co, Posted 7 years ago.