Adhesion and Cohesion


If you haven’t, read my “Hydrogen bonds” blog first if possible. Like I said, this time we are going adhesion and cohesion. Let’s start with adhesion. Adhesion are 2 materials (example: water and glass) that have different polarities and can stick to each other.

 One interesting thing about adhesion is the capillary action that makes water climb up a glass tube. Now you need to imagine. Imagine that you have a plastic tub. Then you have a very thin glass rod, about 3 mm thick, and it’s hollow. You put the glass rod in the tub, and something interesting happens.

 The water will climb up the glass tube. It climbs up the glass tube because it’s more attracted to the glass than to itself. This is also adhesion because it is attracted to each other. They are attracted because water has a polarity and glass also has one.

 Adhesion happens because there are polarities in some atoms, like water and glass. A positive atom will stick to a negative atom. Same goes for cohesion. But, cohesion is a little different.

Cohesion is when a material is attracted to itself, such as water. Water is H2O, and as you probably already know, H stands for hydrogen, and O stands for oxygen.

 Oxygen has a partially positive polarity and hydrogen has a partially negative bond. 2 water molecules can bump and form a hydrogen bond. I explained in in my blog “Hydrogen bonds.” Polarities are why adhesion and cohesion happen.

 Water is very interesting. There is still a lot to learn. I’m going to explain it in future blogs. I’m thinking that I should add acidity too!

Thank you! - Nat

Comments

Post a Comment

Popular posts from this blog

Vectors and Scalars

Image
I want to talk about Vectors and Scalars . This is about physics. Now you might be asking, what is a vector? Vectors have a magnitude and direction. In case you don’t know, magnitude is the size of the movement, but it’s not distance. Since it’s a vector quantity, it’s called displacement .  For example, the displacement of a leaf being blown by the wind is 50 centimeters to the east. This is a vector quantity because it has a magnitude (50 cm) and a direction (east). And there’s more...  If someone asks you the version of speed in a vector quantity, it’s called velocity .  For example, the velocity of a ball being thrown is 5m/s to the east. In other words, five meters per second to the east.  You can find the displacement as long as you have the velocity and time. Multiply them and you will get the displacement. If the velocity is 5m/s and the time is 10 seconds, you need to multiply them ( 5 x 10 ) to get the displacement, which is 50 meters.  A...
Read more

Cheryl's Birthday Problem (from SASMO 2015) and Solution

Image
Hello! Nat here, and in this blog, I am going to discuss and give the solution to the famous Cheryl birthday problem. This was popular because it is a difficult logic puzzle and involving the ability of carefully tracking down hints in the conversation and working with only a small amount of data. Here’s the question: Albert and Bernard just became friends with Cheryl, and they want to know when her birthday is. Cheryl gives them a list of 10 possible dates. May 15           May 16           May 19 June 17          June 18 July 14           July 16 August 14       August 15       August 17 Cheryl then tells Albert and Bernard separately the month and the day of her birthday respectively. Albert: I don’t know when Cheryl’s birthday is, but I know that Bernard doesn’t know too. Bernard: At first I don’t know whe...
Read more

Black Holes

Image
Black Holes are holes in space that absorbs anything in their way, even stars. They are made by a star exploding as supernova and the star must be about 3 times the mass of the sun. This is called the Oppenheimer-Volkoff limit.  Its core will collapse into a neutron star, but its gravity is so strong that it starts sucking in material from outer space and later turns into a black hole.  Once they absorb enough matter to become powerful and massive, they can start creating galaxies. That is why black holes can be found in the heart of galaxies.  Sometimes, black holes will emit the brightest light waves in the universe – quasars.  Now you might be asking, why don’t we see like “blink, blink” from earth? The answer is that they are very far. The furthest quasar from us is about 14 billion light years away. However, we are lucky to be on a planet that isn’t near a black hole. If we were near a black hole, we would get our atmosphere stripped first then ...
Read more