Wednesday, September 22, 2010

The Extraordinary Properties of Water

Water is an incredible element that most of us take for granted. I know I have never once stopped to think about all the things that make up water, or about all the things that make water unique. From my research I have found that their are eight properties of water.

1) The elements that make up water have a polar covalent bond, meaning each side has a different charge; one side has a more positive charge, the other a more negative. The reason this happens is because the oxygen atoms are bigger and take more of their fare share of electrons from the hydrogen atoms. Since the hydrogen atoms have less electrons they tend to be positive; the oxygen has more electrons and tends to be negative.

2) Water is cohesive and adhesive. Cohesion is when water sticks to itself. Cohesion (and surface tension) is the reason we have raindrops, because the water is cohesive it tries to stick together and forms a curved "drop."



Adhesion is when water sticks to other things. Adhesion is the reason we have Hydrogen Bonds. The positively charged hydrogen atoms, in one molecule of water, are attracted to the negatively charged oxygen atoms in another molecule of water, forming Hydrogen Bonds. 









3) Have you ever wondered why you get hurt when you jump into a pool of water from a great height? The reason is because of surface tension. The hydrogen bonds in water pull on each other, causing a tightness across the surface of the water. When you break through that tightness you are breaking the hydrogen bonds, and taking away the surface tension. Surface tension allows things to, not exactly float, but sit on the surface of the water.
http://www.liv.ac.uk/researchintelligence/images/water_strider.jpg


4) Water has a capillary action. Lets say you have water in a straw, and it sits in the straw above the surface level of the rest of the water. The reason that it does this is because of adhesion, the molecules stick to the sides of the straw allowing the water to "climb up."
5) Water has a specific heat. Specific heat is the amount of energy needed to raise 1 g of a substance     1°C. It is hard to increase the temperature of water because water has a high specific heat. The Hydrogen    Bonds are bound really tightly, so a ton of energy is needed to break them.  

6) Water is a universal solvent; meaning almost anything is soluble in water. The polar molecules in the water attract with polar molecules in the substances being dissolved. The polar molecules with positive charges will bond with the positively charges part of the water molecule; while the polar molecules with negative charges will bond with the negatively charged part of the water molecule. Polar molecules, like the ones in water, rarely, if ever, mix with a non-polar substance such as: oil. 

7) Water has it's own density of 1 g/ml. If a  substance is denser than water it will sink in water; if a substance is less dense than water it will float in water. The density of water is special because the solid form of water (ice) is less dense than liquid water. The reason for this is because the hydrogen bonds in the water keep the molecules close together from the start, once the water freezes the bonds get closer. 




8) Water has a buoyant force. A buoyant force is the opposite of gravity, it actually pushes objects upward, making the objects feel lighter than they actually are. For example, if you are in a pool with someone twice your size and weight, you can easily hold them baby style because the buoyant force is pushing them up; if you were on land, however, you would drop them/they would crush you because gravity is pushing them down.      


4 comments:

  1. Lucy,
    I really liked the video you showed with the water on the penny. I t was really interesting and helped me understand how strong the surface tension of the water is.

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  2. Lucy, I really liked the the multimedia used in this post, especially the video that showed how the hydrogen bond works. It was very cool. The examples and how you talked about the straw with the capillary action was really great, I feel like I understand capillary action a little better now.

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  3. Lucy, I really liked the video you included not only because it had awesome music and a picture of a guy lighting his hand on fire, but because the content of the video really helped me see how strong and important the hydrogen bonds in water are.

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  4. It looks like everyone really liked your hydrogen bond video :)
    Very thorough and informative post, just a few things to be careful of, though. Make sure you recognize water as a molecule, not an element (though it is made up of elements covalently bonded together). Also, be clear about why the density of solid water is less than liquid water. As temperatures cool, the bonds between water molecules become more stable and static, thus creating a lattice structure formation between the molecules.

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