What is the difference between Hydrophobic and Hydrophilic?

By Shane H.

2011


Water


shane369_water.jpg
This is a body of water
Hydrophobic and Hydrophilic have a lot to do with water. Like hydrophobic means “water repelling” and hydrophilic means “water loving”! ‘Hydro’ means water! Time for water! Water is lighter when it is a solid and heavier when it is a liquid! That is very rare. One water molecule contains one atom of oxygen and two atoms of hydrogen. But since oxygen is much heavier than hydrogen the oxygen atom is about 79% of the water molecule. Water is H2O. (2 H, one O). There are three physical states of water. They are ice, gas, liquid. The movement of the molecules in the physical states of water depends on heat. Heat turns water into a gas. Everything has some heat, so their molecules are in motion. But, water’s molecules are moving to slow to escape. But, at the water’s surface some of the water’s molecules get bumped by the molecules below them, and they escape. As the water gets hotter the molecules move faster and evaporation speeds up. Atmospheric pressure affects the boiling point. If you lower the pressure the less speed the molecules need to get to escape. But, as pressure increases the molecules need extra heat to get the speed they need to escape. That’s how steam is made. Now, if you take just water and add a lot of weight to it, it causes the pressure of the water to increase with depth. The same thing happens with salt water, but because salt water is really heavy with all those grams of sand, it already has the pressure of the water increasing with depth. So, it freezes at a colder temperature than fresh water does. It freezes at -2 degrees C (28 degrees F), while the fresh water freezes at 0 degrees C (32 degrees F). As the water descends to the freezing point, (Ex. 0 degrees C.) the movement of the water molecules slows. As it freezes, it stays at 0 degrees C and continues to yield heat. Once it is ice it continues to yield heat and stay at 0 degrees C, or it starts to melt. When it melts, the mixture of water and ice stays at 0 degrees C and it stays like that until all the ice has melted. By then, it has gained as much heat as it lost while it was freezing. The amount of heat that was given away or was gained without temperature change is called, “The Hidden Heat of Fusion.
shaneh369_diagram.jpg
the hydrogen is positive and oxygen is negative



Hydrophobic and Hydrophilic

What is the difference between hydrophobic and hydrophilic? Well, that is simple. Hydrophobic is “water-repelling” and Hydrophilic is “water-loving”. But what is Hydrophobic and Hydrophilic? Now that’s the question. How soap works is a good explanation of hydrophobic and hydrophilic. There two ends on a molecule of soap. One of them is hydrophilic end and that end loves the water but keeps away from hydrocarbons, (A molecule that only contain hydrogen and carbons), and the oils and fats. The other part is hydrophobic and keeps away from the water but grabs on to the dirt and oil, etc. Then the oil and fats, etc. can be easily washed away. A way to remember what Hydrophobic and Hydrophilic means is remembering that the word Hydro- is Greek for “water”. Then –Philic means, in Greek, “loving” and –phobic means “fearing”. And that’s the difference between Hydrophobic and hydrophilic. To see examples of Hydrophobic and Hydrophilic, see “Hydrophobic and Hydrophilic Examples”.


Hydrophobic and Hydrophilic Examples.

There are lots of examples of Hydrophobic and Hydrophilic. I found out some of the most common ones. Some examples of Hydrophilic are water, milk, soap, wool, hair, and cellulose (the main constituent of paper, wood, and cotton). These all love water very much. (Well, one of the ends of the soap.) Now for some of the examples of Hydrophobic. Some examples are oil,
waxes, fats, all fatty acids, and the hydrophobic end of the soap. All of these hate water.
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Soap is hydrophilic and hydrophobic
shaneh369_oil.jpg
Oil is hydrophobic.























Glossary
Hydrophilic: A molecule of something that mixes well with water.
Hydrophobic: A molecule of something that doesn’t mix well with water, it repels water.
Cellulose: The main constituent of paper, wood, and cotton.
Constituent: An element; a material.
Fusion: The act of putting two things together.
Atmospheric Pressure: The pressure put in to use by the earth’s atmosphere at any given point.


Citations:

  • Bloomfield, Louis. How everything works: making physics out of the ordinary. Hoboken, NJ: Wiley, 2007. Print.
  • Friedhoffer, Bob. Science lab in a supermarket. New York: Franklin Watts, 1998. Print.
  • "lipid." Encyclopædia Britannica. Encyclopædia Britannica Online School Edition.
Encyclopædia Britannica, Inc., 2011. Web. 19 Sept. 2011.
<http://school.eb.com/eb/article-257716>.
  • Snyder, Carl H. The extraordinary chemistry of ordinary things. New York: John Wiley, 1998. Print.
  • The dictionary.com team, dictionary.com, http://dictionary.reference.com/. LLC, 1995, 9/25/2011.
  • "water." Compton's by Britannica. Encyclopædia Britannica Online School Edition.
Encyclopædia Britannica, Inc., 2011. Web. 19 Sept. 2011.
<http://school.eb.com/all/comptons/article-9277663>.

© Copyright 2011