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Properties of Water. If an alien came down to earth and asked you what a glass of water was, how would you describe it? Most would say, no color, no taste, no odor. Many would say it was a rather plain and ordinary substance.
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If an alien came down to earth and asked you what a glass of water was, how would you describe it? Most would say, no color, no taste, no odor. Many would say it was a rather plain and ordinary substance. But most chemist, would say water was very unusual—unlike anything else.
Structure of Water 1. Is made up of TWO Hydrogen atoms bonded to ONE Oxygen atom. • Each end of the molecule has slight electric charge. Oxygen has slight negative charge. Hydrogen has slight positive charge. Because water consists of polar molecules, it is known as a polar substance.
Have you ever played with magnets? Opposite poles of two magnets attract each other. Same is true for polar substances. Positive hydrogen ends of one water molecule attract the negative oxygen ends of nearby water molecules. As a result, water molecules tend to stick together.
Capillary Action • Combined force of attraction among water molecules and with molecules of surrounding materials. • Allows water to move through materials with pores inside—straws, bricks or piece of wood. • Example: Clothes that wick moisture away from your skin, so you can stay dry.
Surface Tension • Tightness across the surface of water that is caused by the polar molecules pulling on one another. • Molecules at the surface are being pulled by the molecules next to them and below them. • Examples: Water strider, raindrops form round beads when fall onto windshield.
Universal Solvent • A solution is a mixture that forms when one substance dissolves another. • The substance that does the dissolving is called the solvent. • Water can dissolve so many substances that it is called the “Universal Solvent.” • Dissolve solids-sugar, salt, Kool-aid. • Dissolves liquids-bleach. • Dissolves gases-oxygen, carbon dioxide. • Non-polar substances do not dissolve well in water.
Specific Heat • Water has a high specific heat. • The amount of heat needed to increase the temperature of a certain mass of a substance by 1 Celsius. • Example: An effect of water’s high specific heat is land areas located near large bodies of water experience less dramatic temperature changes than far inland areas.
Nature • Water is the only substance that is found on Earth naturally as a solid, a liquid and a gas.
Changing States • Evaporation- Liquid changes to a gaseous state. Ex. Let your hair dry after swimming. • Condensation- Gas changes to a liquid. Example-when you fog up a window by breathing on it. Invisible water vapor of your breath is cooled by the window and forms drops on the window.
Freezing- At O Celsius, when liquid water changes into solid ice. Molecules are moving slower. • Melting- As a cube of ice is heated, molecules begin to move faster. Solid ice melts and becomes liquid water.
