Water and Solutions Chapter 6.3 pgs. 161-165
Why is water so important??
Water molecule: H2O Covalent bonds hold a single water molecule together. The electrons are pulled towards the bond. This leaves one side slightly more positive than the other. This makes water POLAR!
The Polarity of Water Creates Hydrogen Bonds with other water molecules, giving it its properties.
Extraordinary Properties of Water 1. Adhesion Water molecules cling to other surfaces. Example: Capillary action, as in water moving up a plant stem
2. Cohesion Water molecules stick together - this creates Surface Tension
3. Water is less dense as a solid! This allows for aquatic life to live under the ice in the extreme cold.
Why ice really does float:
4. Water is a good solvent Solvent = a substance in which another substance is dissolved in Solute = a substance dissolved in a solvent Solution = when a solvent and solute are combined
pH scales measure if a solution is an ACID OR BASE The scale goes from values 0 through 14.
Bases Acids pH between 0 and 6.9 on the pH scale Taste sour Corrode metals (acid rain) Bases pH between 7.1 and 14 on the pH scale Taste bitter, chalky Feel soapy, slippery
ACID BASE H+ = hydronium ion OH- = hydroxide ion
Buffer Neutral pH number is 7 Examples: blood, water Solutions that keep the pH within a particular pH range. Buffered aspirin has a coting on it to Keep the acid in your stomach from dissolving it right away.