H₂O, dihydrogen oxide, or hydrogen hydroxide

General characteristics of Water:

• 1. polar molecule
  
• 2. High energy required to change temperature
  • 1 calorie = raise 1 g. liquid 1^o C at 20 ^oC
  • freeze 1 g. liquid at 0 ^oC to ice, releases 80 calories
  • boil 1 g. liquid at 100 ^oC to steam, absorbs 540 calories
    
• 3. universal solvent
  
  • hydrophyllic molecules
  • hydrophobic molecules
• 4. exhibits cohesion = molecules hydrogen bond to like molecules
  
• 5. exhibits adhesion = molecules hydrogen bond to dissimilar molecules
  
• 6. solid (plastic) form is less dense than liquid form
  • solid (crystaline) form is 6-sided

Solutions

• Mixtures which involve at least one fluid
  • solvent = the fluid
    • separated to molecular level
  • solute = substance dissolved in solvent
    • may be particles of one to many molecules
• Classification of solutions:
  • suspension = solute particles very large
    • can be separated by gravity alone
  • colloid = solute particles sub-microscopic
    • can be separated by centifuge
  • solution = solute separated to molecular level
    • cannot be separated by gravity nor centrifuge
      
    • concentration refers normally to the relative amount of solute
  • [conc] = (amt solute)/((amt solute) + (amt solvent))

pH

• Water tends to fall apart into
  • one hydrogen ion, H⁺, which is an acid
  • one hydroxl ion, OH^-, which is a base
    (like eating Nabisco Oreo™, a.k.a. Sunshine Hydrox™ cookies)
    with one molecule out of 10,000,000 or 10⁷ falling apart.
    
• Since water is equally acidic and basic, it is defined as "neutral" or pH= 7.

If there were more hydrogen ions, the solution would be more acidic:

Similarly, pH values higher than 7, up to 13.0, are increasingly basic.

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© 2004-2005 TwoOldGuys ™

revised 19 aug 2006