Using earth's resources

• Sometimes chemistry replaces a natural resource witha synthetic one like...

  rubber
• metals are..

  finite
• wood is...

  infinite
• potable water has...

  low levels of dissolved salts and microbes
• most potable water is provided by rainwater that collects in rivers and resevouirs
• Step by step: how do you make water potable?

  -collect water and pass through filter beds-sterilize water with chlorine-add flourine
• why is making potable from the ocean very expensive?

  -have to use either distillation or reverse osmosis to remove salt-both very expensive methods that require lots of energy