4.1

• • Fat in food and dirt on clothes are usually hydrophobic
  • This means they are “afraid of water”
  • Hydrophobic materials do not dissolve in water
  • They need other substances to bond to in order to be removed from dishes and clothing
• • Detergent: a substance that can remove dirt from fabric
  • Most detergents are liquids or powders that can dissolve in wate
• • Detergents contain a cleaning agent called a surfactant 
  • Surfactants are particles that attach themselves to dirt and oil particles
  • This separates them from fabric or other material
• how detergent works - Dirt & grease on fabric

  • The mixture of water, detergent, and clothes is agitated in the washing machine
  • Dirt breaks off clothes
  • Surfactant in detergent surrounds the dirt patches so they can’t re-attach to clothes
• • inn the past, manufacturers added chemicals called phosphates to detergents
  • Phosphates made detergents work better in hard water
  • The phosphates damaged the environment though, by polluting the water
  • Now, detergents do not contain

       phosphates
• • Fat in food and dirt on clothes are usually hydrophobic
  • This means they are “afraid of water”
  • Hydrophobic materials do not dissolve in water
  • They need other substances to bond to in order to be removed from dishes and clothing such as detergent