4.1.5 reaction of metals

• Potassium reacting with water:

  • Potassium is most reactive = reacts very quickly
  • hydrogen produced ignites instantly and the metal also sets alight, sparkling and burning with a lilac flame
• Sodium reacting with water:

  • fizzes rapidly
  • melts to form a ball that moves around on the surface of the water
• Lithium reacting with water:

  • fizzes steadily and floats
  • becomes smaller until eventually disappears
• Most metals react with dilute acids to give a salt (e.g. copper chloride) and hydrogen gas.

  • copper, gold, silver, platinum do not react with dilute acids (are not reactive enough)
• metals dont have to be that reactive to react with dilute acids.

  • some metals react with dilute acids but are not reactive enough to react with cold water e.g. magnesium, aluminium, zinc, and lead. (iron and lead react slowly)
• Reactions with metal + cold water:

  • produces metal hydroxide
  • produces hydrogen gas
• Reactions with metal and acid:

  • produce a salt
  • produce hydrogen gas
• Very unreactive metals (e.g. gold, platinum) are called native metals.
• Reactions of metals

  A) hydroxide

  B) water

  C) salt

  D) acid

  
• metal + acid -> salt + hydrogen