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Chapter 6, Lesson 8 Multimedia

Proton Transfer in Water

  • The hydrogen atom in the water molecule has one proton and an electron that it shares with the oxygen atom. A proton from a hydrogen atom can transfer to another water molecule, creating the ions H3O+ and OH-.
  • A proton from the H3O+ ion can be transferred to the OH-, creating water molecules again.

Water Molecules Trade Protons

Two chemical equations demonstrating proton transfer in water.  In the first equation, water autoionizes to form a hydroxide and hydronium ion.  In the second equation, the hydronium ion donates a proton to the hydroxide ion to form two water molecules.
  • The hydrogen atom in the water molecule has one proton and an electron that it shares with the oxygen atom. A proton from a hydrogen atom can transfer to another water molecule, creating the ions H3O+ and OH-.
  • A proton from the H3O+ ion can be transferred to the OH-, creating water molecules again.

Acids Donate Protons

An acid added to water donates protons to the water molecules. This increases the concentration of H3O+ ions. The H3O+ ions donate protons to the indicator molecules which results in a color change.

Bases Accept Protons

A base added to water accepts protons from the water molecules. This increases the concentration of OH- ions. The H3O+ ions and the indicator molecules donate protons to the OH- ions. This decreases the concentration of H3O+ ions and results in a color change.