What does the dissociation of water mean

Self-dissociation of the water

Acidic and alkaline solutions have to be chemically different so that they can be recognized by an indicator. This is supported by the fact that acidic and alkaline solutions, in contrast to neutral solutions, conduct electricity.

According to Br nsted, acids are proton donors, i.e. they give H.+ -Ions that form oxonium ions with water:

H + + H2O → H3O +

The oxonium ions are the common component of acidic solutions and, depending on the amount (concentration), are responsible for the strength of an acidic solution (pH value) and are displayed by indicators. Oxonium ions are also present in pure water, since the water is dissociated (divided) into ions to a certain extent:

H2O → H + + OH -

or better formulated 2 H2O → H3O+ + OH - This phenomenon is called Self-dissociation of the water. But there are very, very few water molecules that dissociate. However, OH is formed when the water dissociates itself - Ions (hydroxide ions). They shape the alkaline properties of solutions, which is why the hydroxides belong to the group of bases. Indicators show the presence of hydroxide ions. Since the water only dissociates to a small extent and oxonium ions and hydroxide ions are in equal parts, pure water has a pH value of 7, which means that the pH is in the middle Value scale and is neutral.


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