Question: How are electrons used in acid and basic medium?
About the article "Electrochemistry", section "Neutral medium".

Candidate passages:
The same procedure as used on acid medium is applied, for example on balancing using electron ion method to complete combustion of propane.
"Unbalanced reaction": C3H8 + O2 → CO2 + H2O
"Reduction": 4 H+ + O2 + 4 e– → 2 H2O
"Oxidation": 6 H2O + C3H8 → 3 CO2 + 20 e– + 20 H+
As in acid and basic medium, electrons which were used to compensate oxidation changes are multiplied to opposite half reactions, thus solving the equation.
20 H+ + 5 O2 + 20 e– → 10 H2O
6 H2O + C3H8 → 3 CO2 + 20 e– + 20 H+
Equation balanced:
C3H8 + 5 O2 → 3 CO2 + 4 H2O
In basic medium OH– ions and water are added to half reactions to balance the overall reaction.
For example, on reaction between potassium permanganate and sodium sulfite.
"Unbalanced reaction": KMnO4 + Na2SO3 + H2O → MnO2 + Na2SO4 + KOH "Reduction": 3 e– + 2 H2O + MnO4– → MnO2 + 4 OH– "Oxidation": 2 OH– + SO32– → SO42– + H2O + 2 e– The same procedure as followed on acid medium by multiplying electrons to opposite half reactions solve the equation thus balancing the overall reaction.
6 e– + 4 H2O + 2 MnO4– → 2 MnO2 + 8 OH– 6 OH– + 3 SO32– → 3 SO42– + 3 H2O + 6e– Equation balanced: 2 KMnO4 + 3 Na2SO3 + H2O → 2 MnO2 + 3 Na2SO4 + 2 KOH  
Acid catalysis is mainly used for organic chemical reactions.
There are many possible chemical compounds that can act as sources for the protons to be transferred in an acid catalysis system.
A compound such as sulfuric acid, H2SO4, can be used.
Usually this is done to create a more likely leaving group, such as converting an OH group to a H2O+ group, which can then be eliminated as water (H2O).
Acids specifically used for acid catalysis include hydrofluoric acid (in the alkylation process), phosphoric acid, toluenesulfonic acid, polystyrene sulfonate, heteropoly acids, zeolites and graphene oxide.
With carbonyl compounds such as esters, synthesis and hydrolysis go through a tetrahedral transition state, where the central carbon has an oxygen, an alcohol group, and the original alkyl group.
Strong acids protonate the carbonyl, which makes the oxygen positively charged, so that it can easily receive the double bond electrons when the alcohol attacks the carbonyl carbon.
This enables ester synthesis and hydrolysis.
The reaction is an equilibrium between the ester and its cleavage to carboxylic acid and alcohol.
On the contrary, strong bases deprotonate the attacking alcohol or amine, which also promotes the reaction.
However, bases also deprotonate the acid, which is irreversible.
Therefore, in a strongly basic, aqueous environment, esters only hydrolyze. 
In staining during microscopic examination for diagnosis or research, acid dyes are used to color basic tissue proteins.
In contrast, basic dyes are used to stain cell nuclei and some other acidic components of tissues.  
Lewis acids are used to catalyse a wide variety of reactions.
The mechanism steps are:  Lewis acid forms a polar coordinate with a basic site on the reactant (such as an O or N)  Its electrons are drawn towards the catalyst, thus activating the reactant  The reactant is then able to be transformed by a substitution reaction or addition reaction  The product dissociates and catalyst is regenerated Common Lewis acids include aluminium chloride, ferric chloride and boron trifluoride.
These reactions are usually carried out in organic solvents; AlCl3, for example, reacts violently with water.
Typical solvents are dichloromethane and benzene.