Oxidation value ≠ valence. The oxidation value of an element is the artificially prescribed value of the "formal charge" given to an atom of an element or a compound.

Changes in the oxidation number of elements cannot determine the direction of the reaction, nor can they evaluate the electron gain and loss capabilities of the electric pair.

Lifting oxygen loss and positive oxygen negative loss (the compound valence increases and loses electrons and is oxidized as a reducing agent to undergo an oxidation reaction and serves as the negative electrode of the battery.

It’s even better (the valence is lowered and the electrons are reduced to become oxidants)

oxidized ne-reduced form or Ox ne- Red

OH- should not appear in the balanced half-reaction equation in acidic media H should not appear in balanced half-reaction equations in alkaline media

The device that converts the chemical energy of the redox reaction into electrical energy is called a primary cell, or battery for short.

Battery composition (battery symbol)

There are excess negative charges on the surface of the metal plate; the positively charged metal ions in the solution are attracted by the negative charges and are more concentrated near the metal plate, forming a so-called electric double layer structure, and the potential difference between them is called the electrode potential.

The more active the metal, the dilute the solution, the greater the dissolution tendency, the more negative charges on the surface at equilibrium, and the lower the electrode potential.

The electrode potential is the potential difference between the metal surface and its ionic solution, and is related to the nature of the metal, temperature and ion concentration.

It is stipulated that p =100 kPa, c =1 molꞏL-1 under standard conditions, liquid or solid are pure substances

significance

ΔrGm, ΔrHm, ΔrSm are breadth properties, and their values ​​are related to the writing method of electrode reaction measurement coefficient

n is the amount of material that transfers electrons, in mol; the electromotive force E is in V, and Faraday’s constant F = 96485 Cꞏmol-1.

temperature

Number of electron transfers

Standard electrode potential

Independent of substance concentration

The Nernst equation of the electrode reaction at any temperature T shows that the electrode potential of the electric pair in any state is related to Its standard electrode potential and the relationship between concentration, gas partial pressure and temperature. (Also related to medium concentration

acidity

Generate weak acid (weak base)

Precipitate generation

The essence is to change the concentration of a certain substance in the battery and establish a new balance.

Generally speaking, when E>0.3V, the reaction proceeds in the forward direction, and when E<-0.3V, the reaction proceeds in the reverse direction.

When -0.3V<E<0,.3V, the direction can be adjusted by changing the concentration

Like △G, it can only determine the direction, but cannot solve the speed problem.