The original battery
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Last Update: 2021-02-26
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Source: Internet
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Author: User
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any spontaneous redox reactionr G m< 0)is the process by which electrons are transferred from reducing agents to oxidants. For example, insert
Zn
H 2 SO 4
solution,
Zn
H
2
so
4
the following reactions occur: Zn(s)
2H
br br (aq) and Zn br(br) 2 br
(aq)
2
2
(g)due to Zn
and
H
SO
4
direct contact, electrons from Znatoms directly transferred to H ions, so there is no orderly flow of electrons. As the redox reaction progresses, the temperature of the solution will increase, i.e. the chemical energy released in the reaction will be converted into thermal energy.
Put
Zn
4In another beech, a platinum plated platinum plated with platinum black is placed in a solution of thin sulphuric acid, and pure hydrogen is continuously infused at 25degrees C to saturate the platinum black adsorption. Using the salt
the two beg cups, and when the external circuit is switched on, an electric current is found to pass through. The device, which uses a redox reaction to convert chemical energy directly into electrical energy, is called a primary battery.
The reaction of the zinc electrode is:
Zn(s)
(aq)
.
2e
-
negative
( Also known as anodes )
the electrodes whose electrons flow to the outer circuit are called negative poles, so
Zn
very negative
( and because of an oxidation reaction called anode, so br br Zn
electrodes are also called anodes
)
.
reaction of the hydrogen electrode is:
2H
(aq)
2e
-
- H 2
(g)
positive
( also known as cathode )
The electrode of the electrons flowing into the outer circuit is called the positive pole, so here the hydrogen electrode is extremely positive (and because the reduction reaction occurs is called the cathode, the hydrogen electrode is also called the cathode).
)
。
the total reaction of the battery is to combine the positive and negative reactions according to the principle of electron equality: Zn(s) 2H (aq) - Zn
2
(aq)
H2 can be seen from the example above, any spontaneous redox reaction can in principle form the original battery. The oxidant corresponds to the reduced product
( such as H
and
H 2 ) the positive pole of the battery, the reducing agent and its oxidized product
(
such as
Zn
and Zn
2
) The negative poles that make up the battery:
the device that provides the original battery can also be represented by the battery symbol, for example, the battery symbol of the original battery above is br
used to write the negative pole of the battery on the left and the positive pole on the right to
|
" represents the phase interface, and the salt bridge
".
half of the battery must contain two types of substances, one is a reduced state substance, the other is the corresponding oxidizing substance. The oxidizing substance and the reduced substance form the redox electric pair, referred to as the electric pair, which is expressed as the "oxidizing state /
reduction state". For example, the electrode pair of zinc electrodes is Zn 2 /Zn , which is called a metal electrode.
non-metallic elements and their ions to form non-metallic electrodes. For example, the
/H 2 , with the electrode symbol H
| H2 , Pt , where Pt does not participate in electrode reactions, only adsorption of gas and the transfer of electrons, so called inert electrodes. Sometimes inert electrodes, such as graphite, can also be used.
ions of different price states of the same metal can also form redox electrodes. For example, an electric pair of covers a layer of insoluble salt of the metal on the surface of the metal and then immerses it in a solution containing negative ions containing the insoluble salt, which can form a insoluble salt electrode. e.g. electric pair:
AgCl/Ag
, the electrode symbol is
Ag | AgCl
,
cl -
; 2
2 /Hg , with the electrode symbol Pt
,
Hg(1) | Hg
2
Cl
2
,
Cl
-
。
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