When zinc metal is submerged into a quantity of aqueous \(\ceHCl\), the adhering to reaction occurs (Figure \(\PageIndex1\)):

\<\ceZn (s) + 2HCl (aq) → H2 (g) + ZnCl2(aq) \labeleq:1\>

This is one example of what is sometimes called a single replacement reaction because \(\ceZn\) replaces \(\ceH\) in combination with \(\ceCl\).

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Example \(\PageIndex1\): Reducing silver- Ions

Write and also balance the redox reaction that has actually silver ions and also aluminum metal as reactants and also silver metal and aluminum ion as products. Determine the substance oxidized, problem reduced, to reduce agent and also reducing agent.


We begin by using signs of the elements and also ions to stand for the reaction:

\<\ceAg^+ + Al → Ag + Al^3+ \nonumber\>

The equation looks well balanced as it is written. However, as soon as we compare the as whole charges on each side of the equation, we uncover a fee of +1 top top the left however a fee of +3 ~ above the right. This equation is not effectively balanced. Come balance it, let us write the two fifty percent reactions. Silver- ions room reduced, and it bring away one electron to adjust Ag+ to Ag:

Reduction half-reaction: \<\ceAg^+ + e^− → Ag \nonumber\>

Aluminum is oxidized, losing three electron to change from Al to Al3+:

Oxidation half-reaction: \<\ceAl → Al^3+ + 3e^− \nonumber\>

To incorporate these two half reactions and cancel out all the electrons, we have to multiply the silver reduction reaction by 3:


Exercise \(\PageIndex1\)

Write and balance the oxidation reaction that has actually calcium ions and potassium metal as reactants and calcium metal and also potassium ion as products. Recognize the substance oxidized, problem reduced, reduce agent and also reducing agent.


Reduction: Ca2+ + 2e− → Ca

Oxidation: 2 (K → K+ + e−)

Combined: Ca2+ + 2K → Ca + 2K+

The substance oxidized is the reactant that had undergone oxidation: K The substance reduced is the reactant that had undergone reduction: Ca2+ The reducing agent is the same as the problem oxidized: K The oxidizing agent is the same as the problem reduced: Ca2+

Potassium has actually been provided as a reducing certified dealer to obtain various steels in their elemental form.

To your Health: oxidization Reactions and also Pacemaker Batteries

All batteries use redox reaction to it is provided electricity since electricity is usually a present of electron being transferred from one substance to another. Pacemakers—surgically implanted tools for regulation a person’s heartbeat—are powered by tiny batteries, for this reason the suitable operation of a pacemaker counts on a oxidization reaction.

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Pacemakers provided to be it is provided by NiCad batteries, in i m sorry nickel and also cadmium (hence the name of the battery) react with water follow to this redox reaction:

\<\ceCd(s) + 2NiOOH(s) + 2H2O(ℓ) → Cd(OH)2(s) + 2Ni(OH) 2(s) \nonumber\>

The cadmium is oxidized, while the nickel atoms in NiOOH are reduced. Except for the water, every the building material in this reaction space solids, permitting NiCad battery to be recharged numerous times prior to they stop operating. Unfortunately, NiCad battery are fairly heavy batteries to be carrying approximately in a pacemaker. Today, the lighter lithium/iodine battery is provided instead. The iodine is liquified in a heavy polymer support, and also the as whole redox reaction is as follows:

\<\ce2Li(s) + I2(s) → 2LiI (s) \nonumber\>

Lithium is oxidized, and also iodine is reduced. Return the lithium/iodine battery cannot be recharged, among its advantages is the it lasts up to 10 years. Thus, a human being with a pacemaker go not need to worry around periodic recharging; about once per decade a human being requires minor surgical procedure to replace the pacemaker/battery unit. Lithium/iodine batteries are likewise used to power calculators and watches.

Figure \(\PageIndex1\): A small button battery choose this is used to power a watch, pacemaker, or calculator. (CC BY-SA; Gerhard H Wrodnigg via Wikipedia)