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Neutralization
 
 
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In chemistry, neutralization is a chemical reaction
Chemical reaction

A chemical reaction is a process that always results in the interconversion of chemical substances. The substance or substances initially involved in a chemical reaction are called reactants....
 (also called a water forming reaction since a water molecule is formed during the process) in which an acid
Acid

An acid is traditionally considered any chemical compound that, when dissolved in water, gives a solution with a hydrogen ion Activity greater than in pure water, i.e....
 and a base
Base (chemistry)

In chemistry, a base is most commonly thought of as an aqueous substance that can accept protons. A base is also often referred to as an alkali if OH- ions are involved....
 or alkali (soluble base) react to produce salt and water (H2O)
Water

Water is a common chemical substance that is essential for the survival of all known forms of life. In typical usage, water refers only to its liquid form or States of matter, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam....
. During the process, hydrogen
Hydrogen

Hydrogen is the chemical element with atomic number 1. It is represented by the chemical symbol H. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly combustion and explosive Diatomic molecule gas with the molecular formula H2....
 ions H+ (a bare proton) from the acid (proton donor) or a hydronium ion
Hydronium

In chemistry, hydronium is the common name for the aqueous cation hydrogen3oxygen+ derived from protonation of water. It is the simplest type of an oxonium ion....
 H3O+ and hydroxide
Hydroxide

In chemistry, hydroxide is the name for the Diatomic molecule anion OH-, consisting of oxygen and hydrogen atoms, usually derived from the Dissociation of a base ....
 ions OH- or oxide
Oxide

An oxide is a chemical compound contaning at least one oxygen atom as well as at least one other element. Most of the Earth's crust consists of oxides....
 ions O2- from the base (proton acceptor) react together to form a water molecule H2O.






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Encyclopedia


In chemistry, neutralization is a chemical reaction
Chemical reaction

A chemical reaction is a process that always results in the interconversion of chemical substances. The substance or substances initially involved in a chemical reaction are called reactants....
 (also called a water forming reaction since a water molecule is formed during the process) in which an acid
Acid

An acid is traditionally considered any chemical compound that, when dissolved in water, gives a solution with a hydrogen ion Activity greater than in pure water, i.e....
 and a base
Base (chemistry)

In chemistry, a base is most commonly thought of as an aqueous substance that can accept protons. A base is also often referred to as an alkali if OH- ions are involved....
 or alkali (soluble base) react to produce salt and water (H2O)
Water

Water is a common chemical substance that is essential for the survival of all known forms of life. In typical usage, water refers only to its liquid form or States of matter, but the substance also has a solid state, ice, and a gaseous state, water vapor or steam....
. During the process, hydrogen
Hydrogen

Hydrogen is the chemical element with atomic number 1. It is represented by the chemical symbol H. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly combustion and explosive Diatomic molecule gas with the molecular formula H2....
 ions H+ (a bare proton) from the acid (proton donor) or a hydronium ion
Hydronium

In chemistry, hydronium is the common name for the aqueous cation hydrogen3oxygen+ derived from protonation of water. It is the simplest type of an oxonium ion....
 H3O+ and hydroxide
Hydroxide

In chemistry, hydroxide is the name for the Diatomic molecule anion OH-, consisting of oxygen and hydrogen atoms, usually derived from the Dissociation of a base ....
 ions OH- or oxide
Oxide

An oxide is a chemical compound contaning at least one oxygen atom as well as at least one other element. Most of the Earth's crust consists of oxides....
 ions O2- from the base (proton acceptor) react together to form a water molecule H2O. In the process, a salt is also formed when the anion from acid and the cation from base react together.

Neutralization reactions are generally classified as exothermic
Exothermic

File:Explosion1.JPG In thermodynamics, the term exothermic describes a process or reaction that releases energy usually in the form of heat, but also in form of light , electricity , or sound....
 since heat
Heat

In physics and thermodynamics, heat is any transfer of energy from one body or thermodynamic system to another due to a difference in temperature....
 is released into the surroundings. However, an example of endothermic
Endothermic

In thermodynamics, the word endothermic "within-heating" describes a process or reaction that absorbs energy in the form of heat. Its etymology stems from the Greek prefix endo-, meaning ?inside? and the Greek suffix ?thermic, meaning ?to heat?....
 neutralization is the reaction between baking soda (sodium bicarbonate)
Sodium bicarbonate

Sodium bicarbonate or sodium hydrogen carbonate is the chemical compound with the formula NaHCO3. Sodium bicarbonate is a white solid that is crystalline but often appears as a fine powder....
 and vinegar (acetic acid)
Vinegar

Vinegar is an acidic liquid processed from the fermentation of ethanol in a process that yields its key ingredient, acetic acid . It also may come in a diluted form....
 (or any other weak acid
Weak acid

A weak acid is an acid that dissociates incompletely and does not release all of its hydrogens in a solution i.e it does not completely donate all of its protons....
).

Common reactions

Most generally, the following occurs:
acid + base ? salt + water
For example, the reaction between Hydrochloric acid
Hydrochloric acid

Hydrochloric acid is the solution of hydrogen chloride in water. It is a highly corrosive, strong acid mineral acid and has major industrial uses....
 and sodium hydroxide
Sodium hydroxide

Sodium hydroxide , also known as lye, caustic soda and sodium hydrate, is a caustic metallic Base . Sodium hydroxide forms a strong alkaline solution when dissolved in a solvent such as water, however, only the hydroxide ion is basic....
 solutions:
hydrochloric acid + sodium hydroxide ? sodium chloride + water
HCl(aq) + NaOH(aq) ? NaCl(aq) + H2O(l)


Since the HCl and NaOH dissociate into ion
Ion

An ion is an atom or molecule which has lost or gained one or more electrons, giving it a positive or negative electrical charge. According to the Bohr_model this will be from or in the outer shield 'n'....
s in solution, the ionic equation is:
H+(aq) + Cl-(aq) + Na+(aq) + OH-(aq) ? Na+(aq) + Cl-(aq) + H2O(l)


And since the sodium and chloride ions are just spectator ions, the net equation becomes:
H+(aq) + OH-(aq) ? H2O(l) : ?rH = -55.90 kJ mol-1


Generalizing:

  • acid + alkali = metal salt + water
  • acid + metal = metal salt + hydrogen
  • acid + metal oxide = metal salt + water
  • acid + metal hydroxide = metal salt + water
  • acid + ammonia = ammonia salt + water
  • acid + metal carbonate = metal salt + water + carbon dioxide
  • acid + metal hydrogencarbonate = metal salt + water + carbon dioxide
The last two reactions are not considered as neutralization in some contexts because carbon dioxide is formed in addition to salt and water.

Applications

  • Chemical titration
    Titration

    Titration is a common laboratory method of quantitative Analytical chemistry that is used to determine the unknown concentration of a known reactant....
     methods are used for analyzing acids or bases to determine the unknown concentration
    Concentration

    In chemistry, concentration is the measure of how much of a given chemical substance there is mixed with another substance. This can apply to any sort of chemical mixture, but most frequently the concept is limited to homogeneous solutions, where it refers to the amount of solute in the solvent....
    . Either a pH meter
    PH meter

    A pH meter is an electronic instrument used to measure the pH of a liquid . A typical pH meter consists of a special measuring probe connected to an electronic meter that measures and displays the pH reading....
     or a pH indicator
    PH indicator

    A pH indicator is a halochromism chemical chemical compound that is added in small amounts to a solution so that the pH of the solution can be determined easily....
     which shows the point of neutralization by a distinct color change can be employed. Simple stoichiometric calculations with the known volume of the unknown and the known volume and molarity of the added chemical gives the molarity of the unknown.
  • Excess gastric acid
    Gastric acid

    Gastric acid is one of the main secretions of the stomach, together with several enzymes and intrinsic factor. Chemically it is an acid solution with a pH of 1 to 2 in the stomach lumen , consisting mainly of hydrochloric acid , and large quantities of potassium chloride and sodium chloride ....
     in the stomach (acid indigestion
    Acid indigestion

    Acid indigestion is a type of indigestion involving an excess of hydrochloric acid in the stomach. Frequent occurrence of acid indigestion can lead to aggravation of the duodenum or to an aggravation of the lining of the stomach, both of which can lead to Peptic ulcer which can be life-threatening....
    ) is typically neutralized by the ingestion of sodium bicarbonate
    Sodium bicarbonate

    Sodium bicarbonate or sodium hydrogen carbonate is the chemical compound with the formula NaHCO3. Sodium bicarbonate is a white solid that is crystalline but often appears as a fine powder....
     (NaHCO3) or another neutralizing agent such as an antacid.
  • Neutralization can also be used to reduce the pain of insect and plant stings. Bee stings can be neutralized with alkalis and wasps with acids. Nettle stings can be neutralized with alkalis like the one found in dock leaves.
  • In neutron wastewater treatment
    Water treatment

    Water treatment describes those processes used to make water more acceptable for a desired end-use. These can include use as drinking water, industrial processes, medical and many other uses....
    , chemical neutralization methods are often applied to reduce the damage that an effluent may cause upon release to the environment. For pH control, popular chemicals include Calcium Carbonate
    Calcium carbonate

    Calcium carbonate is a chemical compound with the chemical formula CalciumCarbonOxygen3. It is a common substance found as Rock in all parts of the world, and is the main component of seashells, snails, and eggshells....
    , Calcium Oxide
    Calcium oxide

    Calcium oxide , commonly known as burnt lime, Lime or quicklime, is a widely used chemical compound. It is a white, Caustic and alkaline crystalline solid at room temperature....
    , magnesium hydroxide
    Magnesium hydroxide

    Magnesium hydroxide is an inorganic compound with the chemical formula Mg2. As a suspension in water, it may be referred to as Milk of Magnesia....
    , and sodium bicarbonate
    Sodium bicarbonate

    Sodium bicarbonate or sodium hydrogen carbonate is the chemical compound with the formula NaHCO3. Sodium bicarbonate is a white solid that is crystalline but often appears as a fine powder....
    . The selection of an appropriate neutralization chemical depends on the particular application.


Calculations

Equal numbers of moles
Mole (unit)

The mole is a Units of measurement of amount of substance: it is an SI base unit, and one of the few units used to measure this physical quantity....
 of acid and base are needed for neutralization reactions. Hence, the formula becomes

a × [A] × Va = b × [B] × Vb

where a is the number of acidic hydrogens and b is the constant that tells you how many H3O+ ions the base can accept. [A] denotes the concentration of acid and [B], the concentration of base. Va is the volume of acid and Vb is the volume of base.