Zinc, a typical metal, reacting with hydrochloric acid, a typical acid

An acid (from the Latin acidus/acēre meaning sour^[1]) is a substance which reacts with a base. Commonly, acids can be identified as tasting sour, reacting with metals such as calcium, and bases like sodium carbonate. Aqueous acids have a pH of less than 7, where an acid of lower pH is typically stronger. Chemicals or substances having the property of an acid are said to be acidic.

Common examples of acids include acetic acid (in vinegar), sulfuric acid (used in car batteries), and tartaric acid (used in baking). As these three examples show, acids can be solutions, liquids, or solids. Gases such as hydrogen chloride can be acids as well. Strong acids and some concentrated weak acids are corrosive, but there are exceptions such as carboranes and boric acid.

There are three common definitions for acids: the Arrhenius definition, the Brønsted-Lowry definition, and the Lewis definition. The Arrhenius definition states that acids are substances which increase the concentration of hydronium ions (H₃O⁺) in solution. The Brønsted-Lowry definition is an expansion: an acid is a substance which can act as a proton donor. Most acids encountered in everyday life are aqueous solutions, or can be dissolved in water, and these two definitions are most relevant. The reason why pHs of acids are less than 7 is that the concentration of hydronium ions is greater than 10⁻⁷ moles per liter. Since pH is defined as the negative logarithm of the concentration of hydronium ions, acids thus have pHs of less than 7. By the Brønsted-Lowry definition, any compound which can easily be deprotonated can be considered an acid. Examples include alcohols and amines which contain O-H or N-H fragments.

In chemistry, the Lewis definition of acidity is frequently encountered. Lewis acids are electron-pair acceptors. Examples of Lewis acids include all metal cations, and electron-deficient molecules such as boron trifluoride and aluminium trichloride. Hydronium ions are acids according to all three definitions. Interestingly, although alcohols and amines can be Brønsted-Lowry acids as mentioned above, they can also function as Lewis bases due to the lone pairs of electrons on their oxygen and nitrogen atoms.

Definitions and concepts[link]

Modern definitions are concerned with the fundamental chemical reactions common to all acids.

Arrhenius acids[link]

The Swedish chemist Svante Arrhenius attributed the properties of acidity to hydrogen in 1884. An Arrhenius acid is a substance that increases the concentration of the hydronium ion, H₃O⁺, when dissolved in water. This definition stems from the equilibrium dissociation of water into hydronium and hydroxide (OH⁻) ions:^[2]

H₂O(l) + H₂O(l) H₃O⁺(aq) + OH⁻(aq)

In pure water the majority of molecules exist as H₂O, but a small number of molecules are constantly dissociating and re-associating. Pure water is neutral with respect to acidity or basicity because the concentration of hydroxide ions is always equal to the concentration of hydronium ions. An Arrhenius base is a molecule which increases the concentration of the hydroxide ion when dissolved in water. Note that chemists often write H⁺(aq) and refer to the hydrogen ion when describing acid-base reactions but the free hydrogen nucleus, a proton, does not exist alone in water, it exists as the hydronium ion, H₃O⁺ .

Brønsted-Lowry acids[link]

While the Arrhenius concept is useful for describing many reactions, it is also quite limited in its scope. In 1923 chemists Johannes Nicolaus Brønsted and Thomas Martin Lowry independently recognized that acid-base reactions involve the transfer of a proton. A Brønsted-Lowry acid (or simply Brønsted acid) is a species that donates a proton to a Brønsted-Lowry base.^[2] Brønsted-Lowry acid-base theory has several advantages over Arrhenius theory. Consider the following reactions of acetic acid (CH₃COOH), the organic acid that gives vinegar its characteristic taste:

Both theories easily describe the first reaction: CH₃COOH acts as an Arrhenius acid because it acts as a source of H₃O⁺ when dissolved in water, and it acts as a Brønsted acid by donating a proton to water. In the second example CH₃COOH undergoes the same transformation, in this case donating a proton to ammonia (NH₃), but cannot be described using the Arrhenius definition of an acid because the reaction does not produce hydronium. Brønsted-Lowry theory can also be used to describe molecular compounds, whereas Arrhenius acids must be ionic compounds. Hydrogen chloride (HCl) and ammonia combine under several different conditions to form ammonium chloride, NH₄Cl. In aqueous solution HCl behaves as hydrochloric acid and exists as hydronium and chloride ions. The following reactions illustrate the limitations of Arrhenius's definition:

1. H₃O⁺(aq) + Cl⁻(aq) + NH₃ → Cl⁻(aq) + NH₄⁺(aq)
2. HCl(benzene) + NH₃(benzene) → NH₄Cl(s)
3. HCl(g) + NH₃(g) → NH₄Cl(s)

As with the acetic acid reactions, both definitions work for the first example, where water is the solvent and hydronium ion is formed. The next two reactions do not involve the formation of ions but are still proton transfer reactions. In the second reaction hydrogen chloride and ammonia (dissolved in benzene) react to form solid ammonium chloride in a benzene solvent and in the third gaseous HCl and NH₃ combine to form the solid.

Lewis acids[link]

A third concept was proposed in 1923 by Gilbert N. Lewis which includes reactions with acid-base characteristics that do not involve a proton transfer. A Lewis acid is a species that accepts a pair of electrons from another species; in other words, it is an electron pair acceptor.^[2] Brønsted acid-base reactions are proton transfer reactions while Lewis acid-base reactions are electron pair transfers. All Brønsted acids are also Lewis acids, but not all Lewis acids are Brønsted acids. Contrast the following reactions which could be described in terms of acid-base chemistry.

In the first reaction a fluoride ion, F⁻, gives up an electron pair to boron trifluoride to form the product tetrafluoroborate. Fluoride "loses" a pair of valence electrons because the electrons shared in the B—F bond are located in the region of space between the two atomic nuclei and are therefore more distant from the fluoride nucleus than they are in the lone fluoride ion. BF₃ is a Lewis acid because it accepts the electron pair from fluoride. This reaction cannot be described in terms of Brønsted theory because there is no proton transfer. The second reaction can be described using either theory. A proton is transferred from an unspecified Brønsted acid to ammonia, a Brønsted base; alternatively, ammonia acts as a Lewis base and transfers a lone pair of electrons to form a bond with a hydrogen ion. The species that gains the electron pair is the Lewis acid; for example, the oxygen atom in H₃O⁺ gains a pair of electrons when one of the H—O bonds is broken and the electrons shared in the bond become localized on oxygen. Depending on the context, a Lewis acid may also be described as an oxidizer or an electrophile.

The Brønsted-Lowry definition is the most widely used definition; unless otherwise specified acid-base reactions are assumed to involve the transfer of a proton (H⁺) from an acid to a base.

Dissociation and equilibrium[link]

Reactions of acids are often generalized in the form HA H⁺ + A⁻, where HA represents the acid and A⁻ is the conjugate base. Acid-base conjugate pairs differ by one proton, and can be interconverted by the addition or removal of a proton (protonation and deprotonation, respectively). Note that the acid can be the charged species and the conjugate base can be neutral in which case the generalized reaction scheme could be written as HA⁺ H⁺ + A. In solution there exists an equilibrium between the acid and its conjugate base. The equilibrium constant K is an expression of the equilibrium concentrations of the molecules or the ions in solution. Brackets indicate concentration, such that [H₂O] means the concentration of H₂O. The acid dissociation constant K_a is generally used in the context of acid-base reactions. The numerical value of K_a is equal to the concentration of the products divided by the concentration of the reactants, where the reactant is the acid (HA) and the products are the conjugate base and H⁺.

Failed to parse (Missing texvc executable; please see math/README to configure.): K_a = \frac{[\mbox{H}^+] [\mbox{A}^-]}{[\mbox{HA}]}

The stronger of two acids will have a higher K_a than the weaker acid; the ratio of hydrogen ions to acid will be higher for the stronger acid as the stronger acid has a greater tendency to lose its proton. Because the range of possible values for K_a spans many orders of magnitude, a more manageable constant, pK_a is more frequently used, where pK_a = -log₁₀ K_a. Stronger acids have a smaller pK_a than weaker acids. Experimentally determined pK_a at 25 °C in aqueous solution are often quoted in textbooks and reference material.

Nomenclature[link]

In the classical naming system, acids are named according to their anions. That ionic suffix is dropped and replaced with a new suffix (and sometimes prefix), according to the table below. For example, HCl has chloride as its anion, so the -ide suffix makes it take the form hydrochloric acid. In the IUPAC naming system, "aqueous" is simply added to the name of the ionic compound. Thus, for hydrogen chloride, the IUPAC name would be aqueous hydrogen chloride. The prefix "hydro-" is added only if the acid is made up of just hydrogen and one other element.

Classical naming system:

Acid strength[link]

The strength of an acid refers to its ability or tendency to lose a proton. A strong acid is one that completely dissociates in water; in other words, one mole of a strong acid HA dissolves in water yielding one mole of H⁺ and one mole of the conjugate base, A⁻, and none of the protonated acid HA. In contrast a weak acid only partially dissociates and at equilibrium both the acid and the conjugate base are in solution. Examples of strong acids are hydrochloric acid (HCl), hydroiodic acid (HI), hydrobromic acid (HBr), perchloric acid (HClO₄), nitric acid (HNO₃) and sulfuric acid (H₂SO₄). In water each of these essentially ionizes 100%. The stronger an acid is, the more easily it loses a proton, H⁺. Two key factors that contribute to the ease of deprotonation are the polarity of the H—A bond and the size of atom A, which determines the strength of the H—A bond. Acid strengths are also often discussed in terms of the stability of the conjugate base.

Stronger acids have a larger K_a and a more negative pK_a than weaker acids.

Sulfonic acids, which are organic oxyacids, are a class of strong acids. A common example is toluenesulfonic acid (tosylic acid). Unlike sulfuric acid itself, sulfonic acids can be solids. In fact, polystyrene functionalized into polystyrene sulfonate is a solid strongly acidic plastic that is filterable.

Superacids are acids stronger than 100% sulfuric acid. Examples of superacids are fluoroantimonic acid, magic acid and perchloric acid. Superacids can permanently protonate water to give ionic, crystalline hydronium "salts". They can also quantitatively stabilize carbocations.

Chemical characteristics[link]

Monoprotic acids[link]

Monoprotic acids are those acids that are able to donate one proton per molecule during the process of dissociation (sometimes called ionization) as shown below (symbolized by HA):

HA(aq) + H₂O(l) H₃O⁺(aq) + A⁻(aq)         K_a

Common examples of monoprotic acids in mineral acids include hydrochloric acid (HCl) and nitric acid (HNO₃). On the other hand, for organic acids the term mainly indicates the presence of one carboxylic acid group and sometimes these acids are known as monocarboxylic acid. Examples in organic acids include formic acid (HCOOH), acetic acid (CH₃COOH) and benzoic acid (C₆H₅COOH).

Polyprotic acids[link]

Polyprotic acids, also known as polybasic acids, are able to donate more than one proton per acid molecule, in contrast to monoprotic acids that only donate one proton per molecule. Specific types of polyprotic acids have more specific names, such as diprotic acid (two potential protons to donate) and triprotic acid (three potential protons to donate).

A diprotic acid (here symbolized by H₂A) can undergo one or two dissociations depending on the pH. Each dissociation has its own dissociation constant, K_a1 and K_a2.

H₂A(aq) + H₂O(l) H₃O⁺(aq) + HA⁻(aq)       K_a1

HA⁻(aq) + H₂O(l) H₃O⁺(aq) + A²⁻(aq)       K_a2

The first dissociation constant is typically greater than the second; i.e., K_a1 > K_a2. For example, sulfuric acid (H₂SO₄) can donate one proton to form the bisulfate anion (HSO₄⁻), for which K_a1 is very large; then it can donate a second proton to form the sulfate anion (SO₄^2-), wherein the K_a2 is intermediate strength. The large K_a1 for the first dissociation makes sulfuric a strong acid. In a similar manner, the weak unstable carbonic acid (H₂CO₃) can lose one proton to form bicarbonate anion (HCO₃⁻) and lose a second to form carbonate anion (CO₃^2-). Both K_a values are small, but K_a1 > K_a2 .

A triprotic acid (H₃A) can undergo one, two, or three dissociations and has three dissociation constants, where K_a1 > K_a2 > K_a3.

H₃A(aq) + H₂O(l) H₃O⁺(aq) + H₂A⁻(aq)        K_a1

H₂A⁻(aq) + H₂O(l) H₃O⁺(aq) + HA²⁻(aq)       K_a2

HA²⁻(aq) + H₂O(l) H₃O⁺(aq) + A³⁻(aq)         K_a3

An inorganic example of a triprotic acid is orthophosphoric acid (H₃PO₄), usually just called phosphoric acid. All three protons can be successively lost to yield H₂PO₄⁻, then HPO₄^2-, and finally PO₄^3-, the orthophosphate ion, usually just called phosphate. An organic example of a triprotic acid is citric acid, which can successively lose three protons to finally form the citrate ion. Even though the positions of the protons on the original molecule may be equivalent, the successive K_a values will differ since it is energetically less favorable to lose a proton if the conjugate base is more negatively charged.

Although the subsequent loss of each hydrogen ion is less favorable, all of the conjugate bases are present in solution. The fractional concentration, α (alpha), for each species can be calculated. For example, a generic diprotic acid will generate 3 species in solution: H₂A, HA^-, and A^2-. The fractional concentrations can be calculated as below when given either the pH (which can be converted to the [H⁺]) or the concentrations of the acid with all its conjugate bases:

Failed to parse (Missing texvc executable; please see math/README to configure.): \alpha_{H_2 A}={{[H^+]^2} \over {[H^+]^2 + [H^+]K_1 + K_1 K_2}}= {{[H_2 A]} \over {[H_2 A]+[HA^-]+[A^{2-} ]}}

Failed to parse (Missing texvc executable; please see math/README to configure.): \alpha_{HA^- }={{[H^+]K_1} \over {[H^+]^2 + [H^+]K_1 + K_1 K_2}}= {{[HA^-]} \over {[H_2 A]+[HA^-]+[A^{2-} ]}}

Failed to parse (Missing texvc executable; please see math/README to configure.): \alpha_{A^{2-}}={{K_1 K_2} \over {[H^+]^2 + [H^+]K_1 + K_1 K_2}}= {{[A^{2-} ]} \over {[H_2 A]+[HA^-]+[A^{2-} ]}}

A pattern is observed in the above equations and can be expanded to the general n -protic acid that has been deprotonated i -times:

Failed to parse (Missing texvc executable; please see math/README to configure.): \alpha_{H_{n-i} A^{i-} }= {{[H^+ ]^{n-i} \displaystyle \prod_{j=0}^{i}K_j} \over { \displaystyle \sum_{i=0}^n \Big[ [H^+ ]^{n-i} \displaystyle \prod_{j=0}^{i}K_j} \Big] }

where K₀ = 1 and the other K-terms are the dissociation constants for the acid.

Neutralization[link]

Hydrochloric acid (in beaker) reacting with ammonia fumes to produce ammonium chloride (white smoke).

Neutralization is the reaction between an acid and a base, producing a salt and neutralized base; for example, hydrochloric acid and sodium hydroxide form sodium chloride and water:

HCl(aq) + NaOH(aq) → H₂O(l) + NaCl(aq)

Neutralization is the basis of titration, where a pH indicator shows equivalence point when the equivalent number of moles of a base have been added to an acid. It is often wrongly assumed that neutralization should result in a solution with pH 7.0, which is only the case with similar acid and base strengths during a reaction.

Neutralization with a base weaker than the acid results in a weakly acidic salt. An example is the weakly acidic ammonium chloride, which is produced from the strong acid hydrogen chloride and the weak base ammonia. Conversely, neutralizing a weak acid with a strong base gives a weakly basic salt, e.g. sodium fluoride from hydrogen fluoride and sodium hydroxide.

Weak acid–weak base equilibrium[link]

In order to lose a proton, it is necessary that the pH of the system rise above the pK_a of the protonated acid. The decreased concentration of H⁺ in that basic solution shifts the equilibrium towards the conjugate base form (the deprotonated form of the acid). In lower-pH (more acidic) solutions, there is a high enough H⁺ concentration in the solution to cause the acid to remain in its protonated form, or to protonate its conjugate base (the deprotonated form).

Solutions of weak acids and salts of their conjugate bases form buffer solutions.

Applications of acids[link]

There are numerous uses for acids. Acids are often used to remove rust and other corrosion from metals in a process known as pickling. They may be used as an electrolyte in a wet cell battery, such as sulfuric acid in a car battery.

Strong acids, sulfuric acid in particular, are widely used in mineral processing. For example, phosphate minerals react with sulfuric acid to produce phosphoric acid for the production of phosphate fertilizers, and zinc is produced by dissolving zinc oxide into sulfuric acid, purifying the solution and electrowinning.

In the chemical industry, acids react in neutralization reactions to produce salts. For example, nitric acid reacts with ammonia to produce ammonium nitrate, a fertilizer. Additionally, carboxylic acids can be esterified with alcohols, to produce esters.

Acids are used as additives to drinks and foods, as they alter their taste and serve as preservatives. Phosphoric acid, for example, is a component of cola drinks. Acetic acid is used in day to day life as vinegar. Carbonic acid is an important part of some cola drinks and soda. Citric acid is used as a preservative in sauces and pickles.

Tartaric acid is an important component of some commonly used foods like unripened mangoes and tamarind. Natural fruits and vegetables also contain acids. Citric acid is present in oranges, lemon and other citrus fruits. Oxalic acid is present in tomatoes, spinach, and especially in carambola and rhubarb; rhubarb leaves and unripe carambolas are toxic because of high concentrations of oxalic acid.

Ascorbic acid (Vitamin C) is an essential vitamin required in our body and is present in such foods as amla, lemon, citrus fruits, and guava.

Certain acids are used as drugs. Acetylsalicylic acid (Aspirin) is used as a pain killer and for bringing down fevers.

Acids play very important roles in the human body. The hydrochloric acid present in our stomach aids in digestion by breaking down large and complex food molecules. Amino acids are required for synthesis of proteins required for growth and repair of our body tissues. Fatty acids are also required for growth and repair of body tissues. Nucleic acids are important for the manufacturing of DNA, RNA and transmission of characters to offspring through genes. Carbonic acid is important for maintenance of pH equilibrium in the body.

Acid catalysis[link]

Acids are used as catalysts in industrial and organic chemistry; for example, sulfuric acid is used in very large quantities in the alkylation process to produce gasoline. Strong acids, such as sulfuric, phosphoric and hydrochloric acids also effect dehydration and condensation reactions. In biochemistry, many enzymes employ acid catalysis.^[3]

Biological occurrence[link]

Basic structure of an amino acid.

Many biologically important molecules are acids. Nucleic acids, which contain acidic phosphate groups, include DNA and RNA. Nucleic acids contain the genetic code that determines many of an organism's characteristics, and is passed from parents to offspring. DNA contains the chemical blueprint for the synthesis of proteins which are made up of amino acid subunits. Cell membranes contain fatty acid esters such as phospholipids.

An α-amino acid has a central carbon (the α or alpha carbon) which is covalently bonded to a carboxyl group (thus they are carboxylic acids), an amino group, a hydrogen atom and a variable group. The variable group, also called the R group or side chain, determines the identity and many of the properties of a specific amino acid. In glycine, the simplest amino acid, the R group is a hydrogen atom, but in all other amino acids it is contains one or more carbon atoms bonded to hydrogens, and may contain other elements such as sulfur, oxygen or nitrogen. With the exception of glycine, naturally occurring amino acids are chiral and almost invariably occur in the L-configuration. Peptidoglycan, found in some bacterial cell walls contains some D-amino acids. At physiological pH, typically around 7, free amino acids exist in a charged form, where the acidic carboxyl group (-COOH) loses a proton (-COO⁻) and the basic amine group (-NH₂) gains a proton (-NH₃⁺). The entire molecule has a net neutral charge and is a zwitterion, with the exception of amino acids with basic or acidic side chains. Aspartic acid, for example, possesses one protonated amine and two deprotonated carboxyl groups, for a net charge of −1 at physiological pH.

Fatty acids and fatty acid derivatives are another group of carboxylic acids that play a significant role in biology. These contain long hydrocarbon chains and a carboxylic acid group on one end. The cell membrane of nearly all organisms is primarily made up of a phospholipid bilayer, a micelle of hydrophobic fatty acid esters with polar, hydrophilic phosphate "head" groups. Membranes contain additional components, some of which can participate in acid-base reactions.

In humans and many other animals, hydrochloric acid is a part of the gastric acid secreted within the stomach to help hydrolyze proteins and polysaccharides, as well as converting the inactive pro-enzyme, pepsinogen into the enzyme, pepsin. Some organisms produce acids for defense; for example, ants produce formic acid.

Acid-base equilibrium plays a critical role in regulating mammalian breathing. Oxygen gas (O₂) drives cellular respiration, the process by which animals release the chemical potential energy stored in food, producing carbon dioxide (CO₂) as a byproduct. Oxygen and carbon dioxide are exchanged in the lungs, and the body responds to changing energy demands by adjusting the rate of ventilation. For example, during periods of exertion the body rapidly breaks down stored carbohydrates and fat, releasing CO₂ into the blood stream. In aqueous solutions such as blood CO₂ exists in equilibrium with carbonic acid and bicarbonate ion.

CO₂ + H₂O H₂CO₃ H⁺ + HCO₃⁻

It is the decrease in pH that signals the brain to breathe faster and deeper, expelling the excess CO₂ and resupplying the cells with O₂.

Aspirin (acetylsalicylic acid) is a carboxylic acid.

Cell membranes are generally impermeable to charged or large, polar molecules because of the lipophilic fatty acyl chains comprising their interior. Many biologically important molecules, including a number of pharmaceutical agents, are organic weak acids which can cross the membrane in their protonated, uncharged form but not in their charged form (i.e. as the conjugate base). For this reason the activity of many drugs can be enhanced or inhibited by the use of antacids or acidic foods. The charged form, however, is often more soluble in blood and cytosol, both aqueous environments. When the extracellular environment is more acidic than the neutral pH within the cell, certain acids will exist in their neutral form and will be membrane soluble, allowing them to cross the phospholipid bilayer. Acids that lose a proton at the intracellular pH will exist in their soluble, charged form and are thus able to diffuse through the cytosol to their target. Ibuprofen, aspirin and penicillin are examples of drugs that are weak acids.

Common acids[link]

Mineral acids (inorganic acids)[link]

• Hydrogen halides and their solutions: hydrochloric acid (HCl), hydrobromic acid (HBr), hydroiodic acid (HI)
• Halogen oxoacids: hypochlorous acid (HClO), chlorous acid (HClO₂), chloric acid (HClO₃), perchloric acid (HClO₄), and corresponding compounds for bromine and iodine
• Sulfuric acid (H₂SO₄)
• Fluorosulfuric acid (HSO₃F)
• Nitric acid (HNO₃)
• Phosphoric acid (H₃PO₄)
• Fluoroantimonic acid (HSbF₆)
• Fluoroboric acid (HBF₄)
• Hexafluorophosphoric acid (HPF₆)
• Chromic acid (H₂CrO₄)
• Boric acid (H₃BO₃)

Sulfonic acids[link]

• Methanesulfonic acid (or mesylic acid, CH₃SO₃H)
• Ethanesulfonic acid (or esylic acid, CH₃CH₂SO₃H)
• Benzenesulfonic acid (or besylic acid, C₆H₅SO₃H)
• p-Toluenesulfonic acid (or tosylic acid, CH₃C₆H₄SO₃H)
• Trifluoromethanesulfonic acid (or triflic acid, CF₃SO₃H)
• Polystyrene sulfonic acid (sulfonated polystyrene, [CH₂CH(C₆H₄)SO₃H]_n)

Carboxylic acids[link]

• Acetic acid (CH₃COOH)
• Citric acid (C₆H₈O₇)
• Formic acid (HCOOH)
• Gluconic acid HOCH₂-(CHOH)₄-COOH
• Lactic acid (CH₃-CHOH-COOH)
• Oxalic acid (HOOC-COOH)
• Tartaric acid (HOOC-CHOH-CHOH-COOH)

Vinylogous carboxylic acids[link]

In vinylogous carboxylic acids, the proton donor is a carbon atom, even though the electron-withdrawing group is a carbonyl as in regular carboxylic acids.

• Ascorbic acid
• Meldrum's acid

Nucleic acids[link]

• Deoxyribonucleic acid (DNA)
• Ribonucleic acid (RNA)

See also[link]

Chemistry

• Acid-base extraction
• Acid value
• Acid salt
• Base
• Basic salt
• Binary acid
• Hard and soft acids and bases (HSAB theory)
• Titration
• Vitriol

Environment

• Acid rain
• Acid sulfate soil
• Ocean acidification

References[link]

This article includes a list of references, but its sources remain unclear because it has insufficient inline citations. Please help to improve this article by introducing more precise citations. (May 2009)

• Listing of strengths of common acids and bases
• Zumdahl, Chemistry, 4th Edition.
• Ebbing, D.D., & Gammon, S. D. (2005). General chemistry (8th ed.). Boston, MA: Houghton Mifflin. ISBN 0-618-51177-6
• Pavia, D.L., Lampman, G.M., & Kriz, G.S. (2004). Organic chemistry volume 1: Organic chemistry 351. Mason, OH: Cenage Learning. ISBN 978-0-7593-4272-4

External links[link]

• Science Aid: Acids and Bases Information for High School students
• Curtipot: Acid-Base equilibria diagrams, pH calculation and titration curves simulation and analysis – freeware
• A summary of the Properties of Acids for the beginning chemistry student
• The UN ECE Convention on Long-Range Transboundary Air Pollution
• Chem 106 – Acidity Concepts

John Lennon MBE
Lennon rehearses "Give Peace a Chance" in Montreal, Canada, in 1969
Background information
Birth name	John Winston Lennon
Born	(1940-10-09)9 October 1940 Liverpool, England, UK
Died	8 December 1980(1980-12-08) (aged 40) New York, New York, US
Genres	Rock, pop
Occupations	Musician, singer-songwriter, record producer, artist, writer
Instruments	Vocals, guitar, piano, harmonica, harmonium, electronic organ, six-string bass
Years active	1957–75, 1980
Labels	Parlophone, Capitol, Apple, EMI, Geffen, Polydor
Associated acts	The Quarrymen, The Beatles, Plastic Ono Band, The Dirty Mac, Yoko Ono
Website	www.johnlennon.com
Notable instruments
Rickenbacker 325 Epiphone Casino Gibson J-160E

Lennon's signature

John Winston Ono Lennon, MBE (9 October 1940 – 8 December 1980) was an English musician and singer-songwriter who rose to worldwide fame as one of the founder members of The Beatles, one of the most commercially successful and critically acclaimed acts in the history of popular music. Together with Paul McCartney, he formed one of the most celebrated songwriting partnerships of the 20th century.

Born and raised in Liverpool, Lennon became involved as a teenager in the skiffle craze; his first band, The Quarrymen, evolved into The Beatles in 1960. As the group disintegrated towards the end of the decade, Lennon embarked on a solo career that produced the critically acclaimed albums John Lennon/Plastic Ono Band and Imagine, and iconic songs such as "Give Peace a Chance" and "Imagine". After his marriage to Yoko Ono in 1969, he changed his name to John Ono Lennon. Lennon disengaged himself from the music business in 1975 to devote time to raising his infant son Sean, but re-emerged with Ono in 1980 with the new album Double Fantasy. He was murdered three weeks after its release.

Lennon revealed a rebellious nature and acerbic wit in his music, writing, drawings, on film, and in interviews. Controversial through his political and peace activism, he moved to New York City in 1971, where his criticism of the Vietnam War resulted in a lengthy attempt by Richard Nixon's administration to deport him, while some of his songs were adopted as anthems by the anti-war movement.

As of 2012 Lennon's solo album sales in the United States exceed 14 million units, and as writer, co-writer or performer, he is responsible for 25 number-one singles on the US Hot 100 chart. In 2002 a BBC poll on the 100 Greatest Britons voted him eighth, and in 2008, Rolling Stone ranked him the fifth-greatest singer of all-time. He was posthumously inducted into the Songwriters Hall of Fame in 1987 and into the Rock and Roll Hall of Fame in 1994.

History[link]

1940–57: Early years[link]

Lennon was born in war-time England, on 9 October 1940 at Liverpool Maternity Hospital to Julia and Alfred Lennon, a merchant seaman who was away at the time of his son's birth.^[1] He was named John Winston Lennon after his paternal grandfather, John "Jack" Lennon, and then-Prime Minister Winston Churchill.^[2] His father was often away from home but sent regular pay cheques to 9 Newcastle Road, Liverpool, where Lennon lived with his mother,^[3] but the cheques stopped when he went absent without leave in February 1944.^[4][5] When he eventually came home six months later, he offered to look after the family, but Julia—by then pregnant with another man's child—rejected the idea.^[6] After her sister, Mimi Smith, twice complained to Liverpool's Social Services, Julia handed the care of Lennon over to her. In July 1946 Lennon's father visited Smith and took his son to Blackpool, secretly intending to emigrate to New Zealand with him.^[7] Julia followed them—with her partner at the time, 'Bobby' Dykins—and after a heated argument his father forced the five-year-old to choose between them. Lennon twice chose his father, but as his mother walked away, he began to cry and followed her.^[8] It would be 20 years before he had contact with his father again.^[9]

251 Menlove Avenue, the home of George and Mimi Smith, where Lennon lived for most of his childhood and adolescence

Throughout the rest of his childhood and adolescence he lived with his aunt and uncle, Mimi and George Smith, who had no children of their own, at Mendips, 251 Menlove Avenue, Woolton.^[10] His aunt bought him volumes of short stories, and his uncle, a dairyman at his family's farm, bought him a mouth organ and engaged him in solving crossword puzzles.^[11] Julia visited Mendips on a regular basis, and when he was 11 years old he often visited her at 1 Blomfield Road, Liverpool, where she played him Elvis Presley records, and taught him the banjo, learning how to play "Ain't That a Shame" by Fats Domino.^[12]

In September 1980 he talked about his family and his rebellious nature:

Part of me would like to be accepted by all facets of society and not be this loudmouthed lunatic musician. But I cannot be what I am not. Because of my attitude, all the other boys' parents ... instinctively recognised what I was, which was a troublemaker, meaning I did not conform and I would influence their kids, which I did ... I did my best to disrupt every friend's home ... Partly, maybe, it was out of envy that I didn't have this so-called home, but I really did ... There were five women who were my family. Five strong, intelligent women. Five sisters. Those women were fantastic ... that was my first feminist education ... One happened to be my mother ... she just couldn't deal with life. She had a husband who ran away to sea and the war was on and she couldn't cope with me, and when I was four-and-a-half, I ended up living with her elder sister ... the fact that I wasn't with my parents made me see that parents are not gods.^[13]

He regularly visited his cousin, Stanley Parkes, who lived in Fleetwood. Seven years Lennon's senior, Parkes took him on trips, and to local cinemas.^[14] During the school holidays, Parkes often visited Lennon with Leila Harvey, another cousin, often travelling to Blackpool two or three times a week to watch shows. They would visit the Blackpool Tower Circus and see artists such as Dickie Valentine, Arthur Askey, Max Bygraves and Joe Loss, with Parkes recalling that Lennon particularly liked George Formby.^[15] After Parkes's family moved to Scotland, the three cousins often spent their school holidays together there. Parkes recalled, "John, cousin Leila and I were very close. From Edinburgh we would drive up to the family croft at Durness, which was from about the time John was nine years old until he was about 16."^[16] He was 14 years old when his uncle George died of a liver haemorrhage on 5 June 1955 (aged 52).^[17]

Lennon was raised as an Anglican and attended Dovedale Primary School.^[18] From September 1952 to 1957, after passing his Eleven-Plus exam, he attended Quarry Bank High School in Liverpool, and was described by Harvey at the time as, "A happy-go-lucky, good-humoured, easy going, lively lad."^[19] He often drew comical cartoons which appeared in his own self-made school magazine called The Daily Howl,^[20] but despite his artistic talent, his school reports were damning: "Certainly on the road to failure ... hopeless ... rather a clown in class ... wasting other pupils' time."^[21]

His mother bought him his first guitar in 1956, an inexpensive Gallotone Champion acoustic for which she "lent" her son five pounds and ten shillings on the condition that the guitar be delivered to her own house, and not Mimi's, knowing well that her sister was not supportive of her son's musical aspirations.^[22] As Mimi was sceptical of his claim that he would be famous one day, she hoped he would grow bored with music, often telling him, "The guitar's all very well, John, but you'll never make a living out of it".^[23] On 15 July 1958, when Lennon was 17 years old, his mother, walking home after visiting the Smiths' house, was struck by a car and killed.^[24]

Lennon failed all his GCE O-level examinations, and was accepted into the Liverpool College of Art only after his aunt and headmaster intervened.^[25] Once at the college, he started wearing Teddy Boy clothes and acquired a reputation for disrupting classes and ridiculing teachers. As a result, he was excluded from the painting class, then the graphic arts course, and was threatened with expulsion for his behaviour, which included sitting on a nude model's lap during a life drawing class.^[26] He failed an annual exam, despite help from fellow student and future wife Cynthia Powell, and was "thrown out of the college before his final year."^[27]

1957–70: The Quarrymen to The Beatles[link]

1957–65: Formation, commercial break-out, and touring years[link]

Lennon playing with The Beatles in 1964 at the height of Beatlemania

The Beatles evolved from Lennon's first band, the Quarrymen. Named after Quarry Bank High School, the group was established by him in September 1956 when he was 15, and began as a skiffle group.^[28] By the summer of 1957 the Quarrymen played a "spirited set of songs" made up of half skiffle, and half rock and roll.^[29] Lennon first met Paul McCartney at the Quarrymen's second performance, held in Woolton on 6 July at the St. Peter's Church garden fête, after which McCartney was asked to join the band.^[30]

McCartney says that Aunt Mimi: "was very aware that John's friends were lower class", and would often patronise him when he arrived to visit Lennon.^[31] According to Paul's brother Mike, McCartney's father was also disapproving, declaring Lennon would get his son "into trouble";^[32] although he later allowed the fledgling band to rehearse in the McCartneys' front room at 20 Forthlin Road.^[33][34] During this time, the 18-year-old Lennon wrote his first song, "Hello Little Girl", a UK top 10 hit for The Fourmost nearly five years later.^[35]

George Harrison joined the band as lead guitarist,^[36] even though Lennon thought Harrison (at 14 years old) was too young to join the band, so McCartney engineered a second audition on the upper deck of a Liverpool bus, where Harrison played "Raunchy" for Lennon.^[37] Stuart Sutcliffe, Lennon's friend from art school, later joined as bassist.^[38] Lennon, McCartney, Harrison and Sutcliffe became "The Beatles" in early 1960. In August that year The Beatles, engaged for a 48-night residency in Hamburg, Germany, and desperately in need of a drummer, asked Pete Best to join them.^[39] Lennon was now 19, and his aunt, horrified when he told her about the trip, pleaded with him to continue his art studies instead.^[40] After the first Hamburg residency, the band accepted another in April 1961, and a third in April 1962. Like the other band members, Lennon was introduced to Preludin while in Hamburg,^[41] and regularly took the drug, as well as amphetamines, as a stimulant during their long, overnight performances.^[42]

Brian Epstein, The Beatles' manager from 1962, had no prior experience of artist management, but nevertheless had a strong influence on their early dress code and attitude on stage.^[43] Lennon initially resisted his attempts to encourage the band to present a professional appearance, but eventually complied, saying, "I'll wear a bloody balloon if somebody's going to pay me".^[44] McCartney took over on bass after Sutcliffe decided to stay in Hamburg, and drummer Ringo Starr replaced Best, completing the four-piece line-up that would endure until the group's break-up in 1970. The band's first single, "Love Me Do", was released in October 1962 and reached #17 on the British charts. They recorded their debut album, Please Please Me, in under 10 hours on 11 February 1963,^[45] a day when Lennon was suffering the effects of a cold,^[46] which is evident in the vocal on the last song to be recorded that day, Twist and Shout.^[47] The Lennon–McCartney songwriting partnership yielded eight of its fourteen tracks. With few exceptions—one being the album title itself—Lennon had yet to bring his love of wordplay to bear on his song lyrics, saying: "We were just writing songs ... pop songs with no more thought of them than that–to create a sound. And the words were almost irrelevant".^[45] In a 1987 interview, McCartney said that the other Beatles idolised John: "He was like our own little Elvis ... We all looked up to John. He was older and he was very much the leader; he was the quickest wit and the smartest".^[48]

The Beatles achieved mainstream success in the UK during the beginning of 1963. Lennon was on tour when his first son, Julian, was born in April. During their Royal Variety Show performance, attended by the Queen Mother and other British royalty, Lennon poked fun at his audience: "For our next song, I'd like to ask for your help. For the people in the cheaper seats, clap your hands ... and the rest of you, if you'll just rattle your jewellery."^[49] After a year of Beatlemania in the UK, the group's historic February 1964 US debut appearance on The Ed Sullivan Show marked their breakthrough to international stardom. A two-year period of constant touring, moviemaking, and songwriting followed, during which Lennon wrote two books, In His Own Write and A Spaniard in the Works.^[50] The Beatles received recognition from the British Establishment when they were appointed Members of the Order of the British Empire in the Queen's Birthday Honours of 1965.^[51]

Lennon grew concerned that fans attending Beatles' concerts were unable to hear the music above the screaming of fans, and that the band's musicianship was beginning to suffer as a result.^[52] Lennon's "Help!" expressed his own feelings in 1965: "I meant it ... It was me singing 'help'".^[53] He had put on weight (he would later refer to this as his "Fat Elvis" period),^[54] and felt he was subconsciously seeking change.^[55] The following January he was unknowingly introduced to LSD when a dentist, hosting a dinner party attended by Lennon, Harrison and their wives, spiked the guests' coffee with the drug.^[56] When they wanted to leave, their host revealed what they had taken, and strongly advised them not to leave the house because of the likely effects. Later, in an elevator at a nightclub, they all believed it was on fire: "We were all screaming ... hot and hysterical."^[56] A few months later in March, during an interview with Evening Standard reporter Maureen Cleave, Lennon remarked, "Christianity will go. It will vanish and shrink ... We're more popular than Jesus now—I don't know which will go first, rock and roll or Christianity."^[57] The comment went virtually unnoticed in England but caused great offence in the US when quoted by a magazine there five months later. The furore that followed—burning of Beatles' records, Ku Klux Klan activity, and threats against Lennon—contributed to the band's decision to stop touring.^[58]

1966–70: Studio years, break-up and solo work[link]

Deprived of the routine of live performances after their final commercial concert on 29 August 1966, Lennon felt lost and considered leaving the band.^[59] Since his involuntary introduction to LSD in January, he had made increasing use of the drug, and was almost constantly under its influence for much of the year."^[60] According to biographer Ian MacDonald, Lennon's continuous experience with LSD during the year brought him "close to erasing his identity".^[61] 1967 saw the release of "Strawberry Fields Forever", hailed by TIME magazine for its "astonishing inventiveness",^[62] and the group's landmark album Sgt. Pepper's Lonely Hearts Club Band, which revealed Lennon's lyrics contrasting strongly with the simple love songs of the Lennon–McCartney's early years.

In August, after having been introduced to the Maharishi Mahesh Yogi, the group attended a weekend of personal instruction at his Transcendental Meditation seminar in Bangor, Wales,^[63] and were informed of Epstein's death during the seminar. "I knew we were in trouble then", Lennon said later. "I didn't have any misconceptions about our ability to do anything other than play music, and I was scared".^[64] They later travelled to Maharishi's ashram in India for further guidance, where they composed most of the songs for The Beatles and Abbey Road.^[65]

The anti-war, black comedy How I Won the War, featuring Lennon's only appearance in a non–Beatles' full-length film, was shown in cinemas in October 1967.^[66] McCartney organised the group's first post-Epstein project,^[67] the self-written, -produced and -directed television film Magical Mystery Tour, released in December that year. While the film itself proved to be their first critical flop, its soundtrack release, featuring Lennon's acclaimed, Lewis Carroll-inspired "I am the Walrus", was a success.^[68][69] With Epstein gone, the band members became increasingly involved in business activities, and in February 1968 they formed Apple Corps, a multimedia corporation comprising Apple Records and several other subsidiary companies. Lennon described the venture as an attempt to achieve, "artistic freedom within a business structure",^[70] but his increased drug experimentation and growing preoccupation with Yoko Ono, and McCartney's own marriage plans, left Apple in need of professional management. Lennon asked Lord Beeching to take on the role, but he declined, advising Lennon to go back to making records. Lennon approached Allen Klein, who had managed The Rolling Stones and other bands during the British Invasion. Klein was appointed as Apple's chief executive by Lennon, Harrison and Starr,^[71] but McCartney never signed the management contract.^[72]

	"Give Peace a Chance" noicon Sample of "Give Peace a Chance", recorded in 1969 during Lennon and Ono's second Bed-In for Peace. As described by biographer Bill Harry, Lennon wanted to "write a peace anthem that would take over from the song 'We Shall Overcome'—and he succeeded ... it became the main anti-Vietnam protest song."[73]
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At the end of 1968, Lennon featured in the film The Rolling Stones Rock and Roll Circus (not released until 1996) in the role of a Dirty Mac band member. The supergroup, comprising Lennon, Eric Clapton, Keith Richards and Mitch Mitchell, also backed a vocal performance by Ono in the film.^[74] Lennon and Ono were married on 20 March 1969, and soon released a series of 14 lithographs called "Bag One" depicting scenes from their honeymoon,^[75] eight of which were deemed indecent and most of which were banned and confiscated.^[76] Lennon's creative focus continued to move beyond The Beatles and between 1968 and 1969 he and Ono recorded three albums of experimental music together: Unfinished Music No.1: Two Virgins^[77] (known more for its cover than for its music), Unfinished Music No.2: Life with the Lions and Wedding Album. In 1969 they formed The Plastic Ono Band, releasing Live Peace in Toronto 1969. In protest at Britain's involvement in the Nigerian Civil War,^[78] Lennon returned his MBE medal to the Queen, though this had no effect on his MBE status, which could not be renounced.^[79] Between 1969 and 1970 Lennon released the singles "Give Peace a Chance" (widely adopted as an anti-Vietnam-War anthem in 1969),^[80] "Cold Turkey" (documenting his withdrawal symptoms after he became addicted to heroin^[81]) and "Instant Karma!".

Lennon left the group in September 1969,^[82] and agreed not to inform the media while the band renegotiated their recording contract, but he was outraged that McCartney publicised his own departure on releasing his debut solo album in April 1970. Lennon's reaction was, "Jesus Christ! He gets all the credit for it!"^[83] He later wrote, "I started the band. I disbanded it. It's as simple as that."^[84] In later interviews with Rolling Stone magazine, he revealed his bitterness towards McCartney, saying, "I was a fool not to do what Paul did, which was use it to sell a record."^[85] He spoke too of the hostility he perceived the other members had towards Ono, and of how he, Harrison, and Starr "got fed up with being sidemen for Paul ... After Brian Epstein died we collapsed. Paul took over and supposedly led us. But what is leading us when we went round in circles?"^[86]

1970–80: Solo career[link]

1970–72: Initial solo success and activism[link]

Advertisement for "Imagine" from Billboard, 18 September 1971.

In 1970, Lennon and Ono went through primal therapy with Dr. Arthur Janov in Los Angeles, California. Designed to release emotional pain from early childhood, the therapy entailed two half-days a week with Janov for four months; he had wanted to treat the couple for longer, but they felt no need to continue and returned to London.^[87] Lennon's emotional debut solo album, John Lennon/Plastic Ono Band (1970), was received with high praise. Critic Greil Marcus remarked, "John's singing in the last verse of 'God' may be the finest in all of rock."^[88] The album featured the songs "Mother", in which Lennon confronted his feelings of childhood rejection,^[89] and the Dylanesque "Working Class Hero", a bitter attack against the bourgeois social system which, due to the lyric "you're still fucking peasants", fell foul of broadcasters.^[90][91] The same year, Tariq Ali's revolutionary political views, expressed when he interviewed Lennon, inspired the singer to write "Power to the People". Lennon also became involved with Ali during a protest against Oz magazine's prosecution for alleged obscenity. Lennon denounced the proceedings as "disgusting fascism", and he and Ono (as Elastic Oz Band) released the single "God Save Us/Do the Oz" and joined marches in support of the magazine.^[92]

	"Imagine" noicon Sample of "Imagine", Lennon's "most famous post-Beatles' track."[93] Like "Give Peace a Chance", the song became an anti-war anthem, but its lyrics offended religious groups. Lennon's explanation was, "If you can imagine a world at peace, with no denominations of religion—not without religion, but without this 'my God is bigger than your God' thing—then it can be true."[94]
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With Lennon's next album, Imagine (1971), critical response was more guarded. Rolling Stone reported that "it contains a substantial portion of good music" but warned of the possibility that "his posturings will soon seem not merely dull but irrelevant".^[95] The album's title track would become an anthem for anti-war movements,^[96] while another, "How Do You Sleep?", was a musical attack on McCartney in response to lyrics from Ram that Lennon felt, and McCartney later confirmed,^[97] were directed at him and Ono. However, Lennon softened his stance in the mid-1970s and said he had written "How Do You Sleep?" about himself.^[98] He said in 1980: "I used my resentment against Paul ... to create a song ... not a terrible vicious horrible vendetta ... I used my resentment and withdrawing from Paul and The Beatles, and the relationship with Paul, to write 'How Do You Sleep'. I don't really go 'round with those thoughts in my head all the time".^[99]

Lennon and Ono moved to New York in August 1971, and in December released "Happy Xmas (War Is Over)".^[100] To advertise the single, they paid for billboards in 12 cities around the world which declared, in the national language, "WAR IS OVER—IF YOU WANT IT".^[101] The new year saw the Nixon Administration take what it called a "strategic counter-measure" against Lennon's anti-war propaganda, embarking on what would be a four-year attempt to deport him: embroiled in a continuing legal battle, he was denied permanent residency in the US until 1976.^[102]

Recorded as a collaboration with Ono and with backing from the New York band Elephant's Memory, Some Time in New York City was released in 1972. Containing songs about women's rights, race relations, Britain's role in Northern Ireland, and Lennon's problems obtaining a green card,^[103] the album was poorly received—unlistenable, according to one critic.^[104] "Woman Is the Nigger of the World", released as a US single from the album the same year, was televised on 11 May, on The Dick Cavett Show. Many radio stations refused to broadcast the song because of the word "nigger".^[105] Lennon and Ono gave two benefit concerts with Elephant's Memory and guests in New York in aid of patients at the Willowbrook State School mental facility.^[106] Staged at Madison Square Garden on 30 August 1972, they were his last full-length concert appearances.^[107]