In chemistry, neutralization or neutralisation (see spelling differences ) is a chemical reaction in which acid and a base react with an equivalent quantity of each other. In a reaction in water, neutralization results in there being no excess of hydrogen or hydroxide ions present in the solution. The pH of the neutralized solution depends on the acid strength of the reactants.
35-469: An antacid is a substance which neutralizes stomach acidity and is used to relieve heartburn , indigestion , or an upset stomach. Some antacids have been used in the treatment of constipation and diarrhea . Marketed antacids contain salts of aluminum , calcium , magnesium , or sodium . Some preparations contain a combination of two salts , such as magnesium carbonate and aluminum hydroxide (e.g., hydrotalcite ). Antacids are available over
70-412: A is equal to T A / K a to a good approximation. If p K w = 14, This equation explains the following facts: In a titration of a weak acid with a strong base the pH rises more steeply as the end-point is approached. At the end-point, the slope of the curve of pH with respect to amount of titrant is a maximum. Since the end-point occurs at pH greater than 7,
105-442: A titration of an acid with a base, the point of neutralization can also be called the equivalence point . The quantitative nature of the neutralization reaction is most conveniently expressed in terms of the concentrations of acid and alkali . At the equivalence point: In general, for an acid AH n at concentration c 1 reacting with a base B(OH) m at concentration c 2 the volumes are related by: An example of
140-470: A 2013 study. Alternative sodium-free formulations containing magnesium salts may cause diarrhea, whereas those containing calcium or aluminum may cause constipation . Long-term use of antacids containing aluminum may increase the risk of developing osteoporosis . In vitro studies have found a potential for acid rebound to occur due to antacid overuse, however the significance of this finding has been called into question. When an excess amount of acid
175-468: A base being neutralized by an acid is as follows. The same equation relating the concentrations of acid and base applies. The concept of neutralization is not limited to reactions in solution. For example, the reaction of limestone with acid such as sulfuric acid is also a neutralization reaction. Such reactions are important in soil chemistry . A strong acid is one that is fully dissociated in aqueous solution. For example, hydrochloric acid , HCl,
210-474: A liquid preparation over a tablet is that liquids may provide quicker relief, however this may coincide with a shorter duration of action. Chewable tablets are one of the most common forms of antacids, most frequently made from carbonate or hydroxide salts , and are readily available over the counter. Upon reaching the stomach , the powdered antacid salts bind to hydronium (H) ions, producing chloride salts, carbon dioxide, and water. This process reduces
245-401: A solution of an acid, HA, is at equilibrium , by definition the concentrations are related by the expression The solvent (e.g. water) is omitted from the defining expression on the assumption that its concentration is very much greater than the concentration of dissolved acid, [H 2 O] ≫ T A . The equation for mass-balance in hydrogen ions can then be written as where K w represents
280-418: A specific example. Two partial neutralization reactions are possible in this instance. After an acid AH has been neutralized there are no molecules of the acid (or hydrogen ions produced by dissociation of the molecule) left in solution. When an acid is neutralized the amount of base added to it must be equal to the amount of acid present initially. This amount of base is said to be the equivalent amount. In
315-460: Is antacid tablets. These are designed to neutralize excess gastric acid in the stomach ( HCl ) that may be causing discomfort in the stomach or lower esophagus. This can also be remedied by the ingestion of sodium bicarbonate (NaHCO 3 ). Sodium bicarbonate is also commonly used to neutralise acid spills in laboratories, as well as acid burns . In chemical synthesis of nanomaterials, the heat of neutralization reaction can be used to facilitate
350-416: Is a strong acid. A strong base is one that is fully dissociated in aqueous solution. For example, sodium hydroxide , NaOH, is a strong base. Therefore, when a strong acid reacts with a strong base the neutralization reaction can be written as For example, in the reaction between hydrochloric acid and sodium hydroxide the sodium and chloride ions, Na and Cl take no part in the reaction. The reaction
385-464: Is consistent with the Brønsted–Lowry definition because in reality the hydrogen ion exists as the hydronium ion , so that the neutralization reaction may be written as When a strong acid is neutralized by a strong base there are no excess hydrogen ions left in the solution. The solution is said to be neutral as it is neither acidic nor alkaline. The pH of such a solution is close to a value of 7;
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#1732898432473420-439: Is expressed as log K < −2 , or in some texts log K < −1.76 . This means that the value of the dissociation constant cannot be obtained from experimental measurements. The value can, however, be estimated theoretically. For example the value of log K ≈ −6 has been estimated for hydrogen chloride in aqueous solution at room temperature. A chemical compound may behave as a strong acid in solution when its concentration
455-407: Is in fertilizers and control of soil pH . Slaked lime ( calcium hydroxide ) or limestone ( calcium carbonate ) may be worked into soil that is too acidic for plant growth. Fertilizers that improve plant growth are made by neutralizing sulfuric acid (H 2 SO 4 ) or nitric acid (HNO 3 ) with ammonia gas (NH 3 ), making ammonium sulfate or ammonium nitrate . These are salts utilized in
490-399: Is low and as a weak acid when its concentration is very high. Sulfuric acid is an example of such a compound. A weak acid HA is one that does not dissociate fully when it is dissolved in water. Instead an equilibrium mixture is formed: Acetic acid is an example of a weak acid. The pH of the neutralized solution resulting from is not close to 7, as with a strong acid, but depends on
525-409: Is one, such as methyl orange , that changes color at low pH. When a weak acid reacts with an equivalent amount of a weak base, complete neutralization does not always occur. The concentrations of the species in equilibrium with each other will depend on the equilibrium constant , K , for the reaction, which is defined as follows: The neutralization reaction can be considered as the difference of
560-487: Is produced in the stomach , the natural mucous barrier that protects the lining of the stomach can degrade, leading to pain and irritation . There is also potential for the development of acid reflux , which can cause pain and damage to the esophagus . Antacids contain alkaline ions that chemically neutralize stomach gastric acid , reducing damage to the stomach lining and esophagus , and relieving pain. Some antacids also inhibit pepsin , an enzyme that can damage
595-545: Is responsible for some of these interactions (e.g. fluoroquinolones , tetracyclines ), leading to decreased absorption of the chelated drug. Some interactions may be due to the pH increase observed in the stomach following antacid ingestion , leading to increased absorption of weak acids, and decreased absorption of weak bases. Antacids also cause an increase in pH of the urine (alkalization), which may cause increased blood concentrations of weak bases, and increased excretion of weak acids. A proposed method to mitigate
630-555: Is still valid as long as it is understood that in an aqueous solution the substances involved are subject to dissociation , which changes the ionization state of the substances. The arrow sign, →, is used because the reaction is complete, that is, neutralization is a quantitative reaction. A more general definition is based on Brønsted–Lowry acid–base theory . Electrical charges are omitted from generic expressions such as this, as each species A, AH, B, or BH may or may not carry an electrical charge. Neutralization of sulfuric acid provides
665-407: The acid dissociation constant , K a , of the acid. The pH at the end-point or equivalence point in a titration may be calculated as follows. At the end-point the acid is completely neutralized so the analytical hydrogen ion concentration, T H , is zero and the concentration of the conjugate base, A , is equal to the analytical or formal concentration T A of the acid: [A ] = T A . When
700-528: The esophagus in acid reflux . Antacids do not directly inhibit acid secretion , and thus are distinct from acid-reducing drugs like H 2 -receptor antagonists or proton pump inhibitors . Antacids do not kill the bacteria Helicobacter pylori , which causes most ulcers . Antacids are mainly classified into two categories: Antacids are known to interact with several oral medications , including fluoroquinolone and tetracycline antibiotics , iron , itraconazole , and prednisone . Metal chelation
735-878: The mucous membrane of the stomach . Some brands include Alka-Seltzer , Gaviscon, Tums , Gelusil and Eno . [REDACTED] The dictionary definition of antacid at Wiktionary Neutralization (chemistry) In the context of a chemical reaction the term neutralization is used for a reaction between an acid and a base or alkali . Historically, this reaction was represented as x H y A + + y B ( OH ) − x ⟶ B y A x + xy H 2 O {\displaystyle {\ce {{\mathit {x}}H_{\mathit {y}}A{}++{\mathit {y}}B(OH)-_{\mathit {x}}{}->B_{\mathit {y}}A_{\mathit {x}}{}+{\mathit {xy}}H2O}}} For example: The statement
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#1732898432473770-409: The self-dissociation constant of water. Since K w = [H ][OH ], the term K w / [H ] is equal to [OH ], the concentration of hydroxide ions. At neutralization, T H is zero. After multiplying both sides of the equation by [H ], it becomes and, after rearrangement and taking logarithms, With a dilute solution of the weak acid, the term 1 + T A / K
805-415: The benzoic acid is converted to benzoate. Chemical titration methods are used for analyzing acids or bases to determine the unknown concentration . Either a pH meter or a pH indicator 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
840-414: The chemical reduction of metal precursors. Also in the digestive tract, neutralization reactions are used when food is moved from the stomach to the intestines. In order for the nutrients to be absorbed through the intestinal wall, an alkaline environment is needed, so the pancreas produce an antacid bicarbonate to cause this transformation to occur. Another common use, though perhaps not as widely known,
875-453: The coating of the delayed-release tablet will dissolve, leading to degradation of the drug if it is pH sensitive . Antacids may be formulated with other active ingredients such as simethicone to control gas , or alginic acid to act as a physical barrier to acid. Several liquid antacid preparations are marketed . Common liquid preparations include milk of magnesia and magnesium/aluminum combinations . A potential advantage of using
910-741: The concentration of H ions in the stomach, raising the pH and neutralizing the acid. Common carbonate salts available in tablet form include those of calcium, magnesium, aluminum, and sodium. Some common American brands are Tums , Gaviscon chewable tablets, and Maalox chewable tablets. Effervescent tablets are tablets which are designed to dissolve in water , and then release carbon dioxide . Common ingredients include citric acid and sodium bicarbonate , which react when in contact with water to produce carbon dioxide . Effervescent antacids may also contain aspirin , sodium carbonate , or tartaric acid . Those containing aspirin may cause further gastric irritation and ulceration due to aspirin 's effects on
945-433: The counter and are taken by mouth to quickly relieve occasional heartburn , the major symptom of gastroesophageal reflux disease and indigestion . Treatment with antacids alone is symptomatic and only justified for minor symptoms. Alternative uses for antacids include constipation, diarrhea, hyperphosphatemia, and urinary alkalization. Some antacids are also used as an adjunct to pancreatic enzyme replacement therapy in
980-410: The effects of stomach acidity and chelation on drug absorption is to space out the administration of antacids with interacting medications by at least two hours, however this method has not been well studied for drugs affected by urine alkalization . There are concerns regarding interactions between delayed-release tablets and antacids, as antacids may increase the stomach pH to a point at which
1015-439: The exact pH value is dependent on the temperature of the solution. Neutralization is an exothermic reaction. The standard enthalpy change for the reaction H + OH → H 2 O is −57.30 kJ/mol. The term fully dissociated is applied to a solute when the concentration of undissociated solute is below the detection limits , that is, when the undissociated solute's concentration is too low to measured. Quantitatively, this
1050-474: The fertilizer. Industrially, a by-product of the burning of coal , sulfur dioxide gas, may combine with water vapor in the air to eventually produce sulfuric acid, which falls as acid rain. To prevent the sulfur dioxide from being released, a device known as a scrubber gleans the gas from smoke stacks. This device first blows calcium carbonate into the combustion chamber where it decomposes into calcium oxide (lime) and carbon dioxide. This lime then reacts with
1085-535: The following two acid dissociation reactions with the dissociation constants K a,A and K a,B of the acids HA and BH , respectively. Inspection of the reaction quotients shows that K = K a,A / K a,B . A weak acid cannot always be neutralized by a weak base, and vice versa. However, for the neutralization of benzoic acid ( K a,A = 6.5 × 10 ) with ammonia ( K a,B = 5.6 × 10 for ammonium ), K = 1.2 × 10 >> 1, and more than 99% of
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1120-512: The molarity of the unknown. In wastewater treatment , 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 oxide , magnesium hydroxide , and sodium bicarbonate . The selection of an appropriate neutralization chemical depends on the particular application. There are many uses of neutralization reactions that are acid-alkali reactions. A very common use
1155-447: The most suitable indicator to use is one, like phenolphthalein , that changes color at high pH. The situation is analogous to that of weak acids and strong bases. Amines are examples of weak bases. The pH of the neutralized solution depends on the acid dissociation constant of the protonated base, p K a , or, equivalently, on the base association constant, p K b . The most suitable indicator to use for this type of titration
1190-404: The sulfur dioxide produced forming calcium sulfite . A suspension of lime is then injected into the mixture to produce a slurry, which removes the calcium sulfite and any remaining unreacted sulfur dioxide. In the final manufacturing quality control process products often undergo acid treatment & the acid treatments have to be neutralized to prevent corrosion of the product. Neutralization
1225-468: The treatment of pancreatic insufficiency . Non-particulate antacids ( sodium citrate ) increase gastric pH with little or no effect on gastric volume, and therefore may see some limited use in pre-operative procedures. Sodium citrate should be given within 1 hour of surgery to be the most effective. Conventional effervescent tablets contain a significant amount of sodium and are associated with increased odds of adverse cardiovascular events according to
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