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Topic: Acid dissociation constant


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In the News (Tue 10 Nov 09)

  
  A - Glossary of chemical terms
The strength of an acid depends on the extent to to which it dissociates, and is measured by its dissociation constant.
In the Lowry-Brønsted theory of acids and bases (1923), the definition was extended to one in which an acid is a proton donor (a Brønsted acid), and a base is a proton acceptor (a Brønsted base).
Amino acids are compounds containing both a carboxylic acid group (-COOH) and an amino group (-NH The most important are the a-amino acids, in which the -NH group in attached to the C atom adjacent to the -COOH group.
www.ktf-split.hr /periodni/en/abc/a.html   (2092 words)

  
  Essential Biochemistry
The degree of dissociation of a weak acid in water is described by the acid dissociation constant, K
For the dissociation of acetic acid (the acid in vinegar) in water,
CH the equilibrium (or acid dissociation) constant expression for the reaction is given by
www.wiley.com /college/pratt/0471393878/student/review/acid_base/4_strong_and_weak.html   (551 words)

  
  Encyclopedia :: encyclopedia : Biochemistry   (Site not responding. Last check: )
Biochemistry is the study of the structure and function of cellular components, such as proteins, carbohydrates, lipids, nucleic acids, and other biomolecules.
Nucleic acids are found in all living cells and viruses.
Nucleic acid, so called because of its prevalence in cellular nuclei, is the generic name of family of biopolymers.
www.hallencyclopedia.com /Biochemistry   (2589 words)

  
 Dissociation Summary
Dissociation may be accomplished by the addition of energy, as in the case of gaseous molecules dissociated by heat; or by the action of a solvent on a polar compound (i.e., electrolytic decomposition).
Dissociation is a psychological state or condition in which certain thoughts, emotions, sensations, or memories are separated from the rest of the psyche.
Dissociation most often makes the news with regards to soldiers' responses to wartime stress, rape victims with amnesia for details, and in occasional criminal trials where the question of whether a person with Dissociative Identity Disorder (DID) can be responsible for his or her actions.
www.bookrags.com /Dissociation   (1797 words)

  
 NationMaster - Encyclopedia: Isoelectric point
In chemistry and biochemistry, acid dissociation constant, the acidity constant, or the acid-ionization constant () is a specific type of equilibrium constant that indicates the extent of dissociation of hydrogen ions from an acid.
For amino acids with more than two ionizable groups such as lysine for example, the same formula is used but this time, the two pKa's used are those of the two groups that lose and gain a charge from the neutral form of the amino acid.
The isoelectric point is the pH at which the negative charge of the component amino acids of a protein equals the positive charge of the component amino acids so the protein is neutral.
www.nationmaster.com /encyclopedia/Isoelectric-point   (875 words)

  
 Acid
The strength of an acid may be understood by this defintion by the stability of hydronium and the solvated conjugate base upon dissociation.
Acids are named according to the ending of their anion.
Nitric acid, sulfuric acid, and perchloric acid are all strong acids, whereas nitrous acid, sulfurous acid and hypochlorous acid are all weak.
www.brainyencyclopedia.com /encyclopedia/a/ac/acid.html   (1390 words)

  
 Dissociation constant Information Center - dissociation constant pka
In chemistry and biochemistry, acid dissociation constant of edta a dissociation constant or an ionization constant is a specific type of equilibrium constant used for reversible reactions or processes.
That means that it refers to the extent to which a complex, molecule, or salt separates or splits into smaller molecules, ions, or radicals acid dissociation constant dissociation constant in a reversible manner.
For the deprotonation of acids, dissociation constant for ch3coona K is known dissociation constant of inositol as K
www.scipeeps.com /Sci-Biochemistry_Topics_Cp_-_D/Dissociation_constant.html   (226 words)

  
 Acid
The strength of an acid may be understood by this defintion by the stability of hydronium and the solvated conjugate base upon dissociation.
Acids are named according to the ending of their anion.
Nitric acid, sulfuric acid, and perchloric acid are all strong acids, whereas nitrous acid, sulfurous acid and hypochlorous acid are all weak.
www.dejavu.org /cgi-bin/get.cgi?ver=93&url=http%3A%2F%2Farticles.gourt.com%2F%3Farticle%3Dacid%26type%3Den   (1379 words)

  
 Acid dissociation constant
In chemistry and biochemistry, the acid dissociation constant, the acidity constant, or the acid-ionization constant (Ka) is a specific type of equilibrium constant that indicates the extent of dissociation of hydrogen ions from an acid.
The equilibrium is that of a proton transfer from an acid, HA, to water, H2O. The term for the concentration of water, [H2O], is omitted from the general equilibrium constant expression.
Because this constant differs for each acid and varies over many degrees of magnitude, the acidity constant is often represented by the additive inverse of its common logarithm, represented by the symbol pKa (using the same mathematical relationship as [H+] is to pH).
www.kiwipedia.com /acid-dissociation-constant.html   (225 words)

  
 Method for producing 5-phenoxycarbonylbenzotriazole - Patent 6548678
A method according to claim 1, wherein the reacting of 1H-benzotriazole-5carboxylic acid with diphenyl carbonate is conducted in a solvent.
The reaction of the present invention is usually conducted by mixing 1H-benzotriazole-5-carboxylic acid with diphenyl carbonate in a solvent, and preferably the base or metal oxide may be used in such a way that the base or metal oxide is added to the mixture of 1H-benzotriazole-5-carboxylic acid, diphenyl carbonate and the solvent.
N,N-Dimethylformamide (1.88 g), 1H-benzotriazole-5-carboxylic acid (81.6 g, 0.5 mmole), and a metal oxide or a base (an organic or inorganic base) were mixed in an amount as indicated in Table 1, then heated to a temperature as indicated in Table 1 and stirred at the same temperature for five hours.
www.freepatentsonline.com /6548678.html   (1386 words)

  
 dissociation — FactMonster.com
Dissociation is generally reversible; when the atoms or ions of the dissociated substance are returned to the original conditions, they recombine in the original form of the substance.
The dissociation constant is a measure of the extent of dissociation.
The dissociation constant is measured at equilibrium, and its value is usually affected by changes in temperature.
www.factmonster.com /ce6/sci/A0815642.html   (187 words)

  
 Weak acid K
The equilibrium constant for this expression is called the acid dissociation constant, K
For example, acetic acid is a weak acid, because when it is added to water, it reacts with the water in a reversible fashion to form hydronium and acetate ions.
Assume that the initial concentration of weak acid is approximately equal to the equilibrium concentration.
www.mpcfaculty.net /mark_bishop/weak_acid_equilibrium.htm   (579 words)

  
 Spartanburg SC | GoUpstate.com | Spartanburg Herald-Journal   (Site not responding. Last check: )
For a normal equilibrium constant, the concentration of water would be included in its definition, this is not the case for the acid dissociation constant as, because the reaction takes place in aqueous solution, the change in the concentration of water will be negligable.
This is because, if you combine the equations for the dissociation of an acid with those of the dissociation of its conjugate base, you always get the reaction for the self-ionization of water.
Both molecules have the same composition, being two carboxylic acid groups separated by two double-bonded carbon atoms; fumaric acid is the trans isomer, whereas maleic acid is the cis isomer.
www.goupstate.com /apps/pbcs.dll/section?category=NEWS&template=wiki&text=Acid_dissociation_constant   (1097 words)

  
 Suchmaschine
In chemistry and biochemistry, a dissociation constant is a specific type of equilibrium constant that measures the propensity of a larger object to separate (dissociate) reversibly into smaller components, as when a complex falls apart into its component molecules, or when a salt splits up into its component ions.
The dissociation constant is commonly used to describe the affinity between a ligand (L) (such as a drug) and a protein (P) i.e.
The dissociation constant has molar units (M), which correspond to the concentration of ligand [L] at which the binding site on a particular protein is half occupied, i.e.
www.dmoz.ch /lexikon.cgi?sprache=en&q=Dissociation_constant   (745 words)

  
 Inhibitor and anti-inhibitor monoclonal antibodies specific for horseradish peroxidase - Patent 5650324
The antibody of claim 1 wherein the dissociation constant is less than or equal to about 5 nmolar, and which specifically binds to said horseradish peroxidase in such a manner that the enzymatic activity of said horseradish peroxidase is diminished by no more than about 6%.
The water-soluble conjugate of claim 6 wherein the dissociation constant of the monoclonal antibody is less than or equal to about 5 nmolar, and the monoclonal antibody specifically binds to said horseradish peroxidase in such a manner that the enzymatic activity of said horseradish peroxidase is diminished by no more than about 6%.
The dissociation constants (K.sub.d) for inhibitor antibodies were determined by measuring the concentration of the antibody required to inhibit 50% of horseradish peroxidase activity (as compared to enzymatic activity in the absence of antibody).
www.freepatentsonline.com /5650324.html   (4391 words)

  
 NTU Info Centre: Acid dissociation constant   (Site not responding. Last check: )
While strong acids dissociate more or less completely in solution and consequently have large acidity constants, weak acids do not fully dissociate and generally have acidity constants significantly less than 1.
Because this constant differs for each acid and varies over many degrees of magnitude, the acidity constant is often represented by the inverse of its common logarithm, represented by the symbol (similar to the concept of pH, though not related directly).
The acidity constant for the acid HA is the dissociation constant for this equilibrium.
www.nowtryus.com /article:Acid_dissociation_constant   (396 words)

  
 Reference.com/Encyclopedia/Acid
Brønsted-Lowry: According to this definition, an acid is a proton (hydrogen nucleus) donor and a base is a proton (hydrogen nucleus) acceptor.
The strength of an acid may be understood by this definition by the stability of hydronium and the solvated conjugate base upon dissociation.
In the case of highly concentrated acids, the acid should first be wiped off as much as possible, otherwise the reaction of the acid dissolving in the water could cause severe thermal burns.
www.reference.com /browse/wiki/Acid   (1405 words)

  
 NationMaster - Encyclopedia: Sodium benzoate
It is the sodium salt of benzoic acid and exists in this form when dissolved in water.
Citric acid is a weak organic acid found in citrus fruits.
Cats have a significantly lower tolerance against benzoic acid and its salts than rats and mice.
www.nationmaster.com /encyclopedia/Sodium-benzoate   (1081 words)

  
 New Recommendations 4.1
As mentioned in Section 3, equilibrium constants of chemical reactions that are used in biochemistry are taken to be functions of T, P, and I.
If the equilibrium constants were determined with a standard state based on molarity, these equilibrium constants should be converted to a molality basis prior to using equation 13.
As an approximation the acid dissociation constants and magnesium complex dissociation constants are taken to be functions of the ionic strength and the different effects of Na and K
www.chem.qmul.ac.uk /iubmb/thermod/th41.html   (1309 words)

  
 Drug Pathways and Chemical Concepts- 8. Dissociation Constant
The dissociation constant is one of the most important characteristics of a pharmaceutical compound.
It is a numeric representative of the relative proton transfer for that substance, or the likelihood of that compound donating a proton.
This dissociation constant is an important characteristic of drug molecules, and provides a tool to anticipate some of the "behaviors" of that compound.
www.chemcases.com /pheno/pheno08.htm   (885 words)

  
 SparkNotes: pH Calculations: Terms   (Site not responding. Last check: )
Acid - A substance that has the potential to donate a proton or accept an electron pair.
Buffer - A solution composed of an acid and its conjugate base that serves to moderate the pH of the solution.
Conjugate Acid - A molecule that can be described as a base that has gained one proton.
www.sparknotes.com /chemistry/acidsbases/phcalc/terms.html   (304 words)

  
 Reference.com/Encyclopedia/Henderson-Hasselbalch equation
Hasselbalch was using the formula to study metabolic acidosis, which results from carbonic acid in the blood.
The most significant is the assumption that the concentration of the acid and its conjugate base at equilibrium will remain the same as the formal concentration.
This neglects the dissociation of the acid and the hydrolysis of the base.
www.reference.com /browse/wiki/Henderson-Hasselbalch_equation   (302 words)

  
 EPRI: Effects of Dimethylamine on the Surface Charge Properties of Magnetite
This report summarizes the results of a detailed investigation of the acid dissociation constants of dimethylammonium ion in high temperature water (0-290 degrees Celsius) and the effect of dimethylamine (DMA) on magnetite surface charge at 150 and 200 degrees Celsius.
To determine the acid dissociation constant of dimethylammonium ion and the effect of dimethylamine on magnetite surface charge at high temperature.
Researchers measured the acid dissociation equilibria of dimethylammonium ion (DMAH+) with a hydrogen-electrode concentration cell from 0 to 290 degrees Celsius in sodium trifluoromethanesulfonate (NaTr) solutions at ionic strengths of 0.1, 0.3 and 1 molal.
www.epri.com /OrderableitemDesc.asp?product_id=000000000001001029&targetnid=273224&value=06T061143&marketnid=273141&oitype=1&searchdate=11/27/2000   (791 words)

  
 Dissociation constant   (Site not responding. Last check: )
In chemistry and biochemistry, a dissociation constant or an ionization constant is a specific type of equilibrium constant used for reversible reactions or processes.
As a frequently used special case, the dissociation constant of water is often expressed as K
For the deprotonation of acids, K is known as K
www.abitabouteverything.com /files/d/di/dissociation_constant.html   (277 words)

  
 Acid-Base Tutorial - Terminology
Logarithm is another source of confusion in acid base balance and is responsible for the mistaken impression that the body maintains remarkably tight control over its hydrogen ion concentration - it doesn't.
Metabolic acids are not respirable; they have to be neutralized, metabolized, or excreted via the kidney.
The method predicts the quantity of Acid or Alkali required to return the plasma in-vivo to a normal pH under standard conditions.
www.acid-base.com /terminology.php   (2160 words)

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