|Results 1–10 of 212 for acid radical|
Acid radical is an anion left after removal of hydrogen atoms from an acid.
Acid salt is a compound formed by replacing hydrogen in an acid with a metal (or a radical that acts like a metal).
Acid is a type of compound that contains hydrogen and dissociates in water to produce positive hydrogen ions. The reaction for an acid HA is commonly written:
In fact, the hydrogen ion (the proton) is solvated, and the complete reaction is:
This definition of acids comes from the Arrhenius theory. Such acids tend to be corrosive substances with a sharp taste, which turn litmus red and produce colour changes with other indicators. They are referred to as protonic acids and are classified into strong acids, which are almost completely dissociated in water, (e.g. sulphuric acid and hydrochloric acid), and weak acids, which are only partially dissociated (e.g. acetic acid and hydrogen sulphide). The strength of an acid depends on the extent 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). An important feature of the Lowry-Brønsted concept is that when an acid gives up a proton, a conjugate base is formed that is capable of accepting a proton.
Similarly, every base produces its conjugate acid as a result of accepting a proton.
For example, acetate ion is the conjugate base of acetic acid, and ammonium ion is the conjugate acid of ammonia.
As the acid of a conjugate acid/base pair becomes weaker, its conjugate base becomes stronger and vice versa.
A further extension of the idea of acids and bases was made in the Lewis theory. In this, a G. N. Lewis acid is a compound or atom that can accept a pair of electrons and a Lewis base is one that can donate an electron pair. This definition encompasses "traditional" acid-base reactions, but it also includes reactions that do not involve ions, e.g.
in which NH3 is the base (donor) and BCl3 the acid (acceptor).
Acid dissociation constant (Ka) is the equilibrium constant for the dissociation of an acid HA through the reaction
The quantity pKa = -log Ka is often used to express the acid dissociation constant.
Acid halide is organic compound containing the group -COX where X is a halogen atom.
Acid rain is rainwater that shows acid reaction because of nitrogen and sulphur oxides absorption. It is generated mainly by industrial pollutions.
Acid-base indicator is a weak acid or weak base, such as litmus, methyl orange or phenolphthalein, which changes colour when it gains or loses an H+ ion.
Acid-base titration is an analytical technique in volumetric analysis, where an acid of known concentration is used to neutralise a known volume of a base, and the observed volume of the acid required is used to determine the unknown concentration of the base. An acid-base indicator is used to determine the end-point of the titration.
Acrylic acid (propenoic acid) is a colourless liquid, smelling like acetic acid. It can be formed by acrolein oxidation. It readily polymerizes and is used in the manufacture of acrylic resins, transparent plastic materials (organic glass).
Aspartic acid is an electrically charged amino acids with acidic side chains. As a group the charged amino acids are relatively abundant and are generally located on the surface of the protein. Aspartic acid and glutamic acid play important roles as general acids in enzyme active centers, as well as in maintaining the solubility and ionic character of proteins. Aspartic acid (sometimes referred to as asparate depending on pH) is non-essential in mammals, being produced from oxaloacetate by transamination.