Definition of acids and bases?
Definition of acids and bases?
Acids are chemical agents that release hydrogen ions when added to water. Their chemistry makes them one of the most important classes of molecules in nature and science. This article addresses acids and their properties.
Introduction to Acids
So many of us have heard of the term pH, which in general is the measure of the amount of acidity or alkalinity that is in a solution. More specifically, it is a measure of the amount of protons or hydrogen ions that are present in an aqueous solution. Acids are primary contributors to the measure of pH in a solution, and the presence of acids a key characteristic of almost all solutions, from blood in the body to foods and drinks we consume. Let's discuss what an acid is and how it affects the pH of solutions when added.
BASES...
In chemistry, bases are substances that, in aqueous solution, are slippery to the touch, taste astringent, change the color of indicators (e.g., turn red litmus paper blue), react with acids to form salts, promote certain chemical reactions (base catalysis), accept protons from any proton donor, and/or contain completely or partially displaceable OH
−
ions. Examples of bases are the hydroxides of the alkali metals and alkaline earth metals (NaOH, Ca(OH)
, etc.).
These particular substances produce hydroxide ions (OH
−
) in aqueous solutions, and are thus classified as Arrhenius bases. For a substance to be classified as an Arrhenius base, it must produce hydroxide ions in an aqueous solution. In order to do so, Arrhenius believed the base must contain hydroxide in the formula. This makes the Arrhenius model limited, as it cannot explain the basic properties of aqueous solutions of ammonia (NH
3
) or its organic derivatives (amines).
There are also bases that do not contain a hydroxide ion but nevertheless react with water, resulting in an increase in the concentration of the hydroxide ion.
An example of this is the reaction between ammonia and water to produce ammonium and hydroxide.
In this reaction ammonia is the base because it accepts a proton from the water molecule.
Ammonia and other bases similar to it usually have the ability to form a bond with a proton due to the unshared pair of electrons that they possess.
In the more general Brønsted–Lowry acid–base theory, a base is a substance that can accept hydrogen cations (H
+
)—otherwise known as protons. In the Lewis model, a base is an electron pair donor.
In water, by altering the autinization equilibrium, bases yield solutions in which the hydrogen ion activity is lower than it is in pure water, i.e., the water has a pH higher than 7.0 at standard conditions. A soluble base is called an alkali if it contains and releases OH
−
ions quantitatively. However, it is important to realize that basicity is not the same as alkalinity. Metal oxides, hydroxides, and especially alkoxides are basic, and counteranions of weak acids are weak base
The answer was quite lenghthy as the terms acid and bases have great significance in chemistry ..
Acids are chemical agents that release hydrogen ions when added to water. Their chemistry makes them one of the most important classes of molecules in nature and science. This article addresses acids and their properties.
Introduction to Acids
So many of us have heard of the term pH, which in general is the measure of the amount of acidity or alkalinity that is in a solution. More specifically, it is a measure of the amount of protons or hydrogen ions that are present in an aqueous solution. Acids are primary contributors to the measure of pH in a solution, and the presence of acids a key characteristic of almost all solutions, from blood in the body to foods and drinks we consume. Let's discuss what an acid is and how it affects the pH of solutions when added.
BASES...
In chemistry, bases are substances that, in aqueous solution, are slippery to the touch, taste astringent, change the color of indicators (e.g., turn red litmus paper blue), react with acids to form salts, promote certain chemical reactions (base catalysis), accept protons from any proton donor, and/or contain completely or partially displaceable OH
−
ions. Examples of bases are the hydroxides of the alkali metals and alkaline earth metals (NaOH, Ca(OH)
, etc.).
These particular substances produce hydroxide ions (OH
−
) in aqueous solutions, and are thus classified as Arrhenius bases. For a substance to be classified as an Arrhenius base, it must produce hydroxide ions in an aqueous solution. In order to do so, Arrhenius believed the base must contain hydroxide in the formula. This makes the Arrhenius model limited, as it cannot explain the basic properties of aqueous solutions of ammonia (NH
3
) or its organic derivatives (amines).
There are also bases that do not contain a hydroxide ion but nevertheless react with water, resulting in an increase in the concentration of the hydroxide ion.
An example of this is the reaction between ammonia and water to produce ammonium and hydroxide.
In this reaction ammonia is the base because it accepts a proton from the water molecule.
Ammonia and other bases similar to it usually have the ability to form a bond with a proton due to the unshared pair of electrons that they possess.
In the more general Brønsted–Lowry acid–base theory, a base is a substance that can accept hydrogen cations (H
+
)—otherwise known as protons. In the Lewis model, a base is an electron pair donor.
In water, by altering the autinization equilibrium, bases yield solutions in which the hydrogen ion activity is lower than it is in pure water, i.e., the water has a pH higher than 7.0 at standard conditions. A soluble base is called an alkali if it contains and releases OH
−
ions quantitatively. However, it is important to realize that basicity is not the same as alkalinity. Metal oxides, hydroxides, and especially alkoxides are basic, and counteranions of weak acids are weak base
The answer was quite lenghthy as the terms acid and bases have great significance in chemistry ..
