Buffering agent
Encyclopedia
A buffering agent is a weak acid or base used to maintain the acidity (pH
) of a solution
at a chosen value. The function of a buffering agent is to prevent a rapid change in pH when acids or bases are added to the solution. Buffering agents have variable properties—some are more soluble than others; some are acidic while others are basic. As pH managers, they are important in many chemical applications, including agriculture
, food processing
, biochemistry
, medicine
and photography
.
, which maintains a stable pH in spite of other acids and bases being combined with it. For example, buffered aspirin has a buffering agent, such as MgO, that will maintain the pH of the aspirin as it passes through the acidic stomach of the patient. Another use of a buffering agent is in an antacid tablet, whose primary purpose is to lower the acidity of the stomach.
we get an equilibrium expression between the acid and conjugate base. As a result we see that there is little change in the concentrations of the acid and base so therefore the solution is buffered. A buffering agent sets up this concentration ratio by providing the corresponding conjugate acid or base to stabilize the pH of that which it is added to. The resulting pH of this combination can be found by using Le Chatelier's principle
:
where HA is the weak acid and A is the anion of the base.
(MKP) is an example of a buffering agent. It has a mildly acidic reaction; when applied as a fertilizer with urea
or diammonium phosphate
, it minimizes pH
fluctuations which can cause nitrogen
loss and simultaneously provides potassium
nutrient.
, ammonia
) as well as intracellular agents (including protein
s and phosphate
). A dilute mixture of monosodium phosphate
and disodium phosphate
can be made to approach physiological pH and can serve as an agent for phosphate loading or colonic lavage
.
. If either of these substances become too acidic or too alkaline, they could damage fabric, and/or skin and hair.
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
) of a solution
Solution
In chemistry, a solution is a homogeneous mixture composed of only one phase. In such a mixture, a solute is dissolved in another substance, known as a solvent. The solvent does the dissolving.- Types of solutions :...
at a chosen value. The function of a buffering agent is to prevent a rapid change in pH when acids or bases are added to the solution. Buffering agents have variable properties—some are more soluble than others; some are acidic while others are basic. As pH managers, they are important in many chemical applications, including agriculture
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...
, food processing
Food processing
Food processing is the set of methods and techniques used to transform raw ingredients into food or to transform food into other forms for consumption by humans or animals either in the home or by the food processing industry...
, biochemistry
Biochemistry
Biochemistry, sometimes called biological chemistry, is the study of chemical processes in living organisms, including, but not limited to, living matter. Biochemistry governs all living organisms and living processes...
, medicine
Medicine
Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....
and photography
Photography
Photography is the art, science and practice of creating durable images by recording light or other electromagnetic radiation, either electronically by means of an image sensor or chemically by means of a light-sensitive material such as photographic film...
.
What is a buffering agent
A buffering agent can be either a weak acid or weak base. Buffering agents are usually added to water to form a buffer solutionBuffer solution
A buffer solution is an aqueous solution consisting of a mixture of a weak acid and its conjugate base or a weak base and its conjugate acid. It has the property that the pH of the solution changes very little when a small amount of strong acid or base is added to it. Buffer solutions are used as a...
, which maintains a stable pH in spite of other acids and bases being combined with it. For example, buffered aspirin has a buffering agent, such as MgO, that will maintain the pH of the aspirin as it passes through the acidic stomach of the patient. Another use of a buffering agent is in an antacid tablet, whose primary purpose is to lower the acidity of the stomach.
How a buffering agent works
The way buffering agents work is seen in how buffer solutions work. Using the Henderson-Hasselbalch equationHenderson-Hasselbalch equation
In chemistry, the Henderson–Hasselbalch equation describes the derivation of pH as a measure of acidity in biological and chemical systems...
we get an equilibrium expression between the acid and conjugate base. As a result we see that there is little change in the concentrations of the acid and base so therefore the solution is buffered. A buffering agent sets up this concentration ratio by providing the corresponding conjugate acid or base to stabilize the pH of that which it is added to. The resulting pH of this combination can be found by using Le Chatelier's principle
Le Châtelier's principle
In chemistry, Le Chatelier's principle, also called the Chatelier's principle, can be used to predict the effect of a change in conditions on a chemical equilibrium. The principle is named after Henry Louis Le Chatelier and sometimes Karl Ferdinand Braun who discovered it independently...
:
where HA is the weak acid and A is the anion of the base.
Agriculture
Monopotassium phosphateMonopotassium phosphate
Monopotassium phosphate -- 24 -- is a soluble salt which is used as a fertilizer, a food additive and a fungicide. It is a source of phosphorus and potassium. It is also a buffering agent...
(MKP) is an example of a buffering agent. It has a mildly acidic reaction; when applied as a fertilizer with urea
Urea
Urea or carbamide is an organic compound with the chemical formula CO2. The molecule has two —NH2 groups joined by a carbonyl functional group....
or diammonium phosphate
Diammonium phosphate
Diammonium phosphate is one of a series of water-soluble ammonium phosphate salts which can be produced when ammonia reacts with phosphoric acid...
, it minimizes pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
fluctuations which can cause nitrogen
Nitrogen
Nitrogen is a chemical element that has the symbol N, atomic number of 7 and atomic mass 14.00674 u. Elemental nitrogen is a colorless, odorless, tasteless, and mostly inert diatomic gas at standard conditions, constituting 78.08% by volume of Earth's atmosphere...
loss and simultaneously provides potassium
Potassium
Potassium is the chemical element with the symbol K and atomic number 19. Elemental potassium is a soft silvery-white alkali metal that oxidizes rapidly in air and is very reactive with water, generating sufficient heat to ignite the hydrogen emitted in the reaction.Potassium and sodium are...
nutrient.
In humans
Buffering agents in humans, functioning in acid base homeostasis, are extracellular agents (e.g., bicarbonateBicarbonate
In inorganic chemistry, bicarbonate is an intermediate form in the deprotonation of carbonic acid...
, ammonia
Ammonia
Ammonia is a compound of nitrogen and hydrogen with the formula . It is a colourless gas with a characteristic pungent odour. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or...
) as well as intracellular agents (including protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
s and phosphate
Phosphate
A phosphate, an inorganic chemical, is a salt of phosphoric acid. In organic chemistry, a phosphate, or organophosphate, is an ester of phosphoric acid. Organic phosphates are important in biochemistry and biogeochemistry or ecology. Inorganic phosphates are mined to obtain phosphorus for use in...
). A dilute mixture of monosodium phosphate
Monosodium phosphate
Monosodium phosphate , also known as anhydrous monobasic sodium phosphate is a chemical compound of sodium with a phosphate counterion. It is used as a laxative and, in combination with other sodium phosphates, as a pH buffer....
and disodium phosphate
Disodium phosphate
Disodium hydrogen phosphate is a sodium salt of phosphoric acid. It is a white powder that is highly hygroscopic and water soluble. It is therefore used commercially as an anti-caking additive in powdered products. It is also known as disodium hydrogen orthophosphate, sodium hydrogen phosphate...
can be made to approach physiological pH and can serve as an agent for phosphate loading or colonic lavage
Enema
An enema is the procedure of introducing liquids into the rectum and colon via the anus. The increasing volume of the liquid causes rapid expansion of the lower intestinal tract, often resulting in very uncomfortable bloating, cramping, powerful peristalsis, a feeling of extreme urgency and...
.
Shampoos and detergents
Most shampoos are buffered so that they are slightly alkaline. The buffer counteracts the alkalinity of soapSoap
In chemistry, soap is a salt of a fatty acid.IUPAC. "" Compendium of Chemical Terminology, 2nd ed. . Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford . XML on-line corrected version: created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN...
. If either of these substances become too acidic or too alkaline, they could damage fabric, and/or skin and hair.