Welcome to the pH glossary page. On this page you can find definitions for many pH attributes.

 

pH glossary A to Z

 

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

 
A

Acceptor: A substance that is able to accept a proton

Acid: A substance that is able to donate protons and in turn increase the concentration of hydrogen ions when dissolved in water.

Acid dissociation constant: Ka, the equilibrium constant for a reaction in which a proton is removed from an acid

Acidic: A solution that has a greater concentration of hydrogen ions than hydroxide ions

Acidic solution: A solution that has a greater concentration of hydrogen ions than hydroxide ions

Acid-base pair: An acid and a base pair, which only differs in the presence or absence of a proton, such as hydroxide and water

Amphoterism: Amphoterism refers to the ability for certain oxides and hydroxo compounds to act either as acids or bases

Anion: An anion is a negatively charged ion

Aqueous: A solution in which water is the solvent

Aqueous solution: A solution in which water is the solvent

Arrhenius: He formulated the theory of acids and bases based on the production of hydrogen ions and hydroxide ions in aqueous solution

Arrhenius definition: An equation that relates the rate constant for a reaction to the frequency factor, the activation energy, and the temperature

Autoionization: The process whereby water spontaneously forms low concentrations of hydrogen and hydroxide ions by proton transfer from one water molecule to another

B

Base: A substance that produces an excess of hydroxide ions when it dissolves in water; a hydrogen ion acceptor

Basic: A solution that has a greater concentration of hydroxide ions than hydrogen ions

Basic solution: A solution that has a greater concentration of hydroxide ions than hydrogen ions

Bronsted-Lowry: The two chemists who formulated the theory of acids and bases in terms of proton donors (acids) and proton acceptors (bases)

Bronsted acid: Any substance that acts as a source of protons

Bronsted base: Any substance that acts as a proton acceptor

Buffer: A buffer solution resists or suppresses a change in its pH on addition of small amounts of acid or base

Buffer capacity: The amount of acid or base that a buffer can accept without the pH changing appreciatively, determined by the magnitude of [HA] and [A-] in the solution

C

Cation: A cation is a positively charged ion, which migrates toward the cathode in an electrochemical cell

Common ion effect: It is the shift in equilibrium that occurs when an ion already present in the equilibrium reaction is present or added

Concentration: The quantity of solute present in a given quantity of solvent or solution

Conjugate acid: The substance formed by addition of a proton to a base

Conjugate acid-base pair: An acid and a base, which only differ in the presence or absence of a proton, such as acetic acid and acetate ion or hydroxide and water

Conjugate base: Everything that remains of the acid molecule after a proton is lost

D

Dilution: The process of reducing the concentration of a solution by adding more solvent

Donor: A substance being able to give away a proton

E

Electron drift: It occurs when electrons are attracted by highly electronegative atoms away from bonded OH ions which in turn further polarizes and weakens the O-H bond, making a stronger acid

Electro negativity: Electro negativity is a measure of the electron attracting power of an atom; metals have low electro negativities, and non-metals have high electro negativities

Equilibrium: the dynamic state where the concentrations of all reactants and products remain constant with time

Equilibrium constant: the value obtained from the product of the concentrations of all the reaction products, each raised to the power of its coefficient in the balanced equation, divided by the product of the concentrations of the reactants, each raised to the power of its coefficient in the balanced equation

Equivalence point: The point in a titration when enough titrant has been added to react exactly with the substance in solution being titrated (analyzed)

H

Henderson Hasselbalch equation: An equation giving the pH of a solution containing a mixture of a weak acid and its conjugate base

Hydrolysis: The term given to acid-base reactions in aqueous solution in which ions act as acids or bases.

Hydronium ion: a hydrated proton, H3O+

I

Ion: Electrically charged atom or group of atoms, which can be positively or negatively, charged depending on whether electrons are lost or gained by the atoms

Ion product constant: Kw, the product of the concentration of hydrogen ions and the concentration of hydroxide ions in an aqueous solution

K

Ka: The acid dissociation constant. The equilibrium constant for the reaction of an acid dissociating into its conjugate base and the hydronium ion

Kb: The base dissociation constant. The equilibrium constant for the reaction in which a base reacts with water to produce its conjugate acid and the hydroxide ion

Kc: It is the relationship that exists among the molarity concentrations of the reactants and products in a reversible reaction at equilibrium

Ksp: It is the solubility product constant

Kw: The ion product constant.  It always refers to the autoionization of water, and is equal to 1 x 10E-14 at 25 degrees Celsius

L

Lone pair: A pair of electrons found in the valence shell of an atom, which is not involved in bond formation

M

Minute: A very small quantity of substance

Molecule: Is a group of bonded atoms that exists as separate entity and has characteristic physical and chemical properties

N

Neutral: A solution that has an equal concentration of hydroxide and hydrogen ions

Neutral solution: A solution that has an equal concentration of hydroxide and hydrogen ions

P

pH: A convenient way of representing the concentration of hydronium or hydrogen ions in a solution. It is defined as the negative log of the concentration of hydronium ions

pOH: A convenient way of representing the concentration of hydroxide ions in a solution. It is defined as the negative log of the concentration of hydroxide ions

pH scale: A scale ranging from 1 to 14 rating the strengths of acids and bases defined by their pH value. The closer to the ends of the scale, the stronger their strength, whereas the closer to the center of the scale the more neutral they are

Polarity: It describes the ease with which the electron cloud in an atom or molecule can be distorted in an electric field

pK: A convenient way of representing an ionization constant. pK values are useful when comparing the relative strengths of acids (pKa) and bases (pKb)

Process: A method to complete an objective

Proton: Fundamental particles carrying the basic unit of positive electric charge and found in the nuclei of all atoms

Proton acceptor: An atom that is able to accept a proton from another atom;  another name for the hydrogen ion, H+

Proton donor: An atom that is able to donate a proton to another atom or proton acceptor

Q

Qualitative analysis: It determines the presence or absence of a particular metal ion

Quantitative analysis: It determines how much of a given substance is present

R

Reaction: Set of elementary steps or processes by which a reaction is proposed to occur. The mechanism must be consistent with the stoichiometry of the net equation and with the rate law for the net reaction.

S

Solubility product constant: It describes the equilibrium in a saturated solution of a slightly soluble compound

Soluble: A substance that can dilute and dissociate itself in the presence of water thus becoming a solution

Solution: A solution is the liquid or aqueous form of reactants or products

Standard solution: a solution of known concentration

Stoichiometric: It refers to the quantitative measurements and relationships involving substances and mixtures of chemical interest

Stoichiometric point: The point in a titration when enough titrant has been added to react exactly with the substance in solution being titrated (analyzed)

Strong acid: An acid that is completely ionized in aqueous solution

Strong base: A base that is completely ionized in aqueous solution

Substances: A substance has constant composition and properties throughout a given sample and from one sample to another. All substances are either elements or compounds

T

Titrant: the substance in a titration, which is added gradually to the solution being analyzed

Titration: A process in which the concentration of an unknown solution (of acid or base) can be determined by reacting a measured quantity of the unknown solution with a measured volume (of acid or base) of known concentration

Titration curves: A titration curves is a graph of solution pH versus volume of titrant. It outlines how pH changes during and acid-base titration, and it can be used to establish such features as the equivalence point of the titration

W

Weak acid: An acid that is only partially ionized in aqueous solution

Weak base: A base that is only partially ionized in aqueous solution