According to the Brasted-Lowry definitions, a conjugate acid-base pair is any pair of molecules or ions that may be interconverted via proton transfer.

• When an acid transmits a proton to a base, the acid is transformed to the base's conjugate.

• A base is transformed to its corresponding acid when it takes a proton.

• The fact that the constituents of a conjugate acid-base pair differ by a proton is important to these definitions.

The image attached shows the relationships among conjugate acid-base pairs by examining the reaction of hydrogen chloride with water to form chloride ion and the hydronium ion.

The transfer of a proton from an acid to a base may be shown using a curved arrow, the same curved arrow symbol used in the image attached above as it depicts the relocation of electron pairs among resonance contributing structures.

• We describe the Lewis structure of each reactant and product for acid-base reactions, displaying all valence electrons on reacting atoms.

• Curved arrows are then used to depict the change in location of electron pairs during the reaction.

• The new position of the electron pair is shown by the head of the curved arrow. A curving arrow beginning from a lone pair and pointing to a nearby atom.

For example, it suggests the development of a new bond, whereas an arrow originating at a bonding electron pair and pointing toward a previously bound atom signals the breakdown of that link.

• The curving arrow on the left in this equation indicates that an unshared pair of electrons on oxygen shifts position to establish a new covalent bond with hydrogen.

• The curved arrow on the right indicates that the H!Cl link breaks and that its electron pair is completely given to chlorine, resulting in the formation of a chloride ion.

• As a result of the HCl-H2O reaction, a proton is transported from HCl to H2O. An O!An H bond is formed and an H!Cl bond breaks throughout the process.

It is critical to remember that arrows represent the flow of electrons, not atoms.

The equilibrium constants can also be estimated using the pKa values (Ka).

• For example, if an acid's pKa is close to zero, the equilibrium constant for the reaction of that acid protonation of water is close to one.

• Acids with negative pKa values have equilibrium constants more than one, while acids with positive pKa values have equilibrium constants less than one.

Each unit variation in pKa values reflects a tenfold increase or reduction in the strength of the acids under consideration.

Values of pKa in aqueous solution ranging from 2 to 12 can be measured.

• In aqueous solution, pKa values in the range of 2 to 12 may be determined quite precisely.

• Because very powerful acids, such as HCl, HBr, and HI, are totally ionized in water, the only acid present in solutions of these acids is H3O1.

• Less basic solvents such as acetic acid or mixes of water and sulfuric acid are employed for acids that are too strong to be reliably measured in water.

Although none of the halogen acids are entirely ionized in acetic acid, HI exhibits a higher degree of ionization than either HBr or HCl.

• Transition state: refers to the highest energy point on a reaction coordinate diagram.

• The chemical structure at this point is commonly called the activated complex.

• The majority of chemical reactions take place as a result of collisions.

Consider combining two compounds, A-H and B2, in a reaction vessel with a solvent.

• Compounds A-H and B2 will travel through the solvent by jostling about, colliding with, and bouncing off individual solvent molecules.

• On rare occasions, A-H and B2 will clash. The kinetic energy of the molecules determines their movement through the vessel (kinetic meaning motion).

Higher-energy collisions occur when molecules with more kinetic energy collide.