In an electrical circuit, electrons supplied by a battery will flow through an electric wire connecting two chemical species that differ in their affinity for electrons. The tendency of the redox couples in an electron transport chain to accept electrons or to donate electrons to another redox couple is termed as redox potential. The reduction potential of the half cell depends not only on the chemical species present but also on their concentrations.
A strong acid is an acid which dissociates completely (100%) in solution. Strong acids dissociate completely in solution in which the reverse reaction does not occur and hence an equilibrium is not established. Strong acids have a lower pH than weak acids of the same concentration.
Arrhenius concept of dissociation gives a convenient way of measuring the strength of an acid or base. Although water tends to dissociate all acids and bases the degree to which they dissociate depends on their strength. List of strong acids such as HCl, HNO3, and H2SO4 dissociate completely in water, while weak acids dissociate only partially. Practically speaking, a weak acid is an acid that doesn’t dissociate completely in water.
Standard Reduction Potential
Reduction potentials for chemical half reactions are measured in relation to the standard hydrogen electrode, which by convention has a standard reduction potential of zero volts at each temperature at zero ionic strength. The standard hydrogen electrode consists of molecular hydrogen at 1 bar bubbling over a platinum electrode immersed in a solution with hydrogen ions at unit activity. For a chemical half reaction the standard reduction potential Eo is obtained when the concentrations of the species are 1M; this potential and the corresponding thermodynamic properties are taken to be 1functions of the ionic strength.
The magnitude of electrode potential depends upon the following.
● Nature of metal of the electrode
● Concentration of the electrolyte or ions
For comparison of electrode potentials of different electrodes, they are measured under standard conditions that mean metal should be in a pure temperature of 298K and concentration of the metal ions or electrolyte should be 1M. If gases are involved their partial pressure should be 1 atm. Electrode potentials under these conditions are called standard reduction potential and are denoted as Eo.
Examples of Strong Acids
Strong acid cleaners are corrosive to most metals and even concrete. When heated they release toxic fumes. In addition, if the acid solution is at too high of a temperature the solution will redeposit the minerals onto the equipment surfaces. Therefore, use of these cleansers has to be done in a strictly controlled manner. Examples of strong acids include hydrochloric acid, sulfuric acid and sulfamic acid. Phosphoric acid which is also classified as a strong acid cleaner is the least corrosive of the strong acid cleaners.
A monoprotic acid is an acid which can only donate one hydrogen ion per formula. Examples of this are hydrochloric acid, HCl a solid acid and HC2H3O2 a weak acid. A polyprotic acid is an acid which can contribute two or more hydrogen ions per formula. Examples include sulfuric acid, diprotic acid H2SO4, and triprotic acid Phosphoric acid H3PO4.