buffer solution

buffer solution: “A buffer is an aqueous solution that resists changes in pH upon the addition of an acid or a base”. Also, adding water to a buffer or allowing water to evaporate from the buffer does not change the pH of a buffer significantly. Buffers basically constituent a pair of a weak acid and its conjugate base, or a pair of a weak base and its conjugate acid

lewis acid-base theory: the donator of a pair of an electron is base and the receiver of the pair of the electron is acid for example in this equation h2o + HCl .... cl- + h3o+

So, in order to be an effective buffer, The number of moles of the weak acid and its conjugate base must be significantly large compared to the number of moles of strong acid or base that may be added. The best buffering will occur when the ratio of [HA] to almost 1:1. In that case pH = pKa . Buffers are considered to be effective when the ratio of [HA] to [A-] ranges anywhere between 10:1 and 1:10.

blood buffer solution

Maintaining a constant blood pH is critical for the proper functioning of our body. The buffer that maintains the pH of human blood involves a carbonic acid (H2CO3) and bicarbonate ion (HCO3-) system. Why is it so critical to maintain the pH of our blood? Believe it or not, if our blood pH goes to anything below 6.8 or above 7.8, cells of the body can stop functioning and the person can die. This is how important the optimum pH of blood is! Enzymes are very specific in nature, and function optimally at the right temperature and the right pH; if the pH of blood goes out of range, the enzymes stop working and sometimes enzymes can even get permanently denatured, thus disabling their catalytic activity. This in turn affects a lot of biological processes in the human body, leading to various diseases.

Natural Acids: These are obtained from natural sources, such as fruits and animal products. e.g. lactic, citric, and tartaric acid etc. Mineral Acids: Mineral acids are acids prepared from minerals. For example, Hydrochloric acid (HCl), Sulphuric Acid (H2SO4), and nitric acid (HNO3) etc.

amphoteric( like water) : able to react both as a base and as an acid.

Lewis ( Electron) Concept Of Acid- Bases Species that can accept electron pairs are acids and called Lewis acids. Molecules having a central atom with an incomplete octet (less than 8 electrons): BF3, BCl3, AlCl3, MgCl2. BeCl2. etc. Molecules having a central atom with empty d-orbitals: SiX4, GeX4, TiCl4, SnX4, PX3, PF5, SF4, SeF4, TeCl4, etc., Molecules having multiple bonds between atoms of dissimilar electronegativity: CO2, SO2 and SO3. Under the influence of attacking Lewis base, one -electron pair will be shifted towards the more negative atom.   4. Simple cations: Cations that have a greater tendency to accept electrons. H+, Ag+, The following species can act as Lewis bases. Neutral species having at least one lone pair of electrons: Negatively charged species or anions: For example, chloride, cyanide, hydroxide ions, etc., It may be noted that all Bronsted bases are also Lewis bases but all Bronsted acids are not Lewis acids. The following compounds, for example, contain nonbonding pairs of electrons.  

All strong acid and bases are equally ionized and water is amphoteric. So they have the same acidic or basic strength in water. This is known as the levelling effect. The strength of acids also depends upon the solvent. Acetic acid is not receptive to take up protons and has to be forced. Thus acids HCIO4, H2S04, HCl and HN03 which have nearly the same strength in water follow the order of HClO4> H2SO4 > HCl > HNO3 in acetic acid. The real strength of acids can be judged by solvents. On the basis of proton interaction, solvents can be classified into four types:  Protophilic solvents:  Solvents that have a greater tendency to accept protons, i.e., water, alcohol, liquid ammonia, etc. Protogenic solvents:  Solvents that have the tendency to produce protons, i.e., water, liquid hydrogen chloride, glacial acetic acid, etc. Amphiprotic solvents:  Solvents that act both as protophilic or protogenic, e.g., water, ammonia, ethyl alcohol, etc. Aprotic solvents:  Solvents which neither donate nor accept protons, e.g., benzene, carbon tetrachloride, carbon disulphide, etc. HCI acts as an acid in the water, stronger acid in NH3, weak acid in CH3COOH, neutral in C6H6 and a weak base in HF.