Why is Acid Corrosive?
Acids are corrosive in nature. They have the tendency of damaging the surface irreversibly with which they come in contact. Exposure of eyes and skin to acids will destroy the corresponding tissues completely. Eye, if exposed to a strong acid will get damaged heavily and might result in blindness also. The soft tissues in the skin will get easily and intensely damaged by the acid and the bones will be decalcified. The burns that occur due to the strong acid will be very painful and get healed up very slowly. If more skin surface area is exposed to the strong acid, more amount of calcium is inactivated which can lead to poisoning due to systemic fluoride, hypocalcaemia, hypomagnesaemia. The reduced calcium levels in the blood will result in heart malfunction and cardiac arrhythmia. Damage to the kidney and liver also occurs due to heavy exposure to acids. Neuromuscular hyperirritability results from hypomagnesaemia. Inhaling the strong acid like hydrofluoric acid (HF) will cause serious damage to the lungs leading to pulmonary edema. The reaction of skin and other tissues to HF will not occur immediately.
The pH of the acid is less than 7. The pH of strong acid is nearer to 1 and as the pH increases towards 7 the strength of acid decreases. Strong acids have higher ionization constant. HCl and HF readily dissociate into H+ and Cl-, H+ and F- , respectively in water. Hence, they have strong ionizing capacity and act as strong acids. Sulphuric acid is stronger than hydrochloric acid as it acts as both acid and oxidant. Acids and bases are corrosive to both living and non-living things.
The corrosive action of acid on living tissues is due to the catalytic reaction of acid-base in ester and amide hydrolysis. The corrosive acids will react with the skin and hydrolyze the fats which are the chemical forms of esters. Proteins in the skin exist as amides and they are hydrolyzed by acid-base catalysis. Strong acids will denature the proteins and fats in the living tissues and hydrate them. This will remove the water from the living tissues and the reaction is exothermic.