ACIDS AND BASESMOST BIOCHEMICAL REACTIONS OCCUR INAQUEOUS SOLUTIONS.

WATER (H2O) DISSOCIATES TO A SLIGHT EXTENT TO FORM H+ AND OH-

THE CONCENTRATION OF HYDROGEN IONS DETERMINES THE ACIDITY OF THE SOLUTION, WHICH IS USUALLY EXPRESSED IN TERMS OF pH.

THE pH OF A SOLUTION IS THE NEGATIVE LOG OF ITS HYDROGEN CONCENTRATION.

AN ACID IS A SUBSTANCE THAT CAN RE- LEASE HYDROGEN IONS (PROTON).

A BASE IS A SUBSTANCE THAT CAN ACCEPT HYDROGEN IONS

A STRONG ACID IN SOLUTION : ALMOST ALL MOLECULES DISSOCIATE.

A WEAK ACID IN SOLUTION : ONLY A SMALL NUMBER OF THE TOTAL MOLECULES

DISSOCIATE. A WEAK ACID HAS A CHARACTERISTIC:

DISSOCIATION CONSTANT (Ka) IS DE-FINED AS THE pKa.

 THE RELATIONSHIP BETWEEN pH, pKa AND THE CONCENTRATION OF A WEAK ACID AND ITS CONYUGATE BASE IS DESCRIBED BY : HENDERSON-HASSELBALCH EQUATION.pH = pKa + LOG( A-) / (HA).

THE BODY PRODUCES A NUMBER OF ACID SDURING NORMAL METABOLISM.