Day 50:

Why do we use 70% ethanol for disinfection or cleaning microbiological work benches and not absolute alcohol? 

- Absolute alcohol or pure alcohol is a stronger solution as compared to 70% ethanol. 

Pure alcohol coagulates all the proteins in contact. So, when we use pure alcohol, on entering the cell of the microbe, it will coagulate all the proteins that are present immediately inside the cell wall and will not be able to reach the inner parts of the cell due to the formation of a protective coat of the coagulated protein. So, the inner lipids, proteins and other components remain intact inside the cell. This would mean that the cell has become inactive but it is not dead yet. Under favorable conditions, the cell once again becomes active. Consider using 70% ethanol. Since it is diluted with water, the rate at which it coagulates the proteins is comparatively slower than that of pure alcohol. So, it will penetrate deep into the cell before coagulation of protein begins. So, all the proteins inside the cell and  those close to the cell wall get coagulated eventually  and the organism dies. 

This is the reason for using 70% ethanol for disinfection and sterilization..