Why Hand Sanitizer Is 70% Alcohol (Not 100%)

Why is hand sanitizer typically 70% alcohol instead of 100%? In this Bio Break episode, Nick and Nigel explain the chemistry behind alcohol-based sanitizers and how they actually kill bacteria. They explore how alcohol disrupts bacterial membranes, denatures proteins, and why adding water improves the process. You will also learn why pure alcohol can actually preserve bacteria instead of destroying them, and what additional ingredients like glycerol do in sanitizer formulations. Understanding these mechanisms reveals why 70% alcohol has become the standard concentration used in many sanitizing products.