BIOLOGICAL MOLECULES WATER HIGH SURFACE TENSION AND COHESION

BIOLOGICAL MOLECULES WATER HIGH SURFACE TENSION AND COHESION CREDITS – KASHISH MAKHIJA

COHESIVE PROPERTY OF WATER • COHESIVE PROPERTY OF WATER MEANS THAT TWO WATER MOLECULES CAN “STICK” OR “CLING” TOGETHER BECAUSE OF THE ELECTRICAL ATTRACTIVE FORCES BETWEEN THEM. IT IS THIS PROPERTY THAT CAUSES WATER TO FORM DROPS. • IT MAINLY HAPPENS DUE TO THE BIPOLAR BEHAVIOR OF WATER IN WHICH OXYGEN ACQUIRES AN ELECTRONEGATIVE CHARGE WHILE HYDROGEN HAS AN ELECTROPOSITIVE CHARGE. THUS, THIS POLARIZATION WITHIN THE MOLECULE ALLOWS IT TO FORM INTERMOLECULAR BONDS WITH THE ADJACENT MOLECULES. • COHESION, ALONG WITH ADHESION, HELPS EXPLAIN PHENOMENA SUCH AS, SURFACE TENSION AND CAPILLARY ACTION.

ADHESIVE PROPERTY OF WATER • ADHESION IS THE PROPERTY THAT ENABLES TWO DIFFERENT MOLECULES TO CLING TOGETHER. • THERE CAN NE VARIOUS KINDS OF ADHESION : MECHANICAL (WHERE SURFACES INTERLOCK), CHEMICAL (WHERE BONDS ARE FORMED), DISPERSIVE (WHERE MOLECULES ARE HELD TOGETHER BY VAN DER WAAL FORCES) AND ELECTROSTATIC (CAUSED BY DIFFERENCE IN CHARGE). • DISPERSIVE ADHESION TAKES PLACE WITH WATER AND THE FORCES CAN BE QUITE STRONG, ESPECIALLY IF IT IS WITH ANOTHER POLAR OR CHARGED SUBSTANCE.

CAPILLARY ACTION • CAPILLARY ACTION IS THE ABILITY OF WATER TO FLOW BETWEEN PORES OR UP TUBES, WITHOUT THE HELP OF OR, AGAINST OF, GRAVITY. • FOR INSTANCE, ADHESION ENABLES WATER TO “CLIMB” UPWARDS THROUGH THIN GLASS TUBES, CALLED CAPILLARY TUBES, PLACED IN A BEAKER OF WATER. THIS UPWARD MOTION AGAINST GRAVITY DEPENDS ON THE ATTRACTION BETWEEN WATER MOLECULES AND THE GLASS WALLS OF THE TUBE (ADHESION), AS WELL AS ON INTERACTIONS BETWEEN WATER MOLECULES (COHESION).