AP BIOLOGY

Detailed explanation-1: -Surface tension is a measure of how difficult it is to stretch or break the surface of a liquid.

Detailed explanation-2: -However, the surface tension of water can be broken by adding certain substances such as detergents. Soaps and detergents are useful for cleaning because when they break water’s surface tension, they are able to spread out onto dirty surfaces and soak into laundry, breaking up dirt and oil.

Detailed explanation-3: -The Du Noüy ring method is used to determine the surface tension of a liquid. A platinum-iridium ring is drawn out of the liquid while, at the same time, the maximum force caused by the tension of the liquid lamella during the movement of the ring is measured.

Detailed explanation-4: -Surface tension () is expressed as surface energy per unit area and alternatively as force per unit length. Surface tension of liquids can be measured directly and expressed in the units of work or energy per unit area (erg/cm2), which is then simplified (erg/cm2 = dyne.cm/cm2 = dyne/cm) to dyne/cm.