Essay On Surface Tension

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Surface Tension Physical Pharmacy PT 102 For The Pharmaceutics Department Name: Lamis Khaled Mohamed ID: 153491 Group: ( D2 ) Name: Mahmoud Mohamed Ismail ID: 150617 Group: ( D2 ) Name: Mahmoud Abdelmohsen Mohamed ID: 150999 Group: ( D2 ) “ Introduction “ Surface Tension :- It is the cohesive forces between liquid molecules are responsible for the occurrence of surface tension. The molecules at the surface do not have other like molecules that surround them and consequently they cohere stronger than those directly associated with them on the surface. This forms a surface "film" which make it more difficult to move the object through the surface than to moving it when it is completely submerged. Surface tension is measured in dynes/cm, dynes force required to break a film of length 1 cm. evenly, it can be stated as surface energy of ergs per square centimeter. Water at 20°C it’s surface tension of 72.8 dynes/cm compared to 465 for mercury and 22.3 for ethyl alcohol. Surface Tension of Water :- Water surface tension is 72 dynes/cm at…show more content…
This causes the outer layer of the liquid to be like a membrane that is stretched and minimizes the surface area. Just like a filled balloon, "tension" exists on its elastic surface, and the energy is stored on the surface, just like elastic energy which is stored in the rubber of the balloon. To decrease the stretching of the skin, and decrease the amount of energy in tension on the surface, liquid molecules moves to create the lowest surface area possible, this is why falling water drops and inkjet in ink printers form spheres—it allows for the smallest amount of surface area for a certain volume of liquid. This is why its called the elastic pull on the surface that minimizes the area on the liquid-air boundary as surface

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