Sam


 * =Measuring Surface Tension of Water with a Penny= ||

Objective The goal of this project is to investigate how added salt and added detergent affect the surface tension of water. Introduction

Sam Pettinati Mrs. Van Meter Period 8 12/1/09   Science Fair On my science fair project I will be testing to see if a penny will float in water when different substances are added. The first thing I will discuss with you about my project is about cohesion and adhesion. Cohesion of water is how well it sticks to its self. Adhesion of water is how well it sticks to other substances. I need to know these terms because I will be dealing with these things when I do my project. I am also studying surface tension: the area of the surface the elastic like force existing in the surface of a body, esp. a liquid, tending to minimize, caused by asymmetries in the intermolecular forces between surface molecules. This matters to my project because when I try to balance my penny in these substances the penny will be measuring how powerful the surface tension is with these substances. In his experiment believe that the water is gong to mix in with these substances and possibly help the surface tension by lifting the penny higher. I think this will then keep the penny floating in the water. Water molecules are made of one oxygen and two hydrogen atoms. The oxygen atom tends to hold on to the shared electrons from the hydrogen atoms more tightly, so each end of the water molecule ends up with a partial charge. The oxygen portion of the molecule has a partial negative charge, and the hydrogen ends of the molecule have a partial positive charge. “Another way of talking about the partial charges is to say that water molecules are // polarized //. Like a magnet, with a north and South Pole, a water molecule has electrical poles. The oxygen atom is the negative pole, and each hydrogen atom is a positive pole.” Dictionary.references.com Wikipedia.com