GBIO 151 1st Edition Lecture 4 Outline of Last Lecture I Atom Structure and Behavior Outline of Current Lecture II Water A 6 Basic Principles III Acids Bases A pH Current Lecture Water earth s surface is covered in water 2 3 of our bodies are water Life existed in water 2 billion years before proceeding to land Water is polar in nature forms hydrogen bonds Can be cohesive and adhesive Cohesive polar bonds keep water in a liquid state Creates surface tension Allows light things such as leaves to float on the surface Adhesive polar bonds are attracted to electrostatic forces 6 Basic Properties of Water 1 High specific heat needed to break hydrogen bonds in water a Amount of heat required to increase water s temperature 1 C 2 High heat of Vaporization a Amount of heat required to cause a phase change from liquid to gas b Cooling property i e sweat 3 Less dense as a solid than at its liquefied state a Hydrogen bonds are spaced farther apart 4 Strong solvent properties a Dissolving sugars and salts 5 Organize non polar molecules a Gathering substances such as oils fats 6 Forms Ions a Spontaneously b Rare Only happens 1 in every 500 billion water molecules Acids Bases Measured in pH partial hydrogen measures the hydrogen concentration in the solution pH scale starts at 1 and ends at 14 1 7 basic These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute 7 14 acidic 7 neutral Logarithmic scale based on hydrogen concentration a Exponent of concentration of molar hydrogen 1a Ex pH exponent 1 2a If H 10 7 pH 7 If H 10 5 pH 5 1 unit change 10x 2 units change 100x 3 units change 1000x Homeostasis pH needs to be regulated If pH is even slightly out of balance the effects could be fatal Buffers resist changes in pH Release H in presence of base Absorb H in presence of acid