The Chemistry of Life Chapter 2
Ch 2.2-Properties of Water
Structure of the Water Molecule -Polarity: having two opposite extremes -Water has a partial positive and negative charge on opposite ends of the molecule - Hydrogen bonds -The positive and negative charges on one water molecule attract the charges on another water molecule
Properties of Water 1)Cohesion -Water can stick to itself because of the charges and hydrogen bonds 2)Adhesion -Water can stick to anything else that has a charge (ex: glass) -Capillary action: uses cohesion AND adhesion to move liquids that contain water in a tube
Properties of Water 3)Heat Capacity -Water has a high heat capacity -Water will absorb a lot of heat as its temperature rises -It takes a lot of energy to break all the hydrogen bonds in water and make the temperature rise 4)Heat of Vaporization -Water absorbs a lot of heat before turning into a gas
5) Solid Density < Liquid Density - Water molecules expand when freezing Properties of Water
Mixtures - Mixture -Two or more elements or compounds that are physically mixed together but not chemically combined -Can be gases, liquids, or solids -Examples: solutions and suspensions
Solutions Solutes: a substance that dissolves in a liquid (Ex: salt, sugar, etc) Solvent: the liquid in which the solute is dissolved (Ex: water, acid, etc) Solution: the combination of solutes dissolved in the solvent (Ex: salt water)
Suspensions - Mixture of water and non-dissolved material -Movement of water molecules keeps small particles of substance suspended
Acids, Bases, and pH - pH scale -Measures acid or base levels of a substance -7 is neutral - Acid - Below 7 on pH scale - Base - Above 7 on pH scale - Buffer -Prevents sudden changes in pH -Very important for body to maintain a balanced internal environment