I.N. 22 LIVING THINGS: Properties of Water And Acids/Bases Headings Vocabulary Important Words

Living Things Use & Need Energy a.) Energy comes from food, used to maintain body b.) AUTOTROPH: produce own food c.) HETEROTROPH: must consume food d.) DECOMPOSER: breaks down dead material for food

Living things respond to their surrounding a.) Rxn to a stimulus b.) Action causes a rxn c.) Rxn is called a: Response d.) Involves one individual

Question: Describe the properties of water that make it important to living things. Water is Polar: It has an uneven distribution of electrons between the hydrogen and oxygen atoms One side is positive Other is negative

Water Properties: Water is cohesive Cohesion: attraction B/T same molecules causes molecules to draw inward at surface Ex: Some insects & spiders can “walk” on the surface of H2O Water is adhesive Adhesion: attraction between different mol. causes H20 to bend at surface Ex: capillary action-pulls column of water up to the top of a plant Water Properties:

Water is called “Universal solvent”: dissolves many other substances due to polarity Differences in charges pulls/pushes substances apart Water exhibits evaporative cooling: removes heat when it evaporates from a surface Ex: sweating cools skin Water expands during freezing: expands into crystal formation releasing heat Ex: rocks broken up by ice creating soil; ice layer protects fruit from freezing

Acids, Bases and the pH scale The pH scale measures the concentration of H+ ions (how acidic something is) Ranges from 0-14 At 7: H+ ions and OH- ions are equal so it is neutral 0-7: Acidic, has more H+ ions 7-14: Basic, has more OH- ions

ACIDS: release H+ when mixed with water Sour, corrosive Ex: HCl, H2SO4 Always have H at front of formula BASES: release OH- when mixed with water Bitter, slippery, usually in cleaners NaOH, CaOH Always have OH at end of formula

What is a buffer? Buffers are weak acids or bases that react w/strong acids and bases prevent sharp changes in pH Helps to neutralize pH Helps control pH in blood, digestive tract, etc. = maintain Homeostasis