CHEMISTRY Chapter 1: Introduction Section 2: Describing matter

Objectives 1.2 Identify and describe physical and chemical properties. List four observations that a chemical change has occurred. Distinguish between characteristics of matter.

Physical Properties Can be observed without affecting composition Color, Odor, Texture, Density, All Phase change properties Can only be observed by changing the composition Reaction with oxygen, other chemicals; Combustion Chemical Properties

Physical Changes Do not affect composition

Physical Change Physical changes include: Changing the shape or size Dissolving Changing from one state of matter to another

Examples of Physical Change water evaporating or water changing to steam clothes drying in a dryer chopping wood - wood ground to sawdust erosion rock breaking mixing Kool-Aid

Chemical Changes DO affect composition

Copyright © by Houghton Mifflin Company 2-8 Electrolysis, the decomposition of water by an electric current, is a chemical process.

Examples of Chemical Changes fruit rotting, food spoiling rust decay of plants burning wood silver tarnishing car burning gas baking bread

Clues that a chemical reaction has occurred Color change fhttp://upload.wikimedia.org/wikipedia/commons/e/eb/Diffusion.gif

Clues that a chemical reaction has occurred SOLID forms

Clues that a chemical reaction has occurred Bublé

Clues that a chemical reaction has occurred Bubbles form

Clues that a chemical reaction has occurred Heat and/or flame is produced or absorbed

Chemical Equations Reactants react (START) – Left Products form (END) - Right S (s) Solid (l) Liquid (g) Gas (aq) Aqueous

Units Base Metric Units Length : Meter Mass: Gram Volume: Liter Temperature: Kelvin – bit different Byte Watt Etc

Mass Mass is amount of stuff (quantity of matter) Weight = mass x gravity

Volume 8 oz = 1 cup 2 cups = 1 pint 2 pints = 1 quart 2 quarts = ½ gallon 2 (½ gallons) = 1 gallon If you have 4.79 oz, how many gallons do you have? Quarts? Pints?

Volume If you have 4.79 L, how many mL do you have? cL? kL? 4790 mL 479 cL 4.79 x kL

NO MORE INCHES!! Estimated digit = 4 in hundredths place

Density Amount of matter in volume D = M V

Hi. I’m Important! BIGGER SMALLER

Review 1.2 List four observations that a chemical change has occurred. Evolution of a gas Formation of a precipitate Release / Absorb energy Color change Distinguish between characteristics of matter. Mass Volume Differentiate between physical and chemical changes Physical does not change composition; chemical does

Homework Read 1.2 (Chapter 1, section 2) Copy Table 3 into your class notebook