Matter: Physical vs. Chemical

Properties of Matter Characteristics that enable us to distinguish one kind of matter from another. How can we distinguish hydrochloric acid from water?

Types of Properties Extensive Intensive Depends on the amount of matter e.g., volume, mass, amount of energy (cal) Intensive Does not depend on the amount of matter e.g., melting point, boiling point, density, conductivity

Physical & Chemical Properties Physical Property Can be observed or measured without changing a substance’s composition. Demo- Sand… What do you know about sand? Physical & Chemical Properties Demo: Ghost Crystals, Colorful Mixing Demo, Tarnished Silver, Magic Sand

Physical Properties Boiling Point Melting Point Color Density Malleability Conductivity Magnetism Hardness Ability to transmit light

Physical & Chemical Properties Chemical Property Can only be observed by changing the composition of the material Changes its identity

The ability of a substance to… Chemical Properties The ability of a substance to… Rust Decay Burn Ferment React with acid, base, or water

Properties of Water Water expands as it freezes. (Physical) Hydrogen peroxide, H2O2 can decompose to produce water. (Chemical) Water boils quicker in Denver, CO than at the beach. When an electrical current is passed through water, elemental hydrogen and oxygen are produced. Salt can dissolve in water.

Physical & Chemical Changes Physical Change Will change the visible appearance, without changing the composition of the material Changes that effect only physical properties. Does not change the composition!

Physical Changes Physical changes are usually reversible Crush Boil Diffuse Condense Osmosis Cut Split Crack Boil Melt Freeze Distillation Sublimation Expand Demo: Chalk, Shredding paper

Physical & Chemical Changes Changes that involve a change in the composition of the substance. New matter is formed

Chemical Changes Chemical Changes are usually NOT reversible Ferment Decay/Decompose React with acid, base, or water Neutralize Rust Digest Tarnish Explode / Burn Ignite Cook Chemical Changes are usually NOT reversible Rusting of a car

2H2O  2H2 + O2 Reactants the stuff you start with Products- what you make Arrow points from the reactants to the new products The products will have NEW PROPERTIES different from the reactants you started with

Indicators of Chemical Change Color Change Gas produced Temperature change Light produced Precipitate forms Irreversibility Not easily reversed!

Indicators of Chemical Change Color Change Very hard to reverse Think about cooking an egg

Indicators of Chemical Change Gas produced Bubbles are produced Careful  there are examples of bubbles that are not chemical – boiling water bubbles Physical change  Water vapor starts to form inside the liquid in the form of bubbles

Indicators of Chemical Change Temperature change Heat given off- Exothermic Feels hot Feel someone after they workout  they’re hot Heat absorbed- Endothermic Feels cool Sweating while working out

Indicators of Chemical Change Light produced Striking a match  flame produced Fireworks

Indicators of Chemical Change Precipitate forms 2 liquids  solid + liquid

Law of Conservation of Matter In any physical or chemical change, matter is neither created nor destroyed. During any chemical reaction, the mass of the products is always equal to the mass of the reactants

Law of Conservation of Matter All the mass can be accounted for!! Burning of wood results in products that appear to have less mass as ashes. Where is the rest??