Which of These do not belong Burning match Rusting bike Curing cement Mixing baking soda and vinegar

Protecting Materials from…

Review on protecting materials Different methods: –Heat treatments: Ways of changing the properties of materials (quenching of steel increases the hardness but fragility as well) Increases the life span of wood

More methods –Metal Plating –Antirust treatments –Painting –Applying grease/graphite to metal

Most of these types of treatments are attempting to prevent chemical reactions from attacking and degrading the materials, weakening its properties

Chemical Reactions What is a chemical reaction? What are the signs of a chemical reaction?

Chemical Reactions a) Definition: –A reaction that alters the nature and characteristic properties of matter. –The atoms are rearranged. –New molecules are formed

Chemical Reactions b) Observable characteristics: –A chemical reaction occurs when: A gas is released Heat is absorbed (endothermic) or released (exothermic) Light is emitted The color changes A precipitate forms

C) What does a chemical reaction look like? Reactants Products Matter is neither created nor destroyed. In other words; The mass before and after the reaction must remain the same (law of conservation of matter)

Chemical Reactions d) Types of chemical reactions: i) Basic reactions: Synthesis –Two or more reactants become one product Decomposition –One reactant is decomposed into two or more products Oxidation –A reaction where one of the reactants is oxygen (O 2 ) Precipitation –A reaction where two liquid reactants form a solid product

Chemical Reactions ii) Other chemical reactions –Acid-Base Neutralization Reactants: Acid + Base Products: Water + Salt –Combustion Type of oxidation that releases a large amount of energy Combustion requires –Oxidation agent –Ignition temperature –Fuel

Associates known chemical reactions with decomposition or synthesis reactions (e.g. respiration, photosynthesis, combustion, digestion) –Represents the photosynthesis reaction in a balanced equation

Associates a chemical equation in which oxygen is one of the reactants with one of the possible cases of an oxidation reaction –Represents an oxidation reaction using the particle model –Associates known chemical reactions with oxidation reactions (e.g. combustion, corrosion)

Describes the perceivable manifestations of rapid combustion (e.g. heat, light) –Explains a combustion reaction using the fire triangle

Chemical Reactions –Cellular respiration: Takes O 2 + glucose to form CO 2 +water + energy –Photosynthesis: Takes CO 2 + water + energy to form O 2 + glucose

Combustion side note: –Types of combustion: Slow Rapid –Requires outside energy input –gives off heat and light that is observable Spontaneous

Combustion Triumvirate (Fire Triangle)