Topic 4.0 Chemical Reactions

Program of Studies Factors affecting reaction rates Conservation of mass Endothermic and exothermic reactions Reactants and Products

POS cont’d observing heat generated or absorbed in chemical reactions, and identifying examples of exothermic and endothermic reactions Identifying conditions that affect rates of reactions (e.g., investigate and describe how factors such as heat, concentration, surface area and electrical energy can affect a chemical reaction)

Factors affecting reaction rates Heat (Temperature) Heat increases collisions between particles Concentration More atoms available to react Surface area More area available for reaction Breaking material into smaller pieces Electrical energy (electrolysis) Catalyst (enzymes) Teacher demo pg 167

Conservation of mass The amount of products always equals the mass of reactants Mass is neither created or destroyed, but may be converted to other forms (energy)

Ex pg 163 *Remember: mass is measured in grams (g) Mg + S -> MgS 24 g + 32 g -> ? Total mass = 56 g

Endothermic and Exothermic reactions Demos Endothermic Cold Pack Exothermic Whoosh Bottle CaCl2 + NaHCO3 + bromothymol blue (in ziploc) Lab pg 164 sia Hand warmers

Endothermic Thermic-heat Endo-Takes in energy Energy is being absorbed (so the material feels cool)

Exothermic Thermic-heat Exo- Releases energy Energy is being generated (so the material feels hot)

Reactants and Products Reactants: substances that are going to chemically “react” Products: new substances produced in a chemical reaction Ex: hydrogen + oxygen -> water reactant 1 + reactant 2 -> product

The burning of fuel C3H8 + O2 -> CO2 + H2O +energy Identify the type of reaction Identify whether the reaction is endothermic or exothermic Identify the products and reactants Name each compound (C3H8 is propane)

The burning of fuel C3H8 + O2 -> CO2 + H2O +energy Identify the type of reaction Combustion (O2) Identify whether the reaction is endothermic or exothermic Releases energy- exothermic Identify the products and reactants REACTANTS: C3H8 + O2 PRODUCTS: CO2 + H2O +energy Name each compound (C3H8 is propane) propane + oxygen -> carbon dioxide + water + energy

The corrosion of iron iron + oxygen -> iron(II)oxide Identify the type of reaction Identify the products and reactants Write the formula for each compound

The corrosion of iron iron + oxygen -> iron(II)oxide Identify the type of reaction oxidation (rusting) Formation of a metal “oxide” Identify the products and reactants REACTANTS: iron + oxygen PRODUCTS: iron(II)oxide Write the formula for each compound Fe + O2 -> FeO

The reaction: zinc + copper(II)sulfate → zinc sulfate + copper Identify the type of reaction Identify the products and reactants Write the formula for each compound

The reaction: zinc + copper(II)sulfate → zinc sulfate + copper Identify the type of reaction Single replacement Identify the products and reactants REACTANTS: zinc + copper(II)sulfate PRODUCTS: zinc sulfate + copper Write the formula for each compound Zn + CuSO4 → ZnSO4 + Cu

The reaction: zinc + copper(II)sulfate → zinc sulfate + copper If: mZn= 12 g mCuSO4= 28 g mZnSO4= 14 g Then mCu= ?

The reaction: zinc + copper(II)sulfate → zinc sulfate + copper 12 g + 28 g -> 14 g + ? g 40 g -> 14 g + 26 g Then mCu=26 g

Assignments Journals Vocab Worksheets Section 4.0 Q’s Unit Review