Look back at your notes or in the book if you don’t know the answers: Starter 11/21/13 Look back at your notes or in the book if you don’t know the answers: What is the difference between a physical and a chemical change? List three examples of each.

What type of reaction occurs when you burn something? Monday March 14th, 2016 Starter: Name the following compounds AgNO3 N3O7 Ca(OH)2 SiF4 AlPO4 CrSO4 Write the formulas Iron (III) sulfide Strontium nitride Disilicon octahydride Potassium phosphide By the end of the day, Scholars will be able to: Identify the three major parts of a reaction equation. Classify a reaction based on its reactants and products And answer a question like this: What type of reaction occurs when you burn something? Topic: Chemical Reactions 8-10 minutes

Chemical Reactions Day 1

Requires a chemical change to occur. Chemical reaction the process by which one or more substances is changed into one or more different substances Requires a chemical change to occur.

Painting

Phase changes (solid, liquid, gas)

Bleach Spots

Rust

Burning

A new hair cut

House on Fire

Folding paper

Rusty car

Sugar dissolving in water

Chocolate melting

Permanent Hair dye

Crumpling paper

Crystal light and water

Sanding down wood

Boiling Water

Sour Milk

Chemical equation Chemical reactions are described using a chemical equation: Zn + 2HCl  ZnCl2 + H2 There are three parts to a chemical equation Reactants Yield Sign Products

Reactants The starting substances or molecules that participates in a chemical reaction. Reactants are found on the left side of a chemical equation.

Yield Sign Arrow that separates the reactants from the products. Read as: yields, forms, or produces

Products A substance that forms in a chemical reaction Found on the right side of the yield sign.

Types of Reactions There are 5 main types of reactions that we will discuss in this class: Synthesis Decomposition Single Replacement Double Replacement Combustion

Composition/synthesis Two or more substances combine to form one new substance. Many salts are prepared through a synthesis reaction. Most synthesis reactions are exothermic. An exothermic reaction gives out energy in the form of heat or light. Usually written in the form: A + B  AB Example 2 Mg + O2 2 MgO

Decomposition When a compound or molecule breaks up into simpler substances. Decomposition reactions require heat or energy in order to break the bonds in the compound. This means that they are endothermic. An endothermic reaction takes in energy from the surroundings. Usually written in the form: AB  A + B Example 2 H2O ---> 2 H2 + O2

Single Replacement One element replaces another element in a compound. Usually written in the form: A + BC  AC + B Example Mg + 2 H2O ---> Mg(OH)2 + H2

Double Replacement The cations and anions for each compound are switched to form two new compounds Usually written in the form: AB + CD  AD + CB Example Pb(NO3)2 + 2 KI  PbI2 + 2 KNO3

Combustion Hydrocarbon reacts with oxygen to form carbon dioxide and water. Usually written in the form: CxHy + O2 H2O +CO2 Example C10H8 + 12 O2 ---> 10 CO2 + 4 H2O

Sample Problems List what type the following reactions are: NaOH + KNO3 --> NaNO3 + KOH CH4 + 2 O2 --> CO2 + 2 H2O 2 Fe + 6 NaBr --> 2 FeBr3 + 6 Na CaSO4 + Mg(OH)2 --> Ca(OH)2 + MgSO4 Pb + O2 --> PbO2 Na2CO3 --> Na2O + CO2

Solution to Sample Problems Solutions to the Sample Problems double displacement Combustion single displacement Synthesis decomposition

Group Work/Skit With your group, produce a short scene that you can act out to describe one of the following types of reactions: Synthesis Decomposition Single Replacement Double Replacement

Describe the chemical reaction illustrated below :   ___________________________________________ ___________________________________________ ____________ Type of reaction: ________________________________

Describe the chemical reaction illustrated below : ____________________________________________ ____________________________________________ __________ Type of reaction: ________________________________

Describe the chemical reaction illustrated below : ____________________________________________ ____________________________________________ __________ Type of reaction: ________________________________

Describe the chemical reaction illustrated below : ____________________________________________ ____________________________________________ __________ Type of reaction: ________________________________

Writing chemical equations Two types of chemical equations: Word equations Symbol equations

Word Equations Word equations are link together the names of the reactants with those of the products formed. These equations do not need to be balanced. Examples: magnesium + oxygen  magnesium oxide hydrogen + oxygen hydrogen dioxide

Symbol Equations Symbol equations are shorthand notation used to explain a chemical reaction They use the given element symbols found on the period table These equations MUST be balanced Examples: Cl2 + 2KI  2KCl + I2 Zn + CuSO4  ZnSO4 + Cu

Writing Chemical Equations STEP 1: Determine the reactants and the products STEP 2: Assemble the equation STEP 3: Balance the equation (get the same # of atoms of each element on each side)

Examples: Write the word equation: Write the symbol equation: CH4 + 2O2  CO2 + 2H2O C6H12O6 + 6O2  6CO2 + 6H2O Write the symbol equation: Copper + oxygen  copper (II) oxide Dihydrogen monoxide  hydrogen + oxygen

Chemical Equation Examples Write the word equation for the following: 2K + 2H2o  2KOH + H2 CaCO3  CaO + CO2 Mg + 2HCl  MgCl2 + H2 Write the symbol equation for the following: Iron + sulfur  Iron(II)sulfide Aluminum + iodine  aluminum iodide Carbon dioxide + water  glucose + oxygen