Chemical Reactions Chapter 11 L. Bernard, 2015

Identifying Chemical Reactions! L. Bernard, 2015

What are some indications that a chemical reaction has occurred? Do Now! L. Bernard, 2015

reactants  products Chemical Reactions The process by which atoms of the same or different element rearrange themselves to form a new substance Bonds are broken between atoms and re-formed to form new molecules reactants  products L. Bernard, 2015

How do we know a chemical reaction has occurred? Production of heat Absorption of heat (gets cold) Production of gas (bubbles) Production of a precipitate (solid) Change in color Change in odor Change in state of matter L. Bernard, 2015

5 Types of Chemical Reaction Synthesis Decomposition Single-Replacement Double-Replacement Combustion L. Bernard, 2015

1. Synthesis Also known as combination When two or more substances react to form a SINGLE substance L. Bernard, 2015

Synthesis L. Bernard, 2015

2. Decomposition When a single substance breaks down into two or more products Opposite of synthesis L. Bernard, 2015

Decomposition L. Bernard, 2015

3. Single Replacement Where one element replaces another element in a compound Essentially one element switches compounds L. Bernard, 2015

Single Replacment L. Bernard, 2015

4. Double Replacement When there is an exchange of POSITIVE IONS between two compounds The cations exchange places L. Bernard, 2015

Double Replacement L. Bernard, 2015

5. Combustion Where an element or compound reacts with oxygen to produce carbon dioxide and water Produces heat and light L. Bernard, 2015

Combustion L. Bernard, 2015

Practice! Identify the following reactions P4 + 3O2  2P2O3 Synthesis! 2MgI2 + Mn(SO3)2  2MgSO3 + MnI4 Double Displacement! C6H12 + 9O2  6CO2 + 6H2O Combustion! 2AgNO3 + Cu  Cu(NO3)2 + 2Ag Single Displacement! L. Bernard, 2015

Practice! Identify the following reactions Pb + FeSO4  PbSO4 + Fe P4 + 3 O2  2 P2O3 C6H12 + 9 O2  6 CO2 + 6 H2O O3  O. + O2 2 AgNO3 + Cu  Cu(NO3)2 + 2 Ag 2 MgI2 + Mn(SO3)2  2 MgSO3 + MnI4 2 NO2  2 O2 + N2 SeCl6 + O2  SeO2 + 3Cl2 L. Bernard, 2015

Balancing Chemical Equations! L. Bernard, 2015

Why must we balance chemical equations? Law of Conservation of Mass Matter cannot be created nor destroyed Just like with math, both sides of the YIELDS sign must be equal! So the same number of atoms must be on both sides of the equation L. Bernard, 2015

Only Change the Coefficient! L. Bernard, 2015

Methods of Balancing Equations Inspection “ABC” Method Combustion Trick L. Bernard, 2015

Inspection Use when it is easy to see the solution List all the elements within the chemical equation Count the number of elements on each side Balance the coefficients and charges L. Bernard, 2015

Inspection L. Bernard, 2015

“ABC” Method Algebraically solve for the coefficients Assign a letter for each coefficient in the reaction Determine an algebraic equation to solve for the value of each coefficient L. Bernard, 2015

“ABC” Method L. Bernard, 2015

“ABC” Method L. Bernard, 2015

“ABC” Method L. Bernard, 2015

Combustion Trick Use only with combustion reactions! Balance the carbon and hydrogen first using the inspection method Balance the number of oxygens last In the reactants, oxygen will always be alone as O2 L. Bernard, 2015

Combustion Trick 2 2 4 4 4 L. Bernard, 2015

Do Now! Balance the Following Equations Li + H2O → LiOH + H2 K + B2O3 → K2O + B C6H6 + O2 → CO2 + H2O L. Bernard, 2015

The Law of Conservation of Mass Matter can be changed from one form to another Cannot be created or destroyed! Why must we balance equations? L. Bernard, 2015