Decomposition of Nitrogen Triiodide

2 NI3(s) N2(g) + 3 I2(g)

NI3 I2

N2

Exothermic ReactionReactants Products + Energy 10 energy = 8 energy + 2 energy

Reactants

Products

-H

Ene

rgy

Energy of reactants

Energy of products

Reaction Progress

Endothermic ReactionEnergy + Reactants Products

+H Endothermic

Reaction progress

Ene

rgy

Reactants

ProductsActivation Energy

Effect of Catalyst on Reaction Rate

reactants

products

Ene

rgy

activation energy for catalyzed reaction

Reaction Progress

No catalyst

Catalyst lowers the activation energy for the reaction.What is a catalyst? What does it do during a chemical reaction?

An Energy Diagram

activationenergyEa

reactants

products

course of reaction

ener

gy

Animation by Raymond ChangAll rights reserved

Formation of a solid AgCl

AgNO3(aq) + KCl(aq) KNO3 (aq) + AgCl(s)

Single and Double Replacement Reactions

Double-replacement reaction

CaCO3 + 2 HCl CaCl2 + H2CO3

General form: AB + CD AD + CB

Single-replacement reaction

Mg + CuSO4 MgSO4 + Cu

General form: A + BC AC + B

Single displacement is a type of a reaction when a metal reacts with a compound containing a metal, where the single metal in the reaction is more reactive replaces the less reactive metal in the compound.

Single-replacement reaction

Mg + CuSO4 MgSO4 + Cu

General form: A + BC AC + B

DOUBLE DISPLACEMENT REACTIONS: In a double displacement reaction (ionic reaction) the ions of two compounds exchange places in an aqueous solution to form two new compounds.

Double-replacement reaction

CaCO3 + 2 HCl CaCl2 + H2CO3

General form: AB + CD AD + CB

Double Replacement Reaction

Synthesis Reactions - when two compounds or elements combine to make one molecule or compound. A+ B --> AB 2 H2 + O2 -------> 2 H2O

Decomposition Reactions - a compound or molecule breaks down into simpler elements or compounds AB - -> A + B CO2 ------> C + O2

Important Chemical Reactions

Oxidation ReactionsReactant + Oxygen -------> Products

Oxidation reactions are fundamental to our existence

Definition: A chemical change involving oxygen

Oxidation reactions can occur more rapidly in the presence of humidity in the air, or in the presence of light

GALVINIZATION – coating iron materials with zinc to prevent the formation of rust.

Combustion Combustion – Form of oxidation that releases a large

amount of energy (HIGHLY EXOTHERMIC).

Three requirements for a combustion: Fuel – reacts with oxidizing agent to release energy Oxidizing agent – substance that causes a fuel to react

(usually oxygen) Ignition temperature – the required temperature needed to

combust the fuel

Three types of combustions: Rapid – Release a lot of energy in a short period of time Spontaneous – Fuel ignites without the need for outside

energy Slow – Occurs of long period of time

A Combustion reaction usually looks like: Fuel + oxygen ------> CO2 + H2O + Energy

CH4 + O2 -------> CO2 + H2O

Other important Chemical Reactions ...

Cellular Respiration Glucose + Oxygen -----> Carbon Dioxide + Water + Energy

Photosynthesis Light + Carbon Dioxide + Water-----> Oxygen + Glucose