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TYpes of Chemical Reactions Part 3

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Page 1: TYpes of Chemical Reactions Part 3. Types of REactions Synthesis Reactions Decomposition Reactions Single Displacement Reactions Double Displacement Reactions

TYpes of Chemical Reactions

Part 3

Page 2: TYpes of Chemical Reactions Part 3. Types of REactions Synthesis Reactions Decomposition Reactions Single Displacement Reactions Double Displacement Reactions

Types of REactions

Synthesis Reactions

Decomposition Reactions

Single Displacement Reactions

Double Displacement Reactions

Combustion

Corrosion

Page 3: TYpes of Chemical Reactions Part 3. Types of REactions Synthesis Reactions Decomposition Reactions Single Displacement Reactions Double Displacement Reactions

combustion

Combustion is the chemical reaction in which fuel “burns” or reacts quickly with oxygen

The products of this reaction are usually an oxide and energy

Sunrise Propane

Explosion Toronto 2008

Page 4: TYpes of Chemical Reactions Part 3. Types of REactions Synthesis Reactions Decomposition Reactions Single Displacement Reactions Double Displacement Reactions

HydrocarbonsHydrocarbons (HC) are a group of compounds that only contain the elements carbon and hydrogen

Example: Propane, C3H8

HC originate from fossil fuels

The combustion of HCs power cars & buses, warm homes, generate electricity & light candles

Page 5: TYpes of Chemical Reactions Part 3. Types of REactions Synthesis Reactions Decomposition Reactions Single Displacement Reactions Double Displacement Reactions

Complete combustion of Hydrocarbons

Products of HC combustion can vary - depend on availability of oxygen

Plentiful oxygen = complete combustion

Complete combustion of HC:

hydrocarbon + oxygen → CO2 + H2O + energy

CO2 is an important green house gas - more in climate change unit!

Page 6: TYpes of Chemical Reactions Part 3. Types of REactions Synthesis Reactions Decomposition Reactions Single Displacement Reactions Double Displacement Reactions

complete combustion of hydrocarbons

The balanced chemical equation for the complete combustion of hydrocarbons can be represented by the general equation:

CxHy + O2 → CO2 + H2O + energy

During complete combustion, fuel burns clean with no sooty residue

Page 7: TYpes of Chemical Reactions Part 3. Types of REactions Synthesis Reactions Decomposition Reactions Single Displacement Reactions Double Displacement Reactions

Incomplete combustion of hydrocarbons

If oxygen supply is limited, incomplete combustion may occur

Results in release of carbon monoxide gas and carbon (soot) in addition to carbon dioxide and water

An orange flickering flame indicates incomplete combustion

Page 8: TYpes of Chemical Reactions Part 3. Types of REactions Synthesis Reactions Decomposition Reactions Single Displacement Reactions Double Displacement Reactions

Carbon Monoxide (CO)

Carbon monoxide is a colourless, odorless gas

Highly toxic

Symptoms of poisoning - headaches, dizziness, nausea, respiratory problems

Cause of many deaths - incomplete combustion in confined space

Carbon monoxide detectors!

Page 9: TYpes of Chemical Reactions Part 3. Types of REactions Synthesis Reactions Decomposition Reactions Single Displacement Reactions Double Displacement Reactions

soot

Made up of particles of carbon

Causes pollution and wastes energy

Common in older vehicles with poorly maintained engines

Common result of forest fires

Page 10: TYpes of Chemical Reactions Part 3. Types of REactions Synthesis Reactions Decomposition Reactions Single Displacement Reactions Double Displacement Reactions

Other combustion reactions

Many substances (besides HC) undergo combustion

Elements react with oxygen to form oxides

General equation: element + oxygen → oxide + energy

Eg. magnesium burns to form magnesium oxide + energy

Page 11: TYpes of Chemical Reactions Part 3. Types of REactions Synthesis Reactions Decomposition Reactions Single Displacement Reactions Double Displacement Reactions

Corrosion

Is the breakdown of metal as a result of chemical reactions with the environment

Page 12: TYpes of Chemical Reactions Part 3. Types of REactions Synthesis Reactions Decomposition Reactions Single Displacement Reactions Double Displacement Reactions

beneficial corrosion

Example: aluminum exposed to air

Corrodes to form aluminum oxide - one of the hardest substances known

Aluminum oxide tightly coats underlying metal, preventing further corrosion

Application - camping pans

Page 13: TYpes of Chemical Reactions Part 3. Types of REactions Synthesis Reactions Decomposition Reactions Single Displacement Reactions Double Displacement Reactions

rust Familiar reddish-brown flaky material produced when metals containing iron corrode

Rust does not stick well to underlying steel

Readily flakes away so fresh steel is exposed to further corrosion

Continues until steel is completely eaten away!

Page 14: TYpes of Chemical Reactions Part 3. Types of REactions Synthesis Reactions Decomposition Reactions Single Displacement Reactions Double Displacement Reactions

rust

Causes of rust:

Oxygen

Water

Electrolytes - not a cause, but speeds up corrosion once it starts

Page 15: TYpes of Chemical Reactions Part 3. Types of REactions Synthesis Reactions Decomposition Reactions Single Displacement Reactions Double Displacement Reactions

Preventing corrosion Protective Coatings

Cover metal with rust inhibiting paint, chrome or plastic coating

Corrosion still possible with chips/scratches

Corrosion resistant materials

Plastic - Eg. car bumpers

Corrosion resistant alloys (blend of metals) - Eg. surgical knee implant

Page 16: TYpes of Chemical Reactions Part 3. Types of REactions Synthesis Reactions Decomposition Reactions Single Displacement Reactions Double Displacement Reactions

Galvanizing

Galvanized steel is steel coated with thin layer of zinc

Zinc corrodes before steel

Zinc corrodes to form protective oxide layer

Page 17: TYpes of Chemical Reactions Part 3. Types of REactions Synthesis Reactions Decomposition Reactions Single Displacement Reactions Double Displacement Reactions

Demo of the day!

Time for some combustion in action!

Combustion of acetylene

2C2H2 (g) + 5O2 (g) → 4CO2 (g) + 2H2O(g)