Chemical Energy in Fuel and Combustions

Combustion Reactions

Types of chemical reactions

Characteristics of combustion reactions

Complete and incomplete combustion

Writing and balancing combustion equations

Fuels and Chemical Energy

Definition and classification of fuels (Solid, liquid, and

gaseous fuels) Chemical energy and energy release from fuels

Fuel calorific value (Higher and lower heating values)

Determination and comparison of calorific values

Stoichiometry of Combustions

Mole relationships in combustion reactions

Stoichiometric calculations Mass and mole calculations involving fuels

Combustion-related problem solving

Laws of Conservation of Mass

“We may lay it down as an incontestable

axiom that, in all the operations of art and

nature, nothing is created; an equal

amount of matter exists both before and

after the experiment. Upon this principle,

the whole art of performing chemical

experiments depends.”

-Antoine Lavoisier, 1789

Antoine Lavoisier

Proposed Law of Conservation of Mass

Chemical Equation

concise representations of chemical reactions

Subscripts

tell the number of atoms of each element in a molecule.

Coefficients

tell the number of molecules.

Combination reactions

Decomposition reactions

Combustion reactions

Neutralization reactions

Displacement reactions

Types of Chemical Reactions

Combination Reactions

two or more substances react to form one product

Decomposition Reactions

one substances breaks down into two or more substances

Combustion Reactions

a substance reacts with oxygen gas,

releasing energy in the form of light

and heat.

Incomplete Combustion

Instead of producing only CO₂, the

carbon may form carbon monoxide

(CO) or solid carbon (C), commonly

called soot.

Incomplete Combustion

When the supply of oxygen is limited or insufficient, complete oxidation cannot occur.

Fuel

dense repositories of energy that are consumed to provide energy services such as heating, transportation and electrical generation.

Solid Fuels

Liquid Fuels

Gaseous Fuels

Types of Fuel

When burned, chemical

energy is released in the form

of heat, light, or electricity

How do Fuels Generate Energy

Wood

Coal

Charcoal

Types of Solid Fuels

Petrol

Diesel

Kerosene

Types of Liquid Fuels

Natural Gas

LPG

Biogas

Types of Gaseous Fuels

Bond-Breaking

Energy is absorbed

Exothermic Process

Bond-Forming

Energy is released

Exothermic Process

1. Intake

2. Compression

3. Power

4. Exhaust

HOW DOES AN INTERNAL

COMBUSTION ENGINE WORK?

Compression Ratio

degree to which the fuel mixture is compressed before ignition

Knocking

a rapid pinging or knocking sound that comes from an engine when it is pushed to produce a lot of power quickly

Resisting Knocking

Highly branched alkane: burn smoothly and evenly

Octane Rating/ Octane Number

measure of the fuel’s ability to resist knocking

Higher Number, More Resistant

the more compression from the piston the gasoline can withstand before igniting in the

engin

Fuel Calorific Value

The amount of heat that is

liberated by a fuel’s complete

combustion is known as the fuel’s

calorific value or heating value.

1st Law of Thermodynamics

Energy is not created nor destroyed

2nd Law of Thermodynamics

As energy is transferred or transformed, more and more of it is wasted.