Chapter 5

Question 1

What is fire?

Answer 1

• Rapid chemical process that produces heat and usually light
• Fuel in the form of combustible vapors
• For a fuel to burn, must be changed into flammable vapor

Question 2

What is matter?

Answer 2

• Made up of atoms and molecules
• Exists in three states: solid, liquid, and gas
• Understanding of matter helpful in understanding fire behavior

Question 3

Solids

Answer 3

• Defined size and shape
• May change to liquid or gas when heated
• Cold makes them brittle, heat makes them flexible

Question 4

Liquids

Answer 4

• Assume the shape of their container
• Most will expand and turn into gases
• They have a definite volume

Question 5

Gases

Answer 5

• Have neither independent shape nor independent volume
• Expand indefinitely

Question 6

Fuels

Answer 6

• Fuels are materials that store energy
• Think of gas in a tank is stored energy before it causes the car to move through combustion
• Energy released in the form of heat and light has been stored before it is burned

Question 7

Types of Energy

Answer 7

• Chemical
• Mechanical
• Electrical
• Light
• Nuclear

Question 8

Chemical Energy

Answer 8

• Energy created by a chemical reaction
• Exothermic reaction = producing heat (fire)
• Endothermic reaction = absorbing heat (ice melting)
• Most reactions occur because bonds are established between substances or broken as two substances
• Heat is produced
• Fire is the result of a chemical reaction

Question 9

Mechanical Energy

Answer 9

• Converted to heat when two materials rub against each other and create friction (ex: vehicle tires, spinning on pavement)
• Heat is also produced when mechanical energy is used to compressed air in a compressor

Question 10

Electrical Energy

Answer 10

• Converted to heat in multiple ways
• Electricity produces heat while flowing through wire/conductive material
• Examples of electric energy that can produce through heat to start a fire: electric heating elements, overloaded wires, electrical arcs and lighting
• Carried through the electrical wires and can be stored in batteries

Question 11

Light Energy

Answer 11

• Caused by electromagnetic waves packaged indiscreet bundles called photons (radiant energy from the sun)
• Common forms: candles, light bulbs and lasers (emit both heat and light; transfer most of their heat via convection and radiation)

Question 12

Nuclear Energy

Answer 12

• Created by nuclear fission or fusion
• Nuclear reactions release large amounts of energy in the form of heat
• These reactions can be controlled or uncontrolled (both release radioactive material, which can cause injury or death)

Question 13

Conservation of Energy

Answer 13

• Energy cannot be created or destroyed by ordinary means
• Energy can be converted from one form to another

Example 1: chemical energy in gasoline is converted to mechanical energy when a car moves down the road)

Example 2: stored chemical energy in the wood of the house is converted into heat and light energy during the fire

Question 14

Conditions Needed for Fire

Answer 14

Three basic conditions:
(1) a combustible fuel, (2) oxygen in sufficient quantities and (3) a source of heat

• A fourth factor must be added to maintain a self sustaining fire (chemical chain reactions)
• If you remove any of these elements, the fire will go out

Question 15

Chemistry of Combustion

Answer 15

• When one element combines chemically with another, they produce a compound
• Oxidation is the process of chemically combining oxygen with another substance to create a new compound (the process can be slow and does not produce easily measurable heat)
• Combustion (fire) is a rapid chemical process in which the combination of a substance with oxygen produces heat and light (produces numerous toxic by-products)
• Pyrolysis = process that liberates gaseous fuel vapors due to the heating of a solid fuel
• Almost all fuel consists of hydrocarbons
• Incomplete combustion results in large quantities of deadly gases and compounds