Unit 2 Notes:COMBUSTION

Copy the table onto your paper. Predict how long it will take for the candles to burn. Time and Record Actual time.

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Test Tube Time Estimate Actual Time

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Medium

Small

Candle Burning Mini Experiment Part 1

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Procedures:

Burning Candle Experiment Questions

Answers:

What is Flame?

Three Zone of a Flame

What is combustion?

Combustion is the scientific word for burning.

It is the chemical rxn that takes place when a substance burns and reacts with oxygen to produce heat and light energy. Oxygen readily reacts with substances.

Combustion continued...

Conditions necessary for combustion:

1. Fuel2. Air(for oxygen supply)3. Heat( beyond the ignition temp.)

Ethanol: C2H5OH

Combustion continued...

Three main types of combustion:

Rapid combustion: Substance burns rapidly and produces heat and light with the help of external heat

Combustion continued...

2. Spontaneous combustion: Substance burns spontaneously and produces heat and light without the help of external heat (at room temp)

Combustion continued...

3. Explosion: Substance burns suddenly and produces heat, light and sound with the help of heat or pressure.

OXYGEN BREATHE JUST LIKE US...

When Oxygen in the air combines with flammable vapours given off by fuels they create a form of heat at a molecular level. Then, a source of ignition (a match or spark) can cause it to combust.

OXYGEN + HEAT + FUEL = FIRE

The fire triangle

What are the products of combustion?

Ignition TemperatureThe minimum amount of temperature it takes to ignite a substance without the presence of an external spark.

Word equations for combustion

When substances combust, the new substances formed are called ‘oxides’.

What are the word equations for these combustion reactions?

1. Coal (made from carbon) burns and forms carbon dioxide.

2. Hydrogen burns and forms dihydrogen oxide (i.e water!).

3. Methane burns and forms carbon dioxide and water.

methane oxygen carbon dioxide water+ � +

hydrogen oxygen water+ �

carbon oxygen carbon dioxide+ �

Symbol equations for combustion

What are the symbol equations for these combustion reactions?

1. Coal (made from carbon) burns and forms carbon dioxide.

2. Hydrogen burns and forms dihydrogen oxide (i.e water!).

3. Methane burns and forms carbon dioxide and water.

methane oxygen Carbon dioxide+ � water+CH4 2O2

CO2+ � 2H2O+

hydrogen oxygen water+ �

2H2 O2 2H2O+ �

carbon oxygen carbon dioxide+ �

C O2 CO2+ �

2Mg + O2 2MgO

Word equations for combustion continued

4. Magnesium burns and forms Magnesium oxide.

What is the Law of Conservation of Mass?

Matter is neither created nor destroyed. The atoms are rearranged. The amount of reactants equal to the amount of products only in different compositions.

Reactants: It’s what goes into a rxn.Products: It’s what is produced at the end of the rxn.

Where did the spark come from?A small fiery particle (kindling point)thrown off from a fire, alight in ashes, or produced by striking together two hard surfaces such as stone or metal. Also, striking two dry pieces wood will cause a spark.