A flame needs three things at once: a fuel to burn, oxygen from the air, and a temperature above the ignition point.
Take away any one and the fire goes out, which is how water or a lid stops it.
After a candle burns, carbon dioxide and water are left, and limewater turning cloudy shows they are there.
The four buttons are fuel · oxygen · heat · all presets, and the put-out buttons take away fuel, block oxygen, or lower the heat. Ignition °C is written only: paper about 230, wood about 300.
What is Needed for Fire?
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Three conditions of combustion — fuel, oxygen, temperature above ignition point
🔥 Three Elements of Combustion
①Combustion needs three things together
②Fuel: wood, paper, gas, etc.
③Oxygen: fire needs oxygen to burn
④Temperature above the ignition point
⑤Remove any one and the fire goes out!
Three Ways to Put Out Fire
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Fire suppression — removing one of the three conditions
🧯 Principles of Extinguishing
①Remove fuel: shut gas valve or move wood away
②Block oxygen: cover with lid, blanket, or extinguisher powder
③Lower temperature: spray water
④Extinguishers do oxygen-blocking + cooling at once
Products of Combustion
Combustion Reaction
Fuel + Oxygen → CO₂ + Water (vapor) + Heat
Burning produces carbon dioxide and water
💡 Combustion Products
①Burning a candle releases CO₂ and water vapor
②CO₂: turns limewater cloudy (test)
③Water vapor: drops form on cold glass (test)
④Incomplete combustion → soot (carbon)
⑤In a fire: cover nose and mouth with a wet cloth, stay low, and leave.
⑤In a fire: cover nose/mouth with wet cloth, stay low, evacuate
Examples and Unit Test
Example 1
A candle covered fully by a glass goes out shortly after. Which of the three conditions for combustion was removed?
1
Combustion needs fuel, oxygen, and a temperature above the ignition point.
2
Covering it with a glass stops fresh air, so oxygen runs low.
▸ Oxygen (air) was cut off
Removing any one of the three conditions puts the fire out; that is how extinguishing works.
Example 2
After a candle burns, what substances form, and how do you confirm the carbon dioxide?
1
Burning a candle produces carbon dioxide and water (vapor).
2
Carbon dioxide is confirmed because it turns limewater cloudy.
▸ Carbon dioxide and water / limewater turns cloudy
Combustion uses oxygen and releases carbon dioxide and water.
Unit-test style
Which statement about combustion and extinguishing is correct?
①Combustion does not need oxygen
②Spraying water to lower the temperature can put out a fire
③Extinguishing means providing all three conditions for combustion
④Burning a candle creates new oxygen
⑤A fire lights easily below the ignition point
▸ ② Spraying water to lower the temperature can put out a fire
1
Lowering the temperature below the ignition point breaks a combustion condition, so the fire goes out.
2
Combustion needs oxygen (①), extinguishing removes a condition (③), burning produces carbon dioxide and water (④), and a fire needs a temperature above the ignition point (⑤).