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Terms Used in Combustion

What Is Combustion?Burning and It's Conditions


  • 0:4Combustion. It is a process in which a
  • 0:7substance reacts with oxygen to give off
  • 0:10heat. Now look around you, are all the
  • 0:14substances combustible? Do they all burn? Well
  • 0:20there will be certain substances which
  • 0:22undergo combustion and they are known as
  • 0:24combustible substances. And some which do
  • 0:28not undergo combustion or burn, they are
  • 0:30called non-combustible substances. Let's
  • 0:34consider some examples. They are kerosene,
  • 0:38stone, matchstick, straw, glass, charcoal,
  • 0:43paper, iron nails and wood. Now from these
  • 0:48substances, you have to decide which of
  • 0:51them are combustible substances and
  • 0:53which are non combustible substances. Okay,
  • 0:57from these kerosene, matchstick, straw,
  • 1:1charcoal, paper and wood - all of them burn.
  • 1:6They are combustible substances. Whereas
  • 1:10iron nails, stone and glass. All of these do
  • 1:16not burn, so they are called non-
  • 1:18combustible substances. Iron nails, all these
  • 1:22kind of metals which are hard and heavy,
  • 1:24they generally do not undergo combustion.
  • 1:27But there are certain
  • 1:29metals, like sodium and potassium, they
  • 1:32are so reactive that they do undergo
  • 1:34combustion even at room temperature.
  • 1:36Okay. So we know that combustible
  • 1:39substances are those which burn and give
  • 1:41off heat. These substances are called
  • 1:44fuels. Fuels is burn and give off a lot of
  • 1:48heat. This heat energy is used by us in
  • 1:52our daily life. Like there fuels which are
  • 1:55used in homes, there are fuels which are
  • 1:58used in industries, and there are some
  • 2:0fuels which are used for our automobiles.
  • 2:2So can you list them out?
  • 2:4Okay. Your list might contain fuels like
  • 2:7cow dung, wood, LPG, coal, charcoal,
  • 2:12which are commonly used in our homes and
  • 2:15they're also used in industries. Whereas,
  • 2:17there are fuels like petrol, diesel, CNG
  • 2:21they are used in automobiles. Okay. Now
  • 2:25think about this.
  • 2:26You work so much every day. You go to
  • 2:30school, you come home and study, you help
  • 2:33your parents, then go to play.
  • 2:36Oh my god ! so much of work. How does your
  • 2:39body manage all this?
  • 2:41Where does it get so much of energy from?
  • 2:43Is it working on a fuel ? Yes, your body
  • 2:48works on a fuel and that fuel is nothing
  • 2:50but the food you eat. The food you eat is
  • 2:54broken down into simpler substances.
  • 2:55These substances react with oxygen and
  • 3:0give off a lot of heat. Now this heat
  • 3:3energy is utilized by the body to do so
  • 3:5much of work. So, isn't this kind of some
  • 3:9combustion?
  • 3:10Yes, where the food you eat is going under
  • 3:13combustion. So the food is the fuel
  • 3:15to your body. So keep eating healthy food
  • 3:18and fuel your body every day.
  • 3:21Okay. Now let's see some more examples of
  • 3:23combustible and non combustible
  • 3:24substances. For combustible, we have
  • 3:28hydrogen that burn with a popping sound
  • 3:31Then we have carbon monoxide which is
  • 3:33also flammable. Then in non
  • 3:37combustible materials we have oxygen,
  • 3:39Oxygen supports burning but it is not
  • 3:42combustible, it does not burn even
  • 3:46Even Chlorine. Chlorine does not burn. Carbon
  • 3:49dioxide does not burn. Nitrogen, ammonia
  • 3:53, HCl that is hydrochloric acid, sulfur dioxide,
  • 3:57All of these substances do not burn, they
  • 3:59are non-combustible. Now there are
  • 4:2certain substances which support
  • 4:4combustion, and there are some certain
  • 4:6substances which are non supporter of
  • 4:8combustion. So in the presence of substances
  • 4:11like oxygen and chlorine, there will
  • 4:15always be combustion happening if you
  • 4:18burn a substance. Without their presence,
  • 4:21we can't burn any substance. So either
  • 4:23oxygen or chlorine we can use for
  • 4:27combustion.
  • 4:28Then we come to non supporter
  • 4:32of combustion, the examples are
  • 4:33hydrogen, carbon monoxide, carbon dioxide,
  • 4:37nitrogen, ammonia, hydrochloric acid,
  • 4:40sulfuric acid, then sulfur dioxide and
  • 4:42so on. They all are non supporter of
  • 4:45combustion. In their presence only, we
  • 4:49cannot burn any substance if we do not
  • 4:52have oxygen or chlorine present around.

Learn with Videos

Introduction to Combustion
4 min
Conditions for Combustion
5 min
Conditions for Combustion
5 min