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Ignition Temperature

Ignition Temperature

Transcript

  • 0:0Ignition temperature. It is one of the
  • 0:7
  • 0:7essential conditions required for a
  • 0:9
  • 0:9substance to burn or for a substance to
  • 0:12
  • 0:12start its combustion. What are the other
  • 0:15
  • 0:15conditions? We know that the other
  • 0:18
  • 0:18conditions are for combustion, a fuel is
  • 0:20
  • 0:20required and to burn the fuel, oxygen is
  • 0:24
  • 0:24required. An ignition temperature is the
  • 0:26
  • 0:26third essential condition for
  • 0:28
  • 0:28combustion to take place. Let us understand
  • 0:31
  • 0:31this ignition temperature with
  • 0:33
  • 0:33the help of some examples. Take an
  • 0:36
  • 0:36example of a candle. Does a candle burn
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  • 0:39on its own? No. You have to light it
  • 0:43
  • 0:43with a match stick that means you have
  • 0:46
  • 0:46to give it some heat.
  • 0:48
  • 0:48Ok. Take the example of a wood. Can we burn
  • 0:52
  • 0:52the wood with the matchstick? No. We
  • 0:55
  • 0:55have to burn it with some more flame.
  • 0:58
  • 0:58Either you burn it with the paper or
  • 1:0
  • 1:0you burn it with using kerosene oil.
  • 1:4
  • 1:4One more thing, have you seen forest fires? When
  • 1:9
  • 1:9does this forest fire occur? Does it
  • 1:11
  • 1:11occur in all the seasons? No. It
  • 1:15
  • 1:15occurs when there is extreme amount of
  • 1:17
  • 1:17heat in the atmosphere and due to which some
  • 1:21
  • 1:21grasses catch fire and slowly from these
  • 1:24
  • 1:24grasses, entire forests catches fire.
  • 1:27
  • 1:27So all these examples, tell us that
  • 1:30
  • 1:30different substances require different
  • 1:32
  • 1:32amount of heat to burn. More the heat
  • 1:36
  • 1:36required, more will be the temperature
  • 1:38
  • 1:38required for the substance to burn. That
  • 1:41
  • 1:41means, we can say, that the lowest
  • 1:43
  • 1:43temperature required for the substance
  • 1:46
  • 1:46to burn will be known as its ignition
  • 1:49
  • 1:49temperature. So, what is the definition of
  • 1:51
  • 1:51ignition temperature. The lowest
  • 1:54
  • 1:54temperature required for the substance
  • 1:56
  • 1:56to burn is called its
  • 1:58
  • 1:58ignition temperature. So, now let us
  • 2:1
  • 2:1understand this ignition temperature
  • 2:3
  • 2:3better with some activity. We take two
  • 2:7
  • 2:7paper cups. In one of the cups, we put 50
  • 2:10
  • 2:10ml of water.
  • 2:11
  • 2:12Now, let's start burning both the cups
  • 2:14
  • 2:14with the candle.
  • 2:16
  • 2:16What are you observing here? You observe
  • 2:19
  • 2:19that the empty paper cup has started burning
  • 2:22
  • 2:22whereas the paper cup of water has yet not
  • 2:27
  • 2:27started burning.
  • 2:28
  • 2:28What does this indicate? This indicates that the
  • 2:32
  • 2:32empty paper cup has reached its ignition
  • 2:34
  • 2:34temperature. So, it has started burning
  • 2:36
  • 2:36because we're supplying continuous heat
  • 2:39
  • 2:39to it. But in the second case, the cup with
  • 2:42
  • 2:42water has not reached its ignition
  • 2:44
  • 2:44temperature but we're still supplying heat
  • 2:47
  • 2:47to it and where is that heat going? Like
  • 2:50
  • 2:50heat is being transferred to the water
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  • 2:52in the cup
  • 2:53
  • 2:53due to which the paper cup does not
  • 2:57
  • 2:57catch fire because the ignition
  • 3:0
  • 3:0temperature of the paper cup has not
  • 3:1
  • 3:1met. So, this activity clarifies that
  • 3:5
  • 3:5ignition temperature is very much
  • 3:8
  • 3:8essential for a substance to start
  • 3:9
  • 3:9burning. It is the third most requirement
  • 3:13
  • 3:13for starting combustion. Ok. Moving
  • 3:17
  • 3:17further, we have two substances - kerosene
  • 3:20
  • 3:20and wood. We tried burning both of them.
  • 3:23
  • 3:23Which substance will burn quickly? Kerosene,
  • 3:27
  • 3:27right? and wood will take a little more
  • 3:29
  • 3:29time to burn. That means, the heat
  • 3:32
  • 3:32required by kerosene to burn is less compared
  • 3:34
  • 3:34to wood. So, the ignition temperature of
  • 3:37
  • 3:37kerosene, I can say is lower than
  • 3:40
  • 3:40wood. Ok. These substances which catch
  • 3:44
  • 3:44fire very soon are called inflammable
  • 3:48
  • 3:48substances. The ignition temperature are
  • 3:50
  • 3:50much lower. So, how can we define
  • 3:53
  • 3:53inflammable substances? The substances
  • 3:56
  • 3:56which catch fire very soon or the
  • 3:58
  • 3:58substances whose ignition temperature is
  • 4:1
  • 4:1very low are called inflammable substances.
  • 4:5
  • 4:5Now, the other examples of inflammable
  • 4:8
  • 4:8substances are petrol, diesel, CNG, LPG all
  • 4:14
  • 4:14these fuel are much much inflammable.
  • 4:17
  • 4:17Ok. You have to keep them stored in such
  • 4:20
  • 4:20a way, that
  • 4:21
  • 4:21they don't catch fire easily. So, what have
  • 4:24
  • 4:24you learned about ignition temperature?
  • 4:26
  • 4:26That ignition temperature is very much
  • 4:29
  • 4:29essential for a substance to burn. It
  • 4:31
  • 4:31is the third condition required for a
  • 4:33
  • 4:33substance to burn along with fuel and
  • 4:35
  • 4:35oxygen and what is the next thing? We
  • 4:38
  • 4:38learned that there are certain
  • 4:40
  • 4:40substances who have ignition temperature
  • 4:42
  • 4:42much lower than others. Due to which they
  • 4:45
  • 4:45catch very soon. So such subtances are
  • 4:48
  • 4:48called inflammable substances. Examples are
  • 4:51
  • 4:51Kerosene, petrol, diesel, LPG, CNG
  • 4:56
  • 4:56and many more.