WEBVTT - Why doesn't gasoline burn cleanly?

0:00:00.160 --> 0:00:02.760
<v Speaker 1>Streaming TV shows and movies directly to your home is

0:00:02.759 --> 0:00:05.560
<v Speaker 1>a breeze With Netflix. As a Netflix member, you can

0:00:05.600 --> 0:00:09.040
<v Speaker 1>instantly watch TV and movies on your PC, Mac, mobile device,

0:00:09.160 --> 0:00:12.440
<v Speaker 1>or television. Get a free thirty day trial membership. Go

0:00:12.520 --> 0:00:15.200
<v Speaker 1>to Netflix dot com slash stuff and sign up today.

0:00:15.840 --> 0:00:19.120
<v Speaker 1>Welcome to Brainstuff from hose stuff works dot com where

0:00:19.160 --> 0:00:30.440
<v Speaker 1>smart happens. Hi. I'm Marshall Brain with today's question, why

0:00:30.560 --> 0:00:34.199
<v Speaker 1>doesn't gasoline burn cleanly? Why do we end up with

0:00:34.240 --> 0:00:38.960
<v Speaker 1>things like smog and ozone that pollute disguise? Gasoline is

0:00:38.960 --> 0:00:42.720
<v Speaker 1>a liquid formed almost purely of carbon and hydrogen. If

0:00:42.760 --> 0:00:45.960
<v Speaker 1>you could somehow burn gasoline as a vapor with a

0:00:46.000 --> 0:00:49.960
<v Speaker 1>hot flame and plenty of oxygen, you would get nearly

0:00:50.200 --> 0:00:54.440
<v Speaker 1>pure carbon dioxide and water as the combustion products. That's

0:00:54.440 --> 0:00:58.160
<v Speaker 1>why you can burn natural gas, LP gas and kerosene

0:00:58.200 --> 0:01:02.880
<v Speaker 1>indoors in the winter, and appropriately designed kerosene heater, for example,

0:01:02.960 --> 0:01:07.920
<v Speaker 1>can be ventless. Automobile exhaust, unfortunately, contains a lot more

0:01:07.959 --> 0:01:11.480
<v Speaker 1>than carbon dioxide and water. The most important pollutants and

0:01:11.600 --> 0:01:15.960
<v Speaker 1>car exhaust include first, carbon monoxide, which is a poison.

0:01:16.440 --> 0:01:21.119
<v Speaker 1>Carbon monoxide is formed because combustion is incomplete in the cylinder,

0:01:21.600 --> 0:01:25.280
<v Speaker 1>not enough oxygen is available fast enough to react completely

0:01:25.319 --> 0:01:29.600
<v Speaker 1>with all the carbon available. Second is nitrogen oxides. Because

0:01:29.600 --> 0:01:32.880
<v Speaker 1>of the pressure and temperature inside the cylinder, nitrogen and

0:01:32.920 --> 0:01:35.800
<v Speaker 1>oxygen in the air combined in various ways, we would

0:01:35.880 --> 0:01:39.840
<v Speaker 1>rather it didn't. And third is unburned hydrocarbons. Not all

0:01:39.840 --> 0:01:43.000
<v Speaker 1>of the hydrocarbons participate in the reaction because there's so

0:01:43.120 --> 0:01:46.920
<v Speaker 1>little time available during the combustion phase. There can also

0:01:47.000 --> 0:01:49.800
<v Speaker 1>be some impurities, like sulfur in the gas to form

0:01:49.960 --> 0:01:54.120
<v Speaker 1>sulfur oxides. The idea behind a kettalytic converter is to

0:01:54.200 --> 0:01:58.520
<v Speaker 1>try to eliminate the carbon monoxide, nitrogen oxides, and hydrocarbons

0:01:58.840 --> 0:02:03.360
<v Speaker 1>by reacting them with plenty of oxygen on a platinum catalyst. However,

0:02:03.720 --> 0:02:07.080
<v Speaker 1>catalytic converters aren't perfect either, so some of the pollutants

0:02:07.080 --> 0:02:10.720
<v Speaker 1>still escape. On hot summer days, we see the effect

0:02:10.800 --> 0:02:13.440
<v Speaker 1>of these pollutants in the form of smog and ozone.

0:02:13.880 --> 0:02:17.799
<v Speaker 1>Nitrogen oxides and hydrocarbons mixed with air and get bombarded

0:02:17.800 --> 0:02:22.800
<v Speaker 1>by ultraviolet rays and sunlight. Nitrogen dioxide releases an oxygen atom,

0:02:22.840 --> 0:02:25.959
<v Speaker 1>which combines with oxygen gas to form O three or

0:02:26.040 --> 0:02:30.000
<v Speaker 1>ozone at ground level. Do you have any ideas or

0:02:30.040 --> 0:02:33.240
<v Speaker 1>suggestions for this podcast? If so, please send me an

0:02:33.240 --> 0:02:36.520
<v Speaker 1>email at podcast at how stuff works dot com. For

0:02:36.600 --> 0:02:38.880
<v Speaker 1>more on this and thousands of other topics, go to

0:02:38.919 --> 0:02:41.840
<v Speaker 1>how stuff works dot com and be sure to check

0:02:41.840 --> 0:02:44.160
<v Speaker 1>out the brain Stuff blog on the how stuff works

0:02:44.200 --> 0:02:50.079
<v Speaker 1>dot com home page. This episode of brain Stuff is

0:02:50.120 --> 0:02:52.679
<v Speaker 1>brought to you by Linda dot Com. Linda dot Com

0:02:52.760 --> 0:02:56.200
<v Speaker 1>offers thousands of engaging, easy to follow video tutorials taught

0:02:56.200 --> 0:02:59.400
<v Speaker 1>by industry experts to help you learn software, creative and

0:02:59.440 --> 0:03:02.120
<v Speaker 1>business skill pills. Membership starts at twenty five dollars a

0:03:02.120 --> 0:03:05.360
<v Speaker 1>month and provides unlimited twenty four seven access tri Linda

0:03:05.400 --> 0:03:08.079
<v Speaker 1>dot Com free for seven days by visiting Linda dot

0:03:08.080 --> 0:03:09.560
<v Speaker 1>com slash brain Stuff