Fire on water?

Question

My b/f asked me out of the blue one day, "How can water get on fire?" My reply was, "The only way there will be fire on the water is if there is gas, petrol or anything chemical that can catch on fire" Maybe there is a better way of explaining this. He also asked, "So, how long can we keep the fire burning on the water?" I guess as long as there is enough gas,petrol or other chemical on the surface of the water. Am I right? Can someone please explain this science in a simple english term, thank you.

Answer 1

You are correct. And did a good job of explaining.

One common example is marsh gas which can ignite spontaneously on the surface of the water in some swamps. When all of the gas is burned, the fire goes out.

There are places where natural petroleum seeps to the surface of a pond or lake and can be ignited from lightening. As long as the petroleum seeps fast enough, the fire will remain lit.

Ocean oil spills are another example. This is especially true of tankards which have cracked open when they sank. Oil will spill out into the water and then rise to the surface because it is lighter than water and floats. This could be ignited by natural or other means.

Answer 2

No, you have it perfectly right. Since oils don't mix with water, and the density is less than water, they will float on the surface. If they catch on fire, the only way to put them out is to douse with more water or another chemical, but adding more chemicals would worsen the situation in terms of ecological impacts. So it will continue to burn until, like you said, there is no more oil.

Similarly, magnesium is one of the few elements that can actually burn *under* water. This is why emergency flares use magnesium to burn, because even in storm situations, they will continue burning as a beacon for helpers.

Answer 3

It is famous in the U.S. that the river passing through Cleveland, Ohio, once became so polluted in the 1960's that it caught on fire. The story is famous because, as every one knows, rivers cannot burn LOL.