How did my chem teacher light water on fire?

Question

Today in chemistry, our teacher lit "plain" tap water on fire. This is supposedly possible because of the water's impurities. We saw her fill up the beaker straight from the faucet. She then swiped a match and lit the top of the water on fire. There was a yellowish flame for about 30 secs and then it went out. How was this done? Was something added to the water?

Answer 1

actually water can be flammable if you put the right chemicals in it like oil or some other chemicals

Answer 2

Ur teacher added sodium metal on the water which replaces hydrogen in water liberating free hydrogen and amount of energy which burns this hydrogen, and hydrogen gas burns with pop sound so it seems like a nice fire from water.

You can notice the pop sound of burning hydrogen if u increased amount of sodium added.

This reaction can be done with any alkali metal (group 1A) (sodium, potassium,etc...) but as u go down the group, the reaction becomes vigorous and with cesium an explosion occurs

Have fun!!