What is Smoke?

I have been doing shows on the Science of Fire, so I thought we would do a fire related experiment.

As with all experiments that use fire, BE CAREFUL AND SAFE. Follow proper safety procedures and think about things before you try them. You should also have another adult with you, just in case you have an accident. That way, you have someone else to blame.

For our experiment, we are going to take a look at smoke. What is smoke made of? To find out, you will need:

  • a candle
  • a candle holder
  • a metal fork
  • a paper towel

Place the candle in the candle holder. If you don't have a candle holder, you can make one by crumpling a sheet of aluminum foil around the base of the candle and pressing it against a flat surface. Be sure that it holds the candle very well, so it does not fall over. Place the candle and holder on a flat surface and light it. Take a minute to watch the flame. If you look at the base of the flame, you will see that part of it is blue, while the rest of the flame is yellow. You will also notice that the center of the flame is darker than the outer part.

Be sure that you are using a metal fork. A plastic one will not work. Don't worry. We are not going to damage the fork. Hold it by the handle, with the tines (that is what you call the pointy parts of the fork) held flat. Place the tines in the flame, just below the top. Slowly move them downwards. You should notice some black smoke coming from the flame around the fork. Remove the fork and the smoke will stop.

Be careful, as the fork is still hot. Wait a couple of minutes for it to cool and then rub the tines across a paper towel. What do you see? Black stuff. Oh no! Did we burn the fork? No. Rub the fork with the paper towel and all of the black stuff comes off. The fork is not hurt.

Where did the smoke and the black stuff come from? They came out of the flame. When you light the candle, some of the wax melts. This melted wax soaks up the wick, just as water soaks up into a paper towel. As the melted wax gets closer to the flame, it gets hotter and hotter. When it gets hot enough, the wax comes apart, forming several new chemicals. One of them is the chemical carbon. Carbon is the black stuff that is left behind when you burn a piece of paper, a piece of wood or a piece of toast. It is also the black stuff that you wiped off of the fork.

As long as the flame is not disturbed, the carbon burns up inside the flame. This carbon is also what gives the flame its yellow color. The blue bit of flame at the bottom is low enough that the carbon rises above it, so it does not get the yellow color. Without the carbon, the entire flame would be blue.

When you put the fork into the flame, it causes a disturbance in the flame. This allows some of the carbon to escape before it burns up. These tiny bits of carbon rise from the flame to form the smoke that you see.

Not all smoke is made up of bits of carbon. Blow out your candle. Notice the smoke that is rising from it. This smoke is white, not black like what we saw earlier. This smoke is made of tiny bits of wax that have not come apart yet, so there is no visible carbon. That is why the smoke is white instead of black.

For you to be able to see smoke, it has to contain tiny bits of something. Different kinds of smoke are made of different things, depending on what you are burning. Often, it contains chemicals that are harmful. If you breath it, those tiny bits wind up in your lungs, which is not a good thing. In general, it is not a good idea to breath any kind of smoke. Take a look at the paper towel that you rubbed with the fork. Would you want that stuff in your lungs? Not me. If I want some carbon inside me, I will go burn a piece of toast for a snack. Or maybe toast a marshmallow until the outside is black and crispy (carbon). And of course, you can't toast marshmallows without some chocolate and graham crackers...........Well, gotta go fix a snack. Bye for now.