On the internet there are videos showing that snow heated with a lighter “turns” into carbon because of “chemicals” in the air.
In the current experiment we will see how this can be done at home in a simple experiment using clean ice.
The experiment requires adult supervision.
Equipment
Long neck lighter
Tongs
Ice cube / crushed and compacted ice / compacted snow
The Experiment
The course of the experiment can be seen in the video
Explanation
When a lighter or candle is lit a chemical reaction called combustion occurs.
The gas from the lighter or the candle wax reacts with oxygen in the air and burns.
Both the lighter gas (butane) and the candle wax are compounds of hydrogen (H) and carbon (C). During combustion the compounds break down, react with oxygen (O2), and turn into oxides of their elements: water H2O which is essentially hydrogen oxide released as steam, and carbon dioxide CO2.
If a spoon is placed over a candle flame it quickly becomes covered with black soot.
The soot is made of carbon particles (C) that are black and have not yet burned (have not reacted with oxygen) and stick to the relatively cold spoon.
The relative cold of the spoon is enough to stop the combustion before it fully occurs so the carbon remains as an element.
This process is called partial combustion.
A lighter flame is “cleaner” than a candle flame.
It almost does not produce soot and usually does not form a layer of soot when a spoon is placed above it.
This is because the gas molecules in the lighter are much smaller than the candle wax molecules, so they burn more easily and at a lower temperature.
In other words the relative cold of the spoon is not enough to stop the chemical reaction of the flame.
To create soot from a lighter flame something colder is needed like ice or snow and this is what we do in the current experiment.
The ice simply provides the cold that stops the combustion, but the black soot does not come from the ice it comes from the gas.
During the experiment it is also possible to smell characteristic odors caused by different chemical compounds formed from gas molecule fragments reacting with each other when the chemical reaction suddenly stops.
Black soot is also formed in a completely different way that causes partial combustion.
When combustion occurs in an oxygen poor environment carbon and hydrogen compounds burn into water and soot.
In intermediate amounts of oxygen carbon burns into carbon monoxide CO.
Interesting Fact
Soot from a flame has uses in making ink.
The original recipe for black ink used by scribes includes soot from smoke as the source of black color.