The scientific explanation of why snow doesn’t melt with a lighter and turn black

The snowfalls caused by the storm Filomena have filled social networks with pictures of many citizens posing in the snow, but they have also begun to appear hoaxes by some users who claim that snow has plastic because does not melt and it smells funny. Several experts have already dismantled the claims of these people, called “snow deniers”.

The popularizer and biologist Álvaro Bayón has explained in a thread on Twitter “those videos of the snow that does not melt in the lighterand it turns black and smells funny. “

First, it has pointed out relevant “two variables” for this reaction to occur: “We use a butane or gasoline lighter, and we use previously packed snow.”

He has also tried to respond to the two phenomena that occur when the flame of a lighter approaches the snow. “We will explain them separately. First: Why does it turn black and smell funny?“, has indicated.

As he has said, “when using a lighter we are burning a fuel (butane or gasoline), which contains an interesting amount of impurities that, when burned, form soot“That soot, added Bayón, can also be seen when bringing a lighter closer to a clean glass:” You will see that it also turns black, “he says.

According to the biologist, this reaction “is normal”, since “it is the soot of the fuel depositing on the surface (the snowball, or the glass, whatever)”, he clarified.

As for the smell, “it’s the same. Butane gas doesn’t smell, but is mixed with substances that do smell. The smell comes from those impurities that are burning, “said Bayón.

Once that part was clarified, he has given the answer to the second question: Why doesn’t it melt?. “There are two important things here,” this popularizer began by explaining. “The first is that water (even frozen) has a high specific heat. If the snowball is caked (you remove the air between the snowflakes), the ice is in contact with … well, more ice “, has exposed.

“You are applying the flame on a localized point, and most of the heat it receives is going to dissipate through the rest of the ice mass, without actually melting, because of this high specific heat, “continues Bayón.

However, “at the point where the flame strikes most directly, the ice, suddenly go from very low to very high temperature, undergoes a process well known to anyone who has studied physics and chemistry at ESO, which is the sublimation: the passage from ice to vapor without going through the liquid phase “, he pointed out.

In this sense, and as an experiment, the biologist has invited to carry out a test in the microwave in case some incredulous still suspect that there is plastic in the snow: “You can try to put the snow in a container and put it in the microwave. Or in the ceramic hob. Or, I don’t know, leave it on the living room table for a few hours. And then see if, when the snow has melted, the container has plastic or not. “

The same explanation has also been provided on Twitter by Mar Gómez, PhD in Physics: “When we apply the flame to the snow, it does not melt, but rather sublimates, goes directly to gaseous state. The black color is because the fuel in the lighter does not finish burning completely and leaves remains in the snow, hence the smell of burnt plastic, “he summarized.