The weight of the invisible

Author: ilamandarina in General on June 18, 2010 | no comments

Experiment amb SF6 For several months, the Mandarin of Newton has a section on popular science in the program Connexió Barcelona Barcelona's television BTV . During these weeks the public has enjoyed several experiments related to electricity, magnetism, gravity, chemical reactions, pressure ... etc. We have built lemons batteries, motors with a battery and a magnet, we have seen shape-memory materials, we played with indicators and redox reactions, we have challenged the intuition piercing a balloon with a knitting needle or a lighter closer to a inflated balloon ... All in Companyia de Ferran Verges.

A couple of weeks we got to bring the program very interesting two gases, helium (He) and sulfur hexafluoride (SF6).

Helium is a chemical element with atomic number 2, symbol I, having the properties of a noble gas. That is, is inert (not reactive) and as such, is a colorless, odorless monoatomic gas. Helium has the lowest boiling point of all chemical elements and can only be solidified under pressures very large. It is in the stars, although in 1903 he discovered large reserves of helium in the earth in natural gas fields in the United States. Helium is used in cryogenics, its main use in the cooling of superconducting magnets or to protect the weld, sparks arc. Other uses less common but popularly known, are the filling of balloons and airships, or used as a component of air mixtures used in diving to great depths.

Sulfur hexafluoride is an inorganic compound of formula SF6. Under normal pressure and temperature is a colorless, odorless, nontoxic and nonflammable, with the peculiarity of being five times heavier than air, has a density of 6.13 g / l at one atmosphere pressure. SF6 has octaedral geometry, consisting of six fluorine atoms bound to a central atom of sulfur. Is a nonpolar gas, very inert and sparingly soluble in water, although yes in nonpolar organic solvents like alcohol or ether. Is a gas of high dielectric constant, és say is very insulating, so that is commonly used as insulation in distribution systems of electricity, especially in high voltages. It also applies in some industrial processes steel, and eye surgery.

With these two gases did a lot of fun experiments and mysterious thanks to their invisibility and their different densities. We start by floating a balloon into something that looked like nothing, but actually was SF6, we sail off through the same invisible gas and we found ourselves high and low voices inhaling helium and sulfur hexafluoride.

The speed of sound in helium is nearly three times the speed of sound in air. Because the fundamental frequency of a gas filled cavity is proportional to the speed of sound in that gas, if inhale helium occurs a corresponding increase to the heights of the resonance frequencies of the vocal cords, and therefore, our voice is heard more acute and resembles that of the Smurfs. Sulfur hexafluoride, however, affects the human voice as opposed to helium: by inhaling the gas, the gas density will cause less vibration in the vocal cords, making the voice sound more serious.

Helium is relatively easy to get, what you can buy at any store that sells materials for parties. SF6, however, is an expensive gas that is used to isolate circuits in electronics, but will have considerable difficulty acquiring without signing a contract or pay a substantial annual fee. If any of these experiments prováis at home, do not worry, none of them is dangerous ... but if you breathe in gases, remember that not too good to abuse them ...

about me

I'm Irene, ila mandarin, curious and playful, who would like to understand why almost all things and the origins of the universe. Live fascinated by art, dance, shapes and colors. One day I felt certain that for me the science and art combined in disclosure. That day I chose to work as a communicator and popularizing science.
A little over a year Newton was born in Mandarin as a blog. Its origin was in blogspot .
In 2010, tangerine moved to Wordpress and its timid beginnings turn into a business venture.
The Tangerine Newton is a project that combines science and technology with any other discipline, to create activities, exhibitions, meetings, and educational playthings. You can find more information on the web or follow each month in the podcast of science in Catalan of Tangerine Lapuente Irene Newton and Tomás Manzanares.