Tag: video

Sulfur Hexafluoride Density Demonstration

Sulfur hexafluoride is transparent, so if you fill a fish tank with it you can’t really see that that tank’s filled with anything other than air. However, since sulfur hexafluoride is denser than air, you can float a light boat on the invisible gas for a cool demonstration of density.

Note: Air is about 80% nitrogen gas, which has the formula N2, and a molecular mass of 28 atomic mass units: the molecular mass is the sum of the atomic masses of all the atoms in a molecule. Sulfur hexaflouride has the formula SF6 and a molecular mass of 146 amu, making it about 5 times denser than air.

Alloys are (not Always) Stronger

Steel is an alloy of iron and other elements in small amounts. The exact proportions of the small amounts of other elements can make the alloy stronger, more flexible, and/or more resistant to rusting among other things. Similar alloying is used to make aluminum stronger. You’ll often hear the saying, “Alloys are Stronger” (often used as an argument for more diversity). There is a lot of fascinating research and discoveries happening in the fields of metallurgical arts and sciences at the moment. However, YouTube user NurdRage demonstrates with some gallium and an aluminum can, alloys are not always stronger.

“The World has Improved Immensely in the Last 50 Years”

“It is only by measuring we can cross the river of myths.” — Hans Rosling

Hans Rosling explains, in wonderfully graphical form, how as child mortality has improved so has quality of life, which has in turn lead to fewer births and population stabilization.

More details on the general reduction in poverty in The Guardian.

↬The Dish.