50 Fun Facts About States of Matter

How many states of matter are observable in everyday life?

Neon signs and lightning are everyday examples of partially ionised plasma.

Particles in a liquid stay close but slide past each other, so a liquid keeps what?

That is why a liquid keeps its volume but takes the shape of its container.

Which state of matter has both a definite shape and a definite volume?

A solid can only change shape through an outside force, such as being broken or cut.

Which state expands to fill both the shape and the volume of its container?

Gas particles are far apart and move freely, which also makes gases compressible.

What does plasma contain that ordinary gas does not?

The ions and free electrons respond to electric and magnetic fields.

Liquid crystals, used in LCD screens, share properties of which two states?

Austrian botanist Friedrich Reinitzer discovered them in 1888 while studying cholesterol derivatives.

Roughly what fraction of ordinary matter in the universe is plasma?

Stars are almost pure balls of plasma, and it dominates the gas between galaxies.

Who introduced the term "plasma" for ionised gas in 1928?

He borrowed the word from blood plasma, which carries corpuscles the way the gas carries electrons.

Which scientist proposed a "fourth state of matter" in an 1879 paper on low-pressure discharges?

Crookes' glowing tubes were an early glimpse of plasma half a century before the word existed.

The word "gas" was coined by which 17th-century chemist?

It was probably a phonetic spelling of the Greek "chaos", pronounced with a Dutch guttural g.

The word "gas" is thought to be a transcription of which Ancient Greek word?

In Paracelsus's terminology, chaos meant something like "ultra-rarefied water".

Unlike a liquid, a gas is described as what kind of fluid?

Liquids are nearly incompressible, keeping their volume even under pressure.

Which of these is a noble gas made of single atoms?

Hydrogen, nitrogen, oxygen, fluorine and chlorine exist as two-atom molecules; the noble gases are monatomic.

Gas particles spreading out to fill a container evenly is called what?

Diffusion is one of the four gas behaviours that Boyle, Charles, Dalton and Avogadro studied.

Which equation sums up the gas behaviour studied by Boyle, Charles and Avogadro?

It links pressure, volume, temperature and amount of gas in a single equation.

A solid turning directly into a gas, as dry ice does, is called what?

Solid iodine and the naphthalene in mothballs also sublime readily.

Dry ice is the solid form of which substance?

At normal pressure CO2 has no liquid state, so it sublimes straight to gas at −78.5 °C.

At what temperature does dry ice sublime at normal atmospheric pressure?

Liquid CO2 only forms at pressures above about 5.1 atmospheres.

Which preservation method removes water by letting ice sublime under a vacuum?

The food is frozen first, then its ice turns to vapour without ever melting.

Water vapour turning directly into frost without becoming liquid is an example of what?

It is the reverse of sublimation and how hoar frost forms on leaves in sub-freezing air.

Gas changing into liquid is called condensation; what is it the reverse of?

It happens when vapour is cooled or compressed to its saturation limit, as on a cold window.

Evaporation happens where on a liquid?

Boiling, by contrast, forms vapour bubbles inside the bulk of the liquid.

Why does sweating cool you down?

The energy removed from the vaporising liquid lowers the temperature of what remains.

At 1,905 metres altitude, water boils at roughly what temperature?

Lower air pressure means a lower boiling point, which is why mountain cooking takes longer.

Whose 1941 theory of superfluidity earned a Nobel Prize in 1962?

Kapitsa had discovered the effect in 1937; Landau explained it and later won his own Nobel.

Which metal has the highest melting point, about 3,414 °C?

That heat resistance is why it was used as the filament in incandescent light bulbs.

Which element does not freeze at all at normal pressure, even near absolute zero?

It needs more than twenty times atmospheric pressure before it will solidify.

Which is the only metal that is liquid at standard temperature and pressure?

Bromine is the only other element that is liquid under those conditions, and it is not a metal.

Gallium melts at about 29.8 °C, which means it will melt where?

Unlike mercury, liquid gallium wets glass and skin, which makes it messy to handle.

Which non-metal element is liquid at room temperature?

Mercury and bromine are the only two elements that are liquid at standard conditions.

Why are liquids thought to be the rarest state of matter in the universe?

Liquid water is abundant on Earth, but most of the cosmos is plasma or gas.

Ice floats because it is roughly how much less dense than liquid water?

Water expands about 9% in volume when it freezes, which is why pipes burst.

Liquid water is densest at what temperature?

Below 4 °C the molecules begin arranging into the open hexagonal pattern of ice.

Almost all ice on Earth has which crystal structure?

It is called ice Ih, "ice one h"; interstellar ice is mostly low-density amorphous ice instead.

At its triple point, which three phases of a substance coexist in equilibrium?

It sits at 273.16 K (0.01 °C) and a vapour pressure of just 611.657 pascals.

Before 2019, the triple point of water was used to define which SI unit?

The 2019 SI revision tied the kelvin to the Boltzmann constant instead.

Absolute zero is equivalent to what on the Celsius scale?

On the Fahrenheit scale it is −459.67 °F; the Kelvin and Rankine scales start there by definition.

Which law of thermodynamics implies absolute zero cannot be reached in a finite number of steps?

In 2018 researchers in Bremen got within 38 trillionths of a degree of it.

The first Bose–Einstein condensate was created in 1995 using atoms of which element?

Eric Cornell and Carl Wieman cooled the gas to 170 nanokelvins in Boulder, Colorado.

Einstein's 1924–25 prediction of condensates built on a paper by which Indian physicist?

Einstein translated Bose's paper into German himself and submitted it for publication.

Cornell, Wieman and Ketterle shared which award in 2001 for making condensates?

Ketterle at MIT had produced his condensate from sodium atoms later in 1995.

A superfluid is a fluid with what remarkable property?

Superfluid helium flows without losing kinetic energy and can creep up the walls of its container.

Superfluidity was discovered in 1937 in which element?

Pyotr Kapitsa, and independently Allen and Misener, found it in liquid helium-4.

Above its critical point a substance becomes a supercritical fluid, meaning what?

Supercritical CO2 is used to decaffeinate coffee, and such fluids exist in Venus's atmosphere.

Supercritical CO2 is widely used industrially to do what?

It replaces organic solvents in a range of processes, alongside supercritical water in power-station boilers.

Glass is an example of what kind of solid?

Amorphous solids lack the long-range order of a crystal, though they show local order at small scales.

Salting icy roads works because of which effect?

The same principle keeps sea water liquid below 0 °C and makes antifreeze work in cars.

Which collapsed stellar remnants contain matter at nuclear density?

A neutron star packs about 1.4 solar masses into a ball roughly 10 km across.

Quark–gluon plasma forms under which extreme condition?

It is the opposite extreme from Bose–Einstein condensates, which need temperatures near absolute zero.

In a crystalline solid, how are the particles arranged?

Amorphous solids such as glass lack this long-range order.