36Kr

Krypton

Noble gasgasblock p

A noble gas that defined the length of the metre for twenty-three years, before lasers made the speed of light a better ruler.

Atomic number	36
Standard atomic weight	83.798 g/mol ± 0.002
Group · period	18 · 4
Electron configuration	[Ar] 3d¹⁰ 4s² 4p⁶

About Krypton

Ramsay and Travers found krypton in 1898 by slowly boiling off a litre of liquid air and examining the last stubborn residue — hence the name, the hidden one. Its finest hour came in 1960, when the General Conference on Weights and Measures abandoned the platinum-iridium metre bar in favour of a definition anyone with a good lamp could reproduce: one metre equals 1650763.73 wavelengths in vacuum of the orange-red line of krypton-86. That held until 1983, when the metre was redefined via the fixed speed of light. Krypton is rare enough in air, about 1 ppm, that it is expensive, so it appears where performance justifies cost: high-efficiency window fills, photographic flash tubes and some high-intensity lamps. Krypton-85 released from spent-fuel reprocessing is monitored as a nuclear-activity tracer.

Use 83.798 g/mol in these solvers

Moles from Mass (n = m/M)

n = \frac{m}{M}

Opens with M = 83.798 g/mol already filled in

Gas Density from Molar Mass

\rho = \frac{PM}{RT}

Opens with M = 83.798 g/mol already filled in

Faraday's Law of Electrolysis (m = QM/nF)

m = \frac{Q M}{n F}

Opens with M = 83.798 g/mol already filled in

Ion Concentration as CaCO₃ Equivalent

C_{\mathrm{CaCO_3}} = C_{\mathrm{ion}} \times \frac{50.04}{\mathrm{EW}}

Opens with EW = 83.798 g/mol already filled in

Acid Feed to Reduce Alkalinity

\dot m = \frac{\Delta \mathrm{Alk} \, Q \times \frac{\mathrm{EW}}{50.04}}{p/100\%}

Opens with EW = 83.798 g/mol already filled in

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