The other was "Zyklon A" – a liquid pesticide which released hydrogen cyanide in a chemical reaction with water but found to be extremely dangerous for normal use.
Molar mass 27.0253 g/mol
Appearance Very pale, blue, transparent liquid or colorless gas
Odor Oil of bitter almond
Density 0.687 g mL−1
Melting point −14 to −12 °C; 7 to 10 °F; 259 to 261 K
Boiling point...25.6 to 26.6 °C; 78.0 to 79.8 °F; 298.7 to 299.7 K
Solubility in water...Miscible
Solubility in ethanol...Miscible
Vapor pressure...630 mmHg (20 °C)
Henry's law constant (kH)...75 μmol Pa−1 kg−1
Acidity (pKa) 9.21
Basicity (pKb) 4.79 (cyanide anion)
Refractive index (nD)...1.2675 
Viscosity...201 μPa s
Dipole moment...2.98 D
Specific heat capacity (C)...71.00 kJ K−1 mol−1 (at 27 °C)
Std molarentropy (So298)...113.01 J K−1 mol−1
Std enthalpy of formation (ΔfHo298)...109.9 kJ mol−1
Std enthalpy ofcombustion (ΔcHo298)...-426.5 kJ mol−1
Zyklon B is a .2M solution of HCN absorbed under pressure into a substrate. At the time of packaging the substrate and the gas were combined with a stabilizing chemical as well as with a strong-smelling and irritating warning agent. Various different substrates were selected for their ability to retain hydrogen cyanide for a certain, albeit brief, period of time after the cans were opened. Although hydrogen cyanide is a liquid up to just under 26° C, it has a very high vapour pressure and therefore gasifies rapidly even at -10° C. The dilution and use of substrate controlled the rapid vapourization.
Three substrates were used: Pappescheiben, Kieselgur, and Erko (lignin, diatoms and silica).
Zyklon B under electron microscope, sample from Auschwitz
Diatomaceous earth under electron microscope
A comparison between the EDX analysis of a Zyklon-B pellet and a sample of calcium sulfate
Hydrogen Cyanide kills by interfering with cellular respiration. Specifically, it prevents the cell from producing ATP by binding to one of the proteins involved in the electron transport chain. This protein, cytochrome c oxidase, contains several subunits and has ligands containing iron groups. At one of these iron groups, heme a3, the cyanide component of Zb can bind, forming a more stabilized compound through metal-to-ligand pi bonding. As a result of this new iron-cyanide complex, the electrons which would situate themselves on the heme a3 group can no longer do so. Instead, because of the new bond formed between the iron and the cyanide, these electrons would actually destabilize the compound (based on molecular orbital theory); thus, the heme group will no longer accept them. Consequently, electron transport is halted, and the cell can no longer produce the energy needed to synthesize ATP.
Hydrogen Cyanide is flammable but 56 000 ppm (5.6%) is required for an explosive mixture to actualize up to 400 000 ppm (40%)
Air concentrations of
>300 ppm (333 mg/m3
HCN), >200 ppm (222 mg/m3 HCN), >100 ppm (111 mg/m3 HCN), and
>50 ppm (55 mg/m3 HCN) corresponded to blood concentrations of >10, >8–10, >3–8, and >2–
4 mg/L, respectively
The differences are in part to individual variablity in body chemistry, metabolism and a degree of uncertainty to exposure duration. It is not possible to do accurate lethal doses on living people for obvious reasons.
The cyanide ion (CN_) is the toxic moiety in hydrogen cyanide. The toxicity of simple cyanide salts, such as potassium and sodium cyanide is, therefore, similar to that of hydrogen cyanide.
The toxic effects and lethality associated with acute exposure to CN– in humans and animals are generally similar and are believed to result from inactivation of cytochrome oxidase and inhibition of cellular respiration during the terminal reaction of the electron transport chain. This inhibition prevents the formation of adenosine triphosphate (ATP) via oxidative phosphorylation. The IPCS (2004) noted that the lowest reported oral lethal dose in humans is 0.54 mg/kg body weight; the average absorbed dose at the time of death was estimated at 1.4 mg/kg body weight (calculated as hydrogen cyanide [HCN])
dermal contact with HCN. A case report of a worker accidentally exposed to a brief stream of liquid HCN on his hand (amount not specified) reported that the worker became deeply unconscious within 5 minutes of exposure. Breathing was hoarse, his face was flushed, and reflexes were absent. The subject recovered with sodium nitrite and sodium thiosulphate treatment.
In the living human body, prussic acid does not form any combination with haemoglobin of the red blood cells, but in the drawn blood it appears in the form of cyanhaemoglobin, a loose combination, which differs slightly from oxyhaemoglobin in its spectrum and is reduced with greater difficulty so that the blood retains its red color longer. In cases of poisoning with cyanides the dependent parts of the body often present a bright red colour instead of the usual postmortem lividity, and this seems to be due to the cyanhaemoglobin retaining its red colour while ordinary haemoglobin is reduced.
A functioning gas chamber (commodity)
This is merely hypothetical of how gassing would possibly be managed on a mass scale and the quantities of Zyklon B needed and other systems.
As it was not done in this manner it is highly suspected it was not carried out at all. Without the Krieslaff method huge quantites of Zyklon B would be needed (a tonne in Liechenkeller II), which would still not give close to the desired results. Deutschland had huge facilities for fumigation using Zyklon B which would have been highly efficient for mass homicidal gassing but were never used. Simply the claims bye eyewitnesses at Auschwitz are not technically credible
If Zyklon B were to be used a LD50 is not enough for the desired results. The aim is for an LD99 so the immediate death at 270ppm (300mgm-3 0.3, 0.271cmL-1 or 0.271%vol-1, would not suffice. The dosage would need to rise to at least 540 ppm.
This puts the concentration of HCN in the space at 8.14237cmL-1, 8142.37 ppm or 0.81% vol-1.
It is possible to put 4 people into an area of 1m2, so 500 people could be crammed into 125m2, with a ceiling height of 2m the volume of the commodity would be 250m3. People have volume so 500 people have a volume of 33.2m3, which leaves the available space for the HCN to be 217m3. The single 100g can would have a concentration of 385 ppm and would be lethal at the LD50,
Putting 200g of Zyklon B would be 771 ppm and within the LD99. This is provided the Krieslaff system was used insuring even distribution.
In this case 495 people would die within one minute the rest succumbing within 10. The gas is absorbed lethally in the skin so holding the breath will not suffice to save them.