Hydrogen Cyanide (HCN)- CAS Number: 74-90-8
CAS no. (Chemical Abstracts Service Registry Number): 7782-50-5
Chlorine (dichlorine, diatomic chlorine, bertholite, sodium hypochlorite, molecular chlorine) is a greenish-yellow gas. It has a very pungent odour similar to the smell of bleach. Chlorine is mildly soluble in water, becoming hypochlorous acid and hypochloric acid.
As chlorine is heavier than air (approximately 2 ½ times), in areas with limited ventilation or air movement it will often accumulate and spread through low lying areas.
Liquid chlorine will evaporate into the air very quickly. Chlorine combines easily with all gases except for nitrogen and any of the rare gases (excluding xenon). Chlorine itself is not flammable but, being very reactive, it may explode or form explosive compounds when exposed to substances such as ammonia, hydrogen, natural gas or turpentine.
Often for shipping or storage, chlorine is cooled and pressurized turning into liquid chlorine.
Hydrogen sulphide (H2S), otherwise known as hydro-sulfuric acid, sulphuretted hydrogen, stink damp, dihydrogen monosulfide, sulfur hydride, hepatic gas, sewer gas, is a naturally occurring gas. A by-product of decomposition, it is found in natural gas, crude petroleum, volcanic gas and hot springs.
Carbon Monoxide is a colourless, odourless gas, to the human senses it is completely invisible. Carbon Monoxide is a highly toxic gas. It is termed a toxic (blood) asphyxiant, meaning it reduces the oxygen transport properties of the blood. Low ppm doses of Carbon Monoxide can cause headaches and dizziness, if the victim is removed to fresh air no permanent damage will result. High concentrations however, can saturate a person's blood in a matter of minutes and quickly lead to respiratory arrest or death.
Despite the fact Carbon Dioxide is naturally present in the atmosphere (about 400ppm) and we exhale it when breathing, CO2 is one of the most frequently overlooked toxic gases. Both colourless and odourless, CO2 in high concentrations poses an extremely dangerous hazard.
Carbon dioxide is heavier than air, with a density of 1.5 times that of fresh air. When it is released into an enclosed or confined space it tends to settle to the bottom, reaching the highest concentration in the lowest parts of the space.
Oxygen, the most abundant element in the earth’s crust is of great interest due to the fact that it’s essential in the respiratory processes of most living cells. It is found in both the air we breathe and the water we drink. In normal conditions oxygen is a colourless and odourless.