As some side notes to Solar's post:
You will encounter NH3 will working with ammonium hydroxide and it's compounds and wastes. I try to avoid the use of ammonia and it's compounds in my refining process. The common refining compounds that contain the ammonium ion are: ammonium chloride and ammonium hydroxide. It makes your eyes, nose, and mouth water profusely and produces choking, sneezing, and coughing. Ammonia gas smells of rotten fish or urine. It makes thick white fumes that linger in the air when HCl is nearby.
You will encounter H2S when working with Sulfites (sulfur dioxide, sodium meta bisulfite, and sodium sulfite). Anytime you combine an acid or water SO2 (in gas as SO2 or solid form as a sulfite), and a base metal above hydrogen in the reactivity series. Hydrogen Sulfide (H2S) is commonly encountered when testing left over solutions with stannous chloride and smells (if you are part of the 40% of the population that can smell it) of rotten eggs. This is one of the most deadly gases on the list. If you smell it and it drops you to one knee, you will likely be dead shortly thereafter. It takes the form of colorless fumes.
You will commonly encounter Cl2 (chlorine gas) when working with HCl-Cl (muriatic and bleach), AP (muriatic and hydrogen peroxide), AR (nitric acid and muriatic acid). Chlorine gas makes your eyes, nose, and lungs burn and water. It also can make you cough, sneeze, and choke. Chlorine exposure can leave you with burnt lung tissue which can take a very long time to heal. Chlorine has a bitter biting smell that makes you instinctively want to leave the area. It is a yellow green gas that is heavier than air.
Most of you will not ever encounter HCN (hydrogen cyanide), thank goodness. It smells of bitter almonds (if you can smell it as only about 40-50% of the population can). The smell reminds me of those almond cookies my mother makes at Christmas time. It causes your body to quit absorbing oxygen and kills you within a few minutes of a lethal dose. Rapid heartbeat, difficulty breathing, nausea, and disorientation are common indications of cyanide poisoning/exposure. HCN is a colorless gas.
Steve
