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Sodium-potassium cyanide - Video Tutorial

is a powerful and rapidly acting poison for which no antidote is available that


you could stand a chance of administering yourself if anything goes


wrong the preparation involves a reaction between potassium ferrocyanide


and sodium metal it is performed in a rigid stainless steel container such as


this one first of all measure out 40 grams exactly of anhydrous potassium


ferrocyanide it is very important that the salt is completely anhydrous like


this and not the crystalline dihydrate we also use sodium metal remove the


sodium from its protective mineral oil dry it on a paper towel and weigh


exactly 5 grams of metal chunks place a layer of potassium ferrocyanide on the


bottom of the dry steel container


cut the sodium metal into thin slices


using a sharp knife place the slivers into the container and build layers of


ferrocyanide and sodium metal ensuring that the metal is evenly distributed


throughout the mixture finally pinching with a layer of ferrocyanide the


reaction works well on a regular gas burner just make sure that there's no


way for the container to tip over and spill start with a low heat in order to


melt the sodium metal soon the mixture will start to turn brown and then a dark


color at this point stir the mixture and keep stirring until it is a uniform dark


color in about 15 minutes the mixture should liquefy use ventilation because


the fumes given off could contain carbon monoxide which is toxic the liquid forms


a white brittle solid


pour the liquid out and allow to cool whilst cooling protect the solid with a


sheet of foil just in case it shatters when cooled right down place into a


beaker place 50 milliliters of hot water into the metal container and dissolve the


contents as much as possible then pour this into the beaker containing the


solid and gently stir in order to dissolve this should take from six to


seventy mils of water and total when saturated the solution has a glossy


sheen to it set up for vacuum filtration and carefully filter the mixture


the black solid of paint is mostly iron which you can test with a brush or a


brush and then use a magnetic stir bar the filtrate is a saturated solution of


our crude product many organic reactions require an aqueous solution of cyanide


and so this is suitable for use directly although it has a short shelf life due


to hydrolysis and should be used immediately it can also be used to


prepare a solid product but note that there is a considerable loss of


to do this the filtrate is poured into an excess quantity of ethanol although


some of the product remains dissolved the dehydrating action causes a lot to


come out of solution is a fine precipitate stir for 10 to 15 minutes in


order to ensure maximum removal of water here's the solid produced


set up again for filtration and filter the solid drying it thoroughly for 15


minutes on the filter with a pump running


here's the final product after drying in an oven a mixture of dry sodium and


potassium cyanide which should have a good shelf life if not exposed to air or


water


an important note on disposal to dispose of filled trade washings and paper towels


make a little solution of sodium hypoglycerate bleach then carefully add


to the bleach the mixture may warm up so take care


leave this for a few hours to neutralize cyanide before flushing down the drain to


test the filtrate we added a small amount to a


warm copper sulfate solution you can see the copper to cyanide immediately


decomposing to form extremely toxic cyanogen gas this was just for


curiosity and not something you should repeat here's the reaction I can't call


cyanides fun but they are incredibly important and useful in organic


synthesis to be treated with a deserving respect