A Simple Generator for Common Gases at Atmospheric Pressure. The current high east of either a Kipps generator for producing hydrogen sulfide in the undergraduate laboratory, or of the bottled gas, led the writer to construct a simple, economical and efficient generator for use in a laboratory fitted with an efficient fumehwd (this is alwavs necessarv where hydrogen sulfide is used owing to its hiahly toxic nature.. The figure shows a eyl~ndrienlpolyrhenp bottle of 5001000 mI. capacny, havinl: hules of 3 mm diameter drilled in the base and a sufficiently wide mouth for introducing iron(I1) sulfide lumps. A rubber stopper fitted with a bent glass tube is introduced into the mouth, and a rubber tube with a suitable pinchcoek or screwclip is attached to the lass tube. The bottle should fit comfortably (but not tightly) &to a deep beaker. A second beaker of si&ar size &a& ing rinse water should also be available. Sulfuric acid (3 M) is poured into the beaker with the bot3M Sullurlo tle and the clip is released. Hydrogen sultide is released at acid once and can be passed conventionally thmugh a wash bottle before being used in, for example, cation precipitation in inorganic qualitative analysis. To stop the generation of gas, the screw clip is closed and FeS lump the battle is lifted out of the acid to allow complete drainage of the acid from the base of the bottle into the beaker. The bottle is then transferred to the second beaker. Base drllled hole8 To stoo the generation of gas. the screw clip is closed and the bottle is lifted out of the acid to allow complete drainage of theacid fram the base of the bottle into t h e beaker. The bottle is then transferred to the second beaker with rinse water. The screwcli~ n bv x. . is o.~ e n e dto allow comolete ~ s i raising and lowering the bottle a few times. I t can then be left to stand in clean rinse water with the clip closed until required again. This treatment avoids the disagreeable odor normally associated with a Kipps generator of hydrogen sulfide that is not in use. The same generator can be used for producing hydrogen gas (using zinc and 3 M sulfuric acid; aluminium metal pieces immersed in 2 M sodium hydroxide results in an exothermic reaction and requires cooling to control the rate of release of the hydrogen), and carbon dioxide (from lumps of limestone and 5 M hydrochloric acid).
Acknowledgement Kevin Willis is thanked for testing the hydrogen sulfide generator
John F. Elsworth University of Cape Town, Rondebosch South Africa 7700
Volume 69 Number 5
May 1992
419
