The Dissolution Reaction and Attack of Beryllium by HF, HCl, and H[sub 2]SO[sub 4]

Abstract

The kinetics of dissolution of Be in various acids can be studied easily, if the rate of reaction is followed by measuring the volume of hydrogen evolved. However, there is a complete absence of quantitative data in this respect. Inorganic chemistry literature sources state that Be metal dissolves vigorously in dilute acids, except dilute HNO~, where the reaction ceases soon in the cold (1-4). The stoiehiometry of these reactions is not revealed. Since Be exhibits a stable valency of two, it may be expected to react with the three acids as follows [1] [2] Be + 2HF-~ BeF~ + H~ Be % 2HC1-> BeCI.~ + H~ Be + H~SO4 ~ BeSO, + H.~ and [3] The respective salts are soluble in water; no residue should appear therefore. By dissolving a weighed amount of the metal in the acids and measuring the volume of hydrogen evolved the reactions can be checked. Experimental The Be was obtained from the Brush Bery]lium Company as premium grade vacuum cast metal lump and contained about 99.0% Be, the rest mainly oxygen. Iron, aluminum, silicon, magnesium, and carbon were present in still smaller amounts. As the other metals also develop hydrogen while dissolving in acids, it was calculated that the Be sample was approximately equivalent to a metal containing 99.5% Be. The apparatus used for the dissolution of the Be samples and the collection of hydrogen consisted of a constant temperature reaction vessel sealed to a gas burette (5, 6). The reaction temperature was 36.0 ~ +-0.2~ the gas burette was at room temperature , but protected with an outer glass tube from sudden temperature changes. Because of the low atomic weight of Be, the samples were weighed with an accuracy of +-0.00001g on a gold balance. The concentration of the acids was so chosen that the dissolution of the samples was complete in about 30 rain. The air in the reaction vessel was not replaced by an inert gas as no oxidation of the Be ions was expected.