实验手册上查到的提纯方法。 Gold powder [7440-57-5] M 196.97, m 1064.79 o , b 2808 o (2700 o ), d 20 4 19.3, resistivity at 0 is 2.05 -cm. Massive gold reacts very slowly and it is best converted to the powder which is more readily reactive. While working in a well vented fume cupboard, solid gold (10g, 51mmol) is dissolved in Aqua Regia, made from concentrated hydrochloric acid (12M HCl, 50ml) and concentrated nitric acid (16M HNO 3 , 13ml), by heating to 90 o which will hasten dissolution, but will require topping up with Aqua Regia. Alternatively, the suspension is allowed to stand at ~25 o until the solid has dissolved. The solution is evaporated to ca 10ml, concentrated hydrochloric acid (30ml) is added and evaporation is repeated. The solution is diluted with H 2 O (20ml), filtered through a medium sintered-glass funnel, and the filter is washed with small volumes of H 2 O. The filtrate and washings, which contain HAuCl 4 , are heated to boiling and hydroquinone (10g, 91mmol) in hot H 2 O (100ml) is slowly added. The mixture is kept at 90 o for 1 hour (sufficient time to reduce all the HAuCl 4 to Au), cooled and filtered through an extraction thimble. The thimble is placed in a Soxhlet apparatus and extracted with MeOH. Afer 15 minutes, when the circulating MeOH in the thimble is colourless, the thimble is removed and the contents are collected and dried in air to give Au powder quantitatively. [Block Inorg Synth 4 15 1953.]