Addition funnel, stem, glass

The stem on a sep funnel can either be straight or have a ground glass joint on the end (Fig. 53). The ground glass joint fits the other jointware you may have and can be used that way as an addition funnel to add liquids or solutions... 

Instead of stopping the reaction and opening the apparatus, you can put in the new chemicals using an addition or dropping funnel. Addition funnels are separatory funnels (see p. 119) with a ground-glass joint on the stem, and there are two types (Fig. 16.5) ... 

So a compromise was reached (Fig. 856). Since you ll probably do more extractions than additions, with or without reflux, the pressure-equalizing tube went out, but the ground glass joint stayed on. Extractions no problem. The nature of the stem is unimportant. But during additions, you ll have to take the responsibility to see that nasty vacuum buildup doesn t occur. You can remove the stopper every so often or put a drying tube and inlet adapter in place of the stopper. The latter keeps moisture out and prevents vacuum buildup inside the funnel. 

A suspension of the material in 600 ml. of concentrated hydrochloric acid is stirred mechanically in a 3-1. beaker which is set in an ice-salt bath. A solution of 46 g. of sodium nitrite in 150 ml. of water in a 250-ml. dropping funnel fixed with its stem below the surface of the suspension is added slowly while the temperature of the mixture is kept at 4-5° (Note 7). After the addition is completed (in approximately 80 minutes), stirring in the ice-salt bath is continued for 1 hour to crystallize completely the stan-nichloride of the diazonium salt. The reddish brown salt is filtered on a sintered glass funnel (Note 6). 

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