Laboratory funnel

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Laboratory funnels are tools used to guide liquids and powders during chemical work. There are many types for different tasks. Filter funnels, thistle funnels, and dropping funnels have stopcocks to add liquids slowly to a flask. For powders, a powder funnel with a short, wide neck helps prevent clogging. When used with filter paper, filter funnels, Buchner funnels, and Hirsch funnels separate solids from liquids by filtration. For very small particles, the filter paper can be replaced with a sintered glass frit. Separatory funnels are used for liquid-liquid extractions. Borosilicate glass is a common choice because it is less reactive than metals or plastics. Plastics like polyethylene are used for transferring aqueous solutions, and plastic powder funnels are used when solvents are not involved in normal use.