Trap
A component of a chemical apparatus in which undesirable substances are collected, i.e. trapped.
There are a number of situations where materials are trapped: filtration traps solids, a "muck trap" traps unwanted vapours in vacuum lines and an anti-suck-back trap to prevent liquid sucking back into filtration flasks.
Unwanted volatile compounds can be collected in a trap cooled by liquid nitrogen on a vacuum line and water vapour can be removed by a column of glass beads soaked in concentrated sulphuric acid or by a calcium chloride drying tube.
