Assertion: hydrogen fluoride's impurity | /r/HasProperty | removed by fractional distillation
Facets:
value: usually
type: TEMPORAL
Source sentences:
text: These impurities are usually removed by fractional distillation and the resulting hydrogen fluoride has a purity of about 99.8% or better.
text: The main impurities that result from such a reaction (fluosilicic acid, silicon tetrafluoride, sulfur dioxide, sulfuric acid, water) are usually removed by fractional distillation.