sentences:  Titration with sodium or potassium fluoride yields the exothermic precipitation of an insoluble alumino-fluoride salt.Because 6 mole of fluoride react with one mole of aluminium, the titration is particularly precise, and a coefficient of variance (CV) of 0.03 has been achieved in the analysis of alum.When aluminium ion (say as aluminium nitrate) is employed as the titrant, fluoride can be determined using the same chemistry.