The reactiln with silica explains why fluorine reacts with glass and quartz,but if these are rigorously freed from adsorbed water,the reaction is very slow;hence dry fluorine can be manipulated in dry glass apparatus but all glass tape must be lubricated with fluorocarbon grease since hydrocarbon greases would be attacked. The very strong oxidising properties of fluorine in aqueous systems are seen in reactions such as the conversation of chlorate(V)to chlorate(VII)chromium(III)to dichromate(VI)and the oxidation of the hydrogensulphate ion to peroxodisulphate: