It is seen from the given balanced equation of the repacement reaction that every mole of #(CH_2)_n# requires total #2nmol# #F_2#.Here #n# mol goes to replace hydrogen and #n# mol goes to form #2n# mol #HF# and thus one mole of #(CF_2)_n# is formed.
Molar masses of
#F_2->38g"/"mol#
#(CF_2)_n->50ng"/"mol#
Fluorine required for the production of #50ng# #(CF_2)_n# is 2n mol or #76ng#
So to prodoce 1kg #(CF_2)_n# we rrequire #(76n)/(50n)kg=1.52kg# Fluorine, if not recovered from #HF# produced as byproduct.
As #50%# #F_2# goes to form the byproduct #HF#,then its recovery will diminsh the net consumption by #50%# and the consumption of Flurine for productio of 1kg #(CF_2)_n# then will be #50%of1.52kg=0.76kg#
