Reactions involving gold have been of particular interest to alchemists. Consider the following reactions, Au(OH)_(3) + 4 HCl ""^(3)//""_(4)®HAuCl_(4) + 3 H_(2)O, DH = - 28 kcal Au(OH)_(3) + 4 HBr""^(3)//""_(4)®HAuBr_(4) + 3 H_(2)O, DH = -36.8 kcal In an experiment there was an absorption of 0.44 kcal when one mole of HAuBr_(4) was mixed with 4 moles of HCl. Then the fraction of HAuBr_(4) converted into HAuCl_(4) (percentage conversion)

Reactions involving gold have been of particular interest to alchemist

1.	Reactions involving gold have been of particular interest to alchemists. Consider the following reactions, Au(OH)_(3) + 4 HCl ""^(3)//""_(4)®HAuCl_(4) + 3 H_(2)O, DH = - 28 kcal Au(OH)_(3) + 4 HBr""^(3)//""_(4)®HAuBr_(4) + 3 H_(2)O, DH = -36.8 kcal In an experiment there was an absorption of 0.44 kcal when one mole of HAuBr_(4) was mixed with 4 moles of HCl. Then the fraction of HAuBr_(4) converted into HAuCl_(4) (percentage conversion)
Answer» 0.05 0.06 0.07 0.08 Solution :Reaction for GIVEN condition is as follows. `HAuBr_(4) + 4HCl rarr HAuCl_(4) + 4HBr, DELTA H` For this Reaction is `= -28 - (-36.8) = 8.8` K.cal. So one MOLE of `HAuBr_(4)` can be converted in to `HAuCl_(4)` by absorption of 8.8K. Cal So Absorption of 0.44 K.Cal can give `(1)/(8.8) xx 0.44` moles of `HAuCl_(4)`. So no. of mole of `HAuCl_(4)` obtained = 0.05 So % `=(0.05)/(1) xx 100= 5%`