Answer to Question #155511 in General Chemistry for Sage Topaz

Question

One of the suggested methods for removing dangerous mercury compounds from industrial wastes is to cause the compounds to react in such a way as to form elemental mercury, which can be trapped more easily. Consider the reaction of HgCl₂ with Al, to produce Hg and AlCl_3.

The equation: 3 HgCl₂ + 2 Al → 3 Hg + 2 AlCl₃

What amount of Al would be required to react with 436 g HgCl₂? How many g Hg is recovered?

Answer 1

Using a mass-mass relationship

Molar mass Al=27 HgCl2=271.5

If 54g of Al reacts with 814.5g of HgCl2

Then xg of Al reacts with 436g of HgCl2

x=54×436/814.5

X=29g of Al

Mass of Hg recovered =814.5-436

=378.5g