can rat gap

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desert_eagle_tl

hoa tan hoan toan hon hop X gomFe Mgvao HCl 20% thu duoc Y co nong do FeCl2 15,76% nong doMgCl2 cotrong dung dich Y

mol Fe : a ==> mol Mg = 1 - a

Fe + 2HCl ----------->FeCl2 + H2
Mg + 2HCl -------->MgCl2 + H2

==> mol HCl = 2 ==> mol H2 = 1
==> m dd sau phản ứng = 56a + 24(1-a )+ [TEX]\frac{2.36,5.100}{20}[/TEX] - 2 = 32a + 387 (g)

*** Ta có [TEX]\frac{127a}{32a + 387}.100 = 15,76[/TEX] ==> a = 0,5

==> m dd sau pu = 32.0,5 + 387 = 403 gam

==> % MgCl2 = [TEX]\frac{0,5.95}{403}.100% = 11,79%[/TEX]
 
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