hsg hoa 8

T

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đặt $m_{HCl}=m_{H_2SO_4}=m$
PTHH:
$Zn + 2HCl -> ZnCl_2 + H_2$ (1)
0,1___________________?
$2Al + H_2SO_4 -> Al_2(SO_4)_3 + 3H_2$ (2)

$n_{Zn} = \frac{m_{Zn}}{M_{Zn}} $
\Rightarrow $n_{Zn} = \frac{6,5}{65}$
\Rightarrow $n_{Zn} = 0,1 (mol)$
theo PTHH (1), ta có:
$n_{H_{2(1)}} = n_{Zn}$
\Rightarrow $n_{H_{2(1)}} = 0,1 (mol)$
\Rightarrow $m_{H_{2(1)}} = 0,1 . 2 =0,2 (g)$

$n_{Al} = \frac{x}{M_{Al}}$
\Rightarrow $n_{Al} = \frac{x}{27}$

THeo PTHH (2), ta có:
$n_{H_{2(2)}} = \frac{n_{Al}.3}{2} = \frac{x}{18}$
\Rightarrow $m_{H_{2(2)}} = \frac{x}{18} . 2 = \frac{x}{9}$

Theo đề, ta lại có:
$m + m_{Zn} - m_{H_{2(1)}} = m + x - m_{H_{2(2)}}$
\Rightarrow $6,5 - 0,2 = x - \frac{x}{9}$
\Rightarrow $6,3 = \frac{8.x}{9}$
\Rightarrow $x = 7, 0875 (g)$
 
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