1/
$a,BaO+H_2O\xrightarrow{} Ba(OH)_2$
$b,CO_2+H_2O⇄H_2CO_3$
$c,Zn+H_2SO_4\xrightarrow{} ZnSO_4+H_2↑$
$d,3H_2+Fe_2O_3\xrightarrow{t^o} 2Fe+3H_2O$
2/
$a,PTPƯ:Fe+2HCl\xrightarrow{} FeCl_2+H_2↑$
$b,n_{Fe}=\dfrac{2,8}{56}=0,05mol.$
$Theo$ $pt:$ $n_{H_2}=n_{Fe}=0,05mol.$
$⇒V_{H_2}=0,05.22,4=1,12l.$
$c,Theo$ $pt:$ $n_{HCl}=2n_{Fe}=0,1mol.$
$⇒m_{HCl}=0,1.36,5=3,65g.$
$⇒m_{ddHCl}=\dfrac{3,65}{10\%}=36,5g.$
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