Câu 3:
$Al_2(SO_4)_3+6NH_3+6H_2O\to 2Al(OH)_3+3(NH_4)_2SO_4$
$2Al(OH)_3\buildrel{{t^o}}\over\to Al_2O_3+3H_2O$
$n_{Al_2O_3}=\dfrac{1,08}{102}=0,01(mol)$
$\Rightarrow n_{Al(OH)_3}=0,01.2=0,02(mol)$
$\Rightarrow n_{NH_3}=0,02.3=0,06(mol)$
$V=0,06.22,4=1,344l$
Câu 5:
Gọi x, y là số mol Al, Cu.
$\Rightarrow 27x+64y=7,92$ (1)
$n_{NO}=\dfrac{3,136}{22,4}=0,14(mol)$
Bảo toàn e: $3x+2y=0,14.3$ (2)
$(1)(2)\Rightarrow x=0,08; y=0,09$
$m_{Al}=27x=2,16g$
$m_{Fe}=56y=5,04g$
Câu 7:
Gọi x, y là số mol Al, Fe.
$\Rightarrow 27x+56y=11$ (1)
$n_{NO}=\dfrac{6,72}{22,4}=0,3(mol)$
Bảo toàn e: $3x+3y=0,3.3$ (2)
$(1)(2)\Rightarrow x=0,2; y=0,1$
$\%m_{Al}=\dfrac{27x.100}{11}=49\%$
$\%m_{Fe}=51\%$
