Câu 5:
Gọi x, y (l) là thể tích dd X và Y.
$n_{H_2SO_4}=0,02x$
$n_{NaOH}=0,035y$
$2NaOH+H_2SO_4\to Na_2SO_4+2H_2O$
$\Rightarrow n_{H_2SO_4\text{dư}}=0,02x-0,0175y$
$\Rightarrow 0,02x-0,0175y=0,01(x+y)$
$\Leftrightarrow 0,01x=0,0275y$
$\Leftrightarrow \dfrac{x}{y}=\dfrac{11}{4}$
Câu 6:
$n_{H_2(1)}=0,06 mol$
$n_{H_2(2)}=0,045 mol$
$H_2+O\to H_2O$
$\Rightarrow n_O=0,06 mol$
BTKL: $m_M=3,48-0,06.16=2,52g$
$2M+2nHCl\to 2MCl_n+nH_2$
$\Rightarrow n_M=\dfrac{0,09}{n}$
$M_M=\dfrac{2,52n}{0,09}=28n$
$n=2\Rightarrow M_M=56(Fe)$
$n_{Fe} : n_O=0,045:0,06=3:4\to Fe_3O_4$
