Kali pemanganat \(--->\) Kali manganat + Mangan đioxit + Oxi

Chọn C

PTHH: \(K_2CO_3+2HCl\rightarrow2KCl+CO_2\uparrow+H_2O\)

Ta có: \(n_{HCl}=2n_{CO_2}=2\cdot\dfrac{6,72}{22,4}=0,6\left(mol\right)\) \(\Rightarrow C_{M_{HCl}}=\dfrac{0,6}{0,4}=1,5\left(M\right)\)

Chọn A

5a

PTHH: \(K+H_2O\rightarrow KOH+\dfrac{1}{2}H_2\uparrow\)

            \(2KOH+CuSO_4\rightarrow K_2SO_4+Cu\left(OH\right)_2\downarrow\)

            \(Cu\left(OH\right)_2\xrightarrow[]{t^o}CuO+H_2O\)

Ta có: \(n_{CuO}=\dfrac{24}{80}=0,3\left(mol\right)=n_{Cu\left(OH\right)_2}\) 

\(\Rightarrow n_{KOH}=0,6\left(mol\right)=n_K\) \(\Rightarrow m_K=0,6\cdot39=23,4\left(g\right)\)

CuCl₂, FeCl₃, AgCl, NaCl

Chọn XY₂

PTHH: \(2Al\left(OH\right)_3\xrightarrow[]{t^o}Al_2O_3+3H_2O\)

Tính theo sản phẩm

Ta có: \(n_{Al_2O_3}=\dfrac{10,2}{102}=0,1\left(mol\right)\) \(\Rightarrow n_{Al\left(OH\right)_3\left(p.ứ\right)}=0,2\left(mol\right)\)

\(\Rightarrow\left\{{}\begin{matrix}m_{Al\left(OH\right)_3\left(p.ứ\right)}=0,2\cdot78=15,6\left(g\right)\\m_{Al\left(OH\right)_3\left(dư\right)}=18-15,6=2,4\left(g\right)\end{matrix}\right.\)

Bảo toàn khối lượng: \(m_{Fe_3O_4}=m_{Fe}+m_{O_2}=11,6\left(g\right)\)