P+O2-to>P2O5
Cu+O2-to>CuO
2>'
2K+2H2O->2KOH+H2
0,1-------------0,1---------0,05
nK=3,9\39=0,1 mol
=>VH2=0,05.22,4=1,12l
=>mKOH=0,1.56=5,6g
=>C%=5,6\200.100=2,8%
Câu 1:
a) \(P+O_2--t^o->P_2O_5\)
\(Cu+O_2--t^o->CuO\)
b) \(Fe_2O_3+H_2--t^o->Fe+H_2O\)
\(HgO+O_2--t^o->Hg+O_2\)
\(Fe_xO_y+H_2--t^o->Fe+H_2O\)
Câu 2:
a) PTHH: \(2K+2H_2O\rightarrow2KOH+H_2\)
b) Ta có: \(n_K=\frac{3,9}{39}=0,1\left(mol\right)\) \(\Rightarrow n_{H_2}=0,05mol\)
\(\Rightarrow V_{H_2}=0,05\cdot22,4=1,12\left(l\right)\)
c) Theo PTHH: \(\left\{{}\begin{matrix}n_K=n_{KOH}=0,1mol\\n_{H_2}=0,05mol\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}m_{KOH}=0,1\cdot56=5,6\left(g\right)\\m_{H_2}=0,05\cdot2=0,1\left(g\right)\end{matrix}\right.\)
Mặt khác: \(m_{dd}=m_K+m_{H_2O}-m_{H_2}=3,9+200-0,1=203,8\left(g\right)\)
\(\Rightarrow C\%_{KOH}=\frac{5,6}{203,8}\cdot100\approx2,75\%\)
