Ta có:
\(\left\{{}\begin{matrix}m_{Na}=5,4.42,593=2,3\left(g\right)\\m_{Na2O}=5,4-2,4=3,1\left(g\right)\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}n_{Na}=\frac{2,3}{23}=0,1\left(mol\right)\\n_{Na2O}=\frac{3,1}{62}=0,05\left(mol\right)\end{matrix}\right.\)
\(PTHH:2Na+2H_2O\rightarrow2NaOH+H_2\)
__________ 0,1___________0,1________0,05
\(n_{H2}=0,05\left(mol\right)\Rightarrow V_{H2}=0,05.22,4=1,12\left(l\right)\)
\(Na_2O+H_2O\rightarrow2NaOH\)
0,05______________0,1
\(n_{NaOH}=0,1+0,1=0,2\left(mol\right)\)
\(\Rightarrow m_{NaOH\left(tao.thanh\right)}=0,2.40=8\left(g\right)\)