\(n_{Na}=\frac{4,6}{23}=0,2\left(mol\right)\)
PTHH:
\(2Na+2H_2O\rightarrow2NaOH+H_2\uparrow\)
0,2mol _________0,2mol___0,1mol
\(\rightarrow V_{H_2}=0,1.22,4=2,24\left(l\right)\)
Đổi: 500ml = 0,5 l
\(n_{NaOH}=0,2mol\)
\(\rightarrow C_{M_{ddNaOH}}=\frac{n}{V}=\frac{0,2}{0,5}=0,4\left(M\right)\)