Question

Cho 4,6g Na tác dụng hoàn toàn với 35,6g nước. C% dung dịch tạo thành là bn?

Answer 1

2Na+2H2O---->2NaOH+H2

n Na=4,6/23=0,2(mol)

Theo pthh

n H2=1/2 n Na=0,1(mol)

--->m H2=0,2(g)

m dd=35,6+4,6-0,2=40(g)

Theo pthh

n NaOH =n Na=0,2(mol)

C% NaOH=\(\frac{0,2.40}{40}.100\%=20\%\)

Answer 2

https://i.imgur.com/eIsho6R.jpg

Answer 3

\(n_{Na}=\frac{4,6}{23}=0,2\left(mol\right)\)

\(\text{PTHH: 2Na + 2H2O -------> 2NaOH + H2O}\)

..............0,2..................................0,2...................(mol)

\(\Rightarrow\text{C% NaOH =0,2.(23+16+1)/4,6+35,6=19,9%}\)