Question

Hòa tan 12,4g Na2O vào 200g nước. Tính C% dd thu được? Cho Na=23, O=16, H=1

Answer 1

Na2O+h2O->2NaOH

0,2------------------0,4

n Na2O=12,4\62=0,2 mol

=>m NaOH=0,4.40=40,4g

=>C%=40,4\12,4+200=19%

Answer 2

\(n_{Na_2O}=\dfrac{12,4}{62}=0,2\left(mol\right)\\ Na_2O+H_2O\rightarrow2NaOH\\ n_{NaOH}=0,2.2=0,4\left(mol\right)\\ m_{ddNaỌH}=12,4+200=212,4\left(g\right)\\ C\%_{ddNaOH}=\dfrac{0,4.40}{212,4}.100\approx7,533\%\)