nNa2O=\(\frac{6,2}{62}\)=0,1 (mol)
PT
Na2O +H2O→2NaOH
theo pt 1...1...2...mol
theo đb 0,1....0,1....0,2...mol
a) CM=\(\frac{0,2}{5}\)=0,4 mol
b) NaOH +HCl →NaCl +H2O
theopt 1.........1....1.......1...mol
theo đb 0,2....0,2 ..mol
mHCl=0,2 .3,5 =73 (g)