2Na + 2H2O -----> 2NaOH + H2
46.80.22.4
4.6.m.V
V(H2)=22.4*4.6/46=2.24L
m(NaOH)=80*4.6/46=8g
NaOH%=8/(4.6+35.6-0.2)=20%