42 g x g
4 Al + 3 O2 = 2 Al2O3
4*27=108g 2*(27*2+3*16)=204 g
42/108=x/204=>21/54=x/204=>7/18=x/204=>x=(7*204)/18=>
=>x=1428/18=>x=79,33 g Al2O3
360 g x g
2 H2O + 2 Na = H2 + 2 NaOH
2 moli 2 moli
2*(2*1+16)=36 g 2*(23+16+1)=80 g
360/36=x/80=>10=x/80=>x=10*80=>x=800 g NaOH