Metal monovalent: Na
2 Na + 2 H2O --->2 NaOH + H2
la 2 * 18 g H2O........2 * 40 g NaOH........2 g H2
la 36 g H2O.......x g NaOH...........y g H2 x=80 g NaOH si y = 2 g H2
Metal divalent: Mg
Mg + 2 H2O ----> Mg(OH)2 + H2
la 2 * 18 g H2O.....58 g Mg(OH)2........2 g H2
la 36 g H2O.........a g Mg(OH)2...........b g H2 a = 58 g Mg(OH)2 si 2 g H2