ro apa= 1g/cm cub----> m,apa =1g/cm cubx400cm cub= 400g
2mol 2mol 2mol
2Na + 2H2O---> 2NaOH+H2
2x23g..........2x18g..........2x40g
4,6g...............m=3,6g........m=8g
c= mdx100/ms
md=8gNaOH
ms= md+ m,apa; m,apa= 400g-3,6g= 396,4g
ms= 404,4g
c= 8x100/ 404,4----------------------> calculeaza !!!!!