se da : m,Na= 230g
c,NaOH= 40%
se cere ms ?
calculez moli Na: ,stiind M,Na= 23g/mol
niu= m/M= 230g/23g/mol= 10mol Na
calculez moli si masa NaOH din ecuatia chimica
2mol.........................2mol
2Na + 2H2O---> 2NaOH + H2
10mol.........................x= 10molNaOH, M,NaOH= 40g/mol
m=niuxM= 10molx40g/mol=400g
aceasta masa, 400g reprezinta masa dizolvata in solutie,md-- > calculez ms din relatia
c= mdx100/ms---> ms= 400x100/40g=1000g=
