Question

puia68...................

Answer 1

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=