117 g NaOH
n = m : M [ n=nr. moli ; m=masa subst. ; M =masa molara ]
n=117 g : 40g/moli=2,925 moli NaOH
MNaOH=23+16 +1=40-------> 40g/moli
Se poate calcula si prin regula de trei simpla :
40gNaOH----------1mol NaOH
117 g------------------X
X= 117g : 40 g/moli=2,925 moli NaOH