Răspuns:
Explicație:
M Fe = 56 g/mol
M S = 32 g/mol
m = 32 x 4 + 56 x 5 = 128 + 280 = 408 g amestec
408 g amestec .................128 g S .......................280 g Fe
100 ..........................................a...................................b
a = 128*100/408 = 31,37%
b = 280*100/408 = 68,63%