Răspuns:
MK=39g/mol
MK2O=2×39+16=94g/mol
m=n×M=3×39=117g
calculam in grame
2×39g........2×94g
2K + O2 → 2K2O
117g...............xg
x=117×2×94/2×39=282gK2O
calculam in moli
2moli............2moli
2K + O2 → 2K2O
3moli...........ymoli
y=3x2/2=3moli K2O
Explicație: