1) P2O5 + 3H2O = 2H3PO4
2) H2SO4 + Ba(NO3)2 = BaSO4 + 2HNO3
2H[+] + SO4[2-] + Ba[2+] + 2NO3[-] = BaSO4 +2H[+] + 2NO3[-]
SO4[2-] + Ba[2+] = BaSO4
3) SO3 + Na2O = Na2SO4
W(Ca3)=Ar(Ca3)/Mr(Ca3(PO4)2)*100%
Ar(Ca3)=120
Mr(Ca3(PO4)2)=310 г/моль
W(Ca3)=120/310*100%=39%
4.5*100/78=5.77 литр воздуха