puritatea = m pur/ m impur*100 => m pur= puritatea * m impur/100 = 80*20/100=16g Ca
MCa=40g/mol
n=m/M=16/40=0,4 moli Ca
2Ca + O2 => 2CaO
2 moli Ca................1 mol O2
0,4 moli Ca.............x moli O2
x=1*0,4/2=0,2 moli O2
n=V/Vm=>V=n*Vm=0,2*22,4=4,48 L O2
Vaer=5*VO2=5*4,48=22,4 L aer
MCaO = ACa + AO = 40+16=56g/mol
2 moli Ca.........................56g CaO
0,4 moli Ca.......................xg CaO
x=56*0,4/2= Calculeaza !!!