m,C= 1000g carbon impur
-calculez ,masa de C pur
p=m,purx100/m,impur
80/100= m,pur/1000----> m,pur=800g C
1mol.....................1mol 1mol gaz are V,m=22,.4 l
C + O2 ------> CO2
12g........................22,4l
800g............................V =800X22,4/12 L=..................CALCULEAZA !!!