M,CaCO3=100g/mol
M,CO2= 44g/mol
m,CaCO3 pur= m,impurx80/100= 10x80/100= 8g
ecuatia corecta este
1mol..........1mol.......1mol.........1mol
CaCO3 + H2O + CO2---> Ca(HCO3)2
100g......................44g
8g.........................m,CO2=.8X44/100=..........................CALCULEAZA !!!