-calculez masa de substanta pura
p= m,px100/m,i----> mp= 250x80/200kg= 200kg
-din ecuatia chimica, deduc masa de oxid de calciu, cu M= 56g/mol
M,CaCO3=100g/mol
1kmol.....................1kmol sau, in kilograme
CaCO3======> CaO + CO2↑
100kg.....................56kg
200kg...................m=.................................calculeaza !!!!!