[captainsmooty]

"How many kilograms of CaCO3 should be added for every kilogram of iron ore processed in a blast furnace if the limestone is 96.20% pure and the iron ore contains 7.20% SiO2 by mass? (Note: SiO2(s) + CaCO3(s) --> CaSiO3(s) + CO2(g))"

now i am confused simply because they included 2 different %s and i started by finding the % of SiO2 which is 4.33g. i do not understand how I can use the limestone % and what exactly it has to do with the question. the equation is balanced and CaCO3 is represented as the limestone....   question is how to solve this..?

[captainsmooty]

"Calculate the number of moles in 1 Kg of iron ore, check the stoichiometric ratio of the Silica removal reaction, and then use the number of moles of limestone to calculate how many kgs of limestone are needed for that 1 kg."
after many mistakes even the computer had pity on me and i was given this hint. after checking the ratio of silica removal reaction, i still end up with the wrong answer....  and also the 2nd problem lies in the moles of limestone. i figure i would need to utilize the 96.2% somehow....   i just don't know anymore. i tried every possible equation and it is just not clicking. 

[Borek]

Find mass of SiO₂ in 1 kg of ore, find out how much pure CaCO₃ it needs, find out how much limestone contains this amount of pure CaCO₃.