Limiting Reactant

知識就是力量

2009-11-26 5:43 am

In the blast furnace, the overall reaction is
2Fe2O3 (s) + 3C (s) -------> 3CO2 (g) + 4Fe (s)

what is the maximum mass of iron that can be obtained from 700 tonnes of iron (III) oxide and 70 tonnes of coke?
[1 tonne = 1000 kg]

更新1:

Given the relative atomic mass of Fe = 55.8 ; O = 16.0 ; C = 12.0

更新2:

Some calculation errors you make: No. of moles of Fe2O3 added = (700 x 1000 x 1000)/159.6 = 4.403 x 10^6 mol It should be 4.386x10^6 mol But nevermind~

更新3:

Cheers!

回答 (1)

老爺子

2009-11-26 6:44 am

✔ 最佳答案

The maximum mass of Fe can be obtained when coke contains 100% of carbon and the reaction is complete.

2Fe2O3 + 3C → 3CO2 + 4Fe
In the reaction, mole ratio Fe2O3 : C = 2 : 3

Molar mass of Fe2O3 = 55.8x2 + 16x3 = 159.6 g/mol
Molar mass of C = 12 g/mol
No. of moles of Fe2O3 added = (700 x 1000 x 1000)/159.6 = 4.403 x 10^6 mol
No. of moles of C added = (70 x 1000 x 1000)/12 = 5.833 x 10^6 mol
If C is completely reacted, Fe2O3 needed = (5.833 x 10^6) x (2/3) = 3.889 x 10^6 mol
Hence, Fe2O3 is in excess, and C is the limiting reactant (completely reacted).

Mole ratio C : Fe = 3 : 4
No. of moles of C reacted = 5.833 x 10^6 mol
No. of moles of Fe formed = (5.833 x 10^6) x (4/3) = 7.777 x 10^6 mol
Maximum mass of Fe formed = (7.777 x 10^6) x 55.8 = 4.34 x 10^8 g = 434 tonnes

2009-11-25 23:04:50 補充：
Yes, it should be 4.386x10^6 mol, but not 4.403 x 10^6 mol.
However, this step would not affect all the other steps of the answer.

👍 0 👎 0