Chemistry
posted by Marie .
Magnetite, an iron ore with formula Fe3O4, can be reduced by treatment with hydrogen to yield iron metal and water vapor.
(a) Write the balanced equation. (Use the lowest possible coefficients.)
1Fe3O4(s) + 4H2(g)> 3Fe(s) + 4H2O(g)
(b) This process requires 36 kcal for every 1.00 mol of Fe3O4 reduced. How much energy (in kilocalories) is required to produce 63 g of iron?
. kcal
(c) How many grams of hydrogen are needed to produce 69 g of iron?
. g

36 kcal for 3 mols Fe or 12 kcal for 1 mol Fe = 55.85 g Fe.
12 kcal x (63/55.85) = ? kcal 
Magnetite, an iron ore with formula Fe3O4, can be reduced by treatment with hydrogen to yield iron metal and water vapor.
(a) Write the balanced equation. (Use the lowest possible coefficients.)
1Fe3O4(s) + 4H2(g)> 3Fe(s) + 4H2O(g)
How many grams of hydrogen are needed to produce 81g of iron? 
b)
Find the molecular weight of Fe3 which is 167.535
Then divide the 63g of iron by the molecular weight (167.535) and you get 0.376.
Then you multiply 0.376 by the 36 kcal to get your answer of 13.536 or rounded to 14. 
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