Deterioration of buildings, bridges, and other structures through the rusting of

Question

Deterioration of buildings, bridges, and other structures through the rusting of iron costs millions of dollars everyday. Although the actual process also requires water, a simplified equation (with rust shown as iron(III) oxide (Fe2O3) is:

4Fe(s)+3O2(g) --> 2Fe2O3(s)

delta(h reaction =-1.65 x 10^3

How much heat is evolved when 0.250 kg of iron rusts?.....KJ MOLES in SCIENTIFIC NOTATION .
How much rust forms when 9.40x 10^3 kJ of heat is released?..... SCIENTIFIC NOTATION ....

I need both answers in SCIENTIFIC NOTATION .... thank you

thank you.

Explanation / Answer

Solution :-

4Fe(s)+3O2(g) --> 2Fe2O3(s)

delta(h reaction = -1.65 x 10^3 kJ

How much heat is evolved when 0.250 kg of iron rusts?

Solution :- using the mole ratio of the balanced reaction we can calculate the amount of heat produced as follows.

(0.250 kg Fe*1000 g/ 1kg)*(1mol / 55.845 g)*(-1650 kJ / 4 mol Fe) = -1.85*10^3 kJ

Therefore it will give -1.85*10^3 kJ heat (sign is negative because its exothermic reaction)

So we can write it as amount of heat given = 1.85*10^3 kJ

How much rust forms when 9.40x 10^3 kJ of heat is released?

Solution :-

Using the mole ratio of the reaction we can calculate the amount of the rust formed as follows

(9.40*10^3 kJ * 2 mol Fe2O3/ 1.65*10^3 kJ)*(159.687 g / 1 mol Fe2O3) =1.82*10^3 g Fe2O3

Therefore it will give 1.82*10^3 g rust

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