ThermochemistryHard

Question

The enthalpies of formation of FeO(s) and Fe2O3(s) are −65.0 and −197.0 kcal/mol, respectively. A mixture of the two oxides contains FeO and Fe2O3 in the mole ratio 2:1. If by oxidation it is changed in to a 1:2 mole ratio mixture, then how much of thermal energy will be released per mole of the initial mixture?

Options

A.13.4 kcal
B.67 kcal
C.47.2 kcal
D.81 kcal

Solution

$2FeO + \frac{1}{2}O_{2} \rightarrow Fe_{2}O_{3};\Delta H = ( - 197) - 2( - 65) = - 67\text{ kcal}$

Initial $2a a$

Final $2a - 2x a + x$

$\frac{2a - 2x}{a + x} = \frac{1}{2} \Rightarrow x = \frac{3}{5}a$

and heat released = 67x kcal

∴ Heat released per mole of initial mixture = $\frac{67x}{3a} = 13.4\text{ kcal}$

Create a free account to view solution

View Solution Free
Topic: Thermochemistry·Practice all Thermochemistry questions

More Thermochemistry Questions

For the allotropic change represented by the equation C(graphite) → C(diamond); ΔH = +1.9 kJ. If 6.0 g of diamond and 6....A coffee cup calorimeter initially contains 125 g of water, at a temperature of 24.20C. 8g of ammonium nitrate (NH4NO3),...The enthalpy of neutralization of a strong acid by a strong base is −57.32 kJ mol–1. The enthalpy of formation of water ...A solution of 500 ml of 2 M-KOH is added to 500 ml of 2 M-HCl and the mixture is well shaken. The rise in temperature T1...S + O2 + x kcal .......(1)SO2 + O2 → SO2 + y kcal .......(2)The heat of formation of SO3 in the above reactior :...