106Sir, I am a beginner in chemistry.. [3]
1. Given the following equations:
4 NH3 (g) + 5 O2 (g) → 4 NO (g) + 6 H2O (l) ΔH° = -1170 kJ
4 NH3 (g) + 3 O2 (g) → 2 N2 (g) + 6 H2O (l) ΔH° = -1530 kJ
Using these two equations, determine the heat of formation, ΔHf°, nitrogen monoxide, NO.
2. The standard heats of formation of HCl (g) and HBr (g) are -92.0 kJ/mol and -36.4 kJ/mol respectively. Using this information, calculate ΔH for the following reaction:
Cl2 (g) + 2 HBr (g) → 2 HCl (g) + Br2 (g)
3. For the reaction Fe2O3 (s) + 3 CO (g) → 2 Fe (s) + 3 CO2 (s)
ΔG° = -31.3 kJ. Calculate the standard free energy of formation of the ferric oxide, Fe2O3, if ΔG°f of CO = -137 kJ/mol and ΔG°f of CO2 = -394 kJ/mol.
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4 Answers
1061. Divide both eqns by 4 and subtract 2nd eqn from 1st.
So, ΔHf°, nitrogen monoxide, NO. = -1170/4 - (-1530/4)
= -90 kJ
2. 0.5H2 + 0.5Cl2 --> HCl, ΔH = -92 kJ . .. 1
0.5H2 + 0.5Br2 --> HBr, ΔH = -36.4 kJ .... 2
subtracting eqn 2 from 1 and multiplying by 2
We get the reqd eqn
and ΔH = 2(-92-(-36.4)) kJ = -111.2 kJ
1063. ΔGrkn = ΔGprod - ΔGreactant
=> -31.3 = [3(-394) + 2*0] - [ΔGFe2O3 + 3(-137)]
from this ΔGFe2O3 can be found
1357Asish, these were for the beginners.
its ok if you have solved it