Thermodynamics ...

If  the resonance energy of $$NO_2(:O--N==O:)$$ is X kJ The measured enthalpy formation of $$NO_2(\Delta_f H^{ \ominus } )$$ is $$34  kJ  mol^{ -1 }$$. The bond energies given are:
$$N--O \Rightarrow 222  kJ  mol^{ -1 }$$
$$N\equiv N \Rightarrow 946  kJ  mol^{ -1 }$$
$$O==O \Rightarrow 498  kJ  mol^{ -1 }$$
$$N==O \Rightarrow 607  kJ  mol^{ -1 }$$
Find out the value of X

Find the $$\Delta H$$ of the following reaction. $$OF_2(g) + H_2O(g)\longrightarrow O_2(g) + 2HF(g)$$. Average bond energies of $$O-F$$, $$O-H$$, $$O=O$$ and $$H-F$$ are $$44$$, $$111$$, $$118$$ and $$135 $$ kcal mol$$^{ -1 }$$, respectively.

The thermo-chemical equation for solid and liquid rocket fuel are given below:
$$2Al(s) + 1\frac { 1 }{ 2 }O_2(g)\longrightarrow Al_2O_3(s), \Delta H = -1667.8 kJ$$

Calculate the $$\Delta H^{ \ominus }$$ for the reduction of $$Fe_2O_3(s)$$ by $$Al(s)$$ at $$25^{ \circ }C$$. The enthalpies of formation of $$Fe_2O_3(s)$$ and $$Al_2O_3$$ are $$-825.5$$ and $$-1675.7  kJ  mol^{ -1 }$$ respectively.

How much heat is liberated when one mole of gaseous $$Na^{ \oplus }$$ combines with one mole of $$Cl^{ \ominus }$$ ion to form solid $$NaCl$$.

The standard enthalpy of formation of $$FeO$$ and $$Fe_2O_3$$ is $$-65 \: kcal \: mol^{-1}$$ and $$-197 \: kcal \: mol^{-1}$$ respectively. If a mixture containing $$FeO$$ and $$FeO_3$$ in $$2 : 1$$ mole ratio on oxidation is changed into $$1 : 2$$ mole ratio, thermal energy in kcal released per mole of mixture will be :

When $$10  g$$ of $$Al$$ is used for reduction in each of the following alumino thermic reactions, which reaction would generate more heat and by how much ?
a.  $$2Al + Cr_2O_3\rightarrow Al_2O_3 + 2Cr$$
b.  $$2Al + Fe_2O_3\rightarrow Al_2O_3 + 2Fe$$

If $$2Al(s) + 1\frac { 1 }{ 2 }O_2(g)\longrightarrow Al_2O_3(s), \Delta H = -166.78 kJ$$
$$H_2(g) + \frac { 1 }{ 2 }O_2(g)\longrightarrow H_2O(l), \Delta H = -285.9 kJ$$

The heat of combustion of acetylene is 312 kcal. If heat of formation of $$CO_2$$ and $$H_2O$$ are 94.38 and 68.38 kcal respectively,  $$C \equiv\!\! \equiv C$$ bond energy is $$x \:kcal $$. Given that heat of atomisation of C and H are 150.0 and 51.5 kcal respectively and $$C-\! \! \! -H$$ bond energy is 93.64 kcal. Value of $$x$$