Thermodynamics ...

$$\Delta_f H^{ \ominus }$$ of hypothetical $$MgCl$$ is $$-125  kJ  mol^{ -1 }$$ and for $$MgCl_2$$ is $$-642  kJ  mol^{ -1 }$$. The enthalpy of disproportionation of $$MgCl$$ is $$-49x$$. Find the value of x.

Using the enthalpies of formation, calculate the energy (kJ) released when $$3.00  g$$ of $$N{ H }_{ 3\left( g \right)  }$$ reacts according to the following equation?
(Atomic weights: $$N = 14.00,  H = 1.008$$).
          $$4N{ H }_{ 3 }\left( g \right) +5{ O }_{ 2 }\left( g \right) \longrightarrow 4NO\left( g \right) +6{ H }_{ 2 }O\left( g \right) $$
$$\Delta HN{ H }_{ 3 }\left( g \right) =-46.1   { kJ }/{ mole }$$
$$\Delta HNO\left( g \right) =+90.2   { kJ }/{ mole }$$
$$\Delta H{ H }_{ 2 }O\left( g \right) =-241.8   { kJ }/{ mole }$$

a) Calculate heat of dissociation for Acetic acid from the following data:

$$\Delta_f H^{ \ominus }$$ of Cyclohexene $$(l)$$ and benzene at $$25^{ \circ}C$$ is $$-156$$ and $$+46  kJ  mol^{ -1 }$$, respectively. 
$$\Delta_{ hydrogenation }H^{ \ominus }$$ of Cyclohexene $$(l)$$ at $$25^{ \circ }C$$ is $$-119  kJ  mol^{ -1 }$$.

Resonance energy of benzene is found to be $$-38x  kJ  mol^{ -1 }$$. Find the value of x.

For the reaction $$X_2O_4(l)\rightarrow 2XO_2(g)$$

Determine $${ \Delta H }/{ kJ }$$ for the following reaction using the listed enthalpies of reaction:
$$4CO\left( g \right) +8{ H }_{ 2 }\left( g \right) \longrightarrow 3C{ H }_{ 4 }\left( g \right) +C{ O }_{ 2 }\left( g \right) +2{ H }_{ 2 }O\left( l \right) $$

Use the given standard enthalpies of formation to determine the heat of reaction of the following reaction:
               $$2LiOH+C{ O }_{ 2 }\left( g \right) \longrightarrow { Li }_{ 2 }C{ O }_{ 3 }\left( s \right) +{ H }_{ 2 }O\ (l)$$
$$\Delta { H }_{ f }^{ }LiOH\left( s \right) =-487.23{ kJ }/{ mole }$$
$$\Delta { H }_{ f }^{ }{ Li }_{ 2 }C{ O }_{ 3 }\left( s \right) =-1215.6{ kJ }/{ mole }$$
$$\Delta { H }_{ f }^{ }{ H }_{ 2 }O\ (l) =-285.85{ kJ }/{ mole }$$
$$\Delta { H }_{ f }^{ }C{ O }_{ 2 }\left( g \right) =-393.5{ kJ }/{ mole }$$

Determine $$\Delta H$$ of the following reaction using the listed heats of formation:
               $$4HN{ O }_{ 3 }\left( I \right) +{ P }_{ 4 }{ O }_{ 10 }\left( s \right) \longrightarrow 2{ N }_{ 2 }{ O }_{ 5 }\left( s \right) +4HP{ O }_{ 3 }\left( s \right) $$
$$\Delta { H }_{ f }^{ }HN{ O }_{ 3 }\left( I \right) =-174.1{ kJ }/{ mole }$$
$$\Delta { H }_{ f }^{ }{ N }_{ 2 }{ O }_{ 5 }\left( s \right) =-43.1{ kJ }/{ mole }$$
$$\Delta { H }_{ f }^{ }{ P }_{ 4 }{ O }_{ 10 }\left( s \right) =-2984.0{ kJ }/{ mole }$$
$$\Delta { H }_{ f }^{ }HP{ O }_{ 3 }\left( s \right) =-948.5{ kJ }/mole$$

Calculate the value of $${ \Delta H }{\ ( kJ) }$$ for the following reaction using the listed thermochemical equations $$2C(s) + H_2(g) \rightarrow C_2H_ 2 (g)$$.