Enthalpy

From the data of following bond energies:

 $\begin{array}{l}H-Hbondenergy:431.37kJmo{l}^{-1}\\ C=Cbondenergy:606.10kJmo{l}^{-1}\\ C-Cbondenergy:336.49kJmo{l}^{-1}\\ C-Hbondenergy:410.50kJmo{l}^{-1}\end{array}$

Calculate the enthalpy of the following reaction in $kJmo{l}^{-1}$.

Consider the following reactions

(i) ${\text{H}}_{\left(\text{aq}\right)}^{+}+{\text{OH}}_{\left(\text{aq}\right)}^{-}\to {\text{H}}_2\text{O}\left(\mathrm{\ell \; }\right)$

$\Delta \text{H}=-{\text{X}}_1{\text{ k J mol}}^{-1}$

(ii) ${\text{H}}_2\left(\text{g}\right)+\frac{1}{2}{\text{O}}_2\left(\text{g}\right)\to {\text{H}}_2\text{O}\left(\ell \right)$

$\Delta \text{H}=-{\text{X}}_2{\text{ k J mol}}^{-1}$

(iii) ${\mathrm{CO}}_2\left(\mathrm{g}\right)+{\mathrm{H}}_2\left(\mathrm{g}\right)\to \mathrm{CO}\left(\mathrm{g}\right)+{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$

$\Delta \text{H}=-{\text{X}}_3{\text{ k J mol}}^{-1}$

(iv) ${\text{C}}_2{\text{H}}_2\left(\text{g}\right)+\frac{5}{2}{\text{O}}_2\left(\text{g}\right)\to 2{\text{CO}}_2\left(\text{g}\right)+{\text{H}}_2\text{O}\left(\ell \right)$

$\Delta \text{H}=+4{\text{X}}_4{\text{ k J mol}}^{-1}$

Enthalpy of formation of ${\text{H}}_2\text{O}\left(\ell \right)$

What is the enthalpy change for,

$2{\mathrm{H}}_2{\mathrm{O}}_2\left(\mathrm{l}\right)\to 2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)$ if heat of formation of  ${\mathrm{H}}_2{\mathrm{O}}_2\left(\mathrm{l}\right)\mathrm{and}{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$  are $-188$ and $-286 \mathrm{kJ}/\mathrm{mol}$respectively (in standard conditions)?

Bond dissociation enthalpy of  $H_2,C{l}_{\mathrm{2 }}\mathrm{and}HCl\mathrm{ are }434,242\mathrm{ and} \mathrm{431 }\mathrm{k}\mathrm{J}\mathrm{ m}\mathrm{o}{\mathrm{l}}^{-1}$ respectively. The enthalpy of formation of HCl is:  

How many of the following have standard heat of formation value of zero.

$\left(\mathrm{i}\right) {\mathrm{Br}}_{2\left(\mathrm{l}\right)}$

$\left(\mathrm{ii}\right) {{\mathrm{CO}}_2}_{\left(\mathrm{g}\right)}$

$\left(\mathrm{iii}\right) {\mathrm{C}}_{\text{(graphite) }}$

$\left(\mathrm{iv}\right) {\mathrm{Cl}}_{2\left(\mathrm{l}\right)}$

$\left(\mathrm{v}\right) {\mathrm{Cl}}_{2\left(\mathrm{g}\right)}$

$\left(\mathrm{vi}\right) {\mathrm{F}}_{2\left(\mathrm{g}\right)}$

$\left(\mathrm{vii}\right) {\mathrm{F}}_{\left(\mathrm{g}\right)}$

$\left(\mathrm{viii}\right) {\mathrm{I}}_{2\left(\mathrm{g}\right)}$

$\left(\mathrm{ix}\right) {\mathrm{S}}_{\left(\text{monoclinic }\right)}$

$\left(\mathrm{x}\right) {\mathrm{N}}_{2\left(\mathrm{g}\right)}$

$\left(\mathrm{xi}\right) {\mathrm{P}}_{\left(\mathrm{blcak}\right)}$

$\left(\mathrm{xii}\right) {\mathrm{P}}_{\left(\mathrm{red}\right)}$

$\left(\mathrm{xiii}\right) {\mathrm{CH}}_4$

Why heat of a reaction of an exothermic process at constant volume is negative and equal to change in internal energy?

For an exothermic reaction at constant volume, the heat of the reaction is equal to internal energy with a negative sign.

Why heat of a reaction of an endothermic process at constant volume is positive and equal to change in internal energy?

The heat of a reaction at constant volume for an endothermic process is equal to $∆\mathrm{U}$ and it has a positive value.

The heat of reaction for an endothermic reaction at constant volume in equilibrium is $1200 \mathrm{cal}$ more than the heat of reaction at constant pressure at $300 \mathrm{K}$. Calculate the ratio of equilibrium constants ${\mathrm{K}}_{\mathrm{p}}$ and ${\mathrm{K}}_{\mathrm{c}}$.

Predict the signs of $∆\mathrm{U},∆\mathrm{H}$ and $\mathrm{Q}$ for an exothermic reaction at constant volume with reversible work.