Enthalpy

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

The enthalpy change of a reaction is independent of

Define 'Enthalpy'

One mol of a non-ideal gas undergoes a change of state $(2.0 \mathrm{atm}, 3.0 \mathrm{L}, 95 \mathrm{K}) \to (4.0 \mathrm{atm}, 5.0 \mathrm{L}, 245 \mathrm{K})$ with a change in internal energy, $∆\mathrm{U}$$= 30.0 \mathrm{L} \mathrm{atm}$. The change in enthalpy $(∆\mathrm{H})$ of the process in $\mathrm{L} \mathrm{atm}$ is

Calculate the heat of formation of carbon disulphide if the heat of combustion of $\mathrm{C},\mathrm{ }\mathrm{S}$ and $\mathrm{C}{\mathrm{S}}_2$ are $-393.3\mathrm{ }\mathrm{k}\mathrm{J}$ , $-293.7\mathrm{ }\mathrm{k}\mathrm{J}$ and $-1108.76\mathrm{ }\mathrm{k}\mathrm{J}$ . 

Among the following, the transition elements that has the lowest enthalpy of atomisation is:

Select the incorrect pair among the following examples of reactions and the type of heat/enthalpy involved. 

On the basis of following data , calculate the heat of reaction $(\mathrm{kJ}/\mathrm{mol})$ for the given process.

${\mathrm{CH}}_4\left(\mathrm{g}\right)+2{\mathrm{O}}_2\left(\mathrm{g}\right)\mathrm{ }\to {\mathrm{CO}}_2\left(\mathrm{g}\right)+2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right)$

$\mathrm{BE}(\mathrm{C}–\mathrm{H})=414\mathrm{kJ}/\mathrm{mol} , \mathrm{BE}(\mathrm{O}=\mathrm{O})=498\mathrm{kJ}/\mathrm{mol},$

$\mathrm{BE}(\mathrm{C}=\mathrm{O})=741\mathrm{kJ}/\mathrm{mol} , \mathrm{BE}(\mathrm{O}–\mathrm{H})=464\mathrm{kJ}/\mathrm{mol}$

Find the enthalpy of formation of the hydroxyl ion, given the enthalpy of formation of water is  $–285.84\mathrm{ }\mathrm{kJ}\mathrm{ }{\mathrm{mol}}^{-1}$, the enthalpy of neutralization of a strong acid by a strong base is $-57.32\mathrm{ }\mathrm{kJ}\mathrm{ }{\mathrm{mol}}^{-1}.$

If $20\mathrm{ }\mathrm{mL}$ of $\mathrm{HCl}$ is added to $20\mathrm{ }\mathrm{mL}$ of $\mathrm{NaOH}$ solution of same strength, $5°\mathrm{C}$ increment in temperature takes place. If $200$ $\mathrm{mL}$ of same $\mathrm{HCl}$ solution is mixed with $200\mathrm{ }\mathrm{mL}$ of same $\mathrm{NaOH}$ solution, temperature increases by-

Using the following data, calculate the amount of heat evolved during the complete combustion of 100ml of liquid benzene.

(i) $18 \mathrm{g}$ graphite, on complete combustion, evolves $590 \mathrm{kJ}$ heat.
(ii)$15889 \mathrm{kJ}$ of heat is required to dissociate all the molecules of $1 \mathrm{L}$ liquid water into ${\mathrm{H}}_2\mathrm{ }$ and ${\mathrm{O}}_2$ .
(iii) The heat of formation of liquid benzene is $+50$ $\mathrm{kJ}/\mathrm{mol}$ .
(iv) Density of ${\mathrm{C}}_6{\mathrm{H}}_6\left(\mathrm{l}\right)\mathrm{ }=\mathrm{ }0.87\mathrm{g}/\mathrm{mL}$ and that of ${\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)=1\mathrm{g}/\mathrm{mL}$

(all energies measured at standard condition)

Given $∆{\mathrm{H}}_{\mathrm{f}}^0$ of ${\mathrm{N}}_2\mathrm{O}=82$ . (All data at standard state in $\mathrm{kJ}/\mathrm{mol}$ ).
Bond energies of
$\mathrm{N}\equiv \mathrm{N}$     $946$
$\mathrm{N}=\mathrm{N} \mathrm{ }$ $418$
$\mathrm{O}=\mathrm{O}$     $498$
$\mathrm{N}=\mathrm{O}$      $607$

Then calculate the resonance energy of ${\mathrm{N}}_2\mathrm{O}$

Which of the following relationship between x and y will be true when equal volumes of $1 \mathrm{M}\mathrm{ }\mathrm{H}\mathrm{C}\mathrm{l}$ and $1 \mathrm{M}\mathrm{ }{\mathrm{H}}_2\mathrm{S}{\mathrm{O}}_4$ are neutralized completely by dil. NaOH solution and $\mathrm{x}$ $\text{kcal}$ and $\mathrm{\text{y kcal}}$ heat are liberated respectively?

The value of ${\mathrm{\Delta H}}_{\mathrm{O}-\mathrm{H}}$ is $109 \mathrm{kCal}/\mathrm{mol}.$ The enthalpy of  formation of $1 \mathrm{mole}$of water in gaseous state from $\mathrm{H}\left(\mathrm{g}\right)$ and $\mathrm{O}\left(\mathrm{g}\right)$ is:

Figure out the number of reactions among the following which have $\Delta \mathrm{H}$ equal to $∆\mathrm{U}$

i. ${\mathrm{N}}_2\left(\mathrm{g}\right)+3{\mathrm{H}}_2\left(\mathrm{g}\right)⟶2{\mathrm{NH}}_3\left(\mathrm{g}\right)$

ii. $2\mathrm{HI}\left(\mathrm{g}\right)⟶{\mathrm{H}}_2\left(\mathrm{g}\right)+{\mathrm{I}}_2\left(\mathrm{g}\right)$

iii. $\mathrm{C}\left(\mathrm{s}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)⟶{\mathrm{CO}}_2\left(\mathrm{g}\right)$

iv. $2{\mathrm{NO}}_2\left(\mathrm{g}\right)⟶{\mathrm{N}}_2{\mathrm{O}}_4\left(\mathrm{g}\right)$

v. $2{\mathrm{SO}}_2\left(\mathrm{g}\right)+{\mathrm{O}}_2\left(\mathrm{g}\right)⟶2{\mathrm{SO}}_3\left(\mathrm{g}\right)$

vi. ${\mathrm{CH}}_4\left(\mathrm{g}\right)+2{\mathrm{O}}_2\left(\mathrm{g}\right)⟶{\mathrm{CO}}_2\left(\mathrm{g}\right)+2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$

vii. $2{\mathrm{C}}_4{\mathrm{H}}_{10}\left(\mathrm{g}\right)+13{\mathrm{O}}_2\left(\mathrm{g}\right)\to 8{\mathrm{CO}}_2\left(\mathrm{g}\right)+10{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$

viii. ${\mathrm{H}}_2\left(\mathrm{g}\right)+{\mathrm{Br}}_2\left(\mathrm{g}\right)⟶2\mathrm{HBr}\left(\mathrm{g}\right)$

The heat of formation ${\left(∆\mathrm{H}\right)}_{\mathrm{f}}$ of $\mathrm{XY}$ is $-200 \mathrm{KJ} {\mathrm{mol}}^{-1}$ and the ratio of bond dissociation energy of $\mathrm{XY}$, ${\mathrm{X}}_2$ and ${\mathrm{Y}}_2$ are $1:1:0.5$ then, what will be the bond dissociation energy of ${\mathrm{X}}_2$?

The energy released during conversion of million atoms of iodine in gaseous state to iodide ions in gaseous state is $4.9\times {10}^{-13}\mathrm{J}.$ What is the electron gain enthalpy in $\mathrm{e}\mathrm{V}/\mathrm{a}\mathrm{t}\mathrm{o}\mathrm{m}.$
[Report your answer by rounding it up to the nearest whole number]

In a constant pressure calorimeter, 3.5 g of a gas with molecular weight 28 was burnt in excess oxygen at 298.0 K. The temperature of the calorimeter was found to increase from 298.0 K to 298.45 K due to the combustion process. Given that the heat capacity of the calorimeter is 2.5 kJ ${\mathrm{K}}^{-1}$ , the numerical value for the enthalpy of combustion of the gas in kJ $\mathrm{m}\mathrm{o}{\mathrm{l}}^{-1}$ is