List of top Chemistry Questions on Enthalpy change asked in AP EAPCET

The electron gain enthalpy (Cl₂,H) of chlorine is -3.7 eV mol^-1. How much energy (in kcal mol^-1) is released when 71 g of chlorine atoms are completely converted into Cl^- ions in gaseous state? (1 eV = 23 kcal)

The first ionization enthalpies of Na, Mg and Si are respectively 496, 737 and 786 kJ mol⁻¹. What would be the first ionization enthalpy of Al in kJ mol⁻¹?

If the standard molar enthalpies of formation of \( C_2H_5OH(l)) \), \( CO_2(g) \), and \( H_2O(l) \) are -278, -394, and -286 kJ mol\(^{-1}\) respectively, the standard enthalpy of combustion of the reaction \[ C_2H_5OH(l) + 3O_2(g) \rightarrow 2CO_2(g) + 3H_2O(l) \] in kJ mol\(^{-1}\) is:

If for the reaction \[ \text{CCL}_3(g) \rightarrow \text{C}(g) + 3\text{Cl}(g), \] the following data is given: \[ \Delta H^\circ_{\text{CCL}_3(l)} = 30 \, \text{kJ mol}^{-1}, \, \text{vap} = \text{vaporization} \] \[ \Delta H^\circ_{\text{CCl}_3} = -136.0 \, \text{kJ mol}^{-1}, \, f = \text{formation} \] \[ \Delta H^\circ_{\text{C}} = 714.0 \, \text{kJ mol}^{-1}, \, a = \text{atomization} \] \[ \Delta H^\circ_{\text{Cl}} = 242.0 \, \text{kJ mol}^{-1}, \, a = \text{atomization} \] The bond mean enthalpy of C-Cl in CCl\(_4\)(l) is: \[ \text{CCL}_4(g) \rightarrow \text{C}(g) + 3\text{Cl}(g) \text{ gives the bond mean enthalpy.} \]

Identify the isoelectronic pair of ions from the following

Assertion (A): 16th group elements have higher ionization enthalpy values than 15th group elements in the corresponding periods.
Reason (R): 15th group elements have half-filled stable electronic configuration.

Assertion (A): Fluorine has smaller negative electron gain enthalpy than chlorine.
Reason (R): The electron-electron repulsion is higher in chlorine than in fluorine.

$6g$ of graphite is burnt in a bomb calorimeter at $25^{\circ}C$ and $1\, atm$ pressure. The temperature of water increased from $25^{\circ}C$ to $30^{\circ}C$. If $\Delta H$ of this reaction is $-248 \,kJ\, mol^{-1}$, find out $C_v$ (in $kJ\, K^{-1}$) of bomb calorimeter.

From the following data $CH _{3} OH (l)+\frac{3}{2} O _{2}(g) \longrightarrow CO _{2}(g)+2 H _{2} O (l)$ $\Delta_{r} H^{\circ}=-726\, k J\, mol ^{-1}$ $H _{2}(g)+\frac{1}{2} O _{2}(g) \longrightarrow H _{2} O (l) $ $\Delta_r H ^{\circ}=-286\, kJ\, mol ^{-1}$ $C (\text { graphite })+ O _{2}(g) \longrightarrow CO _{2}(g)$ $\Delta_{r} H ^{\circ}=-393\, kJ\, mol ^{-1}$ The standard enthalpy of formation of $CH _{3} OH (l)$ in $kJ\, mol ^{-1}$ is