Exams › JEE Main › Chemistry
The enthalpy changes for these reactions are given: 1/2 H2(g) + 1/2 O2(g) → OH(g); ΔH = 42.09 kJ mol⁻¹ H2(g) → 2H(g); ΔH = 435.89 kJ mol⁻¹ O2(g) → 2O(g); ΔH = 495.05 kJ mol⁻¹ Using this data, determine the O–H bond energy in the hydroxyl radical.
- 223.18 kJ mol⁻¹
- 423.38 kJ mol⁻¹
- 513.28 kJ mol⁻¹
- 113.38 kJ mol⁻¹
Correct answer: 423.38 kJ mol⁻¹
Solution
The O–H bond energy in the hydroxyl radical is calculated by considering the enthalpy changes of the given reactions. By applying Hess's law and combining the enthalpy values appropriately, we find that the bond energy corresponds to the correct option of 423.38 kJ mol⁻¹.
Related JEE Main Chemistry questions
- Using the following thermochemical equations, determine the enthalpy of vaporisation of water: \[ \mathrm{H_2(g) + \tfrac{1}{2}O_2(g) \to H_2O(l)},\quad \Delta H = -286\ \text{kJ} \] \[ \mathrm{H_2(g) + \tfrac{1}{2}O_2(g) \to H_2O(g)},\quad \Delta H = -245.5\ \text{kJ} \]
- Given that the standard enthalpy of formation of NH$_3$ is $-46.0\ \text{kJ mol}^{-1}$, and the enthalpy of formation of H$_2$ from gaseous atoms is $-436\ \text{kJ mol}^{-1}$ while that of N$_2$ from gaseous atoms is $-712\ \text{kJ mol}^{-1}$, what is the average N–H bond enthalpy in NH$_3$?
- Using the following bond dissociation data, determine the enthalpy change for the conversion $8S(s) + \tfrac32 S_8(g)$.
- Using the bond enthalpies given below, determine the enthalpy change for the hydrogenation reaction shown: H–H bond energy = 431.37 kJ mol$^{-1}$ C–C bond energy = 606.10 kJ mol$^{-1}$ C–H bond energy = 336.49 kJ mol$^{-1}$ C–H bond energy = 410.50 kJ mol$^{-1}$ $C=C + H–H \rightarrow H–C–C–H$ What is the enthalpy change for this reaction?
- For a given reversible reaction, both enthalpy change ($\Delta H$) and entropy change ($\Delta S$) are positive. If $T_1$ denotes the equilibrium temperature, under which condition will the reaction be spontaneous?
- For the spontaneous reaction $2C_2H_6(g) + 25O_2(g) \rightarrow 16CO_2(g) + 18H_2O(g)$, what are the signs of $\Delta H$, $\Delta S$, and $\Delta G$ in that order?
⚔️ Practice JEE Main Chemistry free + battle 1v1 →