List of top Chemistry Questions on Enthalpy change

Enthalpy of combustion of benzene, graphite, dihydrogen are $ -3260 $, $ -390 $ and $ -290\text{ kJ/mol} $. Find the enthalpy of formation of benzene

Given below are two statements:
Statement (I): The radius of isoelectronic species increases in the order: \[ \text{Mg}^{2+} < \text{Na}^{+} < \text{F}^{-} < \text{O}^{2-} \] Statement (II): The magnitude of electron gain enthalpy of halogens decreases in the order: \[ \text{Cl} > \text{F} > \text{Br} > \text{I} \] In light of the above statements, choose the most appropriate answer from the options given below:

12g of pure graphite is burnt. Temperature rises from 298 K to 308 K. Heat capacity of the calorimeter is $20.7~kJ~K^{-1}$. Enthalpy change for combustion of 1 mole of graphite $(kJ~mol^{-1})$ is ________.

What is the enthalpy of neutralization for CH₃COOH + NaOH?

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)

Calculate the enthalpy change ($\Delta H$) for the combustion of 1 mole of methane ($\mathrm{CH}_4$) given the reaction: $$ \mathrm{CH}_4(g) + 2 \mathrm{O}_2(g) \rightarrow \mathrm{CO}_2(g) + 2 \mathrm{H}_2 \mathrm{O}(l) $$ Given bond energies: C–H = 413 kJ/mol, O=O = 498 kJ/mol, C=O = 803 kJ/mol, O–H = 467 kJ/mol.

The group 14 elements A and B have the first ionisation enthalpy values of 708 and 715 kJ mol$^{-1}$ respectively. The above values are lowest among their group members. The nature of their ions A$^{2+}$ and B$^{4+}$ respectively is:

The incorrect relationship in the following pairs in relation to ionisation enthalpies is:

Consider the following cases of standard enthalpy of reaction ($ \Delta H_f^\circ $ in kJ mol$^{-1}$): \[ \text{C}_2\text{H}_6(g) + 7 \text{O}_2(g) \rightarrow 2 \text{CO}_2(g) + 3 \text{H}_2\text{O}(l) \quad \Delta H_1^\circ = -1550 \] \[ \text{C(graphite)} + \text{O}_2(g) \rightarrow \text{CO}_2(g) \quad \Delta H_2^\circ = -393.5 \] \[ \text{H}_2(g) + \frac{1}{2} \text{O}_2(g) \rightarrow \text{H}_2\text{O}(g) \quad \Delta H_3^\circ = -286 \] The magnitude of $ \Delta H_f^\circ $ of $ \text{C}_2\text{H}_6(g) $ is $\_\_\_\_\_$ kJ mol$^{-1}$ (Nearest integer).

The bond dissociation energies of gaseous H₂, Cl₂, and HCl are 104, 58, and 103 kcal, respectively. The enthalpy of formation of HCl gas would be:

The enthalpy change for the reaction $ \text{N}_2(g) + 3\text{H}_2(g) \rightarrow 2\text{NH}_3(g) $ is $ -92.4 \, \text{kJ/mol} $. What is the enthalpy change when 4 moles of nitrogen react?

The enthalpy of formation for $ \text{H}_2(g) $, $ \text{O}_2(g) $, and $ \text{H}_2O(l) $ are 0, 0, and -285.8 kJ/mol, respectively. What is the enthalpy change for the following reaction: \[ \text{2H}_2(g) + \text{O}_2(g) \rightarrow 2\text{H}_2O(l) \]

The enthalpy change for the reaction $ \text{C} + \text{O}_2 \rightarrow \text{CO}_2 $ is $ -393.5 \, \text{kJ/mol} $. What is the heat released when 2 moles of carbon react with excess oxygen?

The enthalpy of combustion of methane is 890 kJ/mol. How much heat is released when 8 g of methane is burned completely? (Molar mass of CH$_4$ = 16 g/mol)

Identify the incorrect statement from the following:

An ideal gas undergoes a cyclic transformation starting from the point $ A $ and coming back to the same point by tracing the path $ A \to B \to C \to A $ as shown in the diagram. The total work done in the process is $ \_\_\_\_ $ J.

$\Delta_{vap}H^\circ$ for water is $+40.49 \, \text{kJ mol}^{-1}$ at 1 bar and $100^\circ\text{C}$. Change in internal energy for this vaporisation under same condition is .............. kJ mol$^{-1}$. (Integer answer)
(Given R = 8.3 J K$^{-1}$ mol$^{-1}$)

When equal volume of 1M HCl and 1M H$_2$SO$_4$ are separately neutralized by excess volume of 1M NaOH solution, X and Y kJ of heat is liberated respectively. The value of Y/X is ____.

A transition metal 'M' among Sc, Ti, V , Cr, Mn and Fe has the highest second ionisation enthalpy. The spin only magnetic moment value of M+
ion is ______ BM (Near integer) (Given atomic number Sc : 21, Ti : 22, V : 23, Cr : 24, Mn : 25, Fe : 26)

$\text{Two reactions are given below:}$ \[ 2\text{Fe}_{(s)} + \frac{3}{2}\text{O}_{2(g)} \rightarrow \text{Fe}_2\text{O}_{3(s)}, \Delta H^\circ = -822 \, \text{kJ/mol} \] \[ \text{C}_{(s)} + \frac{1}{2}\text{O}_{2(g)} \rightarrow \text{CO}_{(g)}, \Delta H^\circ = -110 \, \text{kJ/mol} \] $\text{Then enthalpy change for the following reaction}$ \[ 3\text{C}_{(s)} + \text{Fe}_2\text{O}_{3(s)} \rightarrow 2\text{Fe}_{(s)} + 3\text{CO}_{(g)} \]

$\text{Standard enthalpy of vaporisation for CCl}_4 \text{ is 30.5 kJ mol}^{-1}. \text{ Heat required for vaporisation of } 284 \, \text{g of CCl}_4 \text{ at constant temperature is } \_\_\_\_ \, \text{kJ.} \\ \text{(Given molar mass in g mol}^{-1}\text{; C = 12, Cl = 35.5)}$

If standard enthalpy of vaporization of $CCl_4$ is $30.5$ kJ/mol, find heat absorbed for vaporization of $294 $ gm of $CCl_4$. [Nearest integer] [in kJ/mol]

Decreasing order of electron gain enthalpy of the following elements (magnitude only)
Sulphur A, Bromine - B, Fluorine C, Argon D

Arrange the following elements in increasing order of first ionization enthalpy:
Li, Be, B, C, N
Choose the correct answer from the options given below:

Given:
$\Delta H_f^\circ \, \text{CO}_2 (g) = -393.5 \, \text{kJ/mol}$
$\Delta H_f^\circ \, \text{H}_2\text{O}(l) = -286 \, \text{kJ/mol}$
$\Delta H_f^\circ \, \text{C}_3\text{H}_6(g) = +20.6 \, \text{kJ/mol}$
$\Delta H^\circ_{\text{isomerization of Cyclopropane to Propene}} = -33 \, \text{kJ/mol}$
What is the standard enthalpy of combustion of Cyclopropane?