List of top Chemistry Questions on Thermochemistry

Consider the following data: - Heat of formation of \( CO_2(g) \) = -393.5 kJ mol\(^{-1}\) - Heat of formation of \( H_2O(l) \) = -286.0 kJ mol\(^{-1}\) - Heat of combustion of benzene = -3267.0 kJ mol\(^{-1}\) The heat of formation of benzene is ________________________ kJ mol\(^{-1}\) (Nearest integer).
Total enthalpy change for freezing of 1 mol water at 10°C to ice at -10°C is ______ (Given: $ \Delta_{\text{fus}}H = x \, \text{kJ/mol} $, $ C_p[\text{H}_2\text{O}(l)] = y \, \text{J mol}^{-1} \text{K}^{-1} $, and $ C_p[\text{H}_2\text{O}(s)] = z \, \text{J mol}^{-1} \text{K}^{-1} $)
The standard enthalpy of formation for which of the element is not zero at 1 bar pressure and specified temperature?
At T(K), \(K_{\text{sp}}\) of two ionic salts MX\(_2\) and MX is \(5 \times 10^{-13}\) and \(1.6 \times 10^{-11}\) respectively. The ratio of molar solubility of MX\(_2\) and MX is
For the following given equilibrium reaction, K\(_p\) is equal to 1076 at T(K). What is the value of T (in K)? \[ \text{N}_2(g) + 3\text{H}_2(g) \rightleftharpoons 2\text{NH}_3(g) \] Given that \( R = 0.082 \, \text{L atm K}^{-1} \text{mol}^{-1} \), \( K_p = 1076 \), the equation is: \[ K_p = 1076, \, R = 0.082 \, \text{L atm K}^{-1} \text{mol}^{-1} \]
Consider the following gaseous equilibrium reactions (I), (II) and (III) with equilibrium constants \( K_1 \), \( K_2 \), and \( K_3 \) respectively:
I) \( \frac{1}{2} N_2 + \frac{3}{2} H_2 \rightleftharpoons NH_3 \)
II) \( 2NO \rightleftharpoons N_2 + O_2 \)
III) \( H_2 + \frac{1}{2} O_2 \rightleftharpoons H_2O \)
The correct expression for the equilibrium constant for the gaseous equilibrium reaction: \[ 2NH_3 + \frac{5}{2} O_2 \rightleftharpoons 2NO + 3H_2O \]
At \(25 ^\circ\text{C}\), \(K_a\) of formic acid is \(1.8 \times 10^{-4}\). What is the \(K_b\) of \( \text{HCOO}^- \)?
Consider the following gaseous equilibrium reactions (I), (II) and (III) with equilibrium constants \( K_1 \), \( K_2 \), and \( K_3 \) respectively:
I) \( \frac{1}{2} N_2 + \frac{3}{2} H_2 \rightleftharpoons NH_3 \)
II) \( 2NO \rightleftharpoons N_2 + O_2 \)
III) \( H_2 + \frac{1}{2} O_2 \rightleftharpoons H_2O \)
The correct expression for the equilibrium constant for the gaseous equilibrium reaction: \[ 2NH_3 + \frac{5}{2} O_2 \rightleftharpoons 2NO + 3H_2O \]
At \(25 ^\circ\text{C}\), \(K_a\) of formic acid is \(1.8 \times 10^{-4}\). What is the \(K_b\) of \( \text{HCOO}^- \)?
At 25$^\circ$C, the percentage of ionization of x M acetic acid is 4.242. What is the pH of the acetic acid solution?
Given: $\log 4.242 = 0.6275$, $\log 0.04242 = -1.372$, $K_a = 1.8 \times 10^{-5}$
At temperature \(T(K)\), the solubility product of AgBr is \(4 \times 10^{-13}\). What is its solubility in 0.1 M KBr solution?
The enthalpy of atomization of \({CH}_3{NH}_2(g)\) is 2313 kJ mol\(^{-1}\). If \(\Delta_{{C-H}}^{\ominus}\) and \(\Delta_{{N-H}}^{\ominus}\) are 414 and 389 kJ mol\(^{-1}\) respectively, then \(\Delta_{{C-N}}^{\ominus}\) (in kJ mol\(^{-1}\)) will be:
The value of \(\Delta_r H\) for the reaction:
\[ {N}_2{O}_4(g) + 3 {CO}(g) \rightarrow {N}_2{O}(g) + 3 {CO}_2(g) \] (in kJ) is:
(Given: Enthalpies of formation in kJ mol\(^{-1}\) are \({CO}(g) = -110\), \({CO}_2(g) = -393\), \({N}_2{O}(g) = 81\), and \({N}_2{O}_4(g) = 9.7\))
Solid fuel used in rocket is a mixture of Fe₂O₃ and Al (in ratio 1 : 2) the heat evolved (KJ) per gram of the mixture is ______ (Nearest integer)
Given \(\Delta H_f^{\circ}(Al_2O_3) = -1700 \, \text{KJ mol}^{-1}\)
\(\Delta H_f^{\circ}(Fe_2O_3) = -840 \, \text{KJ mol}^{-1}\) }
When 'X' g of graphite is completely burnt in a bomb calorimeter in excess of \( O_2 \) at 298 K and 1 atm pressure as given in the equation $$ \text{C(graphite)} + O_2(g) \rightarrow CO_2(g) $$ The temperature of calorimeter raised from 298 K to 302 K. If the heat capacity of the calorimeter and molar enthalpy change for the reaction at 1 atm and 298 K are 20.7 kJ K\(^{-1} \) and -248.4 kJ mol\(^{-1} \), 'X' in g is
At constant T and P, which one of the following statements is correct for the reaction.
\(\text{CO}(g) + \frac{1}{2} \text{O}_2 \rightarrow \text{CO}_2(g)?\)

Consider the following reactions, C(s) + O2(g) → CO2(g), \(\Delta\) H = -94\(\text{ kcal}\) 2CO(g) + O2 → 2CO2(g), \(\Delta\) H = -135.2\(\text{ kcal}\) Then, the heat of formation of CO (g) is:

For the reactions \(C + O2 \rightarrow CO2\); \(\, \Delta H = -393 \, \text{kJ} 2Zn + O2 \rightarrow 2ZnO\), \(\, \Delta H = -412 \, \text{kJ}\) \(\text{the correct statement is:}\)

Which of the following compounds produces the most heat per mole of compound when reacted with oxygen?
20 g of NaCl is poured into a coffee cup calorimeter containing 250 mL of water. If the temperature inside the calorimeter drops 1°C by the time, the NaCl is totally dissolved, what is the heat of solution for NaCl and water? (specific heat of water is 4.18 J/g°C)