Thermodynamics

The standard Gibbs free energy change ($∆$G°) at 25°C for the dissociation of N₂O₄(g) to NO₂(g) is (given, equilibrium constant = 0.15, R = 8.314 JK/mol)

• 1.1 kJ

• 4.7 kJ

• 8.1 kJ

• 38.2 kJ

Identify the correct statement from the following in a chemical reaction

• The entropy always increases

• The change in entropy along with suitable change in enthalpy decides the rate of reaction

• The enthalpy always decreases

• Both the enthalpy and the entropy remain constant

A plot of ln K against $\frac{1}{\mathrm{T}}$ (abscissa) is expected to be a straight line with intercept on ordinate axis equal to

• $\frac{∆\mathrm{S}°}{2.303 \mathrm{R}}$

• $\frac{∆\mathrm{S}°}{\mathrm{R}}$

• $-\frac{∆\mathrm{S}°}{\mathrm{R}}$

• R × $∆\mathrm{S}°$

In which of the following reactions will $∆$U be equal to $∆$H?

• ${\mathrm{H}}_2\left(\mathrm{g}\right) +\frac{1}{2}{\mathrm{O}}_2\left(\mathrm{g}\right)\to {\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)$

• ${\mathrm{H}}_2\left(\mathrm{g}\right) + {\mathrm{I}}_2\left(\mathrm{g}\right) \to 2\mathrm{HI}\left(\mathrm{g}\right)$

• ${\mathrm{N}}_2{\mathrm{O}}_4\left(\mathrm{g}\right) \to 2{\mathrm{NO}}_2\left(\mathrm{g}\right)$

• $2{\mathrm{SO}}_4\left(\mathrm{g}\right) + {\mathrm{O}}_2\left(\mathrm{g}\right) \to 2{\mathrm{SO}}_3\left(\mathrm{g}\right)$

For the reaction

N₂ (g) + 3H₂ (g) $\rightleftharpoons$ 2NH₃ (g) $∆$H is equal to

• $∆$E - 2RT

• $∆$E - RT

• $∆$E + RT

• $∆$E + 2RT

The standard molar heat of formation of ethane, CO₂ and water (l) are respectively -21.1, -94.1 and -68.3 kcal. The standard molar heat of combustion of ethane will be

• -372 kcal

• 162 kcal

• -240 kcal

• 183.5 kcal

When 1 mole of CO₂ (g) occupying volume 10 L at 27°C is expanded under adiabatic condition, temeprature falls to 150 K. Hence, final volume is

• 5 L

• 20 L

• 40 L

• 80 L

Match List I (Equations) with List II (Types of process) and select the correct option.

• A	B	C	D
  1	2	3	4

• A	B	C	D
  3	4	2	1

• A	B	C	D
  4	1	2	3

• A	B	C	D
  2	1	1	3

Consider the following processes $∆\mathrm{H} (\mathrm{kJ}/\mathrm{mol})$

      $$\begin{gathered} \frac{1}{2}\mathrm{A} \to \mathrm{B} + 150 \\ 3\mathrm{B} \to 2\mathrm{C} + \mathrm{D} - 125 \\ \mathrm{E}+\mathrm{A} \to 2\mathrm{D} + 350 \\ \mathrm{for} \mathrm{B}+ \mathrm{D} \to \mathrm{E} + 2\mathrm{C}, ∆\mathrm{H} \mathrm{will} \mathrm{be} \end{gathered}$$

• 525 k.J/mol

• -175 kJ/mol

• -325kJ/mol

• 325 kJ/mol

Heat of formation, $∆{\mathrm{H}}_{\mathrm{f}}^{°}$ of an explosive compound like NCl₃ is

• positive

• Negative

• Zero

• Positive or Negative