Thermodynamics - Physical Chemistry - Chemistry Previous Year Questions

For the reaction, $2 \mathrm{CO}+\mathrm{O}_2 \rightarrow 2 \mathrm{CO}_2 ; \Delta \mathrm{H}=-560 \mathrm{~kJ}$. Two moles of CO and one mole of $\mathrm{O}_2$ are taken in a container of volume 1 L . They completely form two moles of $\mathrm{CO}_2$, the gases deviate appreciably from ideal behaviour. If the pressure in the vessel changes from 70 to 40 atm , find the magnitude (absolute value) of $\Delta \mathrm{U}$ at 500 K . $(1 \mathrm{~L} \mathrm{~atm}=0.1 \mathrm{~kJ})$

A monatomic ideal gas undergoes a process in which the ratio of P to V at any instant is constant and equals to 1 . What is the molar heat capacity of the gas?

The direct conversion of A to B is difficult; hence, it is carried out by the following shown path:Given,

$$\begin{aligned} & \Delta \mathrm{S}_{(\mathrm{A} \rightarrow \mathrm{C})}=50 \text { e.u. } \\ & \Delta \mathrm{S}_{(\mathrm{C} \rightarrow \mathrm{D})}=30 \text { e.u. } \\ & \Delta \mathrm{S}_{(\mathrm{B} \rightarrow \mathrm{D})}=20 \text { e.u. } \end{aligned}$$

Where e.u. is entropy unit. Then $\Delta \mathrm{S}_{(\mathrm{A} \rightarrow \mathrm{B})}$ is :

The value of log\(_{10}\) K for a reaction $A \rightleftharpoons B$ is

(Given : \({\Delta _r}H{^\circ _{298\,K}} = - 54.07\) kJ mol\(^{-1}\), \({\Delta _r}S{^\circ _{298\,K}} = 10\) J K\(^{-1}\) mol\(^{-1}\) and R = 8.314 J K\(^{-1}\) mol\(^{-1}\); 2.303 \(\times\) 8.314 \(\times\) 298 = 5705)

For the process \(\mathrm{H_2O}(l)\) (1 bar, 373 K) \(\to\) \(\mathrm{H_2O}(g)\) (1 bar, 373 K), the correct set of thermodynamic parameters is:

Statement 1 : There is a natural asymmetry between converting work to heat and converting heat to work.

Statement 2 : No process is possible in which the sole result is the absorption of heat from a reservoir and its complete conversion into work.

In a constant volume calorimeter, 3.5 g of a gas with molecular weight 28 was burnt in excess oxygen at 298.0 K. The temperature of the calorimeter was found to increase from 298.0 K to 298.45 K due to the combustion process. Given that the heat capacity of the calorimeter is 2.5 kJ K\(^{-1}\), the numerical value for the enthalpy of combustion of the gas in kJ mol\(^{-1}\) is ____________.

Among the following, the state function(s) is(are)

One mole of an ideal gas is taken from $\mathbf{a}$ to $\mathbf{b}$ along two paths denoted by the solid and the dashed lines as shown in the graph below. If the work done along the solid line path is $W_{\text {s }}$ and that dotted line path is $W_{\mathrm{d}}$, then the integer closest to the ratio $W_{\mathrm{d}} / W_{\mathrm{s}}$ is

For an ideal gas, consider only P-V work in going from an initial state X to the final state Z. The final state Z can be reached by either of the two paths shown in the figure. Which of the following choice(s) is(are) correct? (Take \(\Delta\)S as change in entropy and W as work done)

Using the data provided, calculate the multiple bond energy (kJ mol^\(-\)1) of a C=C bond in C₂H₂. That energy is (take the bond energy of C-H bond as 350 kJ mol^\(-\)1).

$$\matrix{ \hfill {2C(s) + {H_2}(g) \to {C_2}{H_2}} & \hfill {\Delta H = 225\,kJ\,mo{l^{ - 1}}} \cr \hfill {2C(s) \to 2C(g)} & \hfill {\Delta H = 1410\,kJ\,mo{l^{ - 1}}} \cr \hfill {{H_2}(g) \to 2H(g)} & \hfill {\Delta H = 330\,kJ\,mo{l^{ - 1}}} \cr }$$

The reversible expansion of an ideal gas under adiabatic and isothermal conditions is shown in the figure. Which of the following statement(s) is(are) correct?

The succeeding operations that enable this transformation of states are

The pair of isochoric processes among the transformation of states is