COMPASSLearning

Talk to us Register Login

JEE Main · 2025 · 24 Jan 2025 · Shift 1 · Chemical Thermodynamics

Standard entropies of

X_{2}, Y_{2}

and

X Y_{5}

are 70, 50 and

110 J K^{- 1} mol^{- 1}

respectively. The temperature in Kelvin at which the reaction

\frac{1}{2} X_{2} + \frac{5}{2} Y_{2} \to X Y_{5} Δ H^{-} = - 35 kJ mol^{- 1}

Will be at equilibrium is ____ (Nearest integer)

Answer: 700

Solution

Δ S_{r x n}^{\circ} = S^{\circ} (X Y_{5}) - [\frac{1}{2} S^{\circ} (X_{2}) + \frac{5}{2} S^{\circ} (Y_{2})] = 110 - [\frac{1}{2} (70) + \frac{5}{2} (50)] = 110 - 160 = - 50 J K^{- 1} m o l^{- 1}

At equilibrium,

Δ G^{\circ} = 0

, so

Δ H^{\circ} = T Δ S^{\circ}

:

- 35000 = T \times (- 50) \Rightarrow T = \frac{35000}{50} = 700 K

JEE Main · 2025 · 24 Jan 2025 · Shift 1 · Integer answer

Practise more: all JEE Main PYQs on Chemical Thermodynamics →

More JEE Main questions on Chemical Thermodynamics

Which of the following graphs between pressure 'P' versus volume 'V' represent the maximum work done?
JEE Main 2026View solution →
For the reaction, $N_{2} O_{4} ⇌ 2 NO_{2}$ , graph is plotted as shown below. Identify correct statements.

A. Standard free energy change for the reaction is $- 5.40 kJ mol^{- 1}$ .
B. As $Δ G^{⊖}$ in graph i …
JEE Main 2026View solution →
Use the following data:
Substance $\frac{Δ _{f} H ^{⊖} ( 500 K )}{kJ mol ^{- 1}}$ $\frac{S ^{⊖} ( 500 K )}{J K ^{- 1} mol ^{- 1}}$
| …
JEE Main 2026View solution →
Dissociation of a gas $A_{2}$ takes place according to the following chemical reactions. At equilibrium, the total pressure is 1 bar at 300 K.
$A_{2} (g) ⇌ 2 A (g)$
The standard Gibbs energy of formation of the involv …
JEE Main 2026View solution →
Consider the following data:
$Δ_{f} H^{Θ}$ (methane, g) $= - X kJ mol^{- 1}$
Enthalpy of sublimation of graphite $= Y kJ mol^{- 1}$
Dissociation enthalpy of …
JEE Main 2026View solution →
If the enthalpy of sublimation of Li is $155 kJ mol^{- 1}$ , enthalpy of dissociation of $F_{2}$ is $150 kJ mol^{- 1}$ , ionization enthalpy of Li is $520 kJ mol^{- 1}$ , electron gain enthalpy of F is $- 313 kJ mol^{- 1}$ , standard enthalpy o …
JEE Main 2026View solution →