For the reaction at \(298\ K\),
\(2A+B→C\)
\(∆H = 400\ kJ mol^{-1}\) and \(∆S = 0.2\ kJ K^{-1} mol^{-1}\)
At what temperature will the reaction become spontaneous considering \(∆H\) and \(∆S\) to be constant over the temperature range.
\(2A+B→C\)
\(∆H = 400\ kJ mol^{-1}\) and \(∆S = 0.2\ kJ K^{-1} mol^{-1}\)
At what temperature will the reaction become spontaneous considering \(∆H\) and \(∆S\) to be constant over the temperature range.
Solution and Explanation
From the expression,
\(∆G = ∆H – T∆S\)
Assuming the reaction at equilibrium, \(∆T\) for the reaction would be:
\(T = (△H-△G)\frac {1}{△S}\)
\(T= \frac {△H}{△S}\) (\(∆G = 0\) at equilibrium)
\(T=\frac { 400\ kJ mol^{-1}}{0.2\ kJK^{-1} mol^{-1}}\)
\(T = 2000\ K\)
For the reaction to be spontaneous, \(∆G\) must be negative. Hence, for the given reaction to be spontaneous, \(T\) should be greater than \(2000\ K\).
Top Questions on Gibbs energy change and equilibrium
- For a reaction taking place in four different steps, the rate constants follow a relationship \(K-\frac{K_2K_4}{K_1K_3}\). If the energies of activation E1, E2, E3 and E4 are 10 kJ/mol, 30kJ/mol, 40 kJ/mol and 20 kJ/mol respectively, then the overall energy of activation would be :
- CUET (UG) - 2023
- Chemistry
- Gibbs energy change and equilibrium
- (A) (a) Calculate the standard Gibbs energy (\( \Delta G^\circ \)) of the following reaction at 25°C: \[ \text{Au}(s) + \text{Ca}^{2+}(1M) \to \text{Au}^{3+}(1M) + \text{Ca}(s) \] \[ E^\circ_{\text{Au}^{3+}/\text{Au}} = +1.5 \, \text{V}, \quad E^\circ_{\text{Ca}^{2+}/\text{Ca}} = -2.87 \, \text{V} \] Predict whether the reaction will be spontaneous or not at 25°C. [1 F = 96500 C mol\(^{-1}\)]
- CBSE CLASS XII
- Chemistry
- Gibbs energy change and equilibrium
- (A) (a) Calculate the standard Gibbs energy (\( \Delta G^\circ \)) of the following reaction at 25°C: \[ \text{Au}(s) + \text{Ca}^{2+}(1M) \to \text{Au}^{3+}(1M) + \text{Ca}(s) \] \[ E^\circ_{\text{Au}^{3+}/\text{Au}} = +1.5 \, \text{V}, \quad E^\circ_{\text{Ca}^{2+}/\text{Ca}} = -2.87 \, \text{V} \] Predict whether the reaction will be spontaneous or not at 25°C. [1 F = 96500 C mol\(^{-1}\)]
- CBSE CLASS XII
- Chemistry
- Gibbs energy change and equilibrium
- For the reaction
\(2A(g)+B(g)→2D(g)\)
\(∆U^Θ= -10.5\ kJ\) and \(∆S^Θ= -44.1\ JK^{-1}\).
Calculate \(∆G^Θ\) for the reaction, and predict whether the reaction may occur spontaneously.- CBSE Class XI
- Chemistry
- Gibbs energy change and equilibrium
- For the reaction, \(2Cl(g)→Cl_2(g)\), what are the signs of \(∆H\) and \(∆S\) ?
- CBSE Class XI
- Chemistry
- Gibbs energy change and equilibrium
Questions Asked in CBSE Class XI exam
Give reasons for the following.
(i) King Tut’s body has been subjected to repeated scrutiny.
(ii) Howard Carter’s investigation was resented.
(iii) Carter had to chisel away the solidified resins to raise the king’s remains.
(iv) Tut’s body was buried along with gilded treasures.
(v) The boy king changed his name from Tutankhaten to Tutankhamun.- CBSE Class XI
- Discovering Tut: The saga Continues
- \(\text{tan x}=-\frac{4}{3},\text{x\, in\, quadrant \,II.}\)
- CBSE Class XI
- Trigonometric Functions of Sum and Difference of Two Angles
Find the mean deviation about the median for the data
xi 15 21 27 30 35 fi 3 5 6 7 8 - CBSE Class XI
- Mean Deviation
- The Cartesian product A x A has 9 elements among which are found (-1, 0) and (0, 1). Find the set A and the remaining elements of A x A.
- CBSE Class XI
- Relations and functions
- ‘Have you come back?’ said the woman. ‘I thought that no one had come back.’ Does this statement give some clue about the story? If yes, what is it?
- CBSE Class XI
- The address
Concepts Used:
Gibbs Free Energy
The energy associated with a chemical reaction that can be used to do work.It is the sum of its enthalpy plus the product of the temperature and the entropy (S) of the system.
The Gibbs free energy is the maximum amount of non-expansion work that can be extracted from a thermodynamically closed system. In completely reversible process maximum enthalpy can be obtained.
ΔG=ΔH−TΔS
The Conditions of Equilibrium
If both it’s intensive properties and extensive properties are constant then thermodynamic system is in equilibrium. Extensive properties imply the U, G, A.
