Exams › JEE Advanced › Chemistry
The surface of copper can become tarnished due to the formation of copper oxide. To prevent this, nitrogen gas (N₂) was passed while heating copper at 1250 K. However, the N₂ gas contains 1 mole % of water vapor as an impurity, which oxidizes copper according to the reaction below: 2Cu(s) + H₂O(g) → Cu₂O(s) + H₂(g) The minimum partial pressure of H₂ (in bar) required to stop the oxidation of copper at 1250 K is represented as P_H₂. Determine the value of ln(P_H₂).
- -4.60
- -3.60
- -2.60
- -1.60
Correct answer: -4.60
Solution
The equilibrium constant for the reaction involving copper oxidation depends on the partial pressures of H₂ and H₂O. Using thermodynamic data and the given temperature, the minimum ln(P_H₂) required to prevent oxidation is calculated as -4.60.
Related JEE Advanced Chemistry questions
- K1, K2, and K3 represent the equilibrium constants for the following reactions, respectively: (I) \(N_2O_4 \rightleftharpoons 2NO_2\) (II) \(2NO_2 \rightleftharpoons N_2 + 2O_2\) (III) \(NO_2 \rightleftharpoons \tfrac{1}{2}N_2 + O_2\) Which of the following correctly describes the relationship between these constants?
- Which of the following sequences correctly represents the solubility order of the slightly soluble salts \(Hg_2Cl_2\), \(Cr_2(SO_4)_3\), \(BaSO_4\), and \(CrCl_3\)?
- For the decomposition of ammonium carbamate according to the reaction \(NH_2COONH_4(s) \rightleftharpoons 2NH_3(g) + CO_2(g)\), the equilibrium constant \(K_p\) is \(2.9 \times 10^{-2}\,\text{atm}^3\). If 1 mole of \(NH_2COONH_4\) is initially present, what is the total pressure at equilibrium?
- In which of the following cases can the pH be determined using the equilibrium constant(s) provided?
- In the equilibrium reaction \(NH_2COONH_4(s) \rightleftharpoons 2NH_3(g) + CO_2(g)\), which change will cause the partial pressure of \(NH_3\) to rise?
- For the reaction \(XY_2(g) \rightleftharpoons XY(g) + Y(g)\), if the degree of dissociation \(\alpha\) is very small compared to 1, how is \(\alpha\) related to the pressure \(P\)?
⚔️ Practice JEE Advanced Chemistry free + battle 1v1 →