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Question #44880

Difficulty: 8/10 | 🟢 Free

The Question

A sample of palladium foil is saturated with hydrogen gas to form the interstitial hydride $PdH_{0.60}$ . The foil is immersed in an excess of aqueous acidic $KMnO_4$ solution ( $pH = 1$ ) at 298 K. The reduction of $MnO_4^-$ by the interstitial hydrogen occurs via a Langmuir-Hinshelwood surface-catalyzed mechanism, where both species must adsorb on the Pd surface. Assuming the bulk concentration of $MnO_4^-$ is extremely high, what is the apparent reaction order with respect to bulk $[MnO_4^-]$ , and how many moles of $KMnO_4$ are reduced per mole of Pd?

Options

A.
Zero order, 0.12 mol
B.
Pseudo-first order, 0.12 mol
C.
Zero order, 0.20 mol
D.
Pseudo-first order, 0.20 mol

Check Your Answer

Correct Answer

Step-by-Step Solution

Explanation

How the Examiner Thinks

Mechanism_Trap

Don't get tricked by the process! Learn the mechanical traps used in competitive exam questions.

Concepts Behind This Question

Interstital Compound Formation|KMnO₄ Redox pH Dependency

Why This Question Is Tricky

Common Mistakes

The question tests the 'Reservoir Effect' of interstitial hydrides and the distinction between homogeneous pseudo-order kinetics and heterogeneous surface-controlled kinetics.

Students often mistakenly assume that an excess of a reactant automatically leads to pseudo-first order kinetics.

However, in surface catalysis (Langmuir-Hinshelwood), an extreme excess of a reactant saturates the catalytic sites, changing the actual reaction order to zero with respect to that reactant.

Additionally, it tests the stoichiometric calculation of redox reactions involving non-stoichiometric interstitial compounds in acidic media, trapping students who use the neutral medium n-factor (3) to get 0.20 mol.

Quick Facts About This Question

Question Information

Subject	Chemistry
Chapter	D and F Block Elements - Class 12
Concept	Interstital Compound Formation
Difficulty	8
Cognitive Load	7
Target Solve Time	160 sec
Access	Free