Chemistry Thermochemistry DUHS 2024
PMDC Verified Question 15 of 81
The decomposition of \( H_2O_2 \) is inhibited by:
(Note: Original paper typoed this as \( H_2O \), but chemically refers to Hydrogen Peroxide)
A
Ethanol
B
Glycerin
C
\( MnO_2 \)
D
\( V_2O_5 \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: Glycerin
Concept:

Catalysts speed up reactions, while inhibitors (negative catalysts) specifically bind to reactive intermediates to slow down or completely halt a decomposition reaction.

Formula:

$$ 2H_2O_2 \rightarrow 2H_2O + O_2 \quad \text{(spontaneous but inhibitable)} $$

Solution:

  • Hydrogen peroxide (\( H_2O_2 \)) slowly decomposes into water and oxygen gas upon exposure to light or ambient heat.


  • To prevent this during commercial storage, specific stabilizing chemicals are added.


  • Glycerin (glycerol) forms strong hydrogen bonds with the peroxide and acts as a highly effective inhibitor, slowing the decomposition rate drastically.


Why other options are incorrect:

\( MnO_2 \) is a famous positive catalyst that rapidly accelerates peroxide decomposition. \( V_2O_5 \) is a catalyst used in the Contact Process for sulfuric acid.

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