= Manganese dioxide peroxide contact demonstration
The University of Washington's https://chem.washington.edu/lecture-demos/decomposition-h2o2-mno2[Decomposition of H₂O₂ with MnO₂] describes a supervised demonstration using <solid> <manganese dioxide> and <hydrogen peroxide> listed as 30%. Its cylinder version uses a spatula to introduce the <solid>; the stated readout is immediate <molecular oxygen> bubbles and <heat> production. An alternate bottle version replaces the contents of a tea bag with the <solid> and suspends it above the liquid. Releasing the bag brings it into contact with the liquid. The bag-above-liquid stage supplies a before-contact comparison; the page gives no timed gas collection, replicated blank trials or quantitative <reaction rates>.<Decomposition of H₂O₂ with MnO₂ by University of Washington Department of Chemistry>[Chemicals and Solutions; Materials; Procedure; Alternate Procedure: Genie in a bottle, apparatus and steps 3–6]{ref}
The balanced net <chemical equation> is $2\mathrm{H_2O_2}\longrightarrow2\mathrm{H_2O}+\mathrm{O_2}$. Appearance of gas after contact supports a contact-dependent acceleration of decomposition under these conditions. It does not distinguish surface conversion from a contribution of dissolved material, establish regeneration, or measure an <activation energy>. The simultaneous <heat> release also means that <temperature> can change after contact. A matched no-<solid> comparison and an empty-bag comparison would test background decomposition and the bag's contribution; these are proposed controls, not reported trials. The <catalysed peroxide comparison> supplies a complementary inspected teaching experiment with separate single-addition and paired-addition comparisons.
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