Question:
An example of a non-stoichiometric oxide when heated is
An example of a non-stoichiometric oxide when heated is
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Zinc oxide changes color from white to yellow upon heating due to these non-stoichiometric defects.
Updated On: May 1, 2026
- BeO
- ZnO
- MgO
- CaO
- Li$_2$O
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The Correct Option is B
Solution and Explanation
Concept:
Heating certain metal oxides creates crystal defects where the ratio of metal to oxygen is no longer a simple whole number.
Step 1: {Analyze the effect of heat on Zinc Oxide.}
When $ZnO$ is heated, it loses oxygen atoms from the lattice according to the following equation: $$ZnO \xrightarrow{\Delta} Zn^{2+} + \frac{1}{2}O_2 + 2e^-$$
Step 2: {Identify the resulting lattice defect.}
The excess $Zn^{2+}$ ions and electrons occupy interstitial sites in the crystal. This creates a metal excess defect.
Step 3: {Determine the stoichiometry change.}
Because of the excess zinc, the formula becomes $Zn_{1+x}O$. This makes it a non-stoichiometric oxide.
Step 1: {Analyze the effect of heat on Zinc Oxide.}
When $ZnO$ is heated, it loses oxygen atoms from the lattice according to the following equation: $$ZnO \xrightarrow{\Delta} Zn^{2+} + \frac{1}{2}O_2 + 2e^-$$
Step 2: {Identify the resulting lattice defect.}
The excess $Zn^{2+}$ ions and electrons occupy interstitial sites in the crystal. This creates a metal excess defect.
Step 3: {Determine the stoichiometry change.}
Because of the excess zinc, the formula becomes $Zn_{1+x}O$. This makes it a non-stoichiometric oxide.
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