ZnO shows yellow colour on heating due to: | vedclass

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Question

(D) $ZnO$ is white at room temperature. On heating,it loses oxygen and turns yellow due to the formation of metal excess defect. The reaction is: $ZnO

Vedclass · Accepted Answer

Metal excess defect due to $F$-centres

Vedclass · Answer

(D) $ZnO$ is white at room temperature. On heating,it loses oxygen and turns yellow due to the formation of metal excess defect. The reaction is: $ZnO \xrightarrow{\Delta} Zn^{2+} + \frac{1}{2}O_2 + 2e^-$. The excess $Zn^{2+}$ ions move to interstitial sites and the electrons move to neighboring interstitial sites to maintain electrical neutrality. These trapped electrons in the interstitial sites behave like $F$-centres,which absorb light from the visible region and impart a yellow colour to the crystal.

$ZnO$ shows yellow colour on heating due to:

Similar Questions

Which among the following statements is $NOT$ true about Frenkel defect?

Which of the following molecular formula and type of defect are correct for the following statement?
"In $FeO$ crystal,some $Fe^{2+}$ ions are missing and the loss of positive charge is made up by the presence of $Fe^{3+}$ ions".

Calcium crystallises in a face-centred cubic unit cell with edge length $a = 0.556 \ nm$. Calculate the density. If it contained $0.1 \%$ Frenkel defects,what is the density in $g \ cm^{-3}$?

What type of defect can arise when a solid is heated? Which physical property is affected by it and in what way?

Point defects are present in

Vedclass Test Series

Exam Paper Generator

Online Exam Module