Question

Zno crystal on heating acquires the formula zn 1+x o. Give reason.

Answer 1

Zinc Oxide is originally a white powder. When heated up, it turns yellow but does not decompose and when it is removed from the heat it gradually goes back to its original white color. If you heat it strongly enough to very high temperatures it will sublime without apparent decomposition. The reason for the yellow color is that a minute amount of oxygen evaporates from the lattice (70 ppm) the small number of zinc atoms produce lattice defects that give rise to the color. Doping zinc oxide with minute traces of zinc will give a range of colors, yellow, green brown and red.