Question

when the powder of acommon metal is heated in china dish ,its turns black.however,when hydrogen is passed overthe hot black substance so formed,it regainsits original color.
a)what type of chemical reaction takes place in each of the two given steps.
b)name the metal taken initially in the powder form.

Answer 1

a) Combination reaction/oxidation reaction

2 Cu(copper brown-brown) + O2→2CuO (copper oxide- black)

II )Reduction reaction

2pb (No3)2→2pbO (residue)+4NO2 (Nitrogen dioxide-brown fumes)+O2.

(b) Copper metal is taken initially in the powdered form.