Chem 問題，get唔到題目問什麽

molar mass of copper = 63.5 g/mol
molar mass of copper(II) oxide = 79.5 g/mol


- heat the mixture to red hot, then continuously pass excess pure oxygen over it. this promotes oxidation of copper into copper(II) oxide.
by calculating mass gained OR final resultant mass, total mass of copper, original mass of copper(II) oxide and metallic copper can be calculated.

- heat the mixture with continuous hydrogen gas / town gas passing over it. this promotes reduction of all copper(II) oxide into metallic copper.
again, by calculating mass lost OR final resultant mass, total mass of copper, original mass of copper(II) oxide and metallic copper can be calculated.

- dissolves the mixture in conc. hydrochloric acid (heat if necessary), followed by diluting with water, filtering and washing.
copper(II) oxide dissolves in common acids while metallic copper doesn't. by comparing mass of sample used and resultant mass remained, mass of copper(II) oxide and metallic copper can be found.


2010-11-16 22:20:38 補充：
oxidation:
2Cu + O2 -----> CuO

reduction:
CuO + H2 ------> Cu + H2O

dissolution:
CuO + 2HCl ------> CuCl2 + H2O
reaction product may not be blue, due to formation of yellow-to-green complex ions between copper(II) and chloride.
you can also use dilute sulphuric acid.

The question itself is ambiguous.

"Mass of copper" can mean "mass of copper powder" or "total mass of copper in copper powder and copper(II) oxide".