Answer:
When copper is heated in an atmosphere of hydrogen, the hydrogen gas can react with the oxygen present on the surface of the copper to form water. This reaction is known as reduction. The equation for this reaction is:
2H2 + O2 → 2H2O
In this reaction, the oxygen atoms in the copper are reduced (i.e., they gain electrons) and the hydrogen atoms are oxidized (i.e., they lose electrons). As a result, the oxygen is removed from the surface of the copper, leaving it oxygen-free.
This process is often used to purify copper and remove impurities, such as oxygen, that may be present on the surface of the metal. It is also used to produce high-purity copper for use in electrical and electronic applications, where the presence of oxygen can affect the conductivity of the metal.