Although `H_(2)` is a good reducing agent, it is usually not used in metallurgy-why?

Explanation

During the reduction of metal oxide by `H_(2),H_(2)O(l)` is produced : `MO(s)+H_(2)(g)rarrM(s)+H_(2)O(l)`. As liquid product is obtained, `DeltaS` decreases which leads to an increase in `DeltaG` value of the process. Hence the thermodynamic feasibillity of the reaction decreases. Moreover there are some metals which can react with hydrogen (used as reducing agent in metal extraction) ot produce metal hydrides. As a result of this, the probability of obtaining pure metal decreases. Hence, `H_(2)` is not used as a reducing agent in metallurgy.