Question

Why is molten metal stirred with the logs of green wood in poling?

Answer 1

1. The process of poling is used in the refining of metals like copper and tin. 
2. In this process, molten impure metal is stirred with logs of green wood.
3. The green wood, due to its high moisture content, gives out gases such as hydrogen, hydrocarbons and carbon monoxide when it comes in contact with molten metal.
4. These gases act as powerful reducing agents and reduce any oxide impurities present in the molten metal back to the free metal.
   \[\ce{CuO + H2 -> Cu + H2O}\]
   \[\ce{SnO2 + CO -> Sn + CO2}\]

Thus, poling helps in removing oxide impurities and makes the molten metal (like copper/tin) purer and malleable.