Answer to Question #100417 in General Chemistry for Peabody

Question

In the following:

2 PbS + 3O2 --> 2PbO + 2SO2
PbS + 2O2 --> PbSO4

Why the same reactives in different equations produce different reaction types (simple substitution and combination) instead of the same one? Detailed explanation would be appreciated. Theory about predicting which type of reaction will occur will be helpful, too.

Thanks in advance.

Answer 1

Solution.

In the first reaction, sulfur sulfide is burned to lead oxide and sulfur dioxide. As can be seen from the equation oxygen is taken in short supply here. In the second reaction, sulfide is oxidized to sulfate in excess of oxygen. As can be seen from the equation oxygen is taken in excess. The second reaction takes place under severe conditions, unlike the first.

Answer:

In the first reaction, sulfur sulfide is burned to lead oxide and sulfur dioxide. As can be seen from the equation oxygen is taken in short supply here. In the second reaction, sulfide is oxidized to sulfate in excess of oxygen. As can be seen from the equation oxygen is taken in excess. The second reaction takes place under severe conditions, unlike the first.