Can a substance act as both an oxidising and reducing agent?

Yes, a substance can act as both an oxidising and reducing agent.

In chemistry, there are substances that can act as both oxidising and reducing agents. These substances are known as redox agents or amphoteric substances. The ability of a substance to act as both an oxidising and reducing agent depends on the conditions and the other substances present in the reaction.

An oxidising agent is a substance that has the ability to oxidise other substances, meaning it causes them to lose electrons. In this process, the oxidising agent itself is reduced, meaning it gains electrons. On the other hand, a reducing agent is a substance that has the ability to reduce other substances, meaning it causes them to gain electrons. In this process, the reducing agent itself is oxidised, meaning it loses electrons.

A classic example of a substance that can act as both an oxidising and reducing agent is hydrogen peroxide (H2O2). In certain reactions, hydrogen peroxide can act as an oxidising agent. For example, when it reacts with potassium iodide, the iodide ions are oxidised to iodine, while the hydrogen peroxide is reduced to water. However, in other reactions, hydrogen peroxide can act as a reducing agent. For example, when it reacts with potassium permanganate, the permanganate ions are reduced to manganese(II) ions, while the hydrogen peroxide is oxidised to oxygen.

Another example is water (H2O), which can also act as both an oxidising and reducing agent. For instance, in the electrolysis of water, water acts as a reducing agent to produce hydrogen gas and as an oxidising agent to produce oxygen gas.

Therefore, it is indeed possible for a substance to act as both an oxidising and reducing agent, depending on the specific reaction conditions and the other substances involved.