Potassium permanganate, KMnO4, a common oxidizing agent, is made from various ores that contain manganese (IV) oxide, MnO2. The equation shows the net reaction for one process that forms potassium permanganate

2MnO2+2KOH+O2=2KMnO4+H2
Explain why the oxygen gas is in excess

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In the given equation, we can observe that oxygen gas (O2) is not completely consumed in the reaction. This implies that there is an excess amount of oxygen gas present.

The presence of excess oxygen gas ensures that all the manganese dioxide (MnO2) present in the reaction is fully oxidized to form potassium permanganate (KMnO4). If there was a limited amount of oxygen gas, it would result in the incomplete oxidation of MnO2, leading to an incomplete reaction.

By having an excess of oxygen gas, we can ensure that all the MnO2 reactant is converted to KMnO4 product, resulting in a complete reaction and maximum yield of potassium permanganate. This is why oxygen gas is provided in excess in the reaction.

In this reaction, the oxygen gas (O2) is considered to be in excess, which means that there is more than enough oxygen present to react with all the other reactants.

To understand why the oxygen gas is in excess, we can consider the stoichiometry of the reaction. The balanced equation indicates that you need 1 mole of oxygen gas for every 2 moles of manganese (IV) oxide (MnO2) to produce 2 moles of potassium permanganate (KMnO4).

However, the reaction involves the reaction of 2 moles of manganese (IV) oxide (MnO2) with 2 moles of potassium hydroxide (KOH) and 1 mole of oxygen gas (O2). This means that for every 1 mole of oxygen gas, you need 2 moles of manganese (IV) oxide.

Since the balanced equation shows a 1:2 ratio between oxygen gas and manganese (IV) oxide, having more than 1 mole of oxygen gas available ensures that there is enough oxygen to react with all the manganese (IV) oxide present. Any excess oxygen gas not used in the reaction remains unreacted.

There could be several reasons why excess oxygen gas is used in this reaction. One possibility is that having excess oxygen ensures that all the manganese (IV) oxide is completely converted to potassium permanganate from an efficiency standpoint. Additionally, the presence of excess oxygen helps promote a consistent reaction rate and ensures the reaction reaches completion, as opposed to being limited by a shortage of oxygen.