potassium permanganate, kmno4, a common oxidizing agent, is made from various or

Question

potassium permanganate, kmno4, a common oxidizing agent, is made from various ores that contain manganese(iv) oxide, MnO2. the following equation shows the net reaction for one process that forms potassium permanganate. 2MnO2 + 2KOH + O2   ?    2KMnO4 + H2  

A. What is the maximum mass, in kilograms, of KMnO4 that can be made from the reaction of 835.6 g of MnO2 with 585 g of KOH and excess oxygen gas?

B. Explain why the oxygen gas is in excess.

C. If 1.18 kg of KMnO4 are isolated from the product mixture of the reaction of 835.6 g of MnO2 with 585 g of KOH and excess oxygen gas, what is the percent yield?

Explanation / Answer

The molar mass of MnO2 is 87g (55+16+16) and the molar mass of KOH is 56g (39+16+1). So you have

835.6/(87*2)=4.8 moles of MnO2 on your reactant side
585/(56*2)=5.2 moles of KOH on the reactant side

Basically, since 2 molecules of MnO2 reacts with 2 molecules of KOH to form 2 molecules of KMnO4, it is a 1-to1 ratio
Since you only have 4.8 moles of MnO2, only 4.8 moles of KOH will react with it to form 4.8 moles of KMnO4

So the molar mass of KMnO4 is 157g and you have 4.8 moles of KMnO4 so you multiply those two to get 735.6g which is the equivalent to .7356kg of KMnO4.

So .7356kg is your answer for a.
Having an excess of oxygen gas means that you have an unlimited supply of O2 and it will not limit your reaction

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