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Home Q & A Board Science-Related Homework Help Chemistry (Moderator: Laser_3)
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smotwan smotwan
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12 years ago
How do I write the equation of a chemical reaction when potassium and oxygen combine to form potassium oxide?

I thought it should be      K + O2 --------> KO2

But I searched the formula found K2O instead. Which one is right? And if it is the K2O please explain.
Thank you all!
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#1
12 years ago
The valency of potassium is 1, having 1 electron in outer shell.
The valency of oxygen is 2 having 2 electrons in it's outer shell.

So the product is K2O

Your reaction would indicate a velency of 1 or 2 for potassium depending on valency you give oxygen

So it becomes 4K + O2  -------> 2K2O
wrote...
#2
12 years ago
K2O is correct because Oxygen is a -2 charge and Potassium is a -1 charge. In order for the compound to be neutral, you need 2 Potassiums for each Oxygen.

I think what you tried to do is just combine the products as is, including their subscript numbers. That's the wrong way to go. You need to first combine the ions just by themselves, then you can add subscripts to an ion so the compound is neutral. After your compound is neutral, then you balance the whole equation.

 4K + O2 --------> 2(K2O)
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#3
12 years ago
But the answers are, I'm afraid, incorrect!  The reaction of K (and Rb, Cs) with O2 gives K^+[O-O]^- ,that is, KO2 potassium superoxide.  K2O can be prepared but not from the rxn of K with oxygen.  Li and to some extent Na give the normal oxide M2O when reacted with O2.
google superoxide to confirm.
wrote...
#4
12 years ago
Potassium oxide is an ionic compound of potassium and oxygen. This pale yellow solid, the simplest oxide of potassium, is a rarely encountered, highly reactive species. Some materials of commerce, such as fertilizers and cements, are assayed assuming the percent composition that would be equivalent to K2O.

Potassium oxide is produced from the reaction of oxygen and potassium; this reaction affords potassium peroxide, K2O2. Treatment of the peroxide with potassium produces the oxide:[1]

    K2O2 + 2 K ? 2 K2O
wrote...
#5
12 years ago
K is first group element with atomic number 19 and electronic structure 2,8,8,1 and oxygen in group 6 with atomic number 8,structure 2,6,Potassium looses one electron and oxygen gains two,to complete eight electrons in the last orbit,so two potassium atoms participate and formula is K2O
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