# chemistry

A 1.24 gram sample of potassium chlorate was heated with manganese dioxide until no addition reaction was visible. THe potassium chloride residue was found to be .72 grams. What was the mass of the oxygen evolved in the experiment?

If there is a balanced equation, if you could please tell me what the products are, thanks :)

The next part: what is the percent, by mass, of oxygen based on the data in the question above?

Thanks for your help, show all work if possible! :)

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1. The reaction is as followed:

2KClO3 ---(MnO2)---> 2KCl + 302

MnO2 is a catalyst

2 moles of KCl produces 3 moles of O2

0.72 g of KCl*(1 mole/74.5513 g)= moles of KCl

moles of KCl*(3 moles of O2/1 mole of KCl)= moles of O2

moles of O2*(31.999g/mole)= mass of O2

(Mass of O2/0.72g +Mass of O2)*100=% of O2 by mass

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posted by Devron
2. Isn't it 2 moles of KCL, from the balanced equation? for the 2nd step (mole ratio)

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posted by K
3. Yes, a typo.

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posted by Devron
4. Haha ok, thanks :)

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posted by K

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