Alright, 2PbO2 -->2PbO + O2

15.000g of PbO2 makes 0.018mol of O2

What is the mass of the precipitate (PbO)

What is the percent mass (of PbO)?

 

Thanks

We are not doing your homework!

 

I'll give you some guidelines, but you have to do the computations yourself.

 

How many moles is 15.000 grams of PbO2?

 

You have the equation 2PbO2 --> 2PbO + O2

 

This means that for each mole of oxygen you get two moles of PbO

 

So, you can compute how many moles of PbO you have after the reaction.

The number of moles of PbO formed equals the number of moles of PbO2 which disappeared, so you can compute the number of moles of PbO2 remaining.

 

So, after having done these computations you know how many moles of PbO2 you have left and how many moles of PbO you have.

 

Now you can compute the mass of the formed PbO and you can compute the total mass easily This gives you the percentage.

 

 

Success!