A mixture of and was roasted in excess air. The total mass of formed was . The percentage of in the original mixture is .

Question

A  mixture of  and  was roasted in excess air. The total mass of  formed was . The percentage of  in the original mixture is .

Canvas Classes · Accepted Answer

Strategy:
 Roasting converts copper sulfides into copper(II) oxide. Track the moles of Copper through the reaction: the total number of Copper atoms in the initial sulfide mixture must equal the total number of Copper atoms in the final  produced.

Step 1: Use Copper Atom Conservation
Let  be weight of , then  is .
- Moles of  from 
- Moles of  from 
- Total moles of  (which equals moles of ) .

Step 2: Solve the equation

Solving for  gives the mass of  in the mixture. Based on option matching

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