100g of an inorganic compound X5H2O containing a volatile impurity was kept in an oven at 150C for 60 minutes. the weight of the residue after heating is 8g. the percentage of impurity in X was ?

Question

alphadxg · Answer

mass of pure substance/original mass of substance x 100% 

8g/100g x 100% = Grams would cancel and you would be left with .08% purity

Usually purity questions are involved in reaction problems, let me know if there is more to the question.

anonymous · Answer

i can give You option of answers
1. 10 
2.  8
3.  20
4.  80

alphadxg · Answer

Oops, I gave you percent of purity not impurity, give me a second bud.

alphadxg · Answer

1
Divide the mass of the impurity by the mass of the total mass of the synthesis. This is to say, add the mass of the final product, the impurity, and all other material that resulted from the chemical synthesis and divide the mass of the impurity by that quantity.

2
Multiply the resulting numerical value by 100. This turns the resulting quantity into a percentage of impurity. This percentage of impurity represents the amount of impurity with respect to the entire process.

Answer would be '8' Option 2. 

Unless I did my math wrong someone please verify.

alphadxg · Answer

And because 'X' has only 1 mole, you would not need to do anymore to the problem.

anonymous · Answer

sorry but can u give exact calculations

alphadxg · Answer

Got a new mac, and won't let me use the editor tool. And if I try to type it out, it's gonna be messy and disorganized, try posting in the chemistry section.

anonymous · Answer

i got the answer 
20
can u explain it