Chemistry Forum

Polychlorinated biphenyls (PCBs) were once widely used industrial chemicals but were found to pose a risk to health and enviro- ment. PCBs contain only carbon, hydrogen, and chlorine. Aroclor 1254 is a PCB with mo- lar mass 360.88 g/mol. Combustion of 1.52 g of Aroclor 1254 produced 2.224 g of CO₂, and combustion of 2.53 g produced 0.253 g of H₂O. How many chlorine atoms does an Aroclor 1254 molecule contain?

The combustion equation is: CxHyClz + O₂ -> CO₂ + H₂O + Cl₂

Please help!!! I don't know how to actually plug in the numbers.

Calculate moles of Aroclor in both cases. Calculate the moles of CO₂ and H₂O and get the corresponding moles of C and H
The ratio of it gives the amount of C and H. From this you get the molar mass of CxHy . Subtraktion from the molar mass of Arcolor gives the molar mass off all chlorine, devide through the molar mass of chlorine gives the amount of chlorine,

Would the answer be 6 chlorine atoms? Is my math correct?

Correct.
And how many C and H?