How many moles of PCl₃ contain 3.68 × 10²⁵ chlorine atoms? A)61.1 moles PCl₃ B)20.4 moles PCl₃ C)16.4 moles PCl₃ D)54.5 moles PCl₃ E)49.1 moles PCl₃

Question

Quizplus · Accepted Answer

1 mole of PCl5 contains 5 moles of chlorine atoms. 
Therefore, the number of moles of PCl5 containing 3.68 × 10^25 chlorine atoms is: 
3.68 × 10^25 Cl / 5 mol Cl = 7.36 × 10^24 mol PCl5 
However, the question asks for the number of moles of PCl5, not the number of moles of PCl5 containing the given number of chlorine atoms. 
Therefore, the answer is: 
7.36 × 10^24 mol PCl5 x (1 mol PCl5 / 208.23 g PCl5) = 3.53 x 10^22 g PCl5 
3.53 x 10^22 g PCl5 x (1 mol PCl5 / 208.23 g PCl5) = 16.9 mol PCl5 
Thus, the correct answer is B) 20.4 moles PCl5.

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