Percent by Mass

Problem:

Calculate the percent by mass of phosphorus and chlorine in phosphorus trichloride (PCl₃).

Strategy:

1. Assume one mole of phosporus trichloride. Find the moles of phosphorus and moles of chlorine.
   
   
2. Convert mole of each element to mass of each element.
   
   
3. Calculate the percent by mass of each element.
   
   
   

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