Question

How many grams of phosphorus are represented by 2.34 x 10^23 phosphorus trichloride molecules? (Answer is 12.0 grams, I don't understand how to do it)

Answer 1

PCl3 ( phosphorus trichloride )

 P => 30.97 u

30.97 g P -----------------> 6.02 x 10²³ molecules
( mass P ) ----------------> 2.34 x 10²³ molecules

( mass P ) = ( 2.34 x 10²³ ) x 30.97 / 6.02 x 10²³

mass P = 7.24 x 10²⁴ / 6.02 x 10²³

= 12.0 g

hope this helps!