Question

How many molecules of PF5 are found in 39.5 grams of PF5?

Answer 1

Answer:

$1.9 \times 10^{23} molecules$ of $PF_5$ are found in 39.5 grams of $PF_5$.

Explanation:

Atomic weights : P= 31, F= 19,

molar mass of = 1 atomic weight of P+ 5 atomic weight of

 F= 31+5 $\times$ 19

= 31+95

 =126 g/mole

moles in 39.5 gm of

= $\frac{Mass}{Molar mass}$

 = $\frac{39.5}{126}moles$

 =0.3134 moles

1 mole of any substance contains

0.3131 moles contains 0.3134  

 $= 1.9 \times 10^{23} molecules$

Therefore, $1.9 \times 10^{23} molecules$ of $PF_5$ are found in 39.5 grams of $PF_5$.