Question

A sample of $Al{F}_3$ contains $9.012\times {10}^{23}$ $F^{-}$ ions. The volume occupied by the $Al{F}_3$ sample at STP is:

• A. 22.4 L
• B. 11.2 L
• C. 5.6 L
• D. 17.8 L

Answer 1

The correct option is B 11.2 L

3 $F^{-}$ ions are present in a molecule of $Al{F}_3$.

The number of molecules of $Al{F}_3$ that contain $9.036\times {10}^{23}{F}^{-}\text{ions}=\frac{1\times 9.036\times {10}^{23}}{3}$

Number of moles $=\frac{1\times 9.036\times {10}^{23}}{3\times 6.023\times {10}^{23}}=0.5\text{mol}$
Volume of $Al{F}_3$ occupied at STP $=0.5\times 22.4$ = 11.2 L