# How many molecules are present in a 27*g mass of OF_2(g)?

Dec 30, 2016

$\text{Number of molecules}$ $\equiv$ $\text{Number of moles} \times {N}_{A}$......

#### Explanation:

Where ${N}_{A} = \text{Avogadro's number}$ $=$ $6.022 \times {10}^{23} \cdot m o {l}^{-} 1$

$\text{Number of moles}$ $=$ $\text{Mass"/"Molar mass}$

$=$ $\frac{27 \cdot g}{54.00 \cdot g \cdot m o {l}^{-} 1} = 0.500 \cdot m o l$

And thus $\text{Number of molecules}$ $=$ $6.022 \times {10}^{23} \cdot m o {l}^{-} 1$

$=$ $3.011 \times {10}^{23}$ $O {F}_{2}$ molecules..........

What is the oxdation number of oxygen in this molecule?