# What mass of BF_3 contains the same number of molecules as a 0.53*g mass of water?

Sep 10, 2017

And so you want the MASS of $B {F}_{3}$ that corresponds to the same number of molecules in a $0.53 \cdot g$ mass of water?

#### Explanation:

$\text{Moles of water} \equiv \frac{0.53 \cdot g}{18.01 \cdot g \cdot m o {l}^{-} 1} = 0.0294 \cdot m o l$...

Now the mole is simply a number, i.e. $1 \cdot m o l$ specifies $6.022 \times {10}^{23}$ individual molecules of whatever stuff you got.

ANd so we multiply this molar quantity by the molar mass of $B {F}_{3}$....

$\equiv 0.0294 \cdot m o l \times 67.82 \cdot g \cdot m o {l}^{-} 1 = 2.0 \cdot g$.........