# What is the mass of 3.54*10^24 molecules of rubidium oxide?

May 28, 2016

#### Answer:

It is a fact that ${N}_{A}$ $R {b}_{2} O$ particles have a mass of $186.94 \cdot g$.

#### Explanation:

Given that $6.02214 \times {10}^{24}$ formula units of $R {b}_{2} O$ have a mass of $186.94 \cdot g$, the given number of $R {b}_{2} O$ formula units have a mass of:

$\left(3.54 \times {10}^{24} \text{ formula units of " Rb_2O)/(6.02214xx10^24" formula units } m o {l}^{-} 1 \cdot R {b}_{2} O\right)$

$=$

??" moles of rubidium oxide"

So the mass $\cong$ $\frac{1}{2}$ $m o l$ $\times 186.94 \cdot g \cdot m o {l}^{-} 1 , \text{i.e. } 93 \cdot g$.