# How do you find the formula units in 2.6 g of lithium bromide?

Feb 2, 2017

$\text{Number of formula units of LiBr}$ $\cong$ $2 \times {10}^{22}$

#### Explanation:

$\text{Number of formula units of LiBr"="Mass"/"Molar mass of LiBr} \times {N}_{A}$

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

And thus, (2.6*cancelg)/(86.84*cancelg*cancel(mol^-1))xx6.022xx10^23*cancel(mol^-1)=??

Since all the units cancel out, we get the answer as a number, as required.