To calculate the number of atoms of LiBr present in 1.25 moles, we need to use Avogadro's number. Avogadro's number is a constant value equal to 6.022 × 10^23, which represents the number of atoms, molecules, or ions present in one mole of a substance.

So, the number of atoms of LiBr can be calculated by multiplying the number of moles by Avogadro's number:

Number of atoms of LiBr = (1.25 moles) × (6.022 × 10^23 atoms/mole)

Number of atoms of LiBr = 7.53 × 10^23 atoms

Therefore, if you start with 1.25 moles of LiBr, you will have approximately 7.53 × 10^23 atoms of LiBr.