Answer:
To find the number of molecules of lithium chloride in 78.40 g, we need to first convert the mass to moles using the molar mass of lithium chloride:
moles = mass / molar mass
moles = 78.40 g / 42.39 g/mol
moles = 1.849 mol
Now we can use Avogadro's number to convert from moles to molecules:
molecules = moles x Avogadro's number
molecules = 1.849 mol x 6.022 x 10^23 molecules/mol
molecules = 1.111 x 10^24 molecules
Therefore, there are 1.111 x 10^24 molecules of lithium chloride in 78.40 g.
Step-by-step explanation: