To solve the question we need to:
Step 1 - Calculate the molar mass of BaF2
Step 2 - Use the following formula: moles = mass/molar mass
Step 1:
Atomic mass of Ba is 137.33 g/mol
Atomic mass of F is 19 g/mol
We can find these values at periodic table.
We multiply the atomic mass by the quantity of atoms of each element:
(1x137.33) + (2x19) = 175.33 g/mol
So the molar mass of BaF2 is 175.33 g/mol
Step 2:
moles = mass/molar mass
moles = 147/175.55
moles = 0.838 moles
Answer: 0.838 moles of BaF2