Answer:
There are 3 significant figures
We see from the chemical formula itself that there is 1
mole of F2 for every 1 mole of CaF2, hence the number of moles of CaF2 is also:
moles CaF2 = 1.23 moles
The molar mass of CaF2 is 78.07 g/mol, so the mass is:
mass CaF2 = 78.07 g / mol * 1.23 mol
<span>mass CaF2 = 96.03 grams</span>
Mass of Oxygen : 8 g
<h3>Further explanation</h3>
Given
48g of Magnesium
32g of Oxygen
Required
Mass of Oxygen
Solution
The ratio of Mg and O in MgO :
48 g : 32 g = 3 : 2
Total ratio = 3+2 = 5
So for 20 g MgO, mass of Oxygen :
=2/5 x 20 g
=8 g
Or
%mass O = 32/80 x 100%=40%
mass O in 20 g MgO =
40% x 20 g =8 g
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