Answer:
The molar mass of Mg2SiO4 can be calculated by adding the atomic masses of each element:
Mg: 2 x 24.31 g/mol = 48.62 g/mol
Si: 1 x 28.09 g/mol = 28.09 g/mol
O: 4 x 16.00 g/mol = 64.00 g/mol
Molar mass of Mg2SiO4 = 48.62 + 28.09 + 64.00 = 140.71 g/mol
To calculate the number of oxygen atoms in a 120.0 g sample of forsterite, we first need to calculate the number of moles of Mg2SiO4 in the sample:
n = mass / molar mass = 120.0 g / 140.71 g/mol = 0.853 mol
Next, we can use the molecular formula to determine the number of oxygen atoms in one mole of Mg2SiO4:
Mg2SiO4 has 4 oxygen atoms per molecule, so one mole of Mg2SiO4 has 4 moles of oxygen atoms.
Therefore, the number of oxygen atoms in 0.853 mol of Mg2SiO4 is:
0.853 mol Mg2SiO4 x 4 mol O / 1 mol Mg2SiO4 = 3.412 mol O
Finally, we can convert the number of oxygen atoms to a more convenient unit, such as atoms. One mole of oxygen atoms contains 6.022 x 10^23 atoms, so the total number of oxygen atoms in 0.853 mol of Mg2SiO4 is:
3.412 mol O x 6.022 x 10^23 atoms/mol = 2.055 x 10^24 atoms of oxygen
Rounding this result to 4 significant digits, we get:
2.055 x 10^24 atoms of oxygen (to 4 significant digits)
Step-by-step explanation: