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Chemistry Asked by a SnapAndSolve user · about 2 hours ago

Calculate each of the following a) number of He atoms in 0.850 mole of He b) number of caffeine (C8H10O2N4)...

1. Calculate each of the following
a) number of He atoms in 0.850 mole of He
b) number of caffeine (C8H10O2N4) molecules in 0.850 mol of C8H10O2N4.
2. Zinc phosphate, Zn3(PO4)2, is used as dental cement.
a) How many moles of Zn ions are present in 1.0 mol of Zn3(PO4)2?
b) How many moles of phosphate ions (PO4^3-) are present in 1.0 mol of Zn3(PO4)2?
c) How many moles of oxygen atoms are present in 1.0 mol of Zn3(PO4)2?
d) How many oxygen atoms are present in 1.0 mol of Zn3(PO4)2?
3. Calculate the molar mass of each of the following:
a) silver nitrate (a topical anti-infective)
b) Ca3(PO4)2 (a calcium dietary supplement)

Answer

  1. Number of He atoms in 0.850 mole of He:
    Number of atoms = 0.850 mol × 6.022 × 1023 atoms/mol = 5.12 × 1023 He atoms.

  2. Number of caffeine (C8H10O2N4) molecules in 0.850 mol of C8H10O2N4:
    Number of molecules = 0.850 mol × 6.022 × 1023 molecules/mol = 5.12 × 1023 molecules.

  3. Moles of Zn ions in 1.0 mol of Zn3(PO4)2:
    There are 3 moles of Zn ions per mole of Zn3(PO4)2, so 3 moles of Zn ions.

  4. Moles of phosphate ions (PO43-) in 1.0 mol of Zn3(PO4)2:
    There are 2 moles of PO43- ions per mole of Zn3(PO4)2, so 2 moles of phosphate ions.

  5. Moles of oxygen atoms in 1.0 mol of Zn3(PO4)2:
    Each PO4 contains 4 oxygen atoms, and there are 2 PO4 units, so 8 moles of oxygen atoms.

  6. Oxygen atoms in 1.0 mol of Zn3(PO4)2:
    8 moles of oxygen atoms × 6.022 × 1023 atoms/mol = 4.82 × 1024 oxygen atoms.

  7. Molar mass of silver nitrate (AgNO3):
    Ag: 107.87 g/mol, N: 14.01 g/mol, O: 16.00 g/mol × 3 = 48.00 g/mol
    Total = 107.87 + 14.01 + 48.00 = 169.88 g/mol.

  8. Molar mass of Ca3(PO4)2:
    Ca: 40.08 g/mol × 3 = 120.24 g/mol, P: 30.97 g/mol × 2 = 61.94 g/mol, O: 16.00 g/mol × 8 = 128.00 g/mol
    Total = 120.24 + 61.94 + 128.00 = 310.18 g/mol.

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