To calculate the number of magnesium (Mg) atoms in 20 g of magnesium sulfate (MgSO4), you need to follow these steps:
Determine the molar mass of MgSO4:
- The atomic mass of Mg is 24.31 g/mol.
- The atomic mass of S is 32.06 g/mol.
- The atomic mass of O is 16.00 g/mol.
- Since there are four oxygen atoms in MgSO4, multiply the atomic mass of O by 4.
- Calculate the molar mass by adding the atomic masses of all the elements: Molar mass of MgSO4 = (1 * Mg) + (1 * S) + (4 * O) = 24.31 + 32.06 + (4 * 16.00) = 120.37 g/mol.
Use the molar mass to calculate the number of moles of MgSO4:
- Divide the mass of MgSO4 (20 g) by its molar mass: Moles of MgSO4 = Mass of MgSO4 / Molar mass of MgSO4 = 20 g / 120.37 g/mol ≈ 0.166 mol.
Convert moles of MgSO4 to moles of Mg:
- Since there is one magnesium atom in one molecule of MgSO4, the number of moles of Mg is the same as the moles of MgSO4.
Convert moles of Mg to the number of Mg atoms:
- One mole contains Avogadro's number of particles, which is approximately 6.022 x 10^23.
- Multiply the number of moles of Mg by Avogadro's number to obtain the number of Mg atoms: Number of Mg atoms = Moles of Mg * Avogadro's number.
Substituting the values: Number of Mg atoms = 0.166 mol * (6.022 x 10^23 atoms/mol) ≈ 9.93 x 10^22 Mg atoms.
Therefore, there are approximately 9.93 x 10^22 Mg atoms in 20 g of MgSO4.