Answer :
Approximately 2.48 × 10²³ formula units make up 39.4 g of magnesium chloride (MgCl2).
To determine the number of formula units in 39.4 g of magnesium chloride (MgCl2), we need to use the molar mass of magnesium chloride and Avogadro's number.
1. Find the molar mass of MgCl2:
- The atomic mass of magnesium (Mg) is approximately 24.31 g/mol.
- The atomic mass of chlorine (Cl) is approximately 35.45 g/mol.
- Since there are two chlorine atoms in one formula unit of MgCl2, we multiply the atomic mass of chlorine by 2.
The molar mass of MgCl2 is:
(1 × 24.31 g/mol) + (2 × 35.45 g/mol) = 95.21 g/mol
2. Use the molar mass and the given mass (39.4 g) to find the number of moles of MgCl2:
- Divide the given mass by the molar mass.
39.4 g / 95.21 g/mol ≈ 0.413 mol
3. Convert the number of moles to the number of formula units using Avogadro's number:
- Avogadro's number is approximately 6.022 × 10²³ formula units/mol.
Multiply the number of moles by Avogadro's number:
0.413 mol × 6.022 × 10²³ formula units/mol ≈ 2.48 × 10²³ formula units
Therefore, approximately 2.48 × 10²³ formula units make up 39.4 g of magnesium chloride (MgCl2).
To know more about Avogadro's number visit:
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