How many formula units make up 25.2 of magnesium chloride?
25.2 what? grams.
formula units = grams/formula mass
To determine the number of formula units in 25.2 g of magnesium chloride, we need to use the molar mass of the compound and Avogadro's number.
1. Find the molar mass of magnesium chloride (MgCl2):
- The atomic mass of magnesium (Mg) is 24.31 g/mol.
- The atomic mass of chlorine (Cl) is 35.45 g/mol.
- Since magnesium chloride contains one magnesium atom and two chlorine atoms, the molar mass is:
Mg: 24.31 g/mol
Cl: 35.45 g/mol x 2 = 70.90 g/mol
- The molar mass of MgCl2 is therefore:
MgCl2: 24.31 g/mol + 70.90 g/mol = 95.21 g/mol
2. Calculate the number of moles of magnesium chloride:
- Use the formula: Moles = Mass / Molar mass
- Moles = 25.2 g / 95.21 g/mol = 0.265 moles
3. Apply Avogadro's number:
- Avogadro's number (N) is approximately 6.022 x 10^23 formula units/mol.
- The number of formula units is calculated by multiplying the number of moles by Avogadro's number:
Formula units = Moles x Avogadro's number
Formula units = 0.265 moles x 6.022 x 10^23 formula units/mol
Therefore, there are approximately 1.596 × 10^23 formula units in 25.2 g of magnesium chloride.
To determine the number of formula units in 25.2 g of magnesium chloride, we need to use the concept of molar mass and Avogadro's number.
1. Start by finding the molar mass of magnesium chloride (MgCl2).
- The molar mass of magnesium (Mg) is 24.31 g/mol.
- The molar mass of chlorine (Cl) is 35.45 g/mol.
- Since there are two chlorine atoms in magnesium chloride, the molar mass of MgCl2 is calculated as:
Molar mass = (1 × Mg) + (2 × Cl) = 24.31 + (2 × 35.45) = 95.21 g/mol.
2. Use the molar mass to convert grams to moles.
- Moles = Mass / Molar mass
- Moles = 25.2 g / 95.21 g/mol ≈ 0.264 moles of MgCl2.
3. Apply Avogadro's number to find the number of formula units.
- Avogadro's number is approximately 6.022 x 10^23 formula units per mole.
- Number of formula units = Moles × Avogadro's number
- Number of formula units = 0.264 moles × 6.022 x 10^23 formula units/mol ≈ 1.59 x 10^23 formula units.
Therefore, approximately 1.59 x 10^23 formula units make up 25.2 g of magnesium chloride.