To find the number of formula units in 12.91 grams of Zr(SO4)2, we need to follow a few steps. First, we should calculate the molar mass of Zr(SO4)2.
The formula Zr(SO4)2 consists of:
- 1 Zirconium (Zr) atom
- 2 Sulfate (SO4) groups
Let’s find the molar mass:
- Molar mass of Zr = 91.22 g/mol
- Molar mass of S = 32.07 g/mol
- Molar mass of O = 16.00 g/mol
Now, the molar mass of SO4 is:
- (1 x 32.07) + (4 x 16.00) = 32.07 + 64.00 = 96.07 g/mol
Since there are 2 sulfate groups in the formula, we multiply the molar mass of SO4 by 2:
- 2 x 96.07 g/mol = 192.14 g/mol
Now, we can calculate the total molar mass of Zr(SO4)2:
- 91.22 g/mol (for Zr) + 192.14 g/mol (for SO4) = 283.36 g/mol
Next, we use the molar mass to convert grams to moles:
- Moles of Zr(SO4)2 = mass (g) / molar mass (g/mol)
- Moles = 12.91 g / 283.36 g/mol ≈ 0.0455 moles
To find the number of formula units, we use Avogadro’s number, which is approximately 6.022 x 10²³ units/mol:
- Number of formula units = moles x Avogadro’s number
- Formula units = 0.0455 moles x 6.022 x 10²³ units/mol ≈ 2.743 x 10²² formula units
Therefore, in 12.91 grams of Zr(SO4)2, there are approximately 2.743 x 10²² formula units.