Answer :
Final answer:
To calculate the number of formula units in 159g of PbCrO4, we need to use Avogadro's number. First, calculate the molar mass of PbCrO4 and then use the formula: number of moles = mass / molar mass. Finally, multiply the number of moles by Avogadro's number to get the number of formula units.
Explanation:
To calculate the number of formula units in 159g of PbCrO4, we need to use the concept of Avogadro's number. First, we calculate the molar mass of PbCrO4. The molar mass of PbCrO4 is calculated by adding the atomic masses of each element in the formula: Pb (207.2 g/mol) + Cr (52 g/mol) + O (16 g/mol, multiplied by 4) = 323.2 g/mol.
Next, we use the formula: number of moles = mass (in grams) / molar mass. Plugging in the values, we get: number of moles = 159g / 323.2 g/mol = 0.492 moles.
Finally, we use Avogadro's number (6.022 x 1023) to calculate the number of formula units. The number of formula units = number of moles x Avogadro's number. Plugging in the values, we get: number of formula units = 0.492 moles x 6.022 x 1023 = 2.96 x 1023 formula units.
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