Final answer:
To find the number of formula units in 20.6 g of MgCl2, calculate the moles using the molar mass and then multiply by Avogadro's number, resulting in approximately 1.30 x 10^23 formula units.
Step-by-step explanation:
The question is asking for the number of formula units in 20.6 g of magnesium chloride (MgCl2). To calculate this, we need to use the molar mass of MgCl2 and Avogadro's number.
The molar mass of MgCl2 is 95.21 g/mol. By dividing the mass of the sample by the molar mass, we can find the number of moles:
Number of moles = 20.6 g / 95.21 g/mol = approximately 0.216 moles of MgCl2
Using Avogadro's number, which is 6.022 x 1023 formula units per mole, we can calculate the number of formula units:
Number of formula units = 0.216 moles x 6.022 x 1023 formula units/mole = approximately 1.30 x 1023 formula units of MgCl2