What is the mass in grams of 4.17 x 10^21 formula units of magnesium perchlorate, Mg(ClO4)2?  Write only NUMERIC ANSWER with no units (and in correct SF) to earn computer credit. You must show complete dimensional analysis with all units properly labelled, if it comes as a short answer on your test.

To find the mass in grams of 4.17 x 10^21 formula units of magnesium perchlorate, Mg(ClO4)2, we need to follow these steps:

1. Find the molar mass of Mg(ClO4)2. The molar mass of magnesium is approximately 24.305 g/mol, the molar mass of chlorine is approximately 35.453 g/mol, and the molar mass of oxygen is approximately 15.999 g/mol. Since there are two perchlorate ions, each with one chlorine atom and four oxygen atoms, the molar mass of Mg(ClO4)2 is 24.305 g/mol + 2*(35.453 g/mol + 4*15.999 g/mol) = 223.211 g/mol.

2. Convert the number of formula units to moles using Avogadro's number (6.022 x 10^23 formula units/mol). 4.17 x 10^21 formula units * (1 mol/6.022 x 10^23 formula units) = 0.00693 mol.

3. Convert moles to grams using the molar mass. 0.00693 mol * 223.211 g/mol = 1.547 g.

So, the mass in grams of 4.17 x 10^21 formula units of magnesium perchlorate, Mg(ClO4)2, is approximately 1.547 g.