How many grams are in 8.200 x 10(22) molecules of N2I8?

Answer 1

Hello, Alli,

We need to determine how many moles are represented by 8.200 x 10²². Avogadro's number of 6.02 x 10²³ is the definition of 1 mole. So divide the first by the second:

(8.200 x 10²² molecules N₂I_{8 )}/(6.02 x 10²³ Molecules/mole) = 0.136 mole N₂I₈.

Now we need the molar mass of N₂I₈. N: 2x14 = 28, I: 8x127=1016. Total = 1044 g/mole.

Then multiply the moles by the molar mass:

0.136 mole * (1044 g/mole) = 142g N₂I₈

Even though we only have 0.136 mole, the molar mass is high, so we get the 42g figure.

I hope this helps,

Bob

Answer 2

The periodic table gives the average atomic mass of one mole of each element in grams. So this question is a 2-step problem.

First, you need to convert the number of individual molecules to the number of moles of molecules (using Avogadro's number).

Second, convert the number of moles of molecules to the mass of molecules, using the molar mass for the compound (2 nitrogen and 8 iodine atoms).