Question

How many molecules (or formula units) are present in 1.00g of (NH4)2Cr7O2?

Answer 1

N = 14g x 2 = 28g
H = 1g x 8 = 8g
Cr = 52g x 7 = 364g
O = 16g x 2 = 32g
Total MW. = 432g

Total Moles = 1/432 moles x 6.022x10^23

Total molecules = 1.39x10^21

Check my calculations at the end here. I did not have a good calculator.

Answer 2

I got something like that too but when I checked it in the back of my textbook it says 2.39x10^21 so I'm confused

Answer 3

Typo in the book. It happens a lot.

Answer 4

Alright then. Thank you!

Answer 5

No problem. :-)