Question

How many moles are in 51.06 grams of gold?

Answer 1

= (51.06/196.97) mol. First you must look at the periodic table for gold. Then look at the atomic weight at the bottom of that box. The atomic weight is in grams/mol. So know that if you mulptiply fractions you multiply the numbers straight across and you also scoot the units across as well. So you have (197 gram/mol) x and you are given either grams and want to find moles or vice versa. This problem gives you grams and wants you to find moles. So you set up your equations so that when you multiply the fraction you have grams which should cross out and you'll be left with moles. Make sure the moles are at the top of the fraction and if not then change the (197g/mol) to (1mol/197g). Which you will have to do for this problem.

Finally you should have and equation that looks like this:

(1mol/197g) times (51.06g) = ( 51.06g x mol )/ (197.97g) then the grams cross out (because grams divided by grams cross out) and your left with moles and like I said keep in mind the moles are going to be at the top. Hope that helps