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1.  How many moles of gold are in 2.23 X 10^17 atoms of gold?

 

2.  How many moles of rust (Fe2O3) are in 9.21 X 10^27 formula units of the compound?

 

3. How many atoms of pure copper are in 1.95 mol of copper?

off-topic
 Nov 14, 2018
 #1
avatar+107656 
+1

I can do the first one

 

2.23 x 10^17   x       1 mole

                               ________________   =  

                                6.0221415 × 10^23

 

 

2.23  x 10^17

_______________   moles  =

6.0221415 × 10^23

 

 

 

0.3703001664773237  x  10^(17 - 23)  ≈  .37 x 10^(-6)  =  3.7 x 10^(-7)  moles

 

 

 

cool cool cool

 Nov 14, 2018
 #2
avatar+20440 
0

2. The formula unit for rust is as given....

 

      9.21 x 10^23 molecules / 6.02214 x 10 ^23 molecules/mole = 1.529 moles of rust formula units

 

 

3.     1.95 mole  x   6.022 x 10^23 atoms/mole      =  11.743 x 10^23 atoms  

                                                                               ( I would recommend counting them all just to be sure! )  cheeky

 Nov 14, 2018
 #3
avatar
+1

2) 

EP: Did you mean to: convert 9.21×10^27 molecules of iron(III) oxide to moles? If so, then:

9.21 x 10^27 / 6.022...x 10^23 =15,294 moles.

 Nov 15, 2018
 #4
avatar+20440 
0

Yes, that is what I meant to do......but I typed in the incorrect number for the rust units ....it should be 10^27   not 10^23, so the answer is 100000 times bigger.....sorry.    And thanx!

 

  9.21 x 10^27 molecules / 6.02214 x 10 ^23 molecules/mole = 15290 moles of rust formula units

ElectricPavlov  Nov 15, 2018
edited by ElectricPavlov  Nov 15, 2018

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