Answer:
6. 13.8 moles
7. 0.751 moles
8. 2.04 moles
9. 0.00794 moles
10. 0.158 moles
Step-by-step explanation:
When converting from atoms to moles, use Avogadro's number.
Avogadro's number is 6.02 x 10^23.
After that, then use dimensional analysis for every problem to show your work.
6. (8.31 x 10^24 atoms of magnesium) * 1 mol Mg / (6.02 x 10^23) atoms = 13.80398671.
With sig figs however, it rounds to 13.8. Therefore, there are 13.8 moles of magnesium.
7. (4.52 x 10^23 formula units NaCl) * 1 mol NaCl / (6.02 x 10^23) atoms = 0.750830565.
With sig figs however, it rounds to 0.751. Therefore, there are 0.751 moles of NaCl.
8. (1.23 x 10^24 molecules CO) * 1 mol CO/ (6.02 x 10^23) atoms = 2.043189369.
With sigs figs however, it rounds to 2.04. Therefore, there are 2.04 moles of CO.
9. (4.78 x 10^21 molecules O2) * 1 mol O2 / (6.02 x 10^23) atoms = 0.007940199.
With sigs figs however, it rounds to 0.00794. Therefore, there are 0.00794 moles of O2.
10. (9.50 x 10^22 atoms of C) * 1 mol C / (6.02 x 10^23) atoms = 0.157807309.
With sig figs however, it rounds to 0.158. Therefore, there are 0.158 moles of C.
Hope it helped! Did I explain better than your teacher?