15. Avogadro’s Number
6.02 × 1023
• Number of atoms in 12 grams of Carbon-12
Molar Mass
The mass of 1 mole of a substance
16. Molar Mass
Using the Periodic Table
N2 + 3H2 → 2 NH3
• mass of 1 mol of N2 =
28 g
• mass of 3 mol of H2 =
6 g
• mass of 2 mol of NH3 =
34 g
17. • If you find the mass of a sample of glucose
(C6H12O6) to be 90.0 g, how many moles of
glucose do you have?
• A certain laboratory procedure requires the
use of 0.100 moles of magnesium. How many
grams of magnesium would you mass out on
the balance?
18. 2 step problem
• What would be the mass of 3.75 x
1021
atoms of iron?
• First change number of atoms to moles
• Now, change number of moles to mass