1. Practice: 2 step mole conversions

2. Converting mass to particles
How many molecules are in 23.6 grams of sodium chloride?
1) Given
2) Use molar mass
3) Use Avogadro’s #
1 mol NaCl x
58.44 g NaCl
6.02 x 1023 molecules NaCl=
1 mol NaCl
23.6 g NaCl x
4) Solve, round answer using sig.figs
2.43 x 1023 molecules NaCl

3. Converting particles to mass
How many grams are in 9.9 x 1024 formula units of iron(III) chloride?
1) Start with
2) Use Avogadro’s #
3) Use molar mass
1 mol FeCl x
6.02 x 1023 F.U. FeCl3
g FeCl3 =
1 mol FeCl3
9.9 x 1024 F.U. FeCl3 x
4) Solve, round answer using sig.figs
2,670 g FeCl3