1. Unit: Chemical Quantities
Day 3 - Notes
Unit: Chemical Quantities
Two-step Conversions: Particles to Mass and Vice Versa

2. After today, you will be able to…
Perform two-step conversions using molar mass and representative particles (atoms, molecules, and formula units)

3. We have already learned…
How to convert moles into particles and vice versa by using the conversion factor… 1 mole = 6.02x1023 particles

4. How to convert moles into grams and vice versa by using the conversion factor… 1 mole = atomic mass in grams

5. These two conversion factors can now be combined…
Particles  Moles  Grams Grams  Moles  Particles
6.02x1023
molar mass
molar mass
6.02x1023

6. Example: What is the mass of 1.79x1024 formula units of K3PO4?
K: 1.79x1024 F.U. K3PO4
3 K = 3(39.10) =
1 P = 1(30.97) =
4 O = 4(16.00) =
117.30
U: ? g K3PO4
30.97
+64.00
212.27
1.79x1024 F.U. K3PO4
1 mol K3PO
g K3PO4 x x =
6.02x1023 F.U. K3PO4 1
1 mol K3PO
631 g K3PO4

7. Time to Practice! Complete WS 3
HOMEWORK:
Time to Practice! Complete WS 3