1. Add to U7-3 Warm-Ups Ca3(PO4)2 1 mol 3 mol Ca 2 mol P 8 mol O
Title the assignment:
01/14 Warm-Up: Element to Compound Ratios
Copy the question, show work where applicable, and then write your answer.
Ca3(PO4)2
What is the formula for calcium phosphate?
How many moles of calcium phosphate are represented by its chemical formula?
In the formula for calcium phosphate, how many moles of calcium are represented?
How many moles of phosphorus?
How many moles of oxygen?
1 mol
3 mol Ca
2 mol P
8 mol O

2. Add to U7-3 Warm-Ups
How many moles of oxygen are in 3.75 moles of calcium phosphate?
mol O =
3.75 mol Ca3(PO4)2
8 mol O
1 mol Ca3(PO4)2
= 30 mol O
= 30.0 mol O

3. Add to U7-3 Warm-Ups
How many atoms of oxygen are in 3.75 moles of calcium phosphate?
3.75 mol Ca3(PO4)2
6.02 × atoms O
8 mol O
atoms O =
1 mol Ca3(PO4)2
1 mol O
= × 1025 atoms O
= 1.81 × 1025 atoms O

4. Add to U7-3 Warm-Ups
How many grams of oxygen are in 3.75 moles of calcium phosphate?
3.75 mol Ca3(PO4)2
8 mol O
16.0 g O
grams O =
1 mol Ca3(PO4)2
1 mol O
= 480 g O
= 480. g O or × 102 g O

5. Three conversions factors:
1 mol = 6.02 × 1023 representative particles
Only valid for one substance
 mol element = 1 mol compound
Molar mass:  g = 1 mol compound
Avogadro’s #
subscripts
# for atomic mass from Periodic Table