Transcript 01-14 element to compound ratios for web

Add to U7-3 Warm-Ups
 Title the assignment:
01/14 Warm-Up: Element to Compound Ratios
 Copy the question, show work where applicable, and
then write your answer.
1. What is the formula for calcium phosphate? Ca3(PO4)2
2. How many moles of calcium phosphate are
represented by its chemical formula?
1 mol
3. In the formula for calcium phosphate, how many
moles of calcium are represented?
3 mol Ca
4. How many moles of phosphorus?
2 mol P
5. How many moles of oxygen?
8 mol O
Add to U7-3 Warm-Ups
6. How many moles of oxygen are in 3.75 moles of
calcium phosphate?
mol O =
3.75 mol Ca3(PO4)2
= 30 mol O
= 30.0 mol O
8 mol O
1 mol Ca3(PO4)2
Add to U7-3 Warm-Ups
7. How many atoms of oxygen are in 3.75 moles of
calcium phosphate?
atoms O =
3.75 mol
Ca3(PO4)2
8 mol O
1 mol Ca3(PO4)2
= 1.806 × 1025 atoms O
= 1.81 × 1025 atoms O
6.02 × 1023
atoms O
1 mol O
Add to U7-3 Warm-Ups
8. How many grams of oxygen are in 3.75 moles of
calcium phosphate?
grams O =
3.75 mol
Ca3(PO4)2
8 mol O
1 mol Ca3(PO4)2
= 480 g O
= 480. g O or 4.80 × 102 g O
16.0 g O
1 mol O
Three conversions factors:
1. 1 mol = 6.02 × 1023 representative particles
Avogadro’s #
 Only valid for one substance
2.  mol element = 1 mol compound
subscripts
3. Molar mass:
 g = 1 mol compound
# for atomic mass from Periodic Table
 Only valid for one substance