1. Unit 7: Stoichiometry
WCHS Chemistry

2. UNIT 7: WHAT IS STOICHIOMETRY
BRING PERIODIC TABLE & CALCULATOR EVERYDAY!
“Stoichiometry” is derived from the Greek words stoicheion, meaning “element”, and metron, meaning “measure”
TIPS → Attendance, attendance, attendance!!!
LEAVE NO WORKSHEETS UNDONE!!!!
There will be LOTS of Mini-Quizzes - especially after labs!!
If you MUST be absent:

3. LET’S REFRESH SOME GOOD TECHNIQUE
Let’s talk about rounding:
2 SIGNIFICANT FIGURES AFTER THE DECIMAL!
EXAMPLES:

4. LAB TIPS Copy ALL NUMBERS off the balance (even ZEROS)!!!
Think sig figs
Make sure to label everything with units and names!!!
If you are confused ASK QUESTIONS!!
Make sure you UNDERSTAND the lab - quiz TUESDAY!

5. REFRESHER
If I wanted to know the mass of the liquid in the flask, what would I do?
Mass of everything
- Mass of container
MASS OF LIQUID!

6. LAB: DEHYDRATION OF COPPER SULFATE
Find the formula weight of:
CuSO H2O
Cu: 1(64) = 64
S: 1(32) = 32
O: 4(16) =
160
= 160
= 18

7. LAB: DEHYDRATION OF COPPER SULFATE
Find the formula weight of:
CuSO H2O
= 160
= 18
H2O
Hydrate = WITH water
Dehydrate = “anhydrous” WITHOUT water
H2O
H2O
H2O
H2O
CuSO4
CuSO4
H2O
H2O
H2O
H2O
H2O

8. 26.05 g - 25.28 g = 0.77 g CuSO4 Moles = Mass . = 0.77 g /160
VERY IMPORTANT FORMULA!!!!
26.05 g g = 0.77 g CuSO4
Moles = Mass
= 0.77 g /160
= moles of CuSO4
Formula Weight

9. 1.20 g g = 0.43 g H2O
Hydrate
Dehydrate
Moles = Mass
= 0.43 g / 18
= moles of H2O
Formula Weight
moles of CuSO4 : moles of H2O
0.0048
0.0048
1:5
CuSO4
H2O