1. Chem 106: Class/ Lab Week 9 Sign in: Roster @ front of lab
Work with your fermentation partner(s) for today’s experiment
Chemical Reactions / Stoichiometry
Take out your i-clicker

2. Question
Which of the following bonds is the most polar?
A) B)
C) D)

3. Answer
Which of the following bonds is the most polar?
A) B)
C) D) 3

4. What molecular shape is water?
Tetrahedral
Bent
Trigonal planar
Linear
Note that this question does not require expanded octets.
Goal: Connect Lewis structure of a familiar molecule to the name of the molecule geometry
Correct answer: B
Representative results from pre-general chemistry: 60-67% correct (remaining votes roughly split between C and D)
Follow-up discussion: Ask students about the lewis structure of water. Use the simulation (either the model or real molecules screen) to demonstrate the answer once a Lewis structure is agreed upon.

5. What molecular shape is water?
Tetrahedral
Bent
Trigonal planar
Linear
Note that this question does not require expanded octets.
Goal: Connect Lewis structure of a familiar molecule to the name of the molecule geometry
Correct answer: B
Representative results from pre-general chemistry: 60-67% correct (remaining votes roughly split between C and D)
Follow-up discussion: Ask students about the lewis structure of water. Use the simulation (either the model or real molecules screen) to demonstrate the answer once a Lewis structure is agreed upon.

6. Which of these molecules has a linear molecule geometry?
CO2 O3
Both
Neither
Note that this question does not require expanded octets.
Goal: Extend students application of VSEPR to unfamiliar molecules (carbon dioxide is frequently shown in textbooks as an examples, so many students recall their structure from memory without the need to apply geometry modelling or VSEPR). Ozone is less familiar.
Correct answer: A
Representative results from pre-general chemistry: 52% correct (next most popular answer is C)
Follow-up discussion: Ask students about the lewis structure of each. Use the simulation (either the model or real molecules screen) to demonstrate the answer once a Lewis structure is agreed upon. Follow-up slide can also be shown.
Note: While SO2 provides a more obvious contrasting case to CO2 than O3 does (and SO2 is shown in the real molecules screen of the sim), we chose to use ozone to avoid both the use of expanded octets. Additionally, there is some controversy concerning the best Lewis structure for SO2 which instructors should be aware of. Some textbooks treat it as analogous to O3, with one single and one double bond, while others give it two single bonds and an extra lone pair on S (as shown in the simulation). Both Lewis structures lead to a bent geometry.

7. Which of these molecules has a linear molecule geometry?
CO2 O3
Both
Neither
Note that this question does not require expanded octets.
Goal: Extend students application of VSEPR to unfamiliar molecules (carbon dioxide is frequently shown in textbooks as an examples, so many students recall their structure from memory without the need to apply geometry modelling or VSEPR). Ozone is less familiar.
Correct answer: A
Representative results from pre-general chemistry: 52% correct (next most popular answer is C)
Follow-up discussion: Ask students about the lewis structure of each. Use the simulation (either the model or real molecules screen) to demonstrate the answer once a Lewis structure is agreed upon. Follow-up slide can also be shown.
Note: While SO2 provides a more obvious contrasting case to CO2 than O3 does (and SO2 is shown in the real molecules screen of the sim), we chose to use ozone to avoid both the use of expanded octets. Additionally, there is some controversy concerning the best Lewis structure for SO2 which instructors should be aware of. Some textbooks treat it as analogous to O3, with one single and one double bond, while others give it two single bonds and an extra lone pair on S (as shown in the simulation). Both Lewis structures lead to a bent geometry.

8. Which molecule could be represented with this diagram?
BH3
CH4
NH3
NH4+
Note that this question does not require expanded octets.
Goal: Connect 3D representations to students’ Lewis structure drawings, contrasting the first row elements.
Correct answer: C
Representative results from pre-general chemistry: 70-80% correct (next most popular answer is A)
Follow-up discussion: Ask students about the number of valence electrons of B vs N.

9. Which molecule could be represented with this diagram?
BH3
CH4
NH3
NH4+
Note that this question does not require expanded octets.
Goal: Connect 3D representations to students’ Lewis structure drawings, contrasting the first row elements.
Correct answer: C
Representative results from pre-general chemistry: 70-80% correct (next most popular answer is A)
Follow-up discussion: Ask students about the number of valence electrons of B vs N.

10. Chem 106: Class/ Lab Week 9 Turn in Today Today’s experiment
Moles & Molar Masses Weighing as a Way of Counting (Course/ Lab Manual pp )
Moles & Molar Masses II
Atoms / Compounds / Molecular Formulas (Course/ Lab Manual pp )
Today’s experiment
Chemical Reactions / Stoichiometry
Have Course/ Lab Manual pp. 49 signed

11. (Course/ Lab Manual pp. 33-37) Due today. One per Molview Team.

12. (Course/ Lab Manual pp. 38-39)
Due Today: Turn in one per Team or Individually

13. DUE: Today before midnight
DUE: Today before midnight

14. Types of Chemical Reactions
Today’s experiment
Types of Chemical Reactions
Combination (Synthesis)
Decomposition
Single Displacement
Double Displacement
Combustion: Oxidation-Reduction
Biological Reactions: Enzyme Catalysts
Example: Fermentation
_______________
A 3900-year-old clay tablet, which was found in Iraq between the Tigris and Euphrates rivers, had a Sumerian poem ( honoring Ninkasi, the patron goddess of brewing. It contains the oldest surviving beer recipe, describing the fermentation of the carbohydrates found in bread, bappir, made from barley, honey, dates and sweet aromatic herbs. The global availability of carbohydrates and native microbes (yeasts) has led to the production of many different types of beers, ales, wines, and fruit based alcoholic beverages in many countries throughout the world. [The bottle on the left was found in Eugene, Oregon, ……. But, it dates only to 2016.]

15. General Chemical Reactions

17. Human Circadian Rhythm Oscillating Reactions & Homeostasis
Begin Here
(1 cycle 24 hour Clock)

18. Chemical Reactions Lab Manual pp. 47-51
All pages are to be completed and turned in next week.
Chemical Reactions
Lab Manual pp
Complete all of the procedures/reactions for parts A-D;
record your observations in Lab Manual; have stamped before leaving lab today.
Part A: Synthesis (Combination) Reaction
Part B: Decomposition Reactions
Part C: Single Replacement Reactions
Part D: Double Replacement Reactions

19. Chemical Reactions Combination (Synthesis) A + B C
H2 (g) + O2 (g) H2O (g)
Balancing/ Stoichiometry (Conservation of Atoms):
H2 (g) + O2 (g) H2O (g)

20. Chemical Reactions
Decomposition
A B + C
2 NI3 (s) N2 (g) + 3 I2 (s)

21. Chemical Reactions Single Displacement AB + C CB + A Example:
HCl (aq) + Mg (s) MgCl2 (aq) + H2 (g)
Balanced Equation: ?
2 HCl (aq) + Mg (s) MgCl2 (aq) + H2 (g)
Name HCl(aq) ?
Hydrochloric acid

22. Single Displacement
Cu(s) + 2 AgNO3(aq) Ag(s) + Cu(NO3)2 (aq)

23. Chemical Reactions Double Displacement AB + CD AD + CB Example:
A solution of sodium phosphate reacts with a solution of silver nitrate to produce aqueous sodium nitrate and a precipitate of silver phosphate.
Balanced equation: ?
Na3PO4 (aq) + 3 AgNO3 (aq) Ag3PO4 (s) + 3 NaNO3 (aq)

24. Double Displacement Predict the products: H2SO4(aq) + NaOH(aq) →
H2SO4(aq) + NaOH(aq) → H2O(l) + Na2SO4(aq)
Balance the equation:
H2SO4(aq) + 2 NaOH(aq) → 2 H2O(l) + Na2SO4(aq)

25. Chemical Equations Combustion: C8H18(l)+ O2(g) CO2(g) + H2O(l)
Oxygen reacts with octane to produce carbon dioxide and water.
Reminder: the equation must balance:
2 C8H18(l)+ 25 O2(g) CO2(g)+18 H2O(l)
Carbon is oxidized: looses 4 electrons
Oxygen is reduced: gains 2 electrons

26. Combustion Products Formulas & Multiple Proportions

27. Oxidation-Reduction Reactions “Redox”
Oxidation is the loss of electrons.
Reduction is the gain of electrons.
The reactions occur together. One does not occur without the other.
The terms are used relative to the change in the oxidation state or oxidation number of the reactant(s).

28. Activity increases going up the row
Activity increases going down the row
Activity increases going up the row
Cesium:
Which would be most reactive?
A) Li + I2 B) Na + Cl2 C) Cs + F2
Rubidium:

31. Reactions, Balancing, Stoichiometry Worksheet (Course/ Lab Manual pp
Reactions, Balancing, Stoichiometry Worksheet (Course/ Lab Manual pp ) Due next week.
Either work collaboratively and turn in one per partnership or work individually.
The Mole / Molar Mass and Molecular Formula On-line Quiz DUE Today 11:59PM.
Prepare answers to the following questions for next week.