San Gabriel Final Round InterVarsity 2009 4th speaker

San Gabriel Final Round InterVarsity 2009

San Gabriel Final Round InterVarsity 2009

San Gabriel Final Round InterVarsity 2009

UPDATED GRADES EP 4/1 as of 9/26/2009

43513 79.5%
43566 98.0%
0.0%
43819 94.0%
43889 102.6%
0.0%
0.0%
0.0%
47995 98.0%
48000 99.3%
48005 96.0%
48011 66.9%
48021 94.0%
0.0%
0.0%
50377 96.7%
0.0%
50382 100.6%
0.0%
50399 80.8%
50406 98.0%
50483 98.0%
50449 98.6%
50541 99.3%

UPDATED GRADES EP 4/2 as of 9/26/2009

0.0%
43540 68.0%
43544 92.0%
0.0%
43616 98.8%
43661 94.0%
43697 92.0%
43732 94.0%
43817 99.5%
43822 88.0%
43856 58.5%
0.0%
47993 96.8%
47998 100.3%
47999 99.8%
48006 99.5%
0.0%
48016 78.5%
49694 0.0%
50383 85.3%
50385 99.0%
50388 94.3%
50390 81.5%

Ep 4/2 grade as of Sept 2009

0.0%
43540 60.5%
43544 54.5%
0.0%
43616 65.8%
43661 83.5%
43697 71.0%
43732 83.5%
43817 99.5%
43822 47.5%
43856 58.5%
0.0%
47993 96.8%
47998 100.3%
47999 99.8%
48006 88.3%
0.0%
48016 78.5%
49694 0.0%
50383 0.0%
50385 99.0%
50388 94.3%
50390 42.5%

ep 4/1 grades before midterm

43513 79.5%
43566 98.0%
0.0%
43819 94.0%
43889 102.6%
0.0%
0.0%
0.0%
47995 98.0%
48000 99.3%
48005 96.0%
48011 66.9%
48021 94.0%
0.0%
0.0%
50377 96.7%
0.0%
50382 100.6%
0.0%
50399 80.8%
50406 98.0%
50483 98.0%
50449 98.6%
50541 99.3%

so you want to pass the exam

go through the book, read all the pertinent sample problems, go over the problems we did in the homework. read your notes.

good luck

so you want to pass the exam

go through the book, read all the pertinent sample problems, go over the problems we did in the homework. read your notes.

good luck

Sample Exam question

Compare and contrast the following bonds--covalent--polar, nonpolar, coordinate, network, and ionic along with metallic bonds in terms of electronegativity, dissociation energy, shape, and properties.

British Parliamentary Style First Speaker

EP 5 solubility problems

There are going to be solubility problems on the exam.

Multiple Choice TIPS

When you have 4 choices;

1) Read every Choice!!
2) Eliminate wrong choices.
3) If you have to guess, break it down to the last two viable answers if possible.

IF YOU HAVE NO CLUE...guess the same letter--if you have 5 questions, and have no clue, guess the same letter for all 5 because odds are that letter is the one used at least once. If you guess 5 different letters for 5 different questions, you could miss all 5.

HINT: look at your review sheets for any letters that repeat a lot.

ep 4 I can't remember
ep 5 A was in a lot of answers
ep 6 I"m not telling

To get a GREAT grade on my EXAM

EP 4 go through and read all sample problems in the book ch 7-9

EP 5 do the same but chapter 17-18

ep 6 your chapters are ch 20 redox reactions...

good luck 14 days to go

Le Chatelier's Principle Explained again.

One of my smarter students asked me a question about Le Chatelier's principle--and if he's confused, so is everyone else.

Changes in pressure are attributable to changes in volume. The equilibrium concentrations of the products and reactants do not directly depend on the pressure subjected to the system. However, a change in pressure due to a change in volume of the system will shift the equilibrium.

Once again, let us refer to the reaction of nitrogen gas with hydrogen gas to form ammonia:

N2 + 3 H2 ⇌ 2 NH3 ΔH = −92kJ mol-1
4 volumes ⇌ 2 volumes

Note the number of moles of gas on the left hand side, and the number of moles of gas on the right hand side. When the volume of the system is changed, the partial pressures of the gases change. Because there are more moles of gas on the reactant side, this change is more significant in the denominator of the equilibrium constant expression, causing a shift in equilibrium.


Thus, an increase in pressure due to decreasing volume causes the reaction to shift to the side with the fewer moles of gas.[3] A decrease in pressure due to increasing volume causes the reaction to shift to the side with more moles of gas. There is no effect on a reaction where the number of moles of gas is the same on each side of the chemical equation.

when you increase pressure, it favors the side with more moles--because it spreads the pressure out, and thus, causes the reaction to shift to the side with fewer moles....

is that better?! AHAHAH sorry... i got the excerpt above from wikipedia

Bonus question September 17, 2009

EP 4--what is an emulsion plus describe in your own words, hybridization of ethyne and corresponding pi and sigma bonds

EP 5--what is an oxidation/reduction? plus describe in your own words, using collision theory terminology, how reactants cross the activation energy barrier to form a product discussing the activated transition complex.

EP 6--describe why an oxidizing agent is reduced while a reducing agent is oxidized and why you need one for the other?

EP 4 Must READ

know the tables on page 192 and 200--common ions and polyatomic ions

EP 5 Review

ep 5 review

Matching

Match each item with the correct statement below.
a. activated complex d. activation energy
b. reaction rate e. free energy
c. inhibitor


____ 1. the minimum energy colliding particles must have in order to react

____ 2. arrangement of atoms at the peak of an energy barrier

____ 3. the number of atoms, ions, or molecules that react in a given time to form products

____ 4. a substance that interferes with a catalyst

____ 5. energy available to do work

Match each item with the correct statement below.
a. spontaneous reaction d. reaction mechanism
b. entropy e. elementary reaction
c. chemical equilibrium


____ 6. when the forward and reverse reactions take place at the same rate

____ 7. a reaction that releases free energy

____ 8. the measure of disorder

____ 9. Reactants are converted to products in a single step.

____ 10. includes all elementary reactions of a complex reaction

Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.

____ 11. Activation energy is ____.
a. the heat released in a reaction
b. an energy barrier between reactants and products
c. the energy given off when reactants collide
d. generally very high for a reaction that takes place rapidly


____ 12. Why does a higher concentration make a reaction faster?
a. There are more collisions per second only.
b. Collisions occur with greater energy only.
c. There are more collisions per second and the collisions are of greater energy.
d. There are more collisions per second or the collisions are of greater energy.


____ 13. What happens to a catalyst in a reaction?
a. It is unchanged. c. It is incorporated into the reactants.
b. It is incorporated into the products. d. It evaporates away.


____ 14. Consider the reaction N (g) 3H (g) 2NH (g). What is the effect of decreasing the volume on the contained gases?
a. The reaction shifts toward the product gas.
b. The system reacts by increasing the number of gas molecules.
c. The pressure on the gases decreases momentarily.
d. Ammonia is consumed in the reaction.


____ 15. What happens to a reaction at equilibrium when more reactant is added to the system?
a. The reaction makes more products. c. The reaction is unchanged.
b. The reaction makes more reactants. d. The answer cannot be determined.


____ 16. In an endothermic reaction at equilibrium, what is the effect of raising the temperature?
a. The reaction makes more products. c. The reaction is unchanged.
b. The reaction makes more reactants. d. The answer cannot be determined.


____ 17. What is the effect of adding more water to the following equilibrium reaction?
CO + H O H CO
a. More H CO is produced.
b. CO concentration increases.
c. The equilibrium is pushed in the direction of reactants.
d. There is no effect.


____ 18. In an equilibrium reaction with a K of 1 10 , the ____.
a. reactants are favored c. the products are favored
b. reaction is spontaneous d. reaction is exothermic


____ 19. The K of a reaction is 4 10 . At equilibrium, the ____.
a. reactants are favored
b. products are favored
c. reactants and products are present in equal amounts
d. rate of the forward reaction is much greater than the rate of the reverse reaction


____ 20. The amount of disorder in a system is measured by its ____.
a. activation energy c. equilibrium position
b. entropy d. K


____ 21. Which one of the following systems has the highest entropy?
a. 10 mL of water at 10 C
b. 10 mL of water at 50 C
c. 10 mL of water at 100 C
d. All have the same entropy because all are water.


____ 22. If a system is left to change spontaneously, in what state will it end?
a. the same state in which it began
b. the state with lowest possible energy
c. the state with the maximum disorder
d. the state with the lowest possible energy consistent with the state of maximum disorder


____ 23. The melting of ice at temperatures above 0 C ____.
a. liberates heat c. is not favorable
b. is not spontaneous d. is endothermic


____ 24. What determines whether or not a reaction is spontaneous?
a. change in molar volume and heat change
b. change in enthalpy only
c. enthalpy change and entropy change
d. change in entropy only


____ 25. Which variable is NOT required to calculate the Gibbs free-energy change for a chemical reaction?
a. change in enthalpy c. temperature in kelvins
b. temperature in C d. change in entropy


____ 26. What is the rate law for the following reaction?
A + 2B  C + D
a. rate = k[A][B] c. rate = k[A][B]
b. rate = k[A] [B] d. rate = k[A] [B]


____ 27. What is the order of the following reaction? A + 2B  C + D
a. zero c. second
b. first d. third


____ 28. If a reaction rate decreases by a factor of one-ninth when a reactant concentration is decreased by one-third, what is the order of the reaction with respect to that reactant?
a. fourth c. second
b. third d. first


____ 29. When nitrous oxide is converted to nitrogen and oxygen, what is the term used to describe the oxygen atoms formed?
a. reactants c. activated complexes
b. products d. intermediates


____ 30. For a complex reaction, the reaction progress curve ____.
a. is a flat line c. has several hills and valleys
b. has only one peak d. shows energy versus pressure


Essay

31. Explain the effects of reactant concentration and particle size on the rate of a reaction.

32. What is the effect of a catalyst on the rate of a reaction? Give an example of a catalyst.

ep 5 review
Answer Section

MATCHING

1. ANS: D DIF: L1 REF: p. 543 OBJ: 18.1.1

2. ANS: A DIF: L1 REF: p. 544 OBJ: 18.1.1

3. ANS: B DIF: L1 REF: p. 542 OBJ: 18.1.1

4. ANS: C DIF: L1 REF: p. 547 OBJ: 18.1.2

5. ANS: E DIF: L1 REF: p. 566 OBJ: 18.4.1

6. ANS: C DIF: L1 REF: p. 550 OBJ: 18.2.1

7. ANS: A DIF: L1 REF: p. 567 OBJ: 18.4.1

8. ANS: B DIF: L1 REF: p. 569 OBJ: 18.4.2

9. ANS: E DIF: L1 REF: p. 578 OBJ: 18.5.2

10. ANS: D DIF: L1 REF: p. 578 OBJ: 18.5.2

MULTIPLE CHOICE

11. ANS: B DIF: L1 REF: p. 543 OBJ: 18.1.1

12. ANS: A DIF: L1 REF: p. 545 OBJ: 18.1.2

13. ANS: A DIF: L1 REF: p. 546 OBJ: 18.1.2

14. ANS: A DIF: L2 REF: p. 554 OBJ: 18.2.2

15. ANS: A DIF: L2 REF: p. 552, p. 553
OBJ: 18.2.2

16. ANS: A DIF: L2 REF: p. 554 OBJ: 18.2.2

17. ANS: A DIF: L2 REF: p. 552, p. 553
OBJ: 18.2.2

18. ANS: C DIF: L1 REF: p. 556 OBJ: 18.2.3

19. ANS: A DIF: L1 REF: p. 556 OBJ: 18.2.3

EP 5 Review questions and answers

ep 5 review 2

Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.

____ 1. What happens to the energy produced by burning gasoline in a car engine?
a. The energy is lost as heat in the exhaust.
b. The energy is transformed into work to move the car.
c. The energy heats the parts of the engine.
d. all of the above


____ 2. How does a calorie compare to a joule?
a. A calorie is smaller than a joule. c. A calorie is equal to a joule.
b. A calorie is larger than a joule. d. The relationship cannot be determined.


____ 3. Which of the following is NOT a form of energy?
a. light c. heat
b. pressure d. electricity


____ 4. If heat is released by a chemical system, an equal amount of heat will be ____.
a. absorbed by the surroundings c. released by the surroundings
b. absorbed by the universe d. released by the universe


____ 5. In an exothermic reaction, the energy stored in the chemical bonds of the reactants is ____.
a. equal to the energy stored in the bonds of the products
b. greater than the energy stored in the bonds of the products
c. less than the energy stored in the bonds of the products
d. less than the heat released


____ 6. A process that absorbs heat is a(n) ____.
a. endothermic process c. exothermic process
b. polythermic process d. ectothermic process


____ 7. The quantity of heat required to change the temperature of 1 g of a substance by 1 C is defined as ____.
a. a joule c. a calorie
b. specific heat d. density


____ 8. How many joules are in 148 calories? (1 cal = 4.18 J)
a. 6.61 J c. 148 J
b. 35.4 J d. 619 J


____ 9. What is the specific heat of a substance if 1560 cal are required to raise the temperature of a 312-g sample by 15 C?
a. 0.033 c. 0.99
b. 0.33 d. 1.33


____ 10. The heat capacity of an object depends in part on its ____.
a. mass c. shape
b. enthalpy d. potential energy


____ 11. When 45 g of an alloy, at 25 C, are dropped into 100.0 g of water, the alloy absorbs 956 J of heat. If the final temperature of the alloy is 37 C, what is its specific heat?
a. 0.423 c. 9.88
b. 1.77 d. 48.8


____ 12. How can you describe the specific heat of olive oil if it takes approximately 420 J of heat to raise the temperature of 7 g of olive oil by 30 C?
a. greater than the specific heat of water c. equal to the specific heat of water
b. less than the specific heat of water d. Not enough information is given.


____ 13. In an equilibrium reaction with a K of 1 10 , the ____.
a. reactants are favored c. the products are favored
b. reaction is spontaneous d. reaction is exothermic


Short Answer

14. What is the equilibrium constant for the following reaction?
3A + 2B 2C

15. Calculate the value of K for the following reaction at equilibrium.
2NClO(g) 2NO(g) + Cl (g)
An analysis of the equilibrium mixture in a 1-L flask gives the following results: NClO, 1.6 mol; NO, 6.4 mol; Cl , 0.49 mol

Essay

16. Explain the effects of reactant concentration and particle size on the rate of a reaction.

17. What is the effect of a catalyst on the rate of a reaction? Give an example of a catalyst.

ep 5 review 2
Answer Section

MULTIPLE CHOICE

1. ANS: D DIF: L1 REF: p. 505 OBJ: 17.1.1

2. ANS: B DIF: L1 REF: p. 506 OBJ: 17.1.1

3. ANS: B DIF: L1 REF: p. 505 OBJ: 17.1.1

4. ANS: A DIF: L1 REF: p. 506 OBJ: 17.1.1

5. ANS: B DIF: L2 REF: p. 506 OBJ: 17.1.1

6. ANS: A DIF: L1 REF: p. 506 OBJ: 17.1.2

7. ANS: B DIF: L1 REF: p. 507 OBJ: 17.1.2

8. ANS: D DIF: L1 REF: p. 507 OBJ: 17.1.3

9. ANS: B DIF: L1 REF: p. 509, p. 510
OBJ: 17.1.3

10. ANS: A DIF: L1 REF: p. 508 OBJ: 17.1.3

11. ANS: B DIF: L2 REF: p. 509 OBJ: 17.1.3

12. ANS: B DIF: L2 REF: p. 509, p. 510
OBJ: 17.1.3

13. ANS: C DIF: L1 REF: p. 556 OBJ: 18.2.3

SHORT ANSWER

14. ANS:
Keq =

DIF: L2 REF: p. 556 OBJ: 18.2.3

15. ANS:
K =
= 7.8

DIF: L3 REF: p. 556, p. 557 OBJ: 18.2.3

ESSAY

16. ANS:
A high concentration of reactants increases the reaction rate. This is because more molecules are present to collide each second. A small particle size increases the rate of a reaction. Because there is more surface area for a given mass of particles, more collisions are possible per second.

DIF: L3 REF: p. 545, p. 546 OBJ: 18.1.2

17. ANS:
A catalyst increases the rate of a reaction. A catalyst permits the formation of a less energetic activated complex. Platinum is a catalyst for certain reactions of gases.

DIF: L3 REF: p. 546, p. 547 OBJ: 18.1.2

EP 6 Sample Problem Solution

C +H2SO4--> CO2 +SO2 + H2O


C=0
H=+1 so +2 O4=-8, so S is +6
C=+4 because O2=-4
S=+4 because O2=-4
H2=+2 O=-2

C goes from C=0-->+4 loses electrons Oxidized LEO/reducing agent
S goes from S=+6-->+4 gains electrons reduced GER/oxidizing agent

Sample EP 6 problem explained

Sb+HNO3-->Sb2O5+NO +H2O


sb=0
H=+1, N=+5, 0=(-2) 3


sb2O5=sb=+5, O=(-2)5
N=+2 O=-2

H=+1, O=-2

Sb 0--> +5 loss of electron oxidation, reducing agent
N=+5-->+2 gain electrons reduction, oxidizing agent

EP Sample problems answers

KMnO4 +HCl-->MnCl2+Cl2+H2O+KCl

km is +8 because oxygen is -2 time 4 because there are four of them, so O is -8
H is +1=as rule, so cl=-1 as charge.

Mn becomes +2 because Cl=-1 times two.
Cl2 is 0 because it's a diatomic element by itself
H=+1 while o=-2
K =+1 while Cl=-1


did that help

EP 6 Sample Problems

KMnO4 +HCl-->MnCl2+Cl2+H2O+KCl
Sb+HNO3-->Sb2O5+NO +H2O
C +H2SO4--> CO2 +SO2 + H2O



put the numbers in, I cant make the numbers subscripts on the html.

EP 5 Solubility/Equilbrium Problems from PPT

question 1.
Circle the letters of the terms that complete the sentence correctly. Stresses
that upset the equilibrium of a chemical system include changes in all except b .
a. concentration

c. pressure
d. temperature

question 2

When you add a product to a reversible chemical reaction, the reaction is always pushed in the direction of Reactants
When you remove a product, the reaction is pulled in the direction of products

question 3
What are the exponents in the equilibrium-constant expression?
A. Number of Moles

question 4
At a certain temperature, the equilibrium constant for this reaction is 11.1. Suppose that pure BrCl is placed in a 1-L container and allowed to come to equilibrium. Analysis then shows that the reaction mixture contains 4.00 moles of Cl2. How many moles of Br2 and BrCl are also present in the equilibrium mixture?
2BrCl(g) → Br2(g) + Cl2(g)

Exam Topics by Page Numbers

EP 4 pages 186-268 chapters 7, 8, and 9

EP 5 pages 504-560 ch 17 and 18

EP 6 pages 630-655 ch 20

Exam topics

Format for Exam--approximate 20 multiple choice and 20 problems.

EP 4 Ch 7-9
Naming covalents and ionic compounds
Bonding--covalents, ionic, metallics, and molecular (network solids).
Electron dot structures--polyatomic ions, ionics, and covalents
Hybrid orbitals--VSEPR
ion charge

EP 5 Ch 17-18
Thermochemistry--calorimetry, heat of fusion, heat of vaporization, and change of state
Equilibrium
equilibrium constants
solubility constants

EP 6 ch 20 Reduction/oxidation/
Assigning oxidation numbers
Polyatomic ions oxidation numbers
Balancing reactions

San Gabriel Pix

An awesome tournament!

Assignments for August 31 Week

EP 4 page 236 # 23-28 define vocab on page 237
EP 5 P. 555 #6, p. 559 #11-13, 15
EP 6 worksheet on redox