Search found 51 matches

by KeiannaPineda1B
Fri Mar 13, 2020 7:06 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Activation Energy
Replies: 3
Views: 119

Activation Energy

What is the difference between activation energy and free energy of activation?
by KeiannaPineda1B
Fri Mar 13, 2020 7:04 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Catalyst in Reaction
Replies: 1
Views: 31

Catalyst in Reaction

Can someone please explain how catalysts increase the rate of a reaction?
by KeiannaPineda1B
Fri Mar 13, 2020 7:04 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Catalysts
Replies: 3
Views: 66

Catalysts

Can someone please explain how catalysts lower the activation energy of the transition state?
by KeiannaPineda1B
Fri Mar 13, 2020 7:02 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Collision Model and Activated Complex Model
Replies: 1
Views: 41

Collision Model and Activated Complex Model

Can someone please explain how the collision model and activated complex model account for the temperature dependence of reactions?
by KeiannaPineda1B
Fri Mar 13, 2020 7:00 pm
Forum: General Rate Laws
Topic: Instantaneous Rate
Replies: 2
Views: 59

Instantaneous Rate

How is the instantaneous rate obtained by drawing a tangent to the graph of concentration versus time?
by KeiannaPineda1B
Thu Mar 05, 2020 11:25 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Electrode masses
Replies: 8
Views: 125

Electrode masses

What happens to the battery when you increase or decrease the mass of electrodes?
by KeiannaPineda1B
Thu Mar 05, 2020 11:24 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Cell potential
Replies: 6
Views: 116

Cell potential

How does adding water to a concentration cell affect cell potential? (in the two occasions: anode or cathode)
by KeiannaPineda1B
Thu Mar 05, 2020 11:22 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Standard Potentials
Replies: 4
Views: 87

Standard Potentials

What are the standard potential values based off?
by KeiannaPineda1B
Thu Mar 05, 2020 11:21 pm
Forum: Administrative Questions and Class Announcements
Topic: Excellence in Chemistry Award!
Replies: 27
Views: 6945

Re: Excellence in Chemistry Award!

Congratulations! If you took another professor for Chem 14A, is it still possible to be awarded the book?
by KeiannaPineda1B
Thu Mar 05, 2020 11:20 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Concentration Cells
Replies: 5
Views: 125

Concentration Cells

Why is standard potential 0v in concentration cells?
by KeiannaPineda1B
Sat Feb 29, 2020 7:38 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Potential
Replies: 3
Views: 82

Cell Potential

What is the difference between cell potential and standard cell potential?
by KeiannaPineda1B
Sat Feb 29, 2020 7:36 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Equilibrium constant in terms of standard potential
Replies: 1
Views: 16

Equilibrium constant in terms of standard potential

Based off the equation lnK= nFE/RT...
why does a reaction with a positive Ecell have a K>>1?
by KeiannaPineda1B
Sat Feb 29, 2020 7:26 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Outline of Thermodynamics #3
Replies: 2
Views: 77

Outline of Thermodynamics #3

Why does reaction free energy depend on pressure and the equilibrium constant?
by KeiannaPineda1B
Sat Feb 29, 2020 7:25 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Outline of Thermodynamics #2
Replies: 1
Views: 53

Outline of Thermodynamics #2

Could someone please give me an example of using the Gibbs free energy equations for "coupling a favorable reaction to drive unfavorable reactions"?
by KeiannaPineda1B
Sat Feb 29, 2020 7:23 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Outline of Thermodynamics
Replies: 3
Views: 69

Outline of Thermodynamics

What is the relationship between free energy and work?
by KeiannaPineda1B
Tue Feb 18, 2020 7:48 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 5J.15
Replies: 2
Views: 69

Re: 5J.15

Enthalpy values for specific substances cannot be measured directly. They are diatomic/pure/elemental gases.
by KeiannaPineda1B
Tue Feb 18, 2020 7:44 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: UA's
Replies: 3
Views: 106

UA's

Does anyone else agree that we have some of the coolest UA's ever??? For example: Matthew Tran is the coolest and nicest person ever!! Go to his sessions, THEY ARE SO HELPFUL.
by KeiannaPineda1B
Tue Feb 18, 2020 7:40 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 6M. 13
Replies: 1
Views: 43

6M. 13

6M.13 Identify the reactions with K . 1 in the following list and, for each such reaction, identify the oxidizing agent and calculate the (a) (b) (c) (d) standard cell potential. Cl2(g) 1 2 Br2(aq) S 2 Cl2(aq) 1 Br2(l) MnO42(aq) 1 8 H1(aq) 1 5 Ce31(aq) S 5 Ce41(aq) 1 Mn21(aq) 1 4 H2O(l) 2 Pb21(aq) S...
by KeiannaPineda1B
Tue Feb 18, 2020 7:38 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Concepts
Replies: 3
Views: 63

Concepts

Can someone please explain the relationship between work and cell potential? (wmax= -nFE)
by KeiannaPineda1B
Tue Feb 18, 2020 7:37 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 6M.1
Replies: 1
Views: 45

6M.1

6M.1 A student was given a standard Cu(s)uCu21(aq) half-cell and another half-cell containing an unknown metal M in 1.00 m M(NO3)2(aq) and formed the cell M(s)uM1(aq)uuCu21(aq)uCu(s). The cell potential was found to be 20.689 V. What is the value of E8(M21/M)? Could someone please explain step by st...
by KeiannaPineda1B
Tue Feb 18, 2020 7:36 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 6L.1
Replies: 1
Views: 34

6L.1

6L.1 Calculate the standard reaction Gibbs free energy for the following cell reactions: (a) 2 Ce41(aq) 1 3 I2(aq) S 2 Ce31(aq) 1 I32(aq), Ecell° 5 11.08 V (b) 6 Fe31(aq) 1 2 Cr31(aq) 1 7 H2O(l) S 6 Fe21(aq) 1 Cr2O722(aq) 1 14 H1(aq), Ecell° 5 21.29 V How do I do part B? Could someone please explain...
by KeiannaPineda1B
Tue Feb 18, 2020 7:34 pm
Forum: Balancing Redox Reactions
Topic: 6K.5
Replies: 1
Views: 115

6K.5

6K.5 Balance each of the following skeletal equations by using oxidation and reduction half-reactions. All the reactions take place in basic solution. Identify the oxidizing agent and reducing agent in each reaction. (a) Reaction of ozone with bromide ions: O3(aq) 1 Br2(aq) ¡ O2(g) 1 BrO32(aq) (b) R...
by KeiannaPineda1B
Tue Feb 18, 2020 7:32 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Concepts [ENDORSED]
Replies: 2
Views: 298

Concepts [ENDORSED]

Could someone please clarify why the electromotive force represents the maximum potential difference?
by KeiannaPineda1B
Tue Feb 18, 2020 7:31 pm
Forum: Balancing Redox Reactions
Topic: Electrochemistry Outline
Replies: 1
Views: 32

Electrochemistry Outline

Can someone please explain the relationship between standard cell potential and equilibrium constant of a reaction?
by KeiannaPineda1B
Tue Feb 18, 2020 7:30 pm
Forum: Balancing Redox Reactions
Topic: Concentration Cell
Replies: 1
Views: 29

Concentration Cell

What is an example of a concentration cell?
by KeiannaPineda1B
Wed Feb 05, 2020 2:50 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 4F.15
Replies: 2
Views: 39

Re: 4F.15

According to the internet, the experimental boiling point is 248K, which is fair close to the value calculated in part a. The value 85 J/(k*mol) from Truton's rule that entropy of vaporization of organic liquids is solely an average value, and therefore deviate from expected such average value for i...
by KeiannaPineda1B
Wed Feb 05, 2020 2:42 am
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Step-Up Session Worksheet from 2/4 from 6-8pm Q8
Replies: 1
Views: 60

Step-Up Session Worksheet from 2/4 from 6-8pm Q8

An aspiring young balloonist, lacking helium, doe have sodium bicarbonate, vinegar, and a bomb calorimeter. The two chemicals react according to the following reaction: NaHCO3(s) + CH3COOH(l) ---> Na+(aq) + CH3COO-(aq) + H2O(l) + CO2(g) a) Both compounds are reacted in the bomb calorimeter which has...
by KeiannaPineda1B
Wed Feb 05, 2020 2:35 am
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Step-Up Session Worksheet from 2/4 from 6-8pm Q2B
Replies: 2
Views: 71

Step-Up Session Worksheet from 2/4 from 6-8pm Q2B

Carbon disulfide can be prepared from coke (an impure form of carbon) and elemental sulfur: 4 C(s) + S8(s) ---> 4 CS2(l) where deltaH=+3.58.8 kj. a) How much heat is absorbed in the reaction of 1.25 mol S8 at constant pressure? b) Calculate the heat absorbed in the reaction of 197g of carbon with an...
by KeiannaPineda1B
Wed Feb 05, 2020 2:32 am
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Step-Up Session Worksheet from 2/4 from 6-8pm Q2
Replies: 1
Views: 61

Step-Up Session Worksheet from 2/4 from 6-8pm Q2

At 300. K and 1000. kPa, 1.00 mol ideal gas expands under two different conditions to a final pressure of 100 kPa. For the gas calculate q, w, deltaU, and deltaS for each process.

a) reversible isothermal expansion

b) expansion against a vacuum

Could someone please solve this for me?
by KeiannaPineda1B
Wed Feb 05, 2020 2:26 am
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Lyndon's Step Up 2/3
Replies: 1
Views: 83

Re: Lyndon's Step Up 2/3

Yes! 1. -4.69 * 10^2 J 2. 14.8 kj/C 3. 17 kj 4. Chemistry in the community honestly explains this better than I could ever do... 5. 29.5 kj/mol 6. 75.9 g H2O 7. -113 J 8. q= -406kj 9. 0.28L I am not particularly sure how communication works on here, but message me if you want me to email you the ste...
by KeiannaPineda1B
Sat Feb 01, 2020 12:58 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Ideal Gases: Heat Capacity
Replies: 2
Views: 37

Re: Ideal Gases: Heat Capacity

Go onto Lavelle's website and look at the outlines. It provides details of all the concepts he wants us to know.
by KeiannaPineda1B
Sat Feb 01, 2020 12:50 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Thermodynamic
Replies: 1
Views: 31

Thermodynamic

What is the difference between delta U, delta H and delta S? How do they all relate?
by KeiannaPineda1B
Sat Feb 01, 2020 12:49 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Degeneracy
Replies: 1
Views: 36

Degeneracy

I understood Lavelle's talk about degeneracy, but what is degeneracy's ultimate purpose? What is it used for?
by KeiannaPineda1B
Sat Feb 01, 2020 12:47 am
Forum: Calculating Work of Expansion
Topic: 4A.5
Replies: 1
Views: 33

4A.5

A piston confines 0.200mol Ne(g) 1.20 L at 2525 °C. Two experiments are performed. (a) The gas is allowed to expand through an additional 1.20 L against a constant pressure of 1.00 atm. (b) The gas is allowed to expand reversibly and isothermally to the same final volume. Which process does more wor...
by KeiannaPineda1B
Sat Feb 01, 2020 12:45 am
Forum: Calculating Work of Expansion
Topic: 4A.3
Replies: 2
Views: 44

4A.3

4A.3 Air in a bicycle pump is compressed by pushing in the handle. The inner diameter of the pump is 3.0 cm and the pump is depressed 20. cm with a pressure of 2.00 atm. (a) How much work is done in the compression? (b) Is the work positive or negative with respect to the air in the pump? (c) What i...
by KeiannaPineda1B
Sat Feb 01, 2020 12:40 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5J.5 D
Replies: 5
Views: 59

Re: 5J.5 D

Skyllar Kuppinger 1F wrote:it is because you've copied down the problem incorrectly; the H2 is a product not a reactant :)


There is a typo in the book.
by KeiannaPineda1B
Tue Jan 21, 2020 6:30 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: pKa, Ka, and strength of acid
Replies: 3
Views: 17

pKa, Ka, and strength of acid

I know that a low pKa = high Ka = strong acid. By can someone please go into more detail/proof how a high Ka signifies a stronger acid?
by KeiannaPineda1B
Tue Jan 21, 2020 6:29 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Temperature
Replies: 2
Views: 36

Temperature

I know we went over this in class but I am still confused. Why is it that if a reaction is exothermic, raising the temperature will tend to shift the reaction towards reactants, whereas if the reaction is endothermic, a shift toward products will be seen?
by KeiannaPineda1B
Tue Jan 21, 2020 6:26 pm
Forum: Administrative Questions and Class Announcements
Topic: Grading of Tests
Replies: 18
Views: 251

Grading of Tests

Can you get partial credit on tests for the work you show? Or if you miss a part, you lose all the points?
by KeiannaPineda1B
Tue Jan 21, 2020 6:24 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Test #1
Replies: 2
Views: 52

Test #1

Will there be the 5% rule o (or 10^3 rule) on the chem test?
by KeiannaPineda1B
Tue Jan 21, 2020 6:21 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5J.5 D
Replies: 5
Views: 59

5J.5 D

"State whether reactants or products will be favored by an increase in the total pressure (resulting from compression) on each of the following equilibria. If there is no change, explain why that is so." "(d) 2HD (g) + H2 -> D2 (g)" Is this question a typo? The answer says no cha...
by KeiannaPineda1B
Tue Jan 14, 2020 12:57 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Outline of Chemical Equilibrium
Replies: 1
Views: 25

Outline of Chemical Equilibrium

On the outline Lavelle gave on "Chemical Equilibrium" it says that we should know biological examples such as ATP hydrolysis and osmotic pressure. Could someone please go into detail what that means and explain why they are good examples.
by KeiannaPineda1B
Tue Jan 14, 2020 12:53 am
Forum: Administrative Questions and Class Announcements
Topic: Grading
Replies: 8
Views: 200

Grading

How do Lavelle/TA's grade our Chemistry Community questions? Do they count weekly if we have asked/answered questions? I just don't understand how this works.
by KeiannaPineda1B
Tue Jan 14, 2020 12:51 am
Forum: Administrative Questions and Class Announcements
Topic: Step-up Sessions
Replies: 1
Views: 40

Step-up Sessions

What is the difference between step-up sessions and peer learning sessions?
by KeiannaPineda1B
Tue Jan 14, 2020 12:48 am
Forum: Student Social/Study Group
Topic: Office Hours
Replies: 5
Views: 206

Office Hours

Has anyone attended Lavelle's office hours? What does he do during that time?
by KeiannaPineda1B
Tue Jan 14, 2020 12:45 am
Forum: Administrative Questions and Class Announcements
Topic: Discussion
Replies: 8
Views: 87

Discussion

Is the discussion section graded on attendance?
by KeiannaPineda1B
Fri Jan 10, 2020 10:26 am
Forum: Student Social/Study Group
Topic: Changing Discussions Sections
Replies: 2
Views: 132

Re: Changing Discussions Sections

I really like my TA, he's cute. Sorry I cannot change out.
by KeiannaPineda1B
Fri Jan 10, 2020 10:21 am
Forum: Student Social/Study Group
Topic: Chemistry Community Confessions
Replies: 2
Views: 87

Re: Chemistry Community Confessions

I do not believe there is a way to make a post anonymous.
by KeiannaPineda1B
Fri Jan 10, 2020 10:19 am
Forum: Administrative Questions and Class Announcements
Topic: Peer Learning
Replies: 4
Views: 42

Peer Learning

Hi! I am new to Dr. Lavelle's chemistry class. Can someone please explain to me what "Peer Learning Sessions" are?
by KeiannaPineda1B
Fri Jan 10, 2020 10:15 am
Forum: Administrative Questions and Class Announcements
Topic: Discussion 1J with TA Kevin?
Replies: 2
Views: 67

Re: Discussion 1J with TA Kevin?

This happened with my TA too. According to him the course website on his end showed a different classroom than on MyUCLA.
by KeiannaPineda1B
Fri Jan 10, 2020 10:11 am
Forum: Ideal Gases
Topic: Textbook Help
Replies: 4
Views: 118

Textbook Help

I bought the Sapling learning access for the textbook but I do not know how to access my purchase. I have an access code, but I do not understand the Macmillan learning site and where I am supposed to use my access code.

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