Search found 30 matches

by Emily Huang 1E
Fri Mar 15, 2019 8:54 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Ecell
Replies: 4
Views: 59

Re: Ecell

There are two ways to find Ecell. One way is to use the equation Ecell=E(Cathode)-E(Anode). Remember that cathode is usually on the right whereas anode is on the left. You use the reduction E values of the half reactions and plug into Ecell equation Another way is to not use the equation. Instead yo...
by Emily Huang 1E
Fri Mar 15, 2019 8:49 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Pre-equilibrium approach
Replies: 2
Views: 33

Re: Pre-equilibrium approach

replacing K helps with understanding the rate of the reactions. When writing the rate law, you use rate constants and not K as K just means the reaction is at equilibrium, Having k/k' is more representative of rates in relation to concentration
by Emily Huang 1E
Fri Mar 15, 2019 8:46 pm
Forum: Student Social/Study Group
Topic: Studying for the Final
Replies: 25
Views: 569

Re: Studying for the Final

Doing a lot of practice problems helps a lot. Karen posts worksheets on chemistry community that are helpful
by Emily Huang 1E
Sat Mar 09, 2019 6:43 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Gases and Liquids in Cell Diagrams
Replies: 3
Views: 62

Re: Gases and Liquids in Cell Diagrams

Water should only be included in the cell diagram if H20 is being reduced or oxidized in the reaction. If H20 is reduced to H2(g) then you would include H20 in the cell diagram. Otherwise if nothing is happening to H20 then it does not need to be included
by Emily Huang 1E
Sat Mar 09, 2019 6:41 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Test #2 Question 5 (ph acidic or basic)
Replies: 1
Views: 46

Re: Test #2 Question 5 (ph acidic or basic)

For this question you use the equation of ln(K2/K1)=delta H/R (1/T2 - 1/T1) . K1 is 10^-14 and T1 is 25 degrees celsius. You plug in delta H=58 kj/mol and plug in T2=10 degrees celsius or 283K. You plug in all values to find K2. K2 is equal to the concentration of H30+ and OH-. You know that the con...
by Emily Huang 1E
Sat Mar 09, 2019 6:34 pm
Forum: General Science Questions
Topic: Discussion Section Test
Replies: 3
Views: 163

Discussion Section Test

For the photosynthesis of glucose in the chloroplasts of an old growth redwood tree, why is deltaG>0 the wrong answer. Isn't photosynthesis endergonic?
by Emily Huang 1E
Sun Mar 03, 2019 12:42 pm
Forum: Administrative Questions and Class Announcements
Topic: Final Topics
Replies: 6
Views: 91

Re: Final Topics

The final is cumulative. You probably only need to remember the basic things from 14A that are also applied in 14B like stoichiometry, lewis structures, etc
by Emily Huang 1E
Tue Feb 26, 2019 6:47 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Calculating standard potential of cell
Replies: 1
Views: 40

Calculating standard potential of cell

Do you switch the sign of standard E, (cell potential), when you reverse a reaction or does the sign remain the same?
by Emily Huang 1E
Tue Feb 26, 2019 3:36 pm
Forum: Balancing Redox Reactions
Topic: Cell Diagram
Replies: 4
Views: 80

Re: Cell Diagram

An inert electrode is used when half rxns have no conducting solid
by Emily Huang 1E
Tue Feb 26, 2019 3:33 pm
Forum: Balancing Redox Reactions
Topic: Knowing oxidation states
Replies: 2
Views: 24

Re: Knowing oxidation states

You have to look at what Manganese is bonded to.KMnO4 is the compound and based on the periodic table we know the oxidation state of K is 1+ and the oxidation state of O is 2-. You can figure out an unknown oxidation number by knowing the oxidation number of the element it is bonded to
by Emily Huang 1E
Tue Feb 26, 2019 3:31 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Potential Diff of Electrodes
Replies: 1
Views: 24

Potential Diff of Electrodes

Why is it that when potential diff of electrodes is positive, the electron flow is form left to right?
by Emily Huang 1E
Tue Feb 26, 2019 3:22 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Standard Reduction Potential
Replies: 2
Views: 38

Re: Standard Reduction Potential

For half reactions you might have to change the sign if you need to reverse the reaction depending on whether the reaction should be oxidized or reduced
by Emily Huang 1E
Thu Feb 14, 2019 3:43 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Calorimeter - Type of System
Replies: 5
Views: 181

Re: Calorimeter - Type of System

Calorimeters are isolated systems. that is why you can calculate the final temperature of water inside a calorimeter based on the mass of calorimeter and water and their heat capacities. The heat lost by the calorimeter is absorbed by water since the water is an isolated system and no heat is lost t...
by Emily Huang 1E
Thu Feb 14, 2019 3:40 pm
Forum: Administrative Questions and Class Announcements
Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
Replies: 179
Views: 6734

Re: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)

Why is for delta H combustion, the equation is the the delta h combustion of reactants minus delta h combustion products whereas for delta h of formation it is the opposite?
by Emily Huang 1E
Thu Feb 14, 2019 3:37 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Cp,m
Replies: 5
Views: 176

Re: Cp,m

You use Cp for conditions of constant pressure in isothermal reactions. You use Cv for conditions of constant volume in isothermal reactions.
by Emily Huang 1E
Sat Feb 09, 2019 3:15 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Midterm topics
Replies: 3
Views: 81

Re: Midterm topics

Yes, for the 7th edition Gibbs Free Energy starts at 4J so you need to know the material up to 4I for thermodynamics
by Emily Huang 1E
Sat Feb 09, 2019 2:58 pm
Forum: Phase Changes & Related Calculations
Topic: 4A3 7th Edition
Replies: 3
Views: 57

Re: 4A3 7th Edition

q would equal zero so there is no heat input or output. You can assume the system is adiabatic even though it doesn't explicitly state that
by Emily Huang 1E
Sat Feb 09, 2019 2:55 pm
Forum: Calculating Work of Expansion
Topic: Expansion work
Replies: 1
Views: 64

Re: Expansion work

You would use the equation w=-PdeltaV. To get the final and intial volume you would multiply the grams of water by the density and convert cm3 to L. 1cm3 is 10^-3 L. Then you would use 1070 as the pressure value and plug in deltaV and convert L*atm to Joules to get the final work done.
by Emily Huang 1E
Sat Feb 02, 2019 5:27 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm Review
Replies: 14
Views: 261

Midterm Review

Will we be having a midterm review session before the first midterm?
by Emily Huang 1E
Tue Jan 29, 2019 5:59 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Internal Energy and Titration
Replies: 1
Views: 46

Internal Energy and Titration

Why can we assume that there is no volume change when an acid and base are titrated together for internal energy calculations?
by Emily Huang 1E
Tue Jan 29, 2019 5:55 pm
Forum: Calculating Work of Expansion
Topic: HW problem 4A.3 from 7th edition
Replies: 1
Views: 30

HW problem 4A.3 from 7th edition

I am confused as to why delta V=pi*r^2*d according to the solution manual. Where did the book get that equation from and do we need to know that equation?
by Emily Huang 1E
Sat Jan 26, 2019 1:23 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard enthalpy of formation
Replies: 2
Views: 46

Standard enthalpy of formation

Is there a difference between the standard enthalpy of formation and the standard reaction enthalpy. What do each refer to?
by Emily Huang 1E
Sat Jan 26, 2019 1:20 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Changing sign of enthalpy
Replies: 3
Views: 52

Re: Changing sign of enthalpy

It depends on whether the exothermic or endothermic reaction is favored. If the forward reaction is endothermic and is favored the delta H would be positive. If the reverse reaction is favored, the delta H becomes negative as the reverse reaction is exothermic.
by Emily Huang 1E
Sat Jan 26, 2019 1:17 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond enthalpies to calculate change in enthalpy
Replies: 3
Views: 223

Re: Bond enthalpies to calculate change in enthalpy

You would determine the change in phases and find the bond enthalpy. You subtract the bond enthalpy of the reactants from the bond enthalpy of the products
by Emily Huang 1E
Sun Jan 20, 2019 1:14 pm
Forum: Administrative Questions and Class Announcements
Topic: Peer Learning Sessions [ENDORSED]
Replies: 10
Views: 6612

Re: Peer Learning Sessions [ENDORSED]

Do we get worksheets to work on at step up sessions or peer learning sessions?
by Emily Huang 1E
Sun Jan 20, 2019 1:11 pm
Forum: Administrative Questions and Class Announcements
Topic: Discussion Section Test
Replies: 4
Views: 88

Discussion Section Test

I was wondering if the test is multiple choice or short answer?
by Emily Huang 1E
Sun Jan 20, 2019 1:06 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: HW Problem #12.79 (6th edition)
Replies: 1
Views: 23

Re: HW Problem #12.79 (6th edition)

H2SO4 is a strong acid so it dissociates completely. That is why both the hydrogen atoms are deprotonated and you get SO4 as a product
by Emily Huang 1E
Wed Jan 09, 2019 3:56 pm
Forum: Administrative Questions and Class Announcements
Topic: Audio Visual Topics
Replies: 1
Views: 94

Audio Visual Topics

Is there a deadline for when we should complete the audio visual topics. I am confused if we do one audio visual topic a week or how it works?
by Emily Huang 1E
Wed Jan 09, 2019 3:49 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium Constants Involving Spectator Ions
Replies: 2
Views: 24

Re: Equilibrium Constants Involving Spectator Ions

Spectator ions cancel each other out so you do not need to include them in your calculations
by Emily Huang 1E
Wed Jan 09, 2019 3:44 pm
Forum: General Science Questions
Topic: Lecture Powerpoints
Replies: 9
Views: 264

Lecture Powerpoints

Will the lecture powerpoints that are shown in class be posted on the class website?

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