Search found 142 matches

by Eugene Chung 3F
Mon Mar 16, 2020 1:29 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ATP QUESTION ON FINAL
Replies: 9
Views: 179

Re: ATP QUESTION ON FINAL

Sine it says pi comes from ATP, the two concentrations cancels and K depends on [ADP] only.
by Eugene Chung 3F
Mon Mar 16, 2020 1:27 pm
Forum: Administrative Questions and Class Announcements
Topic: final grades
Replies: 12
Views: 217

Re: final grades

Does this class have a curve at the end?
by Eugene Chung 3F
Mon Mar 16, 2020 1:26 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Final Exam #15
Replies: 3
Views: 137

Re: Final Exam #15

On the final, #15 asked us to find \Delta H ionization for H20 --> OH- + H+. How were we supposed to find this? I googled the \Delta H formation of H2O and OH- and used \sum \Delta H products - \sum \Delta H reactants . Was this the right way to go about it or did we have to use the pH or \Delta H ...
by Eugene Chung 3F
Wed Mar 11, 2020 7:02 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: work
Replies: 7
Views: 58

Re: work

The amount of work possible is dependent on the cell potential of the electrochemical cell
by Eugene Chung 3F
Wed Mar 11, 2020 7:01 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: concentration related to current?
Replies: 4
Views: 35

Re: concentration related to current?

Vuong_2F wrote:
Eugene Chung 3F wrote:electrons will flow from area of high concentration to an area of low concentration. So, the concentration difference makes potential.

so once there is no concentration difference, there is no more potential?


Yup.
by Eugene Chung 3F
Sun Mar 08, 2020 11:21 pm
Forum: Balancing Redox Reactions
Topic: Redox Table
Replies: 6
Views: 35

Re: Redox Table

If all of the reactions in the table represent reductions, for the oxidizing half reaction, it would be made negative, then would the sign in the Ecat-Eanode change to addition or would we subtract it? If you don't want to worry about changing the sign, it's easier to just do Ecat-Eanode and always...
by Eugene Chung 3F
Sun Mar 08, 2020 11:19 pm
Forum: Balancing Redox Reactions
Topic: Why do we flip E for oxidation?
Replies: 13
Views: 76

Re: Why do we flip E for oxidation?

Cindy Adiwidjaja 1B wrote:I know that E is given, however, why do we need to flip the sign when we are trying to use the E for oxidation?


Honestly, for me, I feel like it's easier to do Cathode-anode, that way you don't have to worry about changing the E value given.
by Eugene Chung 3F
Sun Mar 08, 2020 11:18 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Test 2
Replies: 7
Views: 40

Re: Test 2

We know that lower electronegativity and more negative E value means stronger reducing agent. Anode is oxidized and is the reducing agent. So, the one with more negative E value is conventionally the anode.
by Eugene Chung 3F
Sun Mar 08, 2020 11:16 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams
Replies: 13
Views: 44

Re: Cell Diagrams

Gabriel Ordonez 2K wrote:When are the instances that we have to add an inert solid to either end of the cell diagram? Is it always one or two ends of it?


When the other elements in the cell diagram is aq. state.
by Eugene Chung 3F
Sun Mar 08, 2020 11:15 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Use of Platinum
Replies: 10
Views: 64

Re: Use of Platinum

using graphite (carbon) is also common, but I think Dr. Lavelle said we would be using platinum for chem 14b
by Eugene Chung 3F
Mon Mar 02, 2020 12:54 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: work
Replies: 7
Views: 58

Re: work

the deltaG for a cell is the amount of useful work obtainable from a system at constant T and P.
by Eugene Chung 3F
Mon Mar 02, 2020 12:53 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs free energy equations
Replies: 5
Views: 54

Re: Gibbs free energy equations

I think the main thing to remember is deltaG = 1nFEcell. You can use any equation to find delta G then, apply this equation to find electrochemical variable values or vice versa.
by Eugene Chung 3F
Mon Mar 02, 2020 12:51 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: information given
Replies: 1
Views: 30

Re: information given

I just jot down all the equations that are relevant to the question and try to mix match them to figure out the variable I'm looking for.
by Eugene Chung 3F
Mon Mar 02, 2020 12:49 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: concentration related to current?
Replies: 4
Views: 35

Re: concentration related to current?

electrons will flow from area of high concentration to an area of low concentration. So, the concentration difference makes potential.
by Eugene Chung 3F
Sun Feb 23, 2020 11:24 pm
Forum: Balancing Redox Reactions
Topic: acidic solutions
Replies: 3
Views: 31

Re: acidic solutions

I think you just add hydrogen ion H+ where needed.
by Eugene Chung 3F
Sun Feb 23, 2020 11:21 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Reverse Reaction
Replies: 1
Views: 13

Re: Reverse Reaction

Brandon Tao 1K wrote:Is a reaction within a galvanic cell, will it ever reach equilibrium and will we need to find the constants?


I think equilibrium is reached when Ecell = 0 V. This would mean that there is no net electron flow within the cell and the current has stopped.
by Eugene Chung 3F
Sun Feb 23, 2020 11:18 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: salt bridge
Replies: 5
Views: 49

Re: salt bridge

salt bridge maintains the charge balance b/c the electrons are moving from one half cell to the other half cell. the electrons will flow from one adnode to the cathode. So, the reaction reaching equilibrium slows down.
by Eugene Chung 3F
Sun Feb 23, 2020 11:17 pm
Forum: Van't Hoff Equation
Topic: Van't Hoff Equation
Replies: 3
Views: 57

Re: Van't Hoff Equation

Jasleen Kahlon wrote:The Van't Hoff Equation shows temperature dependence of K, but I'm still a little confused on what that means, and does the equation in any way connect to ∆H, ∆S, and ∆G?


deltaG = -RtlnK

and since deltaG = deltaH -T*deltaS, we can rearrange it to solve for deltaH and deltaS.
by Eugene Chung 3F
Sun Feb 23, 2020 11:14 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Gibbs free energy and max work
Replies: 2
Views: 30

Re: Gibbs free energy and max work

I think Gibbs free energy is the maximum work at constant temperature and pressure if the system is reversible and the work is non-expansion work form a closed system.
by Eugene Chung 3F
Sun Feb 16, 2020 9:42 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Isochoric
Replies: 8
Views: 114

Re: Isochoric

isocloric is constant volume. This means that there is no work being done. So the work is 0.
by Eugene Chung 3F
Sun Feb 16, 2020 9:40 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 2
Replies: 11
Views: 90

Re: Test 2

It'll be from the second page of thermodynamics outline to what we learn next week.
by Eugene Chung 3F
Sun Feb 16, 2020 9:39 pm
Forum: General Science Questions
Topic: Studying
Replies: 19
Views: 146

Re: Studying

1. Go to LA sessions if you can and TA office hours. Those are really helpful.
2. Do the HW problems.
by Eugene Chung 3F
Sun Feb 16, 2020 9:38 pm
Forum: Administrative Questions and Class Announcements
Topic: HW7
Replies: 14
Views: 87

Re: HW7

I think it's okay to turn in any homework problems you did to study for the midterm.
by Eugene Chung 3F
Sun Feb 16, 2020 9:35 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Laws of thermodynamics
Replies: 2
Views: 35

Re: Laws of thermodynamics

1. delta U = heat+work
2. For reversible system, deltaS of universe equals 0.
3. at 0K for a perfectly ordered molecule, the entropy change is 0
by Eugene Chung 3F
Sun Feb 16, 2020 9:34 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Enthalpy and Heat
Replies: 3
Views: 46

Re: Enthalpy and Heat

heat is the energy transferred from high temperature to lower temperature whereas enthalpy is heat transfer at a constant pressure. The heat added or lost from system gives the change of enthalpy.
by Eugene Chung 3F
Wed Feb 12, 2020 12:20 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Delta S Universe
Replies: 1
Views: 22

Re: Delta S Universe

reversible processes have delta S universe = 0. Since deltaS(sys) + deltaS(surr) = deltaS(universe) = 0, deltaS(sys) = -deltaS(surr).
by Eugene Chung 3F
Mon Feb 10, 2020 1:35 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: average kinetic energy
Replies: 1
Views: 28

average kinetic energy

HW question 4.19 says to calculate the molar kinetic energy of Kr at different temperatures. What is the formula for average kinetic energy ? Should we know this for the midterm?
by Eugene Chung 3F
Sun Feb 09, 2020 11:54 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: when to change sign of enthalpies
Replies: 7
Views: 60

Re: when to change sign of enthalpies

If you mean question 4a, you would flip the sign if u flip the chemical equation.
by Eugene Chung 3F
Sun Feb 09, 2020 11:52 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: All Laws of Thermodynamics
Replies: 2
Views: 56

Re: All Laws of Thermodynamics

I think we have to know what they are at least for calculations. I'm not too sure about concepts. 1st law: delta U = q+w 2nd law: for irreversible process (all real processes), delta S(uni) > 0. (total entropy of surroundings and system increases) 3rd law: for perfect crystal at 0K, deltaS= 0 --> 1 ...
by Eugene Chung 3F
Sun Feb 09, 2020 11:48 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: HW 4D7
Replies: 4
Views: 37

Re: HW 4D7

205154661_Dis2J wrote:For 4D7, why are we using the equation DeltaH= DeltaU + DeltaNRT? I do not quite understand why we are including DeltaNRT.


We know that delta U = heat + w and that in this case, delta H= heat. We also know that w=-P deltaV. The ideal gas law states PV=nRT. So, -P delta V = -delta nRT.
by Eugene Chung 3F
Sun Feb 09, 2020 11:44 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: graphs
Replies: 3
Views: 28

Re: graphs

y-axis is pressure. Since irreversible systems are isobaric, pressure is constant.
by Eugene Chung 3F
Sun Feb 09, 2020 11:42 pm
Forum: Calculating Work of Expansion
Topic: q=C delta T
Replies: 5
Views: 37

Re: q=C delta T

I think the main difference is whether or not C is given per mol/g or just per T. For example, to calculate q of calorimeter, the question would say that the calorimeter has total heat capacity of 80 j/C, in this case it would just be q= CdeltaT
by Eugene Chung 3F
Sun Feb 09, 2020 11:39 pm
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: Positional/Residual Entropy
Replies: 3
Views: 28

Re: Positional/Residual Entropy

residual entropy is the left-over entropy at 0K. (perfect crystal). The entropy in this case would only depend on the ways in which molecule can position/orient themselves.
by Eugene Chung 3F
Sun Feb 09, 2020 11:33 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: State Functions (Pizza Rolls 3H)
Replies: 1
Views: 17

Re: State Functions (Pizza Rolls 3H)

I'm guessing it's because heat capacity is the measure of enthalpy (heat required to be transferred in rising T by 1C) and enthalpy is a state function. Also, heat capacity does not depend on how heat was added or how the temperature changed.
by Eugene Chung 3F
Sun Feb 09, 2020 11:30 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Reversible Reactions vs. Irreversible Reactions
Replies: 6
Views: 53

Re: Reversible Reactions vs. Irreversible Reactions

I'm not sure but it wouldn't hurt to know! It's pretty easy because irreversible one would just have a straight horizontal line for y-axis because pressure would be constant. Reversible graph has larger surface area below the curve. The surface area represents work. Less work is done for irreversibl...
by Eugene Chung 3F
Sun Feb 09, 2020 11:28 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4D.15
Replies: 2
Views: 30

Re: 4D.15

AlyssaYeh_1B wrote:From the data the question gives, I did the calculation: -1500 - (-1300 + 2(-286)) = 312kJ/mol. However, the answer key shows that it's -312kJ/mol. What did I do wrong?


If you add the standard enthalpies up, it should be -1300 +1560 +2(-286) which comes out to -312
by Eugene Chung 3F
Sun Feb 09, 2020 11:23 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Equations not on eq sheet
Replies: 1
Views: 27

Re: Equations not on eq sheet

Dr.Lavelle posted the constants and formulas on 14b class website so you can look at it and fill in formulas that are not on there. I noticed it didn't have W=X^n. Most equations are from another equation so I read through the formula sheet so that I don't have to memorize all of them
by Eugene Chung 3F
Sun Feb 09, 2020 11:17 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Exothermic reactions
Replies: 5
Views: 33

Re: Exothermic reactions

All spontaneous processes have an increase in entropy. In other words, heat will always flow from hot to cold and never cold to hot spontaneously. So, S(universe) >0 for spontaneous process (2nd law of thermo.). We also know that delta H is negative for exothermic reactions and that delta G = delta ...
by Eugene Chung 3F
Sun Feb 09, 2020 10:57 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: q rev
Replies: 4
Views: 49

Re: q rev

In reality, all natural (real) processes are irreversible because biochemical systems often use highly irreversible rxns to speed up processes. Also, all spontaneous processes are irreversible. (like hot going to cold) Reversible reactions are the "ideal" and "perfect" system. (e...
by Eugene Chung 3F
Fri Feb 07, 2020 4:43 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: hw problem 4D 7 assuming T?
Replies: 3
Views: 29

hw problem 4D 7 assuming T?

Hi,

for 4D #7, the problem doesn't give you the temperature but the solutions suggest that it its assumed as 298K (25C).
Do we assume that T is 25C for certain circumstances?
by Eugene Chung 3F
Sun Feb 02, 2020 10:45 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Spontaneous
Replies: 4
Views: 51

Re: Spontaneous

Generally, reactions are favorable when they result in a decreased enthalpy and increased entropy of the system. When the reaction both decrease enthalpy and increase entropy, it occurs natually.
by Eugene Chung 3F
Sun Feb 02, 2020 10:43 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: expansion
Replies: 5
Views: 35

expansion

what exactly is expansion in terms of thermodynamics?
by Eugene Chung 3F
Sun Feb 02, 2020 10:42 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Week 4 lecture 3 calculating W question
Replies: 2
Views: 22

Week 4 lecture 3 calculating W question

In class, we went over calculating w right before it ended. Could someone explain what the microstates are?
by Eugene Chung 3F
Sun Feb 02, 2020 10:40 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: First law of thermodynamics
Replies: 3
Views: 23

First law of thermodynamics

Could someone explain what the first law of thermodynamics states conceptually? I get how to do the calculations but don't quite get what exactly the law is.
by Eugene Chung 3F
Sun Feb 02, 2020 10:38 pm
Forum: Phase Changes & Related Calculations
Topic: about system and surroundings
Replies: 8
Views: 64

about system and surroundings

How do you know which is the system and which is the surrounding?
For example, for 4A 1, for mercury in a thermometer or gasoline burning in an automobile engine, could someone tell me what is the system and surrounding in these two cases?
by Eugene Chung 3F
Fri Jan 24, 2020 3:26 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Finding OH concentration
Replies: 2
Views: 26

Re: Finding OH concentration

I'm pretty sure the solution is wrong (I have the same problem). Since [H30][OH]=1*10^-14, the answer would not be what it says in the solutions.
by Eugene Chung 3F
Fri Jan 24, 2020 3:23 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Partial Pressure
Replies: 5
Views: 45

Re: Partial Pressure

If partial pressure of reactant is increased, then, the reaction will favor products to make up for the change and vice versa. If overall pressure is increased, meaning that the volume decreased, the side with less gases will be favored (check the stoichiometric coefficients of the gases) and vice v...
by Eugene Chung 3F
Fri Jan 24, 2020 3:19 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: HNO2(aq) + H2O(l) -> H3O+(aq) + NO2-(aq)
Replies: 2
Views: 26

Re: HNO2(aq) + H2O(l) -> H3O+(aq) + NO2-(aq)

I think of it like I do with spectator ion (ex.cl-). ions like Na+, K+, Ca2+ dissociate so in making ICE table, etc, we don't take them into account in terms of calculations
by Eugene Chung 3F
Thu Jan 23, 2020 3:36 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Hw problem 5.35 help
Replies: 3
Views: 40

Hw problem 5.35 help

I understand a but i don’t understand b.
Do i just approximate the partial pressure for each elements?
Also, how to i figure out the volume?
by Eugene Chung 3F
Sun Jan 19, 2020 5:24 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 5J.1
Replies: 4
Views: 39

Re: 5J.1

Le Chatelier's principle tells us that chemical reactions adjust to minimize the effect of changes. Therefore, if CO (reactant) partial pressure increases, the reaction will want to minimize the effect of that change and shift left to produce more CO (kinda like compensating). The result of that is ...
by Eugene Chung 3F
Sun Jan 19, 2020 5:19 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: ICE tables
Replies: 3
Views: 32

Re: ICE tables

ICE table can be used to find K, pH, equilibrium concentrations, etc. It gives information about the initial concentrations and the final equilibrium concentration. We can also calculate how much is remaining after the equilibrium reaction also.
by Eugene Chung 3F
Sun Jan 19, 2020 5:18 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: conjugate seesaw
Replies: 4
Views: 35

Re: conjugate seesaw

To give an example, When HCl (strong acid) dissociate in aqueous solution, than the conjugate base is Cl-, an ion produced as a result of HCl's dissociation. It can technically accept protons to produce acid in reverse direction but because HCl is strong, and dissociates completely, the reaction onl...
by Eugene Chung 3F
Sun Jan 19, 2020 5:13 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5.I.11/13
Replies: 2
Views: 30

Re: 5.I.11/13

It's okay to make the ICE table with just mol (as opposed to mol/L) and then divide it by volume later. But, to be safe, yes, it is better to convert them all beforehand. So, for mmol, you would just multiply 10^-3 and divide by the volume
by Eugene Chung 3F
Sun Jan 19, 2020 5:10 pm
Forum: Ideal Gases
Topic: 5I.15
Replies: 5
Views: 69

Re: 5I.15

Since NH4HS is a solid, u can basically ignore it
by Eugene Chung 3F
Sun Jan 19, 2020 5:06 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Identifying endothermic vs exothermic
Replies: 7
Views: 42

Re: Identifying endothermic vs exothermic

A reaction is exothermic if the products have more energy than the reactants, and it is endothermic if the reactants have more energy than the products. Usually, the reaction would give you a deltaH value if it is asking about temperature. DeltaH would be negative if the reaction is exothermic and ...
by Eugene Chung 3F
Sun Jan 12, 2020 2:35 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Homogenous Equilibrium
Replies: 13
Views: 71

Re: Homogenous Equilibrium

for example, N2 + 3H2 - 2NH3 equilibrium reaction we went over in lecture is homogenous since the reactants and products are all in gas phase.
by Eugene Chung 3F
Sun Jan 12, 2020 2:33 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Factors Affecting K
Replies: 5
Views: 57

Re: Factors Affecting K

the c in Kc represents concentration and p partial pressure.
by Eugene Chung 3F
Sun Dec 08, 2019 3:38 am
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: List of Strong Acids and Weak Acids
Replies: 2
Views: 92

Re: List of Strong Acids and Weak Acids

8 strong acids: HCl, HBr, HClO4, HI, HNO3, H2SO4
everything else is considered weak acid

Strong bases: basically group 1 and 2 hydroxides

common weak bases: NH3 (ammonia), CH3NH2 (Methylamine), C2H5NH2 (ethylamine), diethylamine, pyridine C5H5N
by Eugene Chung 3F
Sun Dec 08, 2019 3:35 am
Forum: Calculating the pH of Salt Solutions
Topic: 6D.11 (d)
Replies: 2
Views: 84

Re: 6D.11 (d)

K+ is in group 1 element which is neutral and we can also know this since the K+ is a conjugate acid of a strong base, KOH
and Br- is conjugate base of strong acid, HBr, so we know that it is also neutral.
by Eugene Chung 3F
Sun Dec 08, 2019 3:32 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Uncertainty
Replies: 6
Views: 283

Re: Uncertainty

yes, they are used interchangeably
by Eugene Chung 3F
Sat Dec 07, 2019 8:14 pm
Forum: Polyprotic Acids & Bases
Topic: HW 6C.17 Which is the stronger base?
Replies: 4
Views: 120

Re: HW 6C.17 Which is the stronger base?

We know that BrO- is stronger base since it has a negative charge. This means that when it accepts a proton H+, it will become neutral whereas for C17H19O3N, it will become positively charged. Neutral charge is more favorable.
by Eugene Chung 3F
Sat Dec 07, 2019 8:04 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: ph concept
Replies: 5
Views: 78

Re: ph concept

please quote my question so i get a notification, thanks in advance! i know there is something wrong with my thought process, but i cannot figure it out. my thought process is that if a base is weaker, less oh- will be dissociated out. taking the -log of that smaller number will result in a smaller...
by Eugene Chung 3F
Sat Dec 07, 2019 7:58 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: H2O and Carbonate
Replies: 3
Views: 52

Re: H2O and Carbonate

1. Water can't act as a polydentate because it is too small to form multiple bonds to a transition metal central atom. The lone pairs are both on the same O atom. 2. Carbonate can act as both mono and bidentate. Since it has two O atoms with - charge (lone pairs), it can interact in two places. It d...
by Eugene Chung 3F
Sat Dec 07, 2019 7:50 pm
Forum: Bond Lengths & Energies
Topic: Radicals
Replies: 1
Views: 73

Re: Radicals

If you mean how do we rank radicals with stability, I believe having resonance increases stability by delocalizing charge.
by Eugene Chung 3F
Sat Dec 07, 2019 7:47 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Chelates
Replies: 5
Views: 142

Re: Chelates

You would look for ligands that act as polydentate. For example, if the coordination compound has ethylenediamine or en, you would know that it is chelating since en is a bidentate.
by Eugene Chung 3F
Thu Dec 05, 2019 5:47 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: HW problem 6C. 19 (f)
Replies: 1
Views: 31

HW problem 6C. 19 (f)

Which is stronger acid and why? (f) H2CO3 or H2GeO3. I understand how higher electronegativity of C will result in it being the stronger acid, but I thought the acidity also depends on the bond length and that weaker (larger) bonds are stronger (Example in lecture was with H-F, H-Cl, H-Br with H-F b...
by Eugene Chung 3F
Mon Dec 02, 2019 2:41 am
Forum: Administrative Questions and Class Announcements
Topic: Calculators on Final
Replies: 6
Views: 61

Re: Calculators on Final

since the test is cumulative, i assume that calculators are allowed.
by Eugene Chung 3F
Mon Dec 02, 2019 2:40 am
Forum: Conjugate Acids & Bases
Topic: Ligands
Replies: 12
Views: 101

Re: Ligands

ligands are electron pair donors.
by Eugene Chung 3F
Mon Dec 02, 2019 2:39 am
Forum: Administrative Questions and Class Announcements
Topic: Curving in Chem 14A
Replies: 7
Views: 214

Re: Curving in Chem 14A

I heard the same. The final distribution can alter your grade by a bit.
by Eugene Chung 3F
Mon Dec 02, 2019 2:38 am
Forum: Administrative Questions and Class Announcements
Topic: Retaking Chem 14A
Replies: 2
Views: 58

Re: Retaking Chem 14A

I heard from past students that the final grade might not be as bad as you think! You should not take the final if you want to retake it however.
by Eugene Chung 3F
Mon Dec 02, 2019 2:37 am
Forum: Student Social/Study Group
Topic: Final topics
Replies: 10
Views: 113

Re: Final topics

The final will be cumulative but probably focusing on the latter topics
by Eugene Chung 3F
Sun Nov 24, 2019 8:22 pm
Forum: Sigma & Pi Bonds
Topic: Sigma and Pi Bonds
Replies: 7
Views: 80

Re: Sigma and Pi Bonds

Sigma bond is the initial, or first bond, so basically all the single bonds and one of the double/triple bonds. Pi bond is the other one/ones in the double/ triple bond, or the bond that comes after sigma bond.
by Eugene Chung 3F
Sun Nov 24, 2019 8:20 pm
Forum: Lewis Structures
Topic: Bent or Angular?
Replies: 15
Views: 306

Re: Bent or Angular?

Bent and angular are use synonymously
by Eugene Chung 3F
Sun Nov 24, 2019 8:19 pm
Forum: Dipole Moments
Topic: Polar or nonpolar
Replies: 8
Views: 104

Re: Polar or nonpolar

Most diatomic molecules like o2 are nonpolar.
by Eugene Chung 3F
Sun Nov 24, 2019 8:16 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Explain VSEPR conceptually
Replies: 12
Views: 129

Re: Explain VSEPR conceptually

Basically, the VSEPR model is the 3D model of a molecule where all ‘things’ are as far as they can be.
by Eugene Chung 3F
Sun Nov 24, 2019 8:15 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polarity
Replies: 4
Views: 47

Re: Polarity

I would first draw the lewis structure, identify the vsepr shape to find out if the molecule is symmetrical or not. If it is symmetrical then it is most likely nonpolar since the dipole moments will cancel out. But if it isn’t symmetrical, draw the dipole moment arrows (towards the more electronegat...
by Eugene Chung 3F
Sun Nov 17, 2019 5:45 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Consequences of polarizability
Replies: 1
Views: 102

Re: Consequences of polarizability

higher polarizability means there will be stronger LDF. So, the molecules will attract one another more strongly and the melting/ boiling points of these covalent substances will increase with size because bigger the size= higher the polarizability.
by Eugene Chung 3F
Sun Nov 17, 2019 5:41 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Preferential
Replies: 3
Views: 42

Re: Preferential

I think what he was trying emphasize is that stability is preferred and we can observe some patterns for different elements to reach that stability by sharing e-, etc
by Eugene Chung 3F
Sun Nov 17, 2019 5:40 pm
Forum: Electronegativity
Topic: Bond type for FeO2?
Replies: 3
Views: 127

Re: Bond type for FeO2?

I believe it is a polar covalent bond with ionic character
by Eugene Chung 3F
Sun Nov 17, 2019 5:38 pm
Forum: Student Social/Study Group
Topic: What will Test 2 be on?
Replies: 8
Views: 102

Re: What will Test 2 be on?

I would focus on Intermolecular forces and VSEPR theory.
by Eugene Chung 3F
Sun Nov 17, 2019 5:37 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: identifying forces
Replies: 2
Views: 32

Re: identifying forces

bond between non-metal and non-metal is usually a covalent bond and between non-metal and metal is ionic bond. Ion-Ion interaction is between ions, the particles with unequal # of protons and electrons (look at charge). Ion-dipole interaction is between ion and someting with partial charge. dipole d...
by Eugene Chung 3F
Sun Nov 03, 2019 11:51 pm
Forum: Lewis Structures
Topic: Valence Electrons
Replies: 2
Views: 27

Re: Valence Electrons

Writing out the electron configuration for Cu, there is one valence electron: [Ar] 3d10 4s1
by Eugene Chung 3F
Sun Nov 03, 2019 11:41 pm
Forum: Photoelectric Effect
Topic: Best way to study for this topic?
Replies: 8
Views: 247

Re: Best way to study for this topic?

There are a video module and assessment questions available on the class website. I find it helpful to work out the problems on there because they deal with both conceptual and calculation problems.
by Eugene Chung 3F
Sun Nov 03, 2019 11:37 pm
Forum: Properties of Light
Topic: UV
Replies: 2
Views: 48

Re: UV

I believe it is 100nm to 400nm.
by Eugene Chung 3F
Sun Nov 03, 2019 11:31 pm
Forum: Lewis Structures
Topic: hw problem 2c.3
Replies: 1
Views: 36

hw problem 2c.3

Should we be able to know the formula (and the charge) based on the names?
by Eugene Chung 3F
Sat Nov 02, 2019 7:59 pm
Forum: Lewis Structures
Topic: ONF lewis structure
Replies: 2
Views: 27

ONF lewis structure

Since the general guideline for determining the central atom is to choose the one with lowest ionization energy, I expected O to be the central atom. However, the solution provides N as central. Could anyone explain to me why?
by Eugene Chung 3F
Sun Oct 27, 2019 2:06 pm
Forum: Properties of Light
Topic: Value for C
Replies: 8
Views: 96

Re: Value for C

During test, they will give you all the constants you need in the front page. I would try to use the ones that are given by the class on the front page.
by Eugene Chung 3F
Sun Oct 27, 2019 2:05 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Atomic spectra post assessment question 42
Replies: 2
Views: 79

Atomic spectra post assessment question 42

I tried using this formula first,
1.14 x 10^14 = 3.29x10^15((1/n^2)- (1/16)
But i ended up getting n=3.

So i just tried with n=5 and n=6 and chose 6.
Is the above formula correct? Or am i missing something?
by Eugene Chung 3F
Sun Oct 27, 2019 2:05 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Atomic spectra post assessment question 42
Replies: 2
Views: 53

Atomic spectra post assessment question 42

I tried using this formula first,
1.14 x 10^14 = 3.29x10^15((1/n^2)- (1/16)
But i ended up getting n=3.

So i just tried with n=5 and n=6 and chose 6.
Is the above formula correct? Or am i missing something?
by Eugene Chung 3F
Sun Oct 27, 2019 2:08 am
Forum: Formal Charge and Oxidation Numbers
Topic: 2B. 23
Replies: 2
Views: 44

Re: 2B. 23

Formal charge of an atom indicates gain/loss of electrons while forming covalent bond. So, to assign formal charge of an atom, first, determine the number of valence electrons for each bound atom, then compare the number of bounding (shared, S) electron and the number of lone pairs (L) of free atom ...
by Eugene Chung 3F
Sun Oct 27, 2019 2:02 am
Forum: DeBroglie Equation
Topic: Post-assessment question 34
Replies: 2
Views: 47

Re: Post-assessment question 34

okay thanks! One more thing, if the answer was 10^-5, would it still be reasonable?
by Eugene Chung 3F
Fri Oct 25, 2019 5:56 pm
Forum: DeBroglie Equation
Topic: Post-assessment question 34
Replies: 2
Views: 47

Post-assessment question 34

I got 1.00 x 10^-5 m/s and thought it was reasonable since it is smaller than the speed of light. Could anyone explain why this is wrong?
by Eugene Chung 3F
Wed Oct 23, 2019 12:34 am
Forum: Photoelectric Effect
Topic: post module assignment Q 19
Replies: 4
Views: 69

post module assignment Q 19

is the answer D? I feel like A, B, C are right because they explain the main photoelectric effect equation showing conservation of energy
by Eugene Chung 3F
Wed Oct 23, 2019 12:09 am
Forum: Photoelectric Effect
Topic: module assessment Q #29
Replies: 2
Views: 47

Re: module assessment Q #29

thank you so much!
by Eugene Chung 3F
Tue Oct 22, 2019 4:38 pm
Forum: Photoelectric Effect
Topic: module assessment Q #29
Replies: 2
Views: 47

module assessment Q #29

Since the work function is 150.6 kJ, I just converted in from KJ to J by multiplying10^3 and chose B.
Can someone help me understand how to solve this problem?
by Eugene Chung 3F
Sun Oct 20, 2019 11:24 pm
Forum: SI Units, Unit Conversions
Topic: Accuracy vs Precision
Replies: 11
Views: 200

Re: Accuracy vs Precision

Image
This image should help!
by Eugene Chung 3F
Sun Oct 20, 2019 11:19 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Clarification on electron configuration
Replies: 5
Views: 41

Re: Clarification on electron configuration

i noticed in some HW questions, it includes more than just first row of d-block. So, it might be helpful to make sure you understand how to do it.
by Eugene Chung 3F
Sun Oct 20, 2019 11:15 pm
Forum: Properties of Light
Topic: speed of light and velocity
Replies: 6
Views: 72

Re: speed of light and velocity

in terms of calculations in this class, I believe it doesn't matter. But, it would help a lot in the future to know that they are two different concepts for Physics.
by Eugene Chung 3F
Mon Oct 14, 2019 12:25 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Are these equations only specific to H-atoms?
Replies: 2
Views: 55

Are these equations only specific to H-atoms?

So, from what I understand, the Bohr Frequency Condition and equation for calculating energy of different n levels are specific to H atoms. Professor Lavelle mentioned C-atom during the lecture and I was wondering if we know the condition for C-atoms? Just to make sure, are these condition and equat...

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