Search found 123 matches

by DarrenKim_1H
Sun Mar 15, 2020 11:45 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Delta U
Replies: 4
Views: 79

Re: Delta U

Multiple factors indicate whether to change the sign. For example if work is done on the system it is positive and if it is done by then it is negative
by DarrenKim_1H
Sat Mar 14, 2020 9:44 am
Forum: Administrative Questions and Class Announcements
Topic: Thanks From the UA’s!
Replies: 5
Views: 219

Re: Thanks From the UA’s!

Thank you all for all the help in Chemistry these past two quarters
by DarrenKim_1H
Sat Mar 14, 2020 9:16 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: diff b/w mechanisms?
Replies: 1
Views: 19

Re: diff b/w mechanisms?

The steady state method can only be used if the first step of a reaction is much slower than the second step, whereas the pre-equilibrium approximation requires the first step to be faster.
by DarrenKim_1H
Sat Mar 14, 2020 9:15 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: pre-eq
Replies: 1
Views: 22

Re: pre-eq

It simplifies the mathematics behind calculating rate law ex) E+S→ES(1) Rate of formation of ES = k1 [E][S] ES→E+S(2) Rate of decay of ES = k-1 [ES] ES→E+P(3) Rate of formation of P = k2 [ES] In this example because E + S -> ES occurs much faster than the second step. We can assume E, S and ES are a...
by DarrenKim_1H
Sat Mar 14, 2020 9:10 am
Forum: Calculating Work of Expansion
Topic: Increase/Decrease
Replies: 6
Views: 80

Re: Increase/Decrease

Against a constant pressure, work = -PdeltaV. So with expansion where volume is increasing and pressure remains constant. work also increases
by DarrenKim_1H
Sat Mar 14, 2020 9:06 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: intermediates
Replies: 8
Views: 68

Re: intermediates

Not sure exactly what you mean. Reaction intermediates are formed from one reaction, like any other part of the equation and then completely consumed in the following reaction
by DarrenKim_1H
Sat Mar 14, 2020 9:04 am
Forum: Administrative Questions and Class Announcements
Topic: Athena
Replies: 34
Views: 1825

Re: Athena

Dear Professor,

Thank you for all your wisdom the past two quarters. With Online Finals out of the way, I hope you can finally get some sleep and rest.
by DarrenKim_1H
Sun Mar 08, 2020 4:10 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6.19
Replies: 1
Views: 25

Re: 6.19

Lactic acid's chemical formula is:

CH3CH(OH)COOH (aq) + H2O -> H3O+ + CH3CH(OH)COO-

Because lactic acid produces hydronium ions, I think we can ensure that it will react with HbO2- to decrease it's concentration
by DarrenKim_1H
Sun Mar 08, 2020 4:06 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5.35
Replies: 1
Views: 27

Re: 5.35

From the graph, you can see that A has a initial P equivalent to 27.5. After the reaction occurs it's final P is around 17.5, meaning that the change in concentration is around 10 kPa. The same as C and double as B, which is why A and C have coefficients of 2
by DarrenKim_1H
Sun Mar 08, 2020 4:03 pm
Forum: Zero Order Reactions
Topic: Zero Order reaction rate constant
Replies: 8
Views: 55

Re: Zero Order reaction rate constant

I believe it is still K
by DarrenKim_1H
Sun Mar 08, 2020 11:28 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: intermediates
Replies: 5
Views: 62

Re: intermediates

I believe that we will be given intermediates. The only step we need to know is how to identify them
by DarrenKim_1H
Sat Mar 07, 2020 5:09 pm
Forum: General Rate Laws
Topic: affect of temperature on K
Replies: 4
Views: 55

Re: affect of temperature on K

I believe for endothermic reactions, like you said if the temperature is raised forward rxn is favored.

In contrast, I believe for exothermic rxn, if T is raised backward rxn is favored
by DarrenKim_1H
Thu Feb 27, 2020 2:25 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Problem 4I.5
Replies: 2
Views: 97

Re: Problem 4I.5

I think it's because since q = mCdeltaT and you set qhot equal to qcold, you can divide both sides by the specific heat capacity of water to cancel them out, since you're finding the equilibrium temperature.
by DarrenKim_1H
Thu Feb 27, 2020 2:18 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 6n13
Replies: 2
Views: 30

Re: 6n13

I got the same answer for e^14.8. Since, for the rest of the question you don't have to use that value. I left it as 2.6 x 10^6.
by DarrenKim_1H
Thu Feb 27, 2020 2:12 pm
Forum: Balancing Redox Reactions
Topic: REDOX Agents
Replies: 9
Views: 77

Re: REDOX Agents

OILRIG

(Oxidized is Losing & Reduction is Gaining)

When something is oxidized it loses an electron because it gives that electron to something else, which makes it a reducing agent.

When something is reduced, it gains an electron by taking it from something else, making it an oxidizing agent
by DarrenKim_1H
Thu Feb 27, 2020 2:11 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: Electrochemical Series
Replies: 6
Views: 115

Re: Electrochemical Series

I don't think we need to know any specifics regarding it. I believe it is another way to show the electronegativity trend across the periodic table
by DarrenKim_1H
Sun Feb 23, 2020 1:12 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.5 D.
Replies: 7
Views: 72

Re: 6L.5 D.

So basically, I think you split the Au+ as the half reactant for both parts. From there, writing the half reaction is pretty standard
by DarrenKim_1H
Sun Feb 23, 2020 1:11 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 6L.5 D.
Replies: 7
Views: 72

Re: 6L.5 D.

Reduction (at cathode): Au+(aq) + e- ->Au(s)

Oxidation (at anode): Au+(aq) -> Au 3+(aq) + 2e-
by DarrenKim_1H
Sun Feb 23, 2020 1:09 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Potential Difference Compared to Hydrogen [ENDORSED]
Replies: 2
Views: 37

Re: Potential Difference Compared to Hydrogen [ENDORSED]

I believe it's because hydrogen is the most standard element to use for measurements. I believe' hydrogen's potential is assumed to be zero at all temperatures
by DarrenKim_1H
Sun Feb 23, 2020 1:07 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Wmax = delta G
Replies: 1
Views: 26

Re: Wmax = delta G

W max is the max amount of work a system can do. G is the max work one at a standard temperature and and pressure. So they can be related.
by DarrenKim_1H
Sun Feb 23, 2020 1:05 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: ∆G=-nFE
Replies: 3
Views: 40

Re: ∆G=-nFE

I think its G* = -nFE is used at equilibrium. The equation you gave is if it's not at equilibrum
by DarrenKim_1H
Sun Feb 23, 2020 1:02 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Salt bridge
Replies: 4
Views: 32

Re: Salt bridge

It's to maintain charge as the electrons are transferred from the anode to cathode
by DarrenKim_1H
Tue Feb 11, 2020 8:34 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Delta H of vaporization
Replies: 1
Views: 16

Re: Delta H of vaporization

melting and Vaporization are endothermic processes, because they require energy to turn ice into water, and water into vapor
by DarrenKim_1H
Tue Feb 11, 2020 8:32 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Delta U
Replies: 8
Views: 85

Re: Delta U

So basically, U = q + w refers to the fact that it is the total energy that the system is involved with, i.e the energy from the heat generated or loss plus the energy of the work done on or against the system
by DarrenKim_1H
Tue Feb 11, 2020 8:31 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Delta U
Replies: 8
Views: 85

Re: Delta U

It refers to the energy contained within a system
by DarrenKim_1H
Tue Feb 11, 2020 8:29 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: completely deprotonating in water
Replies: 1
Views: 23

Re: completely deprotonating in water

It means Kw is equal to the concentration of H3O+ ions times the concentration of OH- ions, since Kw = 10^-14
by DarrenKim_1H
Tue Feb 11, 2020 8:23 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: hydrogenation
Replies: 1
Views: 17

Re: hydrogenation

I believe hydrogenation is given as a Hess's Law question, I don't think there is any specific way to calculate it within what we have learned so far
by DarrenKim_1H
Tue Feb 11, 2020 8:17 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 4.19
Replies: 1
Views: 30

Re: 4.19

I think you did your Kelvin conversions wrong. It's suppose to be 55.85 + 273.15, so 329 K and 328K
by DarrenKim_1H
Tue Feb 11, 2020 8:14 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: HW 41.5
Replies: 2
Views: 73

Re: HW 41.5

So first, you set q(hot water) = -q(cold water) to find the temperature at equilibrium. Then you use the S = Cln(T2/T1) subbing in the Temperature at equilibrium to find the change in entropy for the hot and cold water individually, before you add them together to find the total entropy change
by DarrenKim_1H
Tue Feb 11, 2020 8:10 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: Residual Entropy
Replies: 6
Views: 112

Re: Residual Entropy

residual entropy is the remaining entropy left in molecules at 0 K
by DarrenKim_1H
Tue Feb 11, 2020 8:07 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Why is heat capacity a state function?
Replies: 1
Views: 20

Re: Why is heat capacity a state function?

Because it does not matter HOW the heat was added or HOW much the temperature changes.
by DarrenKim_1H
Tue Feb 11, 2020 8:06 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Pi and sigma bond
Replies: 1
Views: 17

Re: Pi and sigma bond

We don't know what the specific bond enthalpy for breaking a pi bond. So we break both and record the bond enthalpy for a, say, carbon-carbon double bond as different from a single bond
by DarrenKim_1H
Sun Feb 09, 2020 5:50 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4.19
Replies: 1
Views: 33

Re: 4.19

We use variation of Cm = q/n delta T

where Um is the molar entropy and given as:

Um = (3/2)RT
by DarrenKim_1H
Sun Feb 09, 2020 5:44 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Pizza Rolls - State Functions
Replies: 5
Views: 78

Re: Pizza Rolls - State Functions

I think I just keep in mind q and w are the non-state functions.
by DarrenKim_1H
Sun Feb 09, 2020 5:42 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4D.23
Replies: 2
Views: 37

Re: 4D.23

With Hess's law, you can add or subtract different parts of the equation in order to get delta H
by DarrenKim_1H
Sun Feb 09, 2020 5:41 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: 4D.2 Textbook Question
Replies: 1
Views: 34

Re: 4D.2 Textbook Question

more gas implies a volume expansion, aka an increase of delta V, which according to PV = nRT, means there's an increase in the second part of the equations enthalpy = internal energy + nRT
by DarrenKim_1H
Sun Feb 09, 2020 5:34 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Learning outcome fossil fuels
Replies: 2
Views: 48

Re: Learning outcome fossil fuels

I think part of it is understanding that burning fuel is an open system, meaning that both mass and heat are exchanged in the process. Other than that, it probably means to understand how to calculate heat, internal energy change, and other things we learned in class using the chemical equation for ...
by DarrenKim_1H
Wed Jan 29, 2020 11:22 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: 4a.1
Replies: 3
Views: 48

Re: 4a.1

A) Correct B) Closed, because coolant in a refrigerator coil is what "cools" down the refrigerator so heat is transferred C) Isolated, because nothing is exchanged D) Correct, both heat and volume of gas liquid is changing E) Yes closed, because the mercury changes in response to temperatu...
by DarrenKim_1H
Wed Jan 29, 2020 9:07 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 4D.3
Replies: 2
Views: 32

Re: 4D.3

Hi Ayushi,

because since the reaction is endothermic and the temperature raises, we can assume that all the heat is absorbed by the calorimeter
by DarrenKim_1H
Wed Jan 29, 2020 8:51 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 4F.1
Replies: 1
Views: 26

Re: 4F.1

The human body generates 100 W of heat, which we can set equal to q since the human body generates 100 joules per second of heat. So, q = 100 J
by DarrenKim_1H
Wed Jan 29, 2020 8:45 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Cpm and Cvm
Replies: 2
Views: 45

Re: Cpm and Cvm

I believe its because they are fundamentally different constants. Cv is under constant volume and Cp is under constant pressure, so they are different
by DarrenKim_1H
Wed Jan 29, 2020 8:42 pm
Forum: Calculating Work of Expansion
Topic: Sum Equation in Lecture
Replies: 2
Views: 17

Re: Sum Equation in Lecture

I think it was more to derive the equation at the end. However, I think he said that we may use the integral for reversible reactions and the derivation of it for irreversible reaction
by DarrenKim_1H
Mon Jan 20, 2020 10:52 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5.39
Replies: 2
Views: 33

Re: 5.39

I believe if you are calculating x using the information from Table GE.2, the values you would get for x are 1.47x10^-2 or 6.81x10^-3. But you would use 1.47x10^-2 since anything around 10^-3 is too small (I might be wrong about that, but thats my general rule of thumb lol)
by DarrenKim_1H
Mon Jan 20, 2020 10:48 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5.35
Replies: 1
Views: 21

Re: 5.35

I believe dividing by 100 is to convert the units from KPa to bar
by DarrenKim_1H
Mon Jan 20, 2020 10:47 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Homework 6E.1 Rounding Error?
Replies: 1
Views: 32

Re: Homework 6E.1 Rounding Error?

It might just be a minor rounding error. What did you input for -logX? If you put -log(0.16), then you would probably get 0.8
by DarrenKim_1H
Mon Jan 20, 2020 10:45 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Understanding the chart
Replies: 1
Views: 32

Re: Understanding the chart

They are just constants found probably through experiments
by DarrenKim_1H
Mon Jan 20, 2020 10:32 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: 5.39 HW
Replies: 2
Views: 38

Re: 5.39 HW

It is an ice box question, so you need to find x. From the table, the information you need to find is Kc to calculate X
by DarrenKim_1H
Tue Jan 14, 2020 12:54 am
Forum: Administrative Questions and Class Announcements
Topic: Step-up Sessions
Replies: 1
Views: 35

Re: Step-up Sessions

Peer learning sessions refer to all the drop-in hours, step-up sessions, and workshops you can attend. Step up sessions are sessions designed to help students struggling with concepts. In comparison, workshops are designed for students that have already a deep understanding of concepts and need more...
by DarrenKim_1H
Tue Jan 14, 2020 12:49 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: pKa
Replies: 3
Views: 27

Re: pKa

I think Ka is usually 10^-x of something whereas pKa refers to the x
by DarrenKim_1H
Tue Jan 14, 2020 12:47 am
Forum: Administrative Questions and Class Announcements
Topic: Discussion
Replies: 8
Views: 76

Re: Discussion

I don't think it is directly, but we turn in weekly homework at discussion
by DarrenKim_1H
Mon Jan 13, 2020 11:24 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5.39
Replies: 4
Views: 82

Re: 5.39

You can find x using the quadratic formula x = -b + or - square root (b^2-4ac) / 2a
by DarrenKim_1H
Mon Jan 13, 2020 11:14 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: 5.39
Replies: 1
Views: 37

Re: 5.39

I believe so, 10^-3 is the correct answer I think
by DarrenKim_1H
Fri Jan 10, 2020 9:36 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5I.13 Part C
Replies: 2
Views: 28

Re: 5I.13 Part C

I believe whichever K value is less is the thermodynamically more stable one
by DarrenKim_1H
Fri Jan 10, 2020 9:35 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: 5I.13
Replies: 1
Views: 49

Re: 5I.13

Part a is very similar to the example we did with the reaction vessel in lecture today. namely, you have to solve for x.

Part b is essentially the same question, except you are given F2 and are calculating its dissociation instead of Cl.
by DarrenKim_1H
Fri Jan 10, 2020 2:28 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5I.13
Replies: 2
Views: 31

Re: 5I.13

I believe for this question we use Kc
by DarrenKim_1H
Fri Jan 10, 2020 2:26 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium Constant for Multiples of the Chemical Equation
Replies: 2
Views: 28

Re: Equilibrium Constant for Multiples of the Chemical Equation

I do not think we have yet learned a case where we would multiply K by a factor of n. As for why we raise it to the factor of n. Remember, whenever we have a coefficient in front of a reactant/product, we raise its concentration by that coefficient as well. i.e. the K for N2 + 3H2 -> 2 NH3 is [NH3]^...
by DarrenKim_1H
Fri Jan 10, 2020 10:06 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Post-Assessment-Part 3
Replies: 2
Views: 50

Re: Post-Assessment-Part 3

I believe c is another variable for a constant
by DarrenKim_1H
Mon Dec 02, 2019 10:39 am
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Molecules combining with water
Replies: 5
Views: 84

Re: Molecules combining with water

So, I think overall KClO is a salt comprised of K+ a weak acid and ClO- is a strong base. So the anion for ClO- will react with water to form:

ClO- + H2O -> HClO + OH-

Therefore it forms a basic solution
by DarrenKim_1H
Mon Dec 02, 2019 10:31 am
Forum: Identifying Acidic & Basic Salts
Topic: 6D.11
Replies: 1
Views: 56

Re: 6D.11

I would go about answering this question by first asking myself: Does this molecule form an acidic or basic solution when it reacts with water? For example, in part a where you're given NH4Br, you know that NH4+ is the conjugate acid for weak base NH3 such that: NH4^+ + H2O -> NH3 + H3O+. Hence, sin...
by DarrenKim_1H
Mon Dec 02, 2019 10:14 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: pH vs pOH
Replies: 4
Views: 55

Re: pH vs pOH

If we are looking at the same question, they give us the molecule as KOH. Since it is a base it will react with water to from hydroxide (OH-) ions. Therefore, we know to use pOH = -log[OH-]
by DarrenKim_1H
Mon Dec 02, 2019 10:08 am
Forum: Naming
Topic: Oxidation state
Replies: 2
Views: 38

Re: Oxidation state

By oxidation state, are you referring to the charge of an individual atom (ie Fe^3+)? If so, let me try to explain with an example. Suppose you have the molecule Fe(OH)3. Here , we know OH has a negative charge of 1 but the overall compound is neutral. Therefore, Fe has to have a positive three char...
by DarrenKim_1H
Mon Dec 02, 2019 10:00 am
Forum: Lewis Acids & Bases
Topic: 6.13
Replies: 2
Views: 52

Re: 6.13

So I would start the problem by drawing out B(OH)3's Lewis Structure. From there, you notice that the structure has no delocalization of electrons so therefore no relevant resonance. If you draw out the structure for the reaction B(OH)3 + 2 H2O -> H3o+ + B(OH)4^-. You can see that since Boric acid d...
by DarrenKim_1H
Sun Dec 01, 2019 11:45 am
Forum: Conjugate Acids & Bases
Topic: Conjugate Base
Replies: 5
Views: 67

Re: Conjugate Base

I believe pH refers to the concentration of H3O+ ions in a solution. So a conjugate base wouldn't affect this number.

HCl + H2O -> H3O+ + Cl-

In the equation, Cl- is the conjugate base of strong acid HCl, but its not an H3O+ ion so i don't think it affects pH
by DarrenKim_1H
Sun Dec 01, 2019 11:40 am
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Organic vs. Inorganic Acids
Replies: 2
Views: 47

Re: Organic vs. Inorganic Acids

Because in Inorganic acids, the hydrogen is bonded to any highly electronegative element, whereas for organic acids the hydrogen is restricted to being bonded to an O atom, which is bonded to a C atom
by DarrenKim_1H
Sun Dec 01, 2019 11:39 am
Forum: Hybridization
Topic: Hybridized vs. Unhybridized Orbitals
Replies: 2
Views: 37

Re: Hybridized vs. Unhybridized Orbitals

I believe they are different atomic models. So a question would specify whether to place them in one
by DarrenKim_1H
Sun Dec 01, 2019 11:37 am
Forum: Naming
Topic: Not Counting Subscripts?
Replies: 2
Views: 33

Re: Not Counting Subscripts?

Because there are three ammonia molecules. Therefore, TriAmmine
by DarrenKim_1H
Sun Dec 01, 2019 11:36 am
Forum: Naming
Topic: How to Find the Roman Numeral
Replies: 4
Views: 49

Re: How to Find the Roman Numeral

So that coordination compound is shown to be neutral. So you would find the net negative charge of 3 So4^2-, which is -6 (3 times -2). In the cation, NH3 and H2O are both neutral so Cobalt is the only component that has a charge which is +3. Overall, its a net positive charge of +6 since (2 times 3 ...
by DarrenKim_1H
Sun Dec 01, 2019 11:29 am
Forum: Naming
Topic: Roman Numeral
Replies: 13
Views: 94

Re: Roman Numeral

It represents the positive charge on a cation. For example a copper (ii) sulfate CuSO4, represents a Cu^2+ ion which attaches itself to the sulfate anion (SO4^2-)
by DarrenKim_1H
Sun Nov 24, 2019 9:09 pm
Forum: General Science Questions
Topic: Week 9 HW
Replies: 6
Views: 97

Re: Week 9 HW

Probably questions from the Outline on Acids and Bases
by DarrenKim_1H
Sun Nov 24, 2019 9:09 pm
Forum: Hybridization
Topic: Shapes
Replies: 3
Views: 44

Re: Shapes

Specific shapes...rather, specific areas of electron density correspond to different hybridization levels. For example, tetrahedral geometry corresponds to sp^3, octahedral corresponds to sp^3d^2 etc.
by DarrenKim_1H
Sun Nov 24, 2019 9:07 pm
Forum: Administrative Questions and Class Announcements
Topic: Curve
Replies: 3
Views: 84

Re: Curve

I believe he will. There is going to be a slight adjustment he makes to all our grades at the end
by DarrenKim_1H
Mon Nov 18, 2019 6:56 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Class Curve?
Replies: 4
Views: 94

Re: Class Curve?

Yes, Dr. Lavelle will adjust grades accordingly he may decide the cutoff for grades to be 250/500 points, but I do not believe there is any "set" percent ranges for the grades. Therefore, I don't think I can answer your second question.
by DarrenKim_1H
Sun Nov 17, 2019 9:03 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: induced dipole
Replies: 4
Views: 27

Re: induced dipole

Induced dipole occurs when a nonpolar moelcule is turned dipole by an ionic molecule. Whereas dipole moments occur when the molecule already has a different charge
by DarrenKim_1H
Sun Nov 17, 2019 9:01 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: bp trend?
Replies: 2
Views: 22

Re: bp trend?

Heavier halogens have more electrons in their shell which increases Van Der Waal forces and boiling point
by DarrenKim_1H
Sun Nov 17, 2019 8:58 pm
Forum: Student Social/Study Group
Topic: Test 2
Replies: 11
Views: 117

Re: Test 2

The Lecture we had the Friday before the midterm up until the lecture we had last friday.
by DarrenKim_1H
Sun Nov 17, 2019 8:54 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2E. 5 Question
Replies: 4
Views: 39

Re: 2E. 5 Question

I believe in lecture, he explained that the angle less than 120 degrees results from a stronger pull from the central atom.
by DarrenKim_1H
Sun Nov 17, 2019 10:57 am
Forum: Hybridization
Topic: 2F.15
Replies: 1
Views: 32

Re: 2F.15

sp hybridization refers to the mixing of the s and p orbitals. What the answer implies is that decreasing the amount of p orbitals from 3 to 2 increases the bond angle and the answer asserts that increasing the amount of s orbitals for sp hybridization will in contrast increase the bond angle.
by DarrenKim_1H
Sun Nov 10, 2019 7:30 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Interaction Potential Energy
Replies: 1
Views: 21

Re: Interaction Potential Energy

I believe 1/r^6 denotes a inverse relationship between energy and distance. Whereas, the other one you described is the actual equation. It's kind of like how wavelength = c/frequency is the actual equation where as wavelength = 1/frequency denotes that wavelength and frequency are inversely related.
by DarrenKim_1H
Sun Nov 10, 2019 7:26 pm
Forum: Dipole Moments
Topic: Temporary Dipole Moment?
Replies: 4
Views: 39

Re: Temporary Dipole Moment?

Yes, most dipole moments we have discussed are temporary. Since bonds are just areas where electrons are most likely to be found, there is no "permanent" dipole moment.
by DarrenKim_1H
Sun Nov 10, 2019 7:22 pm
Forum: Dipole Moments
Topic: Dipole moment units
Replies: 4
Views: 39

Re: Dipole moment units

Like you said, the SI unit is Coulombs times Meter and it denotes the magnitude of charge times the distance between them
by DarrenKim_1H
Sun Nov 10, 2019 1:43 pm
Forum: Dipole Moments
Topic: Dipoles Cancelling Out
Replies: 4
Views: 43

Re: Dipoles Cancelling Out

I believe cancelling out has to do with the symmetry of a molecule. For example C2Cl4 has no net dipole moment because the molecule is symmetric so the moment cancels out
by DarrenKim_1H
Sun Nov 10, 2019 1:41 pm
Forum: SI Units, Unit Conversions
Topic: Homework from Outline 3 due?
Replies: 5
Views: 157

Re: Homework from Outline 3 due?

I would assume so. Although depending on when your section is, Wednesday lecture may be the first lecture where we cover material on outline 4
by DarrenKim_1H
Sun Nov 10, 2019 1:40 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7951
Views: 1215238

Re: Post All Chemistry Jokes Here

Group 1 Elements Be Like:

What If I...gave you my one valence electron...to form a complete octet...aha ha, just kidding...unless?
by DarrenKim_1H
Sun Nov 10, 2019 1:33 pm
Forum: Administrative Questions and Class Announcements
Topic: how to become a UA
Replies: 1
Views: 58

Re: how to become a UA

Generally, the first step requires understanding the course material in-depth. Most Learning Assistants I've had have told me that they generally received an A or higher in the course. Afterwards, I believe it's only a matter of time commitment and submitting the application by the due date. I've li...
by DarrenKim_1H
Mon Oct 28, 2019 9:52 pm
Forum: Trends in The Periodic Table
Topic: Effective nuclear charge
Replies: 3
Views: 62

Re: Effective nuclear charge

Hi Anna,

I believe what you are referring to is Slater's rule and it allow you to estimate the effective nuclear charge from the real number of protons in the nucleus and the effective shielding of electrons in each orbital "shell."
by DarrenKim_1H
Mon Oct 28, 2019 9:48 pm
Forum: Trends in The Periodic Table
Topic: electronegativity table
Replies: 5
Views: 80

Re: electronegativity table

I think we would just have to know that electronegativity increases bottom to top in groups and left to right across periods
by DarrenKim_1H
Mon Oct 28, 2019 9:47 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration of Tungsten
Replies: 2
Views: 46

Re: Electron Configuration of Tungsten

To my understanding, don't s orbitals get filled first before d orbitals
by DarrenKim_1H
Mon Oct 28, 2019 9:40 pm
Forum: Ionic & Covalent Bonds
Topic: 2A23 Part E
Replies: 2
Views: 46

Re: 2A23 Part E

Bismuth is undergoing the inert-pair effect
by DarrenKim_1H
Mon Oct 28, 2019 9:27 pm
Forum: Ionic & Covalent Bonds
Topic: grading
Replies: 5
Views: 81

Re: grading

On my.ucla.edu sign in and under the Academics tab, click Exam and Homework Grades
by DarrenKim_1H
Sun Oct 27, 2019 10:12 pm
Forum: Lewis Structures
Topic: 2A.11
Replies: 1
Views: 39

Re: 2A.11

In this question it is asking for ions with a positive three charge. So for part a for example: Ar on the periodic table has 18 electrons. Add 18 with the 6 from 3d^6 and you get 24 which would normally be Cr on the periodic table. However, since you are dealing with ions with a +3 charge, the answe...
by DarrenKim_1H
Sun Oct 27, 2019 10:03 pm
Forum: Lewis Structures
Topic: Exceptions to the Octet Rule
Replies: 3
Views: 60

Re: Exceptions to the Octet Rule

Exceptions to the octet rule generally have to deal with molecules that have an odd number of electrons, which is different from normal orbitals being able to accept an even level
by DarrenKim_1H
Sun Oct 27, 2019 10:00 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Stability of D orbitals
Replies: 3
Views: 53

Re: Stability of D orbitals

Because completely filled orbitals are generally more stable than partially filled orbitals
by DarrenKim_1H
Sun Oct 27, 2019 9:59 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Spins
Replies: 4
Views: 73

Re: Spins

From what I remember in lecture, electrons are typically first paired in the s orbital and are placed parallel first in every other orbital
by DarrenKim_1H
Sun Oct 27, 2019 9:55 pm
Forum: Lewis Structures
Topic: Electron Configuration
Replies: 3
Views: 49

Re: Electron Configuration

I was reading up on this...and from what I can garner the answer is a bit complicated. You're welcome to also search for answers but overall it just seems that it is more favorable for an electron to occupy an empty 4d orbital rather than deal with pairing with an electron in the 5s orbital.
by DarrenKim_1H
Sat Oct 19, 2019 7:53 pm
Forum: Properties of Electrons
Topic: Aufbau vs Hund's
Replies: 2
Views: 52

Re: Aufbau vs Hund's

Hund's Rule directly states that other sub levels besides s, have electrons placed in individual orbitals before being paired. In contrast, Aufbau's principle can be explained in three points 1. The number of electrons in an atom is equal to the atomic # 2. Each added electron will enter the orbital...
by DarrenKim_1H
Sat Oct 19, 2019 7:48 pm
Forum: Properties of Electrons
Topic: Building Up
Replies: 2
Views: 37

Re: Building Up

According to Hund's rule, electrons repel each other in the same subshell which is why they must occupy different orbitals with parallel spin
by DarrenKim_1H
Sat Oct 19, 2019 7:26 pm
Forum: *Black Body Radiation
Topic: Applying Wein's Law
Replies: 3
Views: 130

Re: Applying Wein's Law

Wein's Law is used to calculate wavelength using a constant divided by the temperature in Kelvin. Since we have not gone over Black body radiation in lecture yet, I believe it will be better explained by Professor Lavelle in a future lecture.

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