Search found 117 matches

by Michelle N - 2C
Sun Mar 15, 2020 1:30 pm
Forum: Administrative Questions and Class Announcements
Topic: Athena
Replies: 34
Views: 1825

Re: Athena

Hi Dr. Lavelle,

Thank you for these last two quarters. I won't lie, I was stressed. Chemistry was never my strongest subject, and I knew that I would need to push in order to be okay. Thank you for your resources, and thank you for your hard work. Stay safe Dr. Lavelle! :)
by Michelle N - 2C
Thu Mar 12, 2020 8:56 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Rate Constant and Shorter Half Life
Replies: 5
Views: 52

Rate Constant and Shorter Half Life

Can someone explain to me about the relationship about the higher the rate constant, the shorter its half-life? Thank you!
by Michelle N - 2C
Thu Mar 12, 2020 8:54 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: What was your favorite chem topic?
Replies: 24
Views: 190

Re: What was your favorite chem topic?

Chemical Equilibrium for me! :)
by Michelle N - 2C
Thu Mar 12, 2020 8:53 pm
Forum: Second Order Reactions
Topic: Termolecular
Replies: 15
Views: 385

Re: Termolecular

Adding on, how common are these again?
by Michelle N - 2C
Thu Mar 12, 2020 8:52 pm
Forum: General Rate Laws
Topic: Natural Log Rate Order
Replies: 4
Views: 35

Natural Log Rate Order

Is this just a pattern I noticed, or are natural logs usually first-order rate laws? Can someone explain to me why they are/aren't?
by Michelle N - 2C
Tue Mar 10, 2020 4:30 pm
Forum: Administrative Questions and Class Announcements
Topic: ENDGAME Review Session
Replies: 71
Views: 2528

Re: ENDGAME Review Session

Thank you for everything you've done Lyndon! We truly appreciate it!
by Michelle N - 2C
Tue Mar 10, 2020 4:28 pm
Forum: Administrative Questions and Class Announcements
Topic: Coronavirus Concern
Replies: 6
Views: 193

Re: Coronavirus Concern

I am feeling the exact same way. I am highly concerned about both my grades and my safety. The TAs' and UAs' sessions are extremely helpful, but I am conflicted on going to them because of what's going on. I am trusting that they (meaning the department, Dr. Lavelle, etc) are working on a solution t...
by Michelle N - 2C
Sun Mar 08, 2020 10:45 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Adding Pt(s) to a Cell Diagram
Replies: 14
Views: 109

Re: Adding Pt(s) to a Cell Diagram

Just to add onto the question, when do we add Pt(s) to both sides of the cell diagram?
by Michelle N - 2C
Sun Mar 08, 2020 10:44 pm
Forum: Balancing Redox Reactions
Topic: Half rxns
Replies: 27
Views: 297

Re: Half rxns

005384106 wrote:At what point do you add elections to the half reaction?


I believe it's when you need to balance out the charges.
by Michelle N - 2C
Sun Mar 08, 2020 10:40 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Purpose of Nernst Equation
Replies: 5
Views: 32

Purpose of Nernst Equation

What's the purpose of the nernst equation, and what are all the things the nernst equation can be used to find for?
by Michelle N - 2C
Mon Mar 02, 2020 9:46 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Metal in Cell Diagram
Replies: 1
Views: 12

Metal in Cell Diagram

When would we have to mention a metal into a cell diagram?
by Michelle N - 2C
Mon Mar 02, 2020 9:37 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: E° Being Negative
Replies: 1
Views: 18

E° Being Negative

During week 7, there was in an example regarding calculating the potential difference on Cu/Zn battery (Cu2+(aq) + Zn(s) ---> Cu(s) + Zn2+. It was then stated that the E°Cu was 0.34 V and that E°Zn was -0.76 V. So, I wanted to ask: 1) If given a problem similar to this, would the E° values be given?...
by Michelle N - 2C
Sun Mar 01, 2020 10:03 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Nernst Equation
Replies: 4
Views: 36

Re: Nernst Equation

When do we use the Nernst equation compared to the other equations for electrochemistry? In all honesty, I've been basing off what's given in the problem and what it asks. I know this is not the best way, but for me, this is how I've been going with it. However, I do know that the simplified Nernst...
by Michelle N - 2C
Sun Mar 01, 2020 9:57 pm
Forum: Balancing Redox Reactions
Topic: OH and H
Replies: 8
Views: 65

Re: OH and H

I think for this case - balancing redox reactions - I think it's either or since the primary goal is the balance them and their respective elements/charges.
by Michelle N - 2C
Sun Mar 01, 2020 9:54 pm
Forum: Balancing Redox Reactions
Topic: Cell Diagrams
Replies: 14
Views: 84

Re: Cell Diagrams

I just wanted to add to this question, are they also separated when it's a different phase? Can someone explain that aspect to me? Thank you.
by Michelle N - 2C
Sun Mar 01, 2020 9:52 pm
Forum: Balancing Redox Reactions
Topic: Acidic and Basic Reactions
Replies: 9
Views: 71

Re: Acidic and Basic Reactions

Like what everyone was saying, you add H+/OH- to balance the number of hydrogen atoms present and the same for oxygen. You know how much to add by basing of the coefficients, similar to balancing chemical reactions back in Chem 14A. Hope that helps! :)
by Michelle N - 2C
Sun Mar 01, 2020 9:48 pm
Forum: Balancing Redox Reactions
Topic: moles of electrons transferred
Replies: 4
Views: 28

Re: moles of electrons transferred

You would balance the charges out by adding e- where needed to make the charges equal. That is where you should be able to find the moles of electron. Sorry this isn't as detailed, but that's what I know.
by Michelle N - 2C
Sun Feb 23, 2020 3:39 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Bike Example for Closed System?
Replies: 2
Views: 83

Bike Example for Closed System?

As I'm reviewing and rewriting my notes, I wrote down that Dr. Lavelle provided an example about a bike when talking about the 3 ways of changing the energy of system. Can someone explain to me what this was again, and why it was related to this particular topic? Thank you! :)
by Michelle N - 2C
Sat Feb 22, 2020 12:18 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: cell potential equation
Replies: 5
Views: 46

Re: cell potential equation

F stands for Faraday, which represents the charge of one mole of e-. It should usually be given unless indicated.
by Michelle N - 2C
Sat Feb 22, 2020 12:12 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: E as intensive property
Replies: 5
Views: 46

Re: E as intensive property

E° is intensive basically means that it doesn't rely on how many times the reaction occurs. The voltage difference will always remain the same, which is why in the example that Dr. Lavelle did on that day, he did not multiply E° by the coefficient to balance the equation.
by Michelle N - 2C
Fri Feb 21, 2020 11:47 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Explanation of This Diagram
Replies: 1
Views: 28

Explanation of This Diagram

Can someone provide a general explanation of this graph? This was shown on Wednesday at the beginning of the lecture, and then a variation of this diagram was drawn today, and I'm just trying to understand the concept of this. Thank you in advance!
by Michelle N - 2C
Fri Feb 21, 2020 11:40 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Nerst Equation
Replies: 10
Views: 310

Re: Nerst Equation

805097738 wrote:What is the nerst equation?


It's the equation E = E° - (RT/nF) lnQ ^^ the one mentioned today!
by Michelle N - 2C
Fri Feb 21, 2020 11:15 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Platinum [ENDORSED]
Replies: 4
Views: 46

Re: Platinum [ENDORSED]

Ryan Chang 1C wrote:In cell diagrams, is it possible for platinum to only be on one side?


I would like to add to this question. Is graphite also considered an inert conductor? Why/why not?
by Michelle N - 2C
Wed Feb 12, 2020 11:50 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 4A.7
Replies: 4
Views: 51

Re: 4A.7

Hiii! Thank you! ^^ :) I did not take a picture of the table when I was borrowing it.. that makes a lot more sense now.
by Michelle N - 2C
Wed Feb 12, 2020 11:49 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 4A.13
Replies: 2
Views: 42

Re: 4A.13

A constant volume calorimeter was calibrated by carrying out a reaction known to release 3.50kJ heat in a .200 L of solution in the calorimeter resulting in a temperature rise of 7.32 degrees C. In another experiment 100.0 mL of 0.200 M HBr and 100.0 mL of 0.200 M KOH mixed in the calorimeter and t...
by Michelle N - 2C
Wed Feb 12, 2020 11:03 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: types of heat capacities
Replies: 3
Views: 40

Re: types of heat capacities

Heat capacity is the amount of heat energy required to raise the temperature of a substance by 1 degrees C. It is extensive because it depends on how much mass there is. The units are in J/C. Specific heat capacity is the heat capacity divided by a certain amount of mass. It is intensive because th...
by Michelle N - 2C
Wed Feb 12, 2020 10:43 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: 4A.7
Replies: 4
Views: 51

Re: 4A.7

(a) Calculate the heat that must be supplied to a copper kettle of mass 400.0 g containing 300.0 g of water to raise its temperature from 20.0 C to the boiling point of water, 100.0 C. (b) What percentage of the heat is used to raise the temperature of the water? (See Table 4A.2.) How do I solve th...
by Michelle N - 2C
Tue Feb 11, 2020 11:48 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Reversible vs Irreversible
Replies: 7
Views: 123

Re: Reversible vs Irreversible

For a reversible system, the system is isothermal and thus temperature is constant which impacts the formulas utilized since some are used for temperature change and some are used when temperature is constant which is the case of a isothermal, reversible system. Can you or someone here explain what...
by Michelle N - 2C
Mon Feb 10, 2020 8:48 am
Forum: Ideal Gases
Topic: density
Replies: 5
Views: 104

Re: density

The density can be used toward PV=nRT when there are problems that doesn't give you the moles of the molecule. For example, a problem might give you the amount in mL, and so we'd convert it to moles via density (at least that's what I've been told through the sessions). Hope that helps!
by Michelle N - 2C
Fri Feb 07, 2020 10:51 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: biological examples
Replies: 7
Views: 87

Re: biological examples

First, thank you for explaining the ATP part of the biological examples. :) Can someone explain the same for osmotic pressures? I'm not sure we went over this either, but osmotic pressure is basically the pressure needed so that water doesn't pass through a membrane. It's calculated using the conce...
by Michelle N - 2C
Fri Feb 07, 2020 10:47 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: units
Replies: 4
Views: 43

Re: units

I think it really depends on what the problem asks/provides. Like what other people said, the common units are J, K, g, L, etc., since they match with the other units when calculating. As long as you know how to convert them, then I think all should be good. Hope that helps!
by Michelle N - 2C
Fri Feb 07, 2020 10:37 am
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Constant Volume and Pressure
Replies: 7
Views: 42

Re: Constant Volume and Pressure

What does it mean to have a constant volume or constant pressure? Constant volume means that the volume of the subject would not change, and constant pressure is that the pressure of the subject would not change throughout. These given phrases helps you figure out which equation to use, and which c...
by Michelle N - 2C
Fri Feb 07, 2020 10:34 am
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Adiabatic System
Replies: 3
Views: 48

Adiabatic System

Hi! I understand through the lecture that an adiabatic system means no heat flow, but I'm a little confused on how this relates to the notes right before it, which was the reversible pathway and the irreversible pathway. Can someone explain this please? Thank you very much!
by Michelle N - 2C
Fri Feb 07, 2020 10:25 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Equations
Replies: 4
Views: 44

Re: Equations

I am pretty sure that they are given on the equations sheet. However I think it might be more beneficial to us if we understand the relationships between the equations so that we can work through the problems.
by Michelle N - 2C
Sun Feb 02, 2020 1:28 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: biological examples
Replies: 7
Views: 87

Re: biological examples

First, thank you for explaining the ATP part of the biological examples. :) Can someone explain the same for osmotic pressures?
by Michelle N - 2C
Sun Feb 02, 2020 1:25 am
Forum: Ideal Gases
Topic: PLF material
Replies: 3
Views: 54

Re: PLF material

When I was taking the LS7 series I did PLFs for 7B and part of 7C and found them to be very helpful because they focused on key points as well as extensive practice problems. From what I heard from others, the Chem 14 PLFs are also very helpful, as they help recap the lecture material and go into pr...
by Michelle N - 2C
Sun Feb 02, 2020 1:20 am
Forum: Ideal Gases
Topic: pv=nrt
Replies: 9
Views: 75

Re: pv=nrt

Kind of like what the previous person said, R is a gas constant, so that can't really be changed (given on our equations sheet). For everything else though, yes there could be change. That's also where the mini-questions during lectures are formed "What would happen to ____ if ____ increased?&q...
by Michelle N - 2C
Sun Feb 02, 2020 1:16 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Weaker Base, Higher pKb
Replies: 4
Views: 53

Weaker Base, Higher pKb

Hello! I saw that during the lecture (this was from like week 2), Dr. Lavelle mentioned that the weaker the base, the higher its Kb value is, which is seen when he compared two different Kb values. Although I feel like I understand that, I'd like to know if there were any key conceptual points that ...
by Michelle N - 2C
Fri Jan 31, 2020 11:51 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ideal Gas QUestions
Replies: 8
Views: 57

Re: Ideal Gas QUestions

504999222 wrote:If the pressure goes up, would that mean the volume would go down?


Believe it depends on which container and context, but from what I’ve seen in the lecture, yes. It’s like, if you double the pressure, then you halved the volume. Hope this helps. :)
by Michelle N - 2C
Fri Jan 31, 2020 11:50 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5% Rule
Replies: 9
Views: 63

Re: 5% Rule

If I make the assumption because K is less than 10^-3, but the x value is less than 5% do I have to go back and use the quadratic formula to calculate x? I believe the 5% rule applies to when we are to ignore the -x in the problem or not, because what I remembered was that as long as the answer is ...
by Michelle N - 2C
Thu Jan 30, 2020 9:35 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Test #1// #5
Replies: 5
Views: 63

Re: Test #1// #5

Wait ... we got our tests back? I had my discussion on Tuesday and didn't get it back?
by Michelle N - 2C
Tue Jan 28, 2020 10:47 am
Forum: Phase Changes & Related Calculations
Topic: Change in Temperature
Replies: 10
Views: 48

Change in Temperature

So I’m starting to understand a little bit better about endothermic and exothermic reactions, but I wanted a little clarification here? As temperature increases, so does the equilibrium constant? Sorry, just wanted to have a clear understanding if anything.
by Michelle N - 2C
Sat Jan 25, 2020 9:09 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Value of X
Replies: 7
Views: 55

Re: Value of X

Really depends on what's given, but it's generally through an ICE table with the quadratic formula.
by Michelle N - 2C
Sat Jan 25, 2020 9:04 pm
Forum: Ideal Gases
Topic: R Constant
Replies: 26
Views: 245

Re: R Constant

How do you know which variation of the R constant to use? I know that Test 1 is already over, but in the equations sheet that Dr. Lavelle provided, there were many variations of it. To answer your question, the best way to know which R constant to use is to see the units used in the problem. If it ...
by Michelle N - 2C
Sat Jan 25, 2020 9:01 pm
Forum: Ideal Gases
Topic: aqueous elements in eq calculation
Replies: 8
Views: 60

Re: aqueous elements in eq calculation

This is how I've been applying it, but correct me if I'm wrong: Solids and liquids are not included in equilibrium constants. Aqueous elements (aq) are included to find Kc, and gases (g) are included to find Kp.
by Michelle N - 2C
Sat Jan 25, 2020 8:58 pm
Forum: Ideal Gases
Topic: final exam pickup
Replies: 10
Views: 157

Re: final exam pickup

They're in Young Hall 3034 (the information office place). What I've seen is that you give the person there your Bruincard and tell them which lecture you're in (Lecture 1, Lecture 3, and Lecture 4). However as of Friday my friend went and they said they couldn't find hers so it's probably a TA or s...
by Michelle N - 2C
Tue Jan 21, 2020 12:03 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Calculating pH from Concentration of Strong Acid/Base
Replies: 2
Views: 22

Calculating pH from Concentration of Strong Acid/Base

On our lecture on January 13th, Lavelle stated on his notes that “If we know the concentration of the strong base/acid, we can calculate pH or pOH.” He then proceeded to the example that 0.0030 M of Ba(OH)2 gives 0.0060 M of OH-. How did that happen? Can someone explain to me this specific process? ...
by Michelle N - 2C
Mon Jan 20, 2020 10:07 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ignoring the -X
Replies: 1
Views: 28

Ignoring the -X

Hi! So I'm going through some practice problems right now, and I have a general question. It was said through the Step-Ups and I believe once by Lavelle that when solving via the quadratic formula in the ICE table, if the K value is less than 10^-3, then we can ignore the x. Would it matter on the t...
by Michelle N - 2C
Mon Jan 13, 2020 10:03 am
Forum: Ideal Gases
Topic: Le Chatelier's Principle
Replies: 7
Views: 95

Re: Le Chatelier's Principle

In class, Professor Lavelle mentioned Le Chatelier's Principle. What is Le Chatelier's Principle and how does it apply to chemical equilibrium and the ideal gas law? Sorry, I don't have a strong background in chemistry because I didn't take AP Chem and don't remember sophomore year's chemistry. Sam...
by Michelle N - 2C
Mon Jan 13, 2020 9:57 am
Forum: Ideal Gases
Topic: P=(n/v)RT
Replies: 12
Views: 83

Re: P=(n/v)RT

You can write it as V is being divided by the whole thing (P = nRT/v). I think why Dr. Lavelle has been writing the V specifically under the n was just emphasize that n/v is molarity, and therefore the concentration.
by Michelle N - 2C
Mon Jan 13, 2020 9:54 am
Forum: Ideal Gases
Topic: eq at the molecular level
Replies: 4
Views: 36

Re: eq at the molecular level

It could be equal, but in most cases, it's just constant. Hopefully this graph helps!
by Michelle N - 2C
Mon Jan 13, 2020 9:50 am
Forum: Ideal Gases
Topic: pv = nRT purpose
Replies: 5
Views: 39

Re: pv = nRT purpose

Like what others said, so far we've used this formula to convert between pressure and concentration. I think we'll also be using it to understand conceptual parts, like what happens to the concentration if the pressure increases/decreases/etc. But as of right now, we've only used it for conversion.
by Michelle N - 2C
Mon Jan 13, 2020 9:48 am
Forum: Ideal Gases
Topic: equilibrium constant purpose
Replies: 7
Views: 55

Re: equilibrium constant purpose

From what I know, K basically tells us that there's a certain ratio needed from the concentrations of products and from the concentrations of reactants so that it could reach equilibrium. With a certain amount available within the solution, there has will be both forward and reverse rates occurring ...
by Michelle N - 2C
Mon Jan 13, 2020 9:41 am
Forum: Ideal Gases
Topic: ICE Table
Replies: 11
Views: 102

Re: ICE Table

To add on from the previous reply, an ICE table basically lays out the initial concentration, the change it endures, followed by the equilibrium concentration amount afterward. You start off by writing out the table and then inputting what's given in the problem into its respective spots. From then,...
by Michelle N - 2C
Sat Jan 11, 2020 4:31 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5H.3
Replies: 4
Views: 40

Re: 5H.3

You make the two equations into composite equations. Use the two equations that has 2HCl as a product and Br2 + Cl2 as a product. Everything should cancel out and create the equation you are looking for. Make sure that when you add two chemical reactions together you multiply their k values. When I...
by Michelle N - 2C
Sat Jan 11, 2020 4:23 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Partial Pressure
Replies: 7
Views: 44

Re: Partial Pressure

From what I know (and from what everyone said), yep, only used for gases. Partial pressure will refer to one gas in the reaction whereas pressure is all the gases in the reaction. When measuring, the units are usually atm, but since this is on equilibrium constants, we don't put the units. Hope this...
by Michelle N - 2C
Tue Jan 07, 2020 7:09 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Homework Question 5G.9, Part B
Replies: 2
Views: 48

Homework Question 5G.9, Part B

Hello! So the textbook question states: " A sample of ozone, O3, amounting to 0.10 mol, is placed in a sealed container of volume 1.0 L and the reaction 2 O3(g) S 3 O2(g) is allowed to reach equilibrium. Then 0.50 mol O3 is placed in a second container of volume 1.0 L at the same temperature an...
by Michelle N - 2C
Tue Jan 07, 2020 6:13 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5G11
Replies: 5
Views: 74

Re: 5G11

For question 5G11, why are some answers written with P and why are some answers written with brackets? Hi! I just wanted to add another question to this same problem because I'm confused when looking at the answers. How do we know if they're asking for partial pressure or concentration? Is there a ...
by Michelle N - 2C
Mon Jan 06, 2020 9:51 pm
Forum: Ideal Gases
Topic: Dynamic Equilibrium
Replies: 10
Views: 89

Re: Dynamic Equilibrium

Dynamic equilibrium basically emphasizes the idea that when the reactants and products are in equilibrium, that doesn't mean that everything just stays still. Reactions are still occurring, just at the same rate as they're being formed/consumed.
by Michelle N - 2C
Mon Jan 06, 2020 9:39 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium Constant
Replies: 4
Views: 51

Re: Equilibrium Constant

I remembered something like this: Technically, we should be calculating based on the activity of the reactant/product. However, throughout what we learn here, we assume that the activity is the same as the reactant/product. There was definitely more that he went in depth with, but I wasn't able to c...
by Michelle N - 2C
Mon Jan 06, 2020 9:35 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Very Large K
Replies: 12
Views: 128

Re: Very Large K

I believe that having a very large K (like larger than 10^3) indicates that the equilibrium strongly favors the products, and that there's a higher amount of products present at some time.
by Michelle N - 2C
Mon Jan 06, 2020 9:31 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: The Significance of K
Replies: 5
Views: 49

Re: The Significance of K

In general, the significance of K is the same, since it states the equilibrium constant. Kc and Kp just basically denote what the units are. The C would stand for concentration (molarity) and the P would stand for partial pressure. Hope this helps!
by Michelle N - 2C
Sat Dec 07, 2019 9:14 pm
Forum: Hybridization
Topic: Lone pairs in hybridization
Replies: 4
Views: 86

Re: Lone pairs in hybridization

I was confused about this at first, but yes, lone pairs do count in hybridization.

I believe that it's electron geometry when lone pairs do not count. Please double check though!

Best of luck!
by Michelle N - 2C
Fri Dec 06, 2019 9:27 am
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Bacidity w/ atomic radius / electronegativity?
Replies: 1
Views: 28

Bacidity w/ atomic radius / electronegativity?

I was in a Step-Up session yesterday, and one of the practice questions was: Place the following molecules of increasing bacidity of the conjugate bases: HOBr, HOCl, HOI. From what I understand, the stronger the acid, the weaker the base. The strength of the acid is then determined by the the bond l...
by Michelle N - 2C
Fri Dec 06, 2019 9:22 am
Forum: Conjugate Acids & Bases
Topic: how to figure out?
Replies: 12
Views: 169

Re: how to figure out?

When I look at the formula, I look at the reactant and it's equivalent product. If the product looks like it lost a H+, then I know that the product is a conjugate base, and the reactant for it was an acid. The same thing goes the other way: If the product looks like it gained a H+, then I know that...
by Michelle N - 2C
Fri Dec 06, 2019 9:18 am
Forum: Conjugate Acids & Bases
Topic: Conjugate Base
Replies: 4
Views: 42

Re: Conjugate Base

nickianel_4b wrote:^^I know that it becomes CH3COO- just from practice, but can someone remind me again why it donates the H+ at the end and not one of the H+ ions attached to the C?


I think that's because they usually lose H+ at the more electronegative atom first, and oxygen is more electronegative than carbon.
by Michelle N - 2C
Fri Dec 06, 2019 9:14 am
Forum: Conjugate Acids & Bases
Topic: Conjugate Acids and Bases
Replies: 6
Views: 61

Re: Conjugate Acids and Bases

Here's how I work through a problem when identifying acids, bases, conjugate acids, and conjugate bases. Hope this helps you as well, and let me know if there's another method that's more helpful to know: - I know that an acid in general is either a H+ donor or an e- pair acceptor, and that a base i...
by Michelle N - 2C
Mon Dec 02, 2019 2:05 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: H-F, H-Cl, H-Br, and H-I
Replies: 3
Views: 35

H-F, H-Cl, H-Br, and H-I

I'm a little confused about what Dr. Lavelle was talking about today (Monday, December 2nd) about how despite what we know about H - F H -- Cl H --- Br H ---- I H-F is the weakest of something? My apologies if this is very out of context, but can someone help me out on this? I'd very much appreciate...
by Michelle N - 2C
Sat Nov 30, 2019 12:10 am
Forum: Naming
Topic: 9C.7 Chelaxing
Replies: 2
Views: 32

9C.7 Chelaxing

The question asks: "Which of the following isomers of diaminobenzene can form chelaxing complexes? Explain your reasoning." There were also 3 different figures of the isomers.

First, what are chelaxing complexes? Second, how do you approach and solve this question?

Thank you!
by Michelle N - 2C
Sat Nov 30, 2019 12:02 am
Forum: Naming
Topic: 9C.1
Replies: 6
Views: 76

Re: 9C.1

WUng_1D wrote:Why does cyanide turn into cyano instead of cyanido?


According to Lavelle, they're both the same, but cyano is the older version of the term.

^^ Someone on another chem community post found the link (viewtopic.php?t=2351), so props to them. :)
by Michelle N - 2C
Fri Nov 29, 2019 11:58 pm
Forum: Naming
Topic: Meaning of Cis and Trans
Replies: 11
Views: 86

Re: Meaning of Cis and Trans

Cis generally means when the molecules are next to each other one side, while trans generally means that they're opposite of each other, like across from each other. This applies to cisplatin as that is a well-known chemotherapy drug that stops cell division. In other words, I think the reason why c...
by Michelle N - 2C
Fri Nov 29, 2019 11:32 pm
Forum: Naming
Topic: Oxidation number
Replies: 2
Views: 41

Re: Oxidation number

My TA gave this formula, which I found to be very useful:

(# of metal atoms)(oxidation number) + Σ (# ligands)(charge of ligands) = charge of complex.

To find oxidation number, you make it a variable (x) and then solve for it. Hopefully that helps!
by Michelle N - 2C
Fri Nov 29, 2019 10:46 pm
Forum: Naming
Topic: 9C.1
Replies: 6
Views: 76

Re: 9C.1

All the comments above are basically what I wanted to say, but this is where the charges are coming from when working towards finding the oxidation number: https://lavelle.chem.ucla.edu/wp-content/supporting-files/Chem14A/NamingCoordinationCompounds.pdf Also, I used this equation to calculate the ox...
by Michelle N - 2C
Thu Nov 21, 2019 8:33 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: dipole-dipole vs induced dipole
Replies: 9
Views: 88

Re: dipole-dipole vs induced dipole

A dipole-dipole interaction is when two molecules with partial charges are in contact there. Dipole-induced dipole is when there is a dipole (a molecule with a partial charge) next to an induced dipole (an atom/molecule) without a charge). If it gets close enough, the partial charge on the diple wou...
by Michelle N - 2C
Thu Nov 21, 2019 8:28 pm
Forum: Hybridization
Topic: hybridization on the test?
Replies: 10
Views: 131

Re: hybridization on the test?

what do we need to know about pi and sigma bonds? You need to know how they are presented in bonds. So if there's a single bond, then there's only a sigma. If it's a double bond, it's sigma and pi, etc. It should also be on your notes, where Lavelle showed one bond, double, and so forth. Best of lu...
by Michelle N - 2C
Thu Nov 21, 2019 8:26 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Test 2
Replies: 7
Views: 124

Re: Test 2

Really depends on whether or not the lone pairs are present in the structure. Follow the VSEPR formula (AXE) and you can go from there!

Best of luck!
by Michelle N - 2C
Thu Nov 21, 2019 8:23 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Test 2
Replies: 14
Views: 159

Re: Test 2

Definitely know intermolecular forces (dipole moments) and the concept and shapes from the VSEPR model. Good luck! :)
by Michelle N - 2C
Thu Nov 21, 2019 8:22 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Test 2
Replies: 3
Views: 52

Re: Test 2

Test two covers everything from after the midterm, so like intermolecular forces and VSEPR!
by Michelle N - 2C
Mon Nov 11, 2019 3:54 pm
Forum: Ionic & Covalent Bonds
Topic: Solid v. Liquid v. Gas
Replies: 8
Views: 83

Re: Solid v. Liquid v. Gas

As of right now, I think it would be given to us, but I would assume that in the future, we'd have to learn it ourselves...

Kinda like how it was H2O (g) for combustion (burning).
by Michelle N - 2C
Mon Nov 11, 2019 3:47 pm
Forum: Ionic & Covalent Bonds
Topic: Both types of bonds
Replies: 6
Views: 52

Re: Both types of bonds

Yes! Some ionic bonds show covalent characteristics while some covalent bonds show ionic characteristics.
by Michelle N - 2C
Mon Nov 11, 2019 3:46 pm
Forum: Ionic & Covalent Bonds
Topic: Water molecules and ionic substances
Replies: 5
Views: 69

Re: Water molecules and ionic substances

From what I know: Water molecules are a bent shape that allowed the polarity (partial charges) to dissolve well with substances.
by Michelle N - 2C
Mon Nov 11, 2019 3:45 pm
Forum: Ionic & Covalent Bonds
Topic: Bond Strength
Replies: 8
Views: 76

Re: Bond Strength

Ionic bonds (although some share covalent bond features) are generally stronger since they are completely transferring electron(s) to the other. Conceptual reasoning is the fact that their electronegativity differences are more drastic.
by Michelle N - 2C
Mon Nov 11, 2019 3:43 pm
Forum: Ionic & Covalent Bonds
Topic: Resonance (all bonds are a hybrid of different bonds)
Replies: 10
Views: 129

Re: Resonance (all bonds are a hybrid of different bonds)

From what I know, depending on the non-single bonds and its charges, that's how resonance occurs.
by Michelle N - 2C
Thu Nov 07, 2019 9:52 am
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge Equation?
Replies: 12
Views: 75

Formal Charge Equation?

I noticed that there are two equations:

FC = V + (L+B) and FC = V + (L + B/2).

Both depend on how you count the shared bond?
by Michelle N - 2C
Thu Nov 07, 2019 9:47 am
Forum: Balancing Chemical Reactions
Topic: Balancing This Equation
Replies: 11
Views: 273

Re: Balancing This Equation

Combustion always mean that one of the reactants is O2 and the products are CO2 + H2O. Sometimes, they will add in, like in this problem, an extra product.
by Michelle N - 2C
Thu Nov 07, 2019 9:45 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Atoms to Moles
Replies: 6
Views: 211

Re: Atoms to Moles

Question

Would the same apply when it's asking for photons?
by Michelle N - 2C
Thu Nov 07, 2019 9:44 am
Forum: Empirical & Molecular Formulas
Topic: Number 1 in Dino Nuggets
Replies: 3
Views: 165

Re: Number 1 in Dino Nuggets

I could be wrong in this, but the reason why you can't get the mol of oxygen from CO2 and H2O is because you won't know how much of which is in there. Sure, you can find C then get subtract the rest to get O, but I feel like there's a reason on the fact that both CO2 and H2O contain it. It would be ...
by Michelle N - 2C
Thu Nov 07, 2019 9:38 am
Forum: Empirical & Molecular Formulas
Topic: percent composition
Replies: 3
Views: 136

Re: percent composition

I know it's already past the midterm, but I think this is for future review, etc.! I saw that it added up to be 99.95%, which might have been a mistake? You can definitely ask Lyndon about it since he made the review sheet! In terms of solving it, a UA actually did a shortcut on figuring out how man...
by Michelle N - 2C
Thu Nov 07, 2019 9:30 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Mo and Ag exceptions
Replies: 4
Views: 169

Re: Mo and Ag exceptions

The exceptions are due to the fact that 3d^5 and 3^10 would then make the electron configurations back in order in terms of their principle quantum number. I could be wrong, but I think this would apply to all of the elements that are in that column.
by Michelle N - 2C
Thu Nov 07, 2019 9:28 am
Forum: Trends in The Periodic Table
Topic: Midterm Review Problem 10 d
Replies: 5
Views: 143

Re: Midterm Review Problem 10 d

Oh.. yep. Definitely wrote something completely different.

Is oxygen the only exception from this trend then? Asking for future reference and learning.
by Michelle N - 2C
Thu Nov 07, 2019 9:25 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Probability
Replies: 3
Views: 117

Re: Probability

Hi, I could be wrong here, but I tend to think back to Schrodinger's Equation, where Ψ^2 represents the probability of finding an electron within those areas. In terms of each orbital, the orbital's shape plays a role in where the electron could potentially be found. With s-orbitals having no nodal ...
by Michelle N - 2C
Thu Oct 31, 2019 8:25 am
Forum: Properties of Electrons
Topic: Electron removal
Replies: 11
Views: 131

Re: Electron removal

Electrons further away from the nucleus are easier to remove because:

1) Since they're further out from the nucleus (where all the protons are), the attraction is less between the two.
2) The inner electrons often shield them away, but also repulsing them.
by Michelle N - 2C
Thu Oct 31, 2019 8:23 am
Forum: Properties of Electrons
Topic: Chemical bonds
Replies: 2
Views: 52

Re: Chemical bonds

Most elements tend to be in their lowest energy state possible. From what I know... - Forming an ionic bond would allow the oppositely charged (usually) ions to transfer their electrons to result in lowest energy state. - Forming a molecule is similar since they try to achieve a lower energy state. ...
by Michelle N - 2C
Thu Oct 31, 2019 8:19 am
Forum: Ionic & Covalent Bonds
Topic: What is the Octet Rule?
Replies: 5
Views: 47

What is the Octet Rule?

I am still a little confused about what the Octet Rule is. Can someone explain to me what the concept is?
by Michelle N - 2C
Thu Oct 31, 2019 8:15 am
Forum: Ionic & Covalent Bonds
Topic: Radicals
Replies: 9
Views: 83

Re: Radicals

Like what everyone said, radicals are basically when the elements are highly reactive since they have unpaired electron(s). This can be noted when there's only one lone pair (the dot) seen instead of two. Most natural elements tend to be in the lowest energy state possible. Therefore, radicals don't...
by Michelle N - 2C
Thu Oct 31, 2019 8:09 am
Forum: Ionic & Covalent Bonds
Topic: Ionic and Covalent Bonds
Replies: 6
Views: 59

Re: Ionic and Covalent Bonds

An ionic bond is when electrons are transferred to one atom from the other. They usually consist of two atoms with oppositely charged ions (Na+, Cl-). A covalent bond is when the electrons are shared between the atoms, not completely transferred over. That being said, an ionic bond is usually strong...
by Michelle N - 2C
Tue Oct 22, 2019 9:49 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Atomic radius vs. Ionic radius
Replies: 5
Views: 50

Re: Atomic radius vs. Ionic radius

They're both generally the same, with the ionic radius being one of the types of atomic radius.

Atomic radius is defined as half the distance between the center of neighboring atoms.
Ionic radius is the then distance of the two ions that are joined by an ionic bond.
by Michelle N - 2C
Tue Oct 22, 2019 9:46 pm
Forum: Properties of Electrons
Topic: Electron Configuration
Replies: 4
Views: 79

Re: Electron Configuration

When the d-orbital is not full, they are generally lower in energy. Plus, it would then follow the trend and order of the numbers.

Sorry this is vague, but that's how I was able to get it..
by Michelle N - 2C
Tue Oct 22, 2019 9:40 pm
Forum: Properties of Electrons
Topic: x,y,z for Electrons
Replies: 10
Views: 124

Re: x,y,z for Electrons

I went to a Step-Up program a few hours ago, and I saw that the Px, Py, and Pz were just the three coordinates that were for the p-orbital.

Something like this:
____ ____ ____
Px Py Pz

It's basically the three planes as well (3d graph).
by Michelle N - 2C
Tue Oct 22, 2019 9:29 pm
Forum: Trends in The Periodic Table
Topic: Effective Nuclear Charge
Replies: 7
Views: 49

Re: Effective Nuclear Charge

If I understand correctly, it's basically all about how the electrons are pulled/attracted to the nucleus. The further they're out (the larger the atomic radius), the less attraction they'd feel since it's 1) they're further away, and 2) the other electrons are repulsing them as well.

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