Search found 94 matches

by Hayden Lee 1C
Sun Mar 07, 2021 10:25 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Solving Multiple Reactant Problems
Replies: 3
Views: 11

Re: Solving Multiple Reactant Problems

The overall rate of the reaction will generally be determined by the slowest step of the reaction. Therefore, the overall reaction rate is dependent on the rate of the reactant that has the slowest unique rate.
by Hayden Lee 1C
Sun Mar 07, 2021 10:12 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Chemical Reactions and Temperature
Replies: 3
Views: 8

Re: Chemical Reactions and Temperature

The rate of chemical reactions is generally increased with a rise in temperature as a result of the fact that the kinetic energy of the reactants is being increased. If the reactants possess a greater average kinetic energy, there will be less energy required for the reaction to continue.
by Hayden Lee 1C
Sun Mar 07, 2021 9:57 pm
Forum: General Rate Laws
Topic: Unique Rate
Replies: 2
Views: 9

Re: Unique Rate

The unique rate of a reaction is the rate in reference to a single reactant or product. Since reactants turn into products at differing rates, we can look at specific species in order to see how quickly they are appearing/disappearing. Depending on whether you are looking at the reactant or product ...
by Hayden Lee 1C
Sun Feb 28, 2021 7:51 pm
Forum: Balancing Redox Reactions
Topic: Balancing Redox Reactions in Basic Conditions
Replies: 7
Views: 22

Re: Balancing Redox Reactions in Basic Conditions

In order to balance a redox reaction, we can use the following steps: - separate half-reactions of the overall reaction - balance each half-reaction: - Begin with elements other than O and H. Balance oxygen atoms by adding H2O to the side that requires them. Do the same for hydrogen using hydrogen i...
by Hayden Lee 1C
Sun Feb 28, 2021 7:43 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: How Electricity is Quantified
Replies: 3
Views: 19

Re: How Electricity is Quantified

Electricity is the flow of electrons within a given system. It can be quantified using charge, current, and potential. Charge is a physical property of matter. Charge causes matter to experience force within a given electromagnetic field. Current is defined as the amount of charge that passes in a s...
by Hayden Lee 1C
Sun Feb 28, 2021 7:33 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Reduction Potential Clarification
Replies: 4
Views: 13

Re: Reduction Potential Clarification

Yes, you change the sign of E when the direction of the half-reaction is flipped. However, if the reaction is multiplied by a constant, E must not be multiplied by this constant (like with free energy values).
by Hayden Lee 1C
Sun Feb 28, 2021 7:31 pm
Forum: Balancing Redox Reactions
Topic: Sapling week 7/8 #5
Replies: 7
Views: 48

Re: Sapling week 7/8 #5

It seems that you balanced the reaction correctly. Did you include the correct phases of each species? This is required in the problem and it may be the reason why you aren't getting it right.
by Hayden Lee 1C
Sun Feb 28, 2021 7:27 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Sapling week 7/8 number 15
Replies: 3
Views: 35

Re: Sapling week 7/8 number 15

First, write and balance the half-reactions. After you do this and determine the reduction potentials for each half-reaction, you can determine the overall standard cell potential. After you have the standard cell potential, you can plug values into the Nernst equation and solve. All values are give...
by Hayden Lee 1C
Sun Feb 21, 2021 9:51 pm
Forum: Balancing Redox Reactions
Topic: Sapling Week 7/8 #1
Replies: 10
Views: 49

Re: Sapling Week 7/8 #1

You can start this problem by identifying the oxidation number of the cation. Then, do the same for the anion of the compound. As you probably know, the oxidation number of a pure element (non-ionic) will be zero.
by Hayden Lee 1C
Sun Feb 21, 2021 9:44 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Trouton's rule
Replies: 4
Views: 11

Re: Trouton's rule

Trouton's rule basically states that various types of liquids possess similar entropies of vaporization at their boiling points. The enthalpy of vaporization divided by the boiling point of the liquid is the entropy of vaporization for a particular liquid. I am also unsure of whether we discussed th...
by Hayden Lee 1C
Sun Feb 21, 2021 9:36 pm
Forum: Balancing Redox Reactions
Topic: Sapling week 7/8 #2
Replies: 5
Views: 31

Re: Sapling week 7/8 #2

Combine the respective reactants and products of each reaction. In other words, the reactants of one half-reaction and the reactants of the other half-reaction will combine to be the reactants of the overall reaction (the same applies to the products). After you have done this, balance the overall r...
by Hayden Lee 1C
Sun Feb 21, 2021 9:32 pm
Forum: Phase Changes & Related Calculations
Topic: Textbook Problem 4A1 part C
Replies: 3
Views: 11

Re: Textbook Problem 4A1 part C

A bomb calorimeter is considered to be an isolated system because no matter or heat can be exchanged with the surroundings. While the system within the calorimeter can release heat, it is not released to the surroundings.
by Hayden Lee 1C
Sun Feb 21, 2021 9:26 pm
Forum: Balancing Redox Reactions
Topic: Sapling week 7/8 #5
Replies: 2
Views: 24

Re: Sapling week 7/8 #5

A good way of initiating this problem is by identifying the oxidation numbers of each element in the reactants and products. This way, you can see which elements have gained or lost electrons.
by Hayden Lee 1C
Sun Feb 21, 2021 9:23 pm
Forum: Balancing Redox Reactions
Topic: Sapling week 7/8 #5
Replies: 2
Views: 24

Re: Sapling week 7/8 #5

What issue are you having with this problem, specifically? Just identifying the oxidizing/reducing agents in general?
by Hayden Lee 1C
Sun Feb 14, 2021 10:18 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Spontaneity of a System
Replies: 37
Views: 88

Re: Spontaneity of a System

In terms of Gibbs Free Energy, a reaction will be spontaneous depending on the sign of the value of the free energy change. If the value of Gibbs Free Energy is negative, then the reaction is spontaneous. If the value is positive, then the reverse reaction is spontaneous. A negative Gibbs Free Energ...
by Hayden Lee 1C
Sun Feb 14, 2021 10:10 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Sapling Weeks 5-6 #3
Replies: 4
Views: 18

Re: Sapling Weeks 5-6 #3

You are on the right track! Your reasoning is entirely right, so all you need to do is apply that concept to the problem. If the phase changes from solid to liquid to gas will always have positive values of entropy and enthalpy, then what category would you put these phase changes in? If the same (b...
by Hayden Lee 1C
Sun Feb 14, 2021 10:05 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Internal Energy Confusion
Replies: 4
Views: 16

Re: Internal Energy Confusion

When I am trying to determine whether internal energy is decreasing or increasing, I simply think of what is happening with its constituents (Heat and Work). If applicable, I try to determine whether the heat is leaving/entering the system and whether work is being done on/by the system. This may no...
by Hayden Lee 1C
Sun Feb 14, 2021 9:59 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Sapling #1
Replies: 4
Views: 22

Re: Sapling #1

Yes, this bond formation is a result of formal charge optimization. We are responsible for knowing how to calculate formal charge (as we have done this in the past), but I do not know if this information will be necessary for the upcoming midterm. I hope this helps!
by Hayden Lee 1C
Sun Feb 14, 2021 9:57 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Determining the Sign of S
Replies: 8
Views: 29

Re: Determining the Sign of S

The sign of entropy change is dependent on whether a system has greater or fewer microstates from one state to the next. For example, the entropy of the vaporization of liquid water is positive because the entropy in the gas state is greater than that of the liquid state. In other words, there is a ...
by Hayden Lee 1C
Sun Feb 07, 2021 8:57 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Molar Heat Capacities at Constant Volume/Pressure
Replies: 3
Views: 17

Molar Heat Capacities at Constant Volume/Pressure

Hi there,

Will we need to memorize the molar heat capacities for atoms, linear molecules, and nonlinear molecules in constant pressure and constant volume processes? For example, question 20 of Week 3/4 Sapling shows the molar heat capacities of types of gases at constant volume. Thanks in advance!
by Hayden Lee 1C
Sun Feb 07, 2021 8:44 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Sapling #20
Replies: 9
Views: 48

Re: Sapling #20

We are informed in this scenario that the volume remains constant. If there is no change in volume, work cannot be performed. The value of work is dependent on a change in volume, which does not occur. Since the change in internal energy is equal to the heat plus work (U = Q + W), the change in inte...
by Hayden Lee 1C
Sun Feb 07, 2021 8:37 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Sap #19 internal energy
Replies: 4
Views: 26

Re: Sap #19 internal energy

The internal energy value is negative as a result of the fact that the internal energy of the system decreases in this scenario. Since there is no change in volume (meaning no work is performed), the only change in energy that occurs is the release of heat. Since heat is being released, it is a nega...
by Hayden Lee 1C
Sun Feb 07, 2021 8:34 pm
Forum: Calculating Work of Expansion
Topic: Work of Expansion
Replies: 2
Views: 14

Re: Work of Expansion

Work of expansion occurs when a gas performs work on its surroundings, causing the volume of the system to expand. Since the gas performs work on its surroundings against a given external pressure, this value is negative. This can be mathematically expressed as W = -P*(change in volume), where W is ...
by Hayden Lee 1C
Sun Feb 07, 2021 8:30 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Sapling #12 Week 3/4
Replies: 1
Views: 22

Re: Sapling #12 Week 3/4

In order to calculate the heat of combustion per gram of compound B, you must multiply the heat capacity of the calorimeter (C) by the temperature change that occurs in the calorimeter. This value must be divided by the mass of compound B in order to find the heat of combustion per gram. Keep the si...
by Hayden Lee 1C
Sun Jan 31, 2021 10:17 pm
Forum: Administrative Questions and Class Announcements
Topic: Reflecting on the midterm
Replies: 17
Views: 103

Re: Reflecting on the midterm

When I was taking my midterm, I also experienced instances of working through a tedious math problem, receiving the incorrect answer, then trying again. Since this only occurred roughly twice during this midterm, I did not have too much of an issue with time management. However, I have had trouble w...
by Hayden Lee 1C
Sun Jan 31, 2021 10:10 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Work-/+
Replies: 9
Views: 44

Re: Work-/+

The value of work is positive if work is being done ON the system. For example, if the system is being compressed (the volume is reduced by an external force), the work will be positive. The value of work will be negative if the gas of the system is doing work. If the system is expanding (the volume...
by Hayden Lee 1C
Sun Jan 31, 2021 10:03 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: System and Surrounding
Replies: 4
Views: 26

Re: System and Surrounding

The purpose of referring to the surroundings of the system as "the universe" is to place emphasis on the fact that the surroundings are everything other than the system in focus. The equation "system + surroundings = 0" references that heat lost or gained from the surroundings wi...
by Hayden Lee 1C
Sun Jan 31, 2021 9:10 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Sapling #16
Replies: 2
Views: 42

Re: Sapling #16

Yes, we have covered this material. You can solve this problem by keeping the law of conservation of energy in mind, applying the rule "change in internal energy is equal to the work done on/by the system plus the heat transfer into/out of the system).
by Hayden Lee 1C
Sun Jan 31, 2021 9:08 pm
Forum: Student Social/Study Group
Topic: Students Who Have a Job
Replies: 79
Views: 336

Re: Students Who Have a Job

Hi there! I also have a part-time job, working 20-25 hrs a week. I usually maintain a part-time job throughout the quarter with no trouble, but it has been slightly more difficult this quarter as a result of the fact that I am taking an extra class. Working during the pandemic has also added some st...
by Hayden Lee 1C
Sun Jan 24, 2021 10:37 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: How to find equations
Replies: 4
Views: 18

Re: How to find equations

All of the chemical equations you would need are included on the "Constants and Equations" sheet on the class website!
by Hayden Lee 1C
Sun Jan 24, 2021 10:25 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Determining whether a reaction is Exothermic/Endothermic
Replies: 4
Views: 37

Determining whether a reaction is Exothermic/Endothermic

How do you determine whether a reaction is endothermic or exothermic based on the strength of the bonds being broken and formed? For example, #4 on this week's Sapling homework asks you to classify the nature of a reaction based on relative bond strengths. Thanks! :)
by Hayden Lee 1C
Sun Jan 24, 2021 10:18 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpy vs Temperature
Replies: 4
Views: 13

Re: Enthalpy vs Temperature

The value of the temperature represents the average kinetic energy of every molecule within a particular system. The absolute enthalpy of a substance represents its total heat energy content. Enthalpy is a state function as a result of the fact that its value depends only on the initial and final co...
by Hayden Lee 1C
Sun Jan 24, 2021 10:11 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Neutral Solution
Replies: 9
Views: 76

Re: Neutral Solution

In neutral water, the concentration of both H3O+ and OH- are 1x10^-7 mol/L.
by Hayden Lee 1C
Sun Jan 24, 2021 9:58 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Relationship between Ka and pKa
Replies: 11
Views: 60

Re: Relationship between Ka and pKa

The pKa value is a way of indicating the strength of a particular acid. The pKa is the power, or the negative log, of Ka (the acid dissociation constant for a particular compound).
by Hayden Lee 1C
Sun Jan 17, 2021 10:42 pm
Forum: Student Social/Study Group
Topic: Logistics for the Midterm
Replies: 11
Views: 53

Re: Logistics for the Midterm

Yes, our midterms will be taken during lecture time. Our first midterm will be held on January 29th in class and TAs will be proctoring the exam (as far as I know). I hope this helps!
by Hayden Lee 1C
Sun Jan 17, 2021 10:35 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: cancelling out variables in K eq
Replies: 4
Views: 17

Re: cancelling out variables in K eq

In the equation you provided, the values of x would not cancel out. Since they are opposite signs, you would either add one 2x to the other side to produce 4x or subtract one 2x to the other side to produce -4x.
by Hayden Lee 1C
Sun Jan 17, 2021 10:33 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Making the Assumption that Change x is Small
Replies: 4
Views: 24

Making the Assumption that Change x is Small

When determining equilibrium concentrations, there are times that we can make the assumption that a change in concentration 'x' is very small compared to the initial concentration, allowing us to ultimately ignore it. What is the K value threshold for which we can make this assumption? Is it 10^-3 o...
by Hayden Lee 1C
Sun Jan 17, 2021 10:14 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Total pressure calculation
Replies: 8
Views: 51

Re: Total pressure calculation

To calculate the total pressure, you must use an ICE table to find each partial pressure of the system. Set the Kp value equal to the partial pressures of the products over the partial pressures of the reactants. Ensure that you have accounted for the changes in pressure that will occur when the rea...
by Hayden Lee 1C
Sun Jan 17, 2021 10:05 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling Week 2 Question 5
Replies: 2
Views: 52

Re: Sapling Week 2 Question 5

Hi there!

I believe that we assume the reaction is at equilibrium as a result of the fact that the problem states the amine is protonated, meaning the reaction has already occurred. I wish I could be more thorough, but that's all the info I'm able to provide!
by Hayden Lee 1C
Sun Jan 10, 2021 10:53 pm
Forum: Student Social/Study Group
Topic: Midterms During Lecture
Replies: 44
Views: 257

Midterms During Lecture

Hi there,

I recently saw on Chemistry Community that midterms are being held during lecture this quarter. Is this true? If so, where did this info come from? Thanks a lot, I appreciate it :).
by Hayden Lee 1C
Sun Jan 10, 2021 10:47 pm
Forum: Student Social/Study Group
Topic: Exam Changes
Replies: 12
Views: 80

Re: Exam Changes

Hi there! It was my understanding that we would be taking them during discussion sections still. I haven't heard anything different, but I could be wrong! I looked at the syllabus and it isn't explicitly stated whether or not this is the case.
by Hayden Lee 1C
Sun Jan 10, 2021 10:21 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Favoring Products or Reactants
Replies: 1
Views: 27

Re: Favoring Products or Reactants

We did not go over this thoroughly in lecture/discussion, but I recall Lavelle stating that this phenomenon is quite rare. There will most likely be some sort of favoritism to the products or reactants in any given reaction, especially when considering the environment in which reactions occur can be...
by Hayden Lee 1C
Sun Jan 10, 2021 10:16 pm
Forum: Student Social/Study Group
Topic: Advice for study
Replies: 31
Views: 112

Re: Advice for study

There are several things that I do to study, but I have found that reading the text is incredibly impactful for understanding the material. I love Lavelle's lectures and Sapling is helpful for practice, but reading the text and completing the assigned problems from the book helps me like nothing else.
by Hayden Lee 1C
Wed Jan 06, 2021 8:28 pm
Forum: Student Social/Study Group
Topic: Groupme for 14B
Replies: 5
Views: 67

Groupme for 14B

Hi there,

Sorry if this question has already been asked, but is there a Groupme for Lecture 2 of 14B with Lavelle? If so, I'd be really grateful if you could send the link. Thanks!
by Hayden Lee 1C
Wed Dec 16, 2020 10:36 pm
Forum: Student Social/Study Group
Topic: Existing 14B Groupme
Replies: 4
Views: 53

Existing 14B Groupme

Hi there!
I was wondering if there is an existing 14B Groupme chat that has been created by students just finishing 14A. If not, I would love to create one! Let me know, thanks :)
by Hayden Lee 1C
Wed Dec 16, 2020 10:20 pm
Forum: Student Social/Study Group
Topic: Winter Break Study Group
Replies: 6
Views: 70

Re: Winter Break Study Group

Hi there!
I would also like to be a part of a study group! Creating a Groupme would be really useful, especially if we could share resources to prep for the upcoming quarter. Feel free to contact me!
by Hayden Lee 1C
Wed Dec 16, 2020 9:19 pm
Forum: Student Social/Study Group
Topic: grade calculation
Replies: 12
Views: 125

Re: grade calculation

There's plenty of online calculators that will allow you to put in grades and the weight of grades to estimate your final grade. Google something like "final grade calculator" or "percentage grade calculator". Use the syllabus and grade book to fill them out with the grades we h...
by Hayden Lee 1C
Wed Dec 16, 2020 6:22 pm
Forum: General Science Questions
Topic: final timing
Replies: 25
Views: 129

Re: final timing

Personally, I felt like the time during the final flew by quite fast. I agree that when taking the midterms we had a comfortable amount of time to both answer each question and review responses for accuracy. I don't believe that there was a problem with the time provided, though; I simply feel that ...
by Hayden Lee 1C
Mon Dec 14, 2020 11:49 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: axial/equatorial
Replies: 5
Views: 59

Re: axial/equatorial

An atom in an axial position is perpendicular to the plane of the "ring," or the atoms that lie in the plane with the central atom. Atoms in equatorial positions are around this plane of the ring and are perpendicular to the axial atoms.
by Hayden Lee 1C
Sun Dec 06, 2020 11:19 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: pH vs pOH
Replies: 9
Views: 68

Re: pH vs pOH

Yes, there is a pOH scale that exists. The same principles of the pH scale apply to that of the pOH scale, only 7+ is acidic and below 7 is basic. A pOH of 7 still indicates a neutral solution. Hope this helps!
by Hayden Lee 1C
Sun Dec 06, 2020 11:16 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angle
Replies: 4
Views: 16

Re: Bond Angle

I'm not sure if there is a molecular geometry chart provided with bond angles included, but you should memorize the bond angles for common shapes. I do not think we'll be provided with this information on the exam, so it would be best just to have these common bond angles memorized.
by Hayden Lee 1C
Sun Dec 06, 2020 11:13 pm
Forum: Student Social/Study Group
Topic: Naming Coordination Compounds
Replies: 1
Views: 9

Naming Coordination Compounds

Hi,

I've been trying to memorize the process of naming coordination compounds, but I am having some trouble doing so. Does anyone have a method they use to remember how to name coordination compounds? If not, an effective way of studying this process? Thanks!
by Hayden Lee 1C
Sun Dec 06, 2020 10:49 pm
Forum: *Molecular Orbital Theory Applied To Transition Metals
Topic: Orbitals and coordination numbers
Replies: 2
Views: 16

Re: Orbitals and coordination numbers

Hi, The coordination number is the number of atoms bonded to the transition metal. If there is an atom bonded to the transition metal, it will be included within the brackets of its chemical formula. The transition metal complex can form ionic bonds, but these bonds may not be located on the transit...
by Hayden Lee 1C
Sun Dec 06, 2020 10:44 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Tips for Coordination #
Replies: 4
Views: 30

Re: Tips for Coordination #

Hi there,

The coordination number is simply the number of atoms bonded to the central atom (the transition metal). Everything bonded to the transition metal will be included within brackets. For your example, the coordination number is 4. I hope this helps!
by Hayden Lee 1C
Sun Nov 29, 2020 7:05 pm
Forum: Electronegativity
Topic: Sapling Week 8 Polarity
Replies: 5
Views: 66

Re: Sapling Week 8 Polarity

Due to the fact that a polar bond exists within the molecule, the molecule is polar. There are no other polar bonds in the molecule that cancel out this bond's polarity, so the molecule as a whole is considered to be polar as well. Electrons will be more attracted to the oxygen atom, causing the mol...
by Hayden Lee 1C
Sun Nov 29, 2020 6:41 pm
Forum: Student Social/Study Group
Topic: Studying for Final Exam
Replies: 57
Views: 406

Studying for Final Exam

Hi there,

Out of curiosity, how will you be studying for this final exam? What methods/strategies do you use when studying for the chem final? I study a lot but I often lack organization and efficiency when doing so. Thanks for the help!
by Hayden Lee 1C
Sun Nov 29, 2020 5:56 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: molecule shape polarity
Replies: 5
Views: 56

Re: molecule shape polarity

To determine the polarity of a molecule, we must first observe the polarities of the bonds within it. When looking at BeCl2, it can be observed that the bonds between the Be and Cl atoms are polar due to differing electronegativities. However, since the molecule only has these two regions of electro...
by Hayden Lee 1C
Sun Nov 29, 2020 5:50 pm
Forum: Hybridization
Topic: Definition of Hybridization
Replies: 5
Views: 62

Re: Definition of Hybridization

In response to your first question, orbital hybridization can be defined as the "mixing" of different orbitals to form new, hybridized orbitals that have different energies and shapes than the original components. Hybridization simply tells us what types of bonds exist between atoms.
by Hayden Lee 1C
Sun Nov 29, 2020 5:39 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: #13 Sapling Week 8
Replies: 18
Views: 109

Re: #13 Sapling Week 8

Four regions of electron density indicate a tetrahedral geometry, so that response would be correct. I am not sure why it marked yours wrong (my response was marked as correct). I hope this helped!
by Hayden Lee 1C
Sun Nov 22, 2020 11:40 pm
Forum: Student Social/Study Group
Topic: Final Format
Replies: 35
Views: 329

Final Format

Hi there,

I know this may be a little early, but does anyone know the general format of the final exam and the allotted time for it? Just trying to get a sense of what it will be like. Thanks!
by Hayden Lee 1C
Sun Nov 22, 2020 11:24 pm
Forum: Sigma & Pi Bonds
Topic: Delocalized pi Bonds
Replies: 2
Views: 28

Delocalized pi Bonds

What causes the delocalization of a pi bond? What does a delocalized pi bond entail for the stability of the bond? I've been having a little bit of trouble finding the answer. Thanks a lot!
by Hayden Lee 1C
Sun Nov 22, 2020 11:12 pm
Forum: Electronegativity
Topic: Polarity of Molecules
Replies: 7
Views: 73

Polarity of Molecules

When looking at the Lewis structure for a certain molecule, how can we determine its polarity? I know polar bonds occur due to differences in electronegativity between atoms, but how would we determine the polarity of a molecule without knowing the specific electronegativities of its atoms? Thanks!
by Hayden Lee 1C
Sun Nov 22, 2020 11:04 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 25
Views: 196

Bond Angles

Hi there,

For the final exam, will we be required to memorize the bond angles of certain molecular geometry? Thanks!
by Hayden Lee 1C
Sun Nov 22, 2020 10:48 pm
Forum: Ionic & Covalent Bonds
Topic: C-H bond polarity
Replies: 10
Views: 90

Re: C-H bond polarity

If you search the difference in electronegativity between the two atoms, it is only 0.35. Since the difference between their electronegativities is so small, we can state that the bond is nonpolar (electrons will be more equally shared). The two atoms have similar electronegativities, therefore the ...
by Hayden Lee 1C
Sun Nov 15, 2020 10:52 pm
Forum: Bond Lengths & Energies
Topic: Bonds and Accepting Electrons
Replies: 2
Views: 50

Re: Bonds and Accepting Electrons

I believe that CO2 would be considered a Lewis Acid due to its polarity because of the positive charge that is on the central carbon atom. Since the carbon atom is partially positive while the adjacent oxygen atoms are partially negative, the carbon is able to attract lone pair electrons. Molecules ...
by Hayden Lee 1C
Sun Nov 15, 2020 10:37 pm
Forum: Ionic & Covalent Bonds
Topic: Hydrogen Bonding in Water
Replies: 2
Views: 35

Hydrogen Bonding in Water

Hi, In lecture, we were told that a hydrogen atom involved in a hydrogen bond in water is bonded to an electronegative atom (oxygen) while being close to another electronegative atom with a lone pair of electrons. Why must it be close to another electronegative atom with a lone pair? I've tried look...
by Hayden Lee 1C
Sun Nov 15, 2020 10:24 pm
Forum: Bond Lengths & Energies
Topic: Bond Character
Replies: 3
Views: 37

Bond Character

Hi there, On one of our Sapling homework problems, we are asked to state whether a bond has "ample" or "overwhelming" bond character. Specifically, we are asked to state whether a carbon-nitrogen bond has ample double-bond character or an overwhelmingly single-bond character (the...
by Hayden Lee 1C
Sun Nov 15, 2020 9:44 pm
Forum: Lewis Structures
Topic: Sapling Week 5/6 HW #3
Replies: 7
Views: 50

Re: Sapling Week 5/6 HW #3

If I recall correctly, Dr. Lavelle stated in lecture that we would be provided with the chemical formulas for all given compounds on each midterm. If this was not the case, a good way of differentiating between -ite and -ate is that -ite indicates a low oxidation state while -ate indicates a high ox...
by Hayden Lee 1C
Sun Nov 15, 2020 9:30 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Best Formal Charge Equations
Replies: 24
Views: 145

Re: Best Formal Charge Equations

The way that I calculate the formal charge is by using the following equation:

Formal Charge = (Valence e-) - (Nonbinding Valence e-) - (Bonding e-)*1/2

I suppose that one way to more easily memorize this equation is to memorize its abbreviated form (FC = V - NB - B/2). Hope this helps!
by Hayden Lee 1C
Sun Nov 08, 2020 1:11 pm
Forum: Ionic & Covalent Bonds
Topic: Silver Halides
Replies: 3
Views: 23

Silver Halides

Hi! In lecture last Friday, it was stated that increasing the covalent character of silver halides like AgF, AgCl, and AgBr makes them less soluble in water. In other words, increasing the size of the anion in these bonds causes the compound to be less soluble, which is a characteristic of salts. Wh...
by Hayden Lee 1C
Sun Nov 08, 2020 12:58 pm
Forum: Octet Exceptions
Topic: Why are there exceptions to the octect rule?
Replies: 2
Views: 23

Why are there exceptions to the octect rule?

Hi there, I understand that there are exceptions to the octet rule, but I don't know why this is the case. For example, there are multiple compounds in which Boron only has 6 electrons in place of 8. Wouldn't this cause Boron to be reactive? This has probably already been asked but I couldn't find a...
by Hayden Lee 1C
Sun Nov 08, 2020 12:52 pm
Forum: Ionic & Covalent Bonds
Topic: Classifying Distortion
Replies: 4
Views: 37

Classifying Distortion

Hello, While I understand that distortion in an ionic bond occurs because the cation's positive charge attracts the anion's electrons, I do not understand how this distortion is recognized and classified. In other words, how can one experimentally verify that the electron cloud of an element is dist...
by Hayden Lee 1C
Sun Nov 08, 2020 12:32 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Distortion
Replies: 8
Views: 80

Re: Distortion

Hi! When electrons in an atom are distorted, this is due to the positive charge of another element attracting the electrons of said atom. For example, in an ionic bond, the cation exerts an electrostatic attraction on the electrons of the surrounding anion. The positive charge of the cation attracts...
by Hayden Lee 1C
Sun Nov 08, 2020 12:21 pm
Forum: Ionic & Covalent Bonds
Topic: Covalent Character
Replies: 7
Views: 74

Re: Covalent Character

Hi there! Covalent bonds can have ionic character because elements within a bond have differing electronegativities. If one element in a bond has a greater electronegativity than the other, it will attract the electron more than the other element, causing the electron to be unevenly shared (having i...
by Hayden Lee 1C
Sun Nov 01, 2020 7:24 pm
Forum: Student Social/Study Group
Topic: Midterm 1
Replies: 4
Views: 41

Midterm 1

Hi there,

I doubt that we are, but I was wondering if anyone knew whether we will be reviewing the midterm either in discussion or otherwise after it has been graded. Let me know! Thanks:)
by Hayden Lee 1C
Sun Nov 01, 2020 7:17 pm
Forum: DeBroglie Equation
Topic: energy of a photon
Replies: 3
Views: 35

Re: energy of a photon

Hi! Since the energy of a photon is equal to its frequency multiplied by Planck's constant, we can rewrite the equation (c = wavelength * frequency) to solve for frequency in terms of wavelength. We can then replace frequency in the E = hv equation with the term from the rewritten (c = wavelength * ...
by Hayden Lee 1C
Sun Nov 01, 2020 7:09 pm
Forum: Trends in The Periodic Table
Topic: Isoelectronic Ions
Replies: 5
Views: 19

Re: Isoelectronic Ions

Hi! When two elements are isoelectronic, this signifies that they share the same number of electrons. For example, F- and Ne are isoelectronic, due to the fact that they both possess 10 electrons. While they may have the same number of electrons, this does not mean they share properties. Two element...
by Hayden Lee 1C
Sun Nov 01, 2020 7:04 pm
Forum: Trends in The Periodic Table
Topic: Sapling question 24
Replies: 3
Views: 30

Re: Sapling question 24

Hi, Having a high effective nuclear charge signifies that the electrons are more attracted to the nucleus, resulting in a smaller atomic radius. The effective nuclear charge is the net positive charge from the nucleus on an electron. So, having a higher effective nuclear charge means the electrons a...
by Hayden Lee 1C
Sun Nov 01, 2020 6:53 pm
Forum: Student Social/Study Group
Topic: Sappling #26
Replies: 3
Views: 63

Re: Sappling #26

Hi there, We can find the minimum uncertainty of velocity when only given this information by using Heisenberg's Uncertainty Principle. We are provided with the information that the position is known within 11 Angstrom. Using the uncertainty principle, the only unknown information remaining is the u...
by Hayden Lee 1C
Sun Oct 25, 2020 7:40 pm
Forum: Student Social/Study Group
Topic: Questions for Midterm 1
Replies: 5
Views: 75

Questions for Midterm 1

Hi!

I have heard that the midterm will have 10 questions, but I have not confirmed that this is true. Will there really be 10 questions? If not, do you know how many questions will be on the midterm? Thanks, I appreciate it.
by Hayden Lee 1C
Sun Oct 25, 2020 7:30 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Effective Nuclear Charge
Replies: 2
Views: 16

Effective Nuclear Charge

Hello, It was stated in our lecture on Friday that inner electrons shield outer electrons from electrostatic attraction of the positive nucleus. These outer electrons feel reduced electrostatic attraction, resulting in an "effective nuclear charge". What does this mean exactly? I understan...
by Hayden Lee 1C
Sun Oct 25, 2020 7:23 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Electrostatic Potential Energy
Replies: 1
Views: 18

Electrostatic Potential Energy

Hello!

Can someone describe the concept of electrostatic potential energy to me? We recently covered this in our most previous lecture, but I couldn't quite understand what it is and how it is related to the charges of protons and electrons within an atom. Thanks a lot!
by Hayden Lee 1C
Sun Oct 25, 2020 7:19 pm
Forum: *Shrodinger Equation
Topic: Wave Function
Replies: 5
Views: 63

Re: Wave Function

Hi! Simply put, the wave function is a mathematical expression that describes the state of an electron. It is a function that defines the probability of a particle's quantum state. This is done by incorporating the following factors: the energy of an electron, the angular momentum, orbital orientati...
by Hayden Lee 1C
Sun Oct 25, 2020 7:04 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Differing Energies within the Same Shell
Replies: 1
Views: 18

Differing Energies within the Same Shell

Hi there!

In the lecture on Friday, we were told that s-electrons have lower energy than p-electrons within the same shell. Additionally, we were told that the energies of the orbitals in the same shell are ranked as such: s<p<d<f. Why is this the case? Thanks!
by Hayden Lee 1C
Sun Oct 18, 2020 9:50 pm
Forum: Significant Figures
Topic: How do I know how many sig figs to use?
Replies: 6
Views: 132

Re: How do I know how many sig figs to use?

Hi there! The amount of sig figs used is dependent on how you completed the problem. With multiplication and division, the lowest number of sig figs used will be the number of sig figs included in your answer. With addition and subtraction, you assign significant figures based on the number of decim...
by Hayden Lee 1C
Sun Oct 18, 2020 9:44 pm
Forum: Student Social/Study Group
Topic: Midterm 1
Replies: 8
Views: 64

Midterm 1

Hi!

I was just wondering what content would be included in the midterm. What weeks of material can we expect to see? Thanks a lot.
by Hayden Lee 1C
Sun Oct 18, 2020 9:27 pm
Forum: Administrative Questions and Class Announcements
Topic: Respondus Browser
Replies: 4
Views: 37

Respondus Browser

Hi there!

When using respondus, will I have to point my camera down onto the paper I am writing on? If so, will I be able to project my work onto a separate monitor so I can see what I'm doing more clearly! Thank you!
by Hayden Lee 1C
Sun Oct 18, 2020 9:19 pm
Forum: Photoelectric Effect
Topic: Kinetic energy equation
Replies: 3
Views: 36

Re: Kinetic energy equation

Hi there,

In this equation, m represents the mass in kilograms of an object. This component of the equation is necessary in order to calculate the kinetic energy. Hope this helps!
by Hayden Lee 1C
Sun Oct 18, 2020 9:14 pm
Forum: Balancing Chemical Reactions
Topic: Syntax Question
Replies: 4
Views: 49

Re: Syntax Question

Hi there!

Yes, both ways of writing signify the same thing. The reason why it is written as (OH)2 instead of O2H2 is that it is the simplified form, nothing more. Hope this helps!
by Hayden Lee 1C
Sun Oct 11, 2020 8:53 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Textbook Homework E9
Replies: 6
Views: 106

Re: Textbook Homework E9

Hi there! While watching one of the lectures, I heard that we would be provided with compounds on tests and that we would not be required to memorize them. While I have not seen this written on the syllabus or any other materials, I am fairly confident that we will not have to memorize compounds as ...
by Hayden Lee 1C
Sun Oct 11, 2020 8:46 pm
Forum: SI Units, Unit Conversions
Topic: Showing Unit Conversions in work
Replies: 7
Views: 107

Re: Showing Unit Conversions in work

Hi there! I would imagine that writing units with each calculation would be required on tests in order for graders to see the sequence of your work. Regardless, I personally feel like it's always helpful to do. I tend to get scattered if I write out numbers without including their respective units. ...
by Hayden Lee 1C
Sun Oct 11, 2020 8:34 pm
Forum: Student Social/Study Group
Topic: Groupme for Disc. 1C/Lecture 1
Replies: 2
Views: 59

Groupme for Disc. 1C/Lecture 1

Hi there,

I was just wondering if there was a GroupMe created for discussion 1C. Also, if there is a GroupMe for Lecture 1, it would be great if I could get the link to that. I really appreciate it! Thanks.
by Hayden Lee 1C
Sun Oct 11, 2020 8:19 pm
Forum: Significant Figures
Topic: Establishing Significant Figures
Replies: 8
Views: 95

Establishing Significant Figures

Hi there, While I understand that the number 5000 only has one significant figure, I do not understand the rationale as to why this is. What makes the number "5000." consist of four significant figures while 5000 has only one? Not an entirely relevant question, just something that I had be...
by Hayden Lee 1C
Sun Oct 11, 2020 6:05 pm
Forum: Molarity, Solutions, Dilutions
Topic: Sapling HW #6
Replies: 8
Views: 82

Re: Sapling HW #6

Based on the math I can see here, it looks like you are solving the problem properly. Check to see if the molar mass of CuNO3 that you calculated is correct (this is the only thing that I can see potentially causing this issue). Other than that, everything looks completely fine to me.

Go to advanced search