Search found 75 matches

by Kyle Walsh 2J
Sun Feb 07, 2021 8:55 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Sapling #14 Week 3/4
Replies: 7
Views: 55

Re: Sapling #14 Week 3/4

Just as Sara said, you would use the equation work is equal to the negative of external pressure times the change in volume. In other words, w=-P(ex)ΔV. Hope this helps!
by Kyle Walsh 2J
Sun Feb 07, 2021 7:38 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Sapling HW Week 3/4 #20
Replies: 5
Views: 32

Sapling HW Week 3/4 #20

Hi, I was just wondering how to get started on question 20 for this week's homework, I'm still pretty fuzzy on the whole delta U stuff. I copied the question below for convenience. Any help is appreciated, thanks! "A 0.201 mol sample of N2(g) initially at 298 K and 1.00 atm is held at constant ...
by Kyle Walsh 2J
Sun Feb 07, 2021 7:14 pm
Forum: Calculating Work of Expansion
Topic: Deriving equation for work of a reversible reaction
Replies: 1
Views: 11

Re: Deriving equation for work of a reversible reaction

Hi! I'm also not sure if this was gone over in lecture, but I found a website that summarizes the derivation pretty well. Hope this helps! "If the gas expands reversibly, the external pressure ( p­ext ) can be replaced by a single value ( p ) which represents both the pressure of the gas and th...
by Kyle Walsh 2J
Sun Feb 07, 2021 7:04 pm
Forum: Calculating Work of Expansion
Topic: Converting Units
Replies: 4
Views: 15

Re: Converting Units

Hi! I think the reason sapling usually asks for you to convert L*atm to Joules is because Joules is the standard unit for work. Hope this helps!
by Kyle Walsh 2J
Sun Feb 07, 2021 6:58 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Heat in isothermal expansion
Replies: 5
Views: 19

Re: Heat in isothermal expansion

I believe this has to do with the fact that isothermal expansion is using energy to increase the volume. If heat is applied during isothermal expansion, the volume increases instead of the temperature. Hope this helps!
by Kyle Walsh 2J
Sun Jan 31, 2021 1:44 am
Forum: Calculating Work of Expansion
Topic: Integral vs Infinite Sum [ENDORSED]
Replies: 3
Views: 39

Integral vs Infinite Sum [ENDORSED]

In the lecture, Lavelle showed us an infinite sum formula and then showed an "equivalent" integral that is supposed to convey the same thing (calculating the work of expansion). I was just curious if we need to know the sum formula, and if there are any instances where we would use that in...
by Kyle Walsh 2J
Sun Jan 31, 2021 12:54 am
Forum: Calculating Work of Expansion
Topic: Sapling HW Week 3/4 #15
Replies: 1
Views: 16

Sapling HW Week 3/4 #15

Any help on how to start this problem would be appreciated, I don't really understand work calculations at all. I copied it below for convenience. Thanks! Automobile airbags contain solid sodium azide, NaN3, that reacts to produce nitrogen gas when heated, thus inflating the bag. 2NaN3(s)⟶2Na(s)+3N2...
by Kyle Walsh 2J
Sun Jan 31, 2021 12:52 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Would an aq agent be included in K?
Replies: 27
Views: 83

Re: Would an aq agent be included in K?

Yes, aqueous solutions are always included in the K for a given reaction. Hope this helps!
by Kyle Walsh 2J
Sun Jan 31, 2021 12:50 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Pressure affects only gas reactions?
Replies: 23
Views: 69

Re: Pressure affects only gas reactions?

I believe that it's not the pressure that affects gas reactions, it's the volume changing. But the pressure change is just a byproduct of the changing volume.
by Kyle Walsh 2J
Sun Jan 31, 2021 12:33 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Sapling HW Week 3/4 #9
Replies: 2
Views: 25

Sapling HW Week 3/4 #9

Hi, I was just wondering if anybody could help me get started on this problem, I know it has something to do with specific heat capacity but the equation doesn't quite work. The question is: If you combine 290.0 mL of water at 25.00 ∘C and 110.0 mL of water at 95.00 ∘C, what is the final temperature...
by Kyle Walsh 2J
Sun Jan 24, 2021 10:33 pm
Forum: Ideal Gases
Topic: Acids & Bases
Replies: 6
Views: 47

Re: Acids & Bases

I try to think of it as finding the strong cation/anion, as there is a much smaller list of strong acids/bases as compared to weak ones. If the cation is from a strong base, then it's basic, if the anion is from a strong acid then it's acidic, and if they're both from strong acids/bases then it is n...
by Kyle Walsh 2J
Sun Jan 24, 2021 10:24 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Determining if endothermic or exothermic
Replies: 2
Views: 27

Re: Determining if endothermic or exothermic

For endothermic processes, I tend to think of them as something that requires energy. Baking a cake requires energy from you, but a car using gasoline doesn't require energy, it produces it in the form of heat. Ice melting requires heat, or else it wouldn't melt, but water condensing doesn't require...
by Kyle Walsh 2J
Sun Jan 24, 2021 10:14 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Standard Enthalpy
Replies: 2
Views: 24

Re: Standard Enthalpy

I believe we'd just find the standard enthalpy in a list or index that was given to us. From what Lavelle was saying, we won't usually have to convert the molecule to a different form, but even if we do, then you just add the enthalpy of vaporization if it's a liquid, or enthalpy of melting and vapo...
by Kyle Walsh 2J
Sun Jan 24, 2021 10:10 pm
Forum: Phase Changes & Related Calculations
Topic: Bond Effects During Phase Changes
Replies: 5
Views: 24

Bond Effects During Phase Changes

In Lecture, Lavelle mentioned that water vaporization has a large enthalpy value due to the hydrogen bonds. I don't entirely understand this, because then why is the enthalpy value of ice melting still relatively small? Why does the bond type only affect vaporization?
by Kyle Walsh 2J
Sun Jan 24, 2021 9:41 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hess's Law Specifics
Replies: 2
Views: 18

Hess's Law Specifics

So I remember seeing more complicated examples of Hess's law equations in high school chemistry where equations were multiplied by 1/2 or 1/3, then flipped, then added together, etc. I know that when multiplying the coefficients, you multiply the delta H by the same factor, and flipping the equation...
by Kyle Walsh 2J
Sun Jan 17, 2021 9:20 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Total Pressure
Replies: 26
Views: 114

Re: Total Pressure

Hi! Total pressure is just the combined pressures of each of the gases in a given reaction. To find total pressure at equilibrium, you would simply add up the equilibrium pressures found through an ICE table. Hope this helps!
by Kyle Walsh 2J
Sun Jan 17, 2021 9:17 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling Week 1 #6
Replies: 10
Views: 60

Re: Sapling Week 1 #6

Hi! The reaction quotient Q is found using the same formula as K (products/reactants) and is more of a symbolic shorthand to show that this reaction is not at equilibrium and is instead at a random point in it's reaction. So long story short, for this question you would just plug in the concentratio...
by Kyle Walsh 2J
Sun Jan 17, 2021 9:15 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: changing volume by adding more solid reactants.
Replies: 3
Views: 23

Re: changing volume by adding more solid reactants.

Hi! While I do think that the theory behind your question is accurate, I doubt any questions about this would ever be asked. Just from a practical standpoint, why would you add an excess of a low density solid as opposed to just changing the volume of the reaction vessel otherwise. The solid would h...
by Kyle Walsh 2J
Sun Jan 17, 2021 9:09 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kp to Kc conversion
Replies: 5
Views: 34

Re: Kp to Kc conversion

Hi! I can't say for sure that we need to know it since I'm not the one designing the course, but my guess would be it never hurts to know, especially if there is a curveball question on a test.
by Kyle Walsh 2J
Sun Jan 17, 2021 8:41 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling HW Week 1 #5
Replies: 8
Views: 50

Sapling HW Week 1 #5

Hi! I don't remember if this type of question was covered, but I don't seem to have any notes on it and I'm kinda just lost on how to get started. Any help is appreciated, and I copied the question below for convenience. Thank you! Consider the reaction of NH3 and I2 to give N2 and HI. 2NH3(g)+3I2(g...
by Kyle Walsh 2J
Sun Jan 10, 2021 11:45 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Principle Explanation
Replies: 4
Views: 46

Principle Explanation

So, I remember using the line "away from what you add, towards what you take", when discussing Le Chatelier's Principle in high school chemistry, and it seems that it still holds true now. However, Lavelle emphasized that we should have a deeper understanding, and I still don't exactly get...
by Kyle Walsh 2J
Sun Jan 10, 2021 11:37 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q and K on and reactant/product concentrations
Replies: 8
Views: 35

Re: Q and K on and reactant/product concentrations

Fancy seeing you here. I believe that it's not possible for Q to be smaller than K while [P] is greater than [R], because Q is equal to [P]/[R]. Meaning that when [P] is greater than [R], Q is going to be some number over 1, whereas K would be 1, as [P]=[Q] for K.
by Kyle Walsh 2J
Sun Jan 10, 2021 11:22 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: mL to L^-1
Replies: 3
Views: 14

Re: mL to L^-1

I believe that the unit is mol*L^-1, which is just another way to say mol/L, or M. He might have just had a typo in the slides or something.
by Kyle Walsh 2J
Sun Jan 10, 2021 11:20 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Is there a correct step to solve for K?
Replies: 3
Views: 20

Re: Is there a correct step to solve for K?

Solving for the concentration at the end should not affect results, as long as the ICE table is set up correctly and you plug in the equilibrium concentrations.
by Kyle Walsh 2J
Sun Jan 10, 2021 11:17 pm
Forum: Ideal Gases
Topic: Inert Gases
Replies: 11
Views: 38

Re: Inert Gases

Hi! I believe that adding an inert gas does not change the concentrations of the reactant or product because it doesn't react with any part of the equilibrium reaction, which is just a property of inert gases. I believe the reason Lavelle brought this up in lecture was to highlight that you can't al...
by Kyle Walsh 2J
Fri Dec 11, 2020 12:56 pm
Forum: Lewis Acids & Bases
Topic: Stength of Acid
Replies: 2
Views: 35

Re: Stength of Acid

Fancy seeing you here. I'm pretty sure that this is a correct assumption, but it's important to note that there is a difference between compound surface area and atom size. Since an increase in atom size means an increase in bond length, this weakens the bond and overall strengthens the acid. Hopefu...
by Kyle Walsh 2J
Fri Dec 11, 2020 12:45 pm
Forum: Lewis Acids & Bases
Topic: Textbook question
Replies: 3
Views: 43

Re: Textbook question

Hi! So in this question, B(OH)3 is acting as the Lewis acid, as it is accepting the electron pair from the (OH)- to turn into B(OH)4-. You can double check this by confirming that H30+ is formed, meaning that the original compound was acidic and the conjugate is basic. Hope this helped!
by Kyle Walsh 2J
Fri Dec 11, 2020 12:03 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Textbook 2E.15
Replies: 2
Views: 19

Re: Textbook 2E.15

Hi! I'm pretty sure you're exactly right, and this is just a textbook error. I found an old archived post on this from a while back, which I'll link below, and it basically just confirms what you're saying. Hope this helps!

viewtopic.php?f=41&t=1024
by Kyle Walsh 2J
Thu Dec 10, 2020 11:55 pm
Forum: Hybridization
Topic: Textbook Question 2.45
Replies: 1
Views: 21

Re: Textbook Question 2.45

Hi! So you're actually most of the way solved with the problem conceptually already, the 1 and 2 are just the energy levels of the orbitals, as those are the outermost shells for each atom and therefore where hybridization occurs. For example, carbon's outermost shell is the 2p orbital, and that's w...
by Kyle Walsh 2J
Thu Dec 10, 2020 5:11 pm
Forum: *Making Buffers & Calculating Buffer pH (Henderson-Hasselbalch Equation)
Topic: Equation
Replies: 2
Views: 39

Re: Equation

Hi! I'm pretty sure this and buffers in acid/base reactions is a chem 14b topic that we won't be tested on this quarter.
by Kyle Walsh 2J
Thu Dec 10, 2020 4:50 pm
Forum: Sigma & Pi Bonds
Topic: What to Know about the bonds
Replies: 1
Views: 16

Re: What to Know about the bonds

Hi! Sigma bonds are the weaker and more flexible of the two, allowing for rotation of bound atoms, and are bound end-to-end. The overall strength of a pi bond is much higher, and therefore does not allow for rotation of the bound atoms, and pi bonds are bound side-by-side. In addition, pi bonds are ...
by Kyle Walsh 2J
Thu Dec 10, 2020 4:45 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Sapling HW Q5 Part 1
Replies: 2
Views: 24

Re: Sapling HW Q5 Part 1

Hi! So to find the pH from the concentration of H+ ions, you just need to take the -log[H+]. Then to find pOH you take 14 and subtract the pH that you found from the first step. Finally, to find the concentration of OH- ions, you convert the pOH that you found from a log into the concentration (whic...
by Kyle Walsh 2J
Thu Dec 10, 2020 4:42 pm
Forum: Hybridization
Topic: Non-polar or polar
Replies: 1
Views: 15

Re: Non-polar or polar

Hi! I don't believe polarity is directly tied to hybridization, rather both of these are characteristics of the shape of a molecule. Hybridization is determined by how many lone pairs/bonds are attached to the central atom, which then gives a molecular geometry, and from there, polarity can be deter...
by Kyle Walsh 2J
Thu Dec 10, 2020 4:29 pm
Forum: Identifying Acidic & Basic Salts
Topic: Sapling HW Week 10 #7
Replies: 1
Views: 21

Sapling HW Week 10 #7

Hi! So I'm not sure if this has been discussed before, but I was just wondering how to determine whether a salt is acidic or basic as asked in the Sapling HW for this week (their examples were NH4ClO4, Na2S, K2SO3, KCl, and LiClO4). I might just be misremembering but I don't recall this being covere...
by Kyle Walsh 2J
Thu Dec 10, 2020 4:03 pm
Forum: Identifying Acidic & Basic Salts
Topic: Titration
Replies: 4
Views: 43

Re: Titration

Hi! So the majority of the time, these titrations only work because you can experimentally determine when the solution is an acid or a base, either through an indicator or some other form of pH test. For every titration, you will know the whether it the solution starts as an acid or a base because t...
by Kyle Walsh 2J
Thu Dec 10, 2020 3:55 pm
Forum: Bronsted Acids & Bases
Topic: Textbook problem J.17
Replies: 3
Views: 31

Re: Textbook problem J.17

Hi! So a similar question was asked at a bit ago and there are some pretty thorough explanations there. Hopefully this helps!
viewtopic.php?f=62&t=70283
by Kyle Walsh 2J
Thu Dec 10, 2020 3:51 pm
Forum: Identifying Acidic & Basic Salts
Topic: textbook problem, fundamentals: J #17
Replies: 3
Views: 48

Re: textbook problem, fundamentals: J #17

Hi! So how I approached this problem was to first determine whether the cation or anion was the weak acid/base based on what was told to us in lecture. So for part a) I chose C6H5O- as the weak base in water because Na+ won't affect pH as a group one element. Then, I just wrote out the reaction that...
by Kyle Walsh 2J
Thu Dec 10, 2020 3:47 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Strength and Stability of Acids and bases
Replies: 3
Views: 31

Re: Strength and Stability of Acids and bases

So for weak/strong acids, there is actually a list of defined strong acids, HCl04, HBr, HI, HCl, HNO3, H2SO4, and all the rest are considered weak acids. As for stability, the stronger an acid is, the more stable it will be. Determining the relative stability of individual weak acids can be done by ...
by Kyle Walsh 2J
Thu Dec 10, 2020 3:39 pm
Forum: Lewis Acids & Bases
Topic: Lewis Acids and Bases
Replies: 2
Views: 21

Re: Lewis Acids and Bases

Hi! Since individual ions can be considered Lewis acids/bases themselves, these pairings to the outer atoms should be considered as well. For example, ZnCl2 is considered a Lewis acid, because the Zn can accept protons, but the individual Cl- ions are also considered Lewis bases, as they are donatin...
by Kyle Walsh 2J
Thu Dec 10, 2020 3:29 pm
Forum: Sigma & Pi Bonds
Topic: Sapling Week 7/8 #18
Replies: 2
Views: 17

Re: Sapling Week 7/8 #18

So as I understand it, the hydrogen atoms in H2CCCH2 are actually perpendicular, as the pi bonds from the double bonds on each side of the central C are perpendicular to each other. This is contrasted with H2CCH2, which only has one pi bond, so it has to lie in the same plane. Then for H2CCCCH2, the...
by Kyle Walsh 2J
Sun Nov 29, 2020 11:54 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Electron vs Molecular Geometry
Replies: 4
Views: 41

Re: Electron vs Molecular Geometry

Hi! So, basically electron geometry is the arrangement of the electrons in a molecule, whereas the molecular geometry is the actual shape. The notable difference here is that lone pairs do not affect the electron geometry, whereas they definitely do affect molecular geometry. As for how to find it, ...
by Kyle Walsh 2J
Sun Nov 29, 2020 11:50 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Sapling #20
Replies: 1
Views: 21

Re: Sapling #20

Hi! I believe that this molecule is nonpolar because every atom has the same polarity (as they are all oxygen), and they are all evenly spaced in a tetrahedral formation (since there are no lone pairs), and therefore their dipoles cancel. Hope this helped!
by Kyle Walsh 2J
Sun Nov 29, 2020 11:48 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: Overall Review of Intermolecular Forces
Replies: 4
Views: 60

Overall Review of Intermolecular Forces

Hi! I was rereading my notes on this section and realized that I was somewhat unclear on what I wrote down, especially like the actual applications of intermolecular forces and why they matter in general chemistry. I know the general trends in strength, but what effect does the strength have in the ...
by Kyle Walsh 2J
Sun Nov 29, 2020 11:44 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Determining Type of Bond from Shape
Replies: 12
Views: 58

Determining Type of Bond from Shape

Hi! I was just curious as to if the type of bond (i.e. pi or sigma), can be determined purely from the shape of the molecule, or if you need to draw out the Lewis structure every time. I might just be forgetting but I can't remember if this was discussed. Thanks!
by Kyle Walsh 2J
Wed Nov 25, 2020 3:22 pm
Forum: Hybridization
Topic: Hybridization Explanation
Replies: 6
Views: 75

Hybridization Explanation

Hi! So I'm still not entirely clear on why hybridization occurs. I understand that it is necessary to explain the experimentally determined structures of molecules, but there must be some natural process that causes hybridization to occur. If not, is hybridization merely a thought process used to ex...
by Kyle Walsh 2J
Thu Nov 12, 2020 3:34 pm
Forum: Dipole Moments
Topic: Determining Polarity
Replies: 3
Views: 39

Determining Polarity

So I remember from high school chemistry that polarity can be determined by using molecular geometry, but since we haven't learned that yet, I am still a little confused as to how to determine polarity with just what we know. I'm pretty sure Dr. Lavelle went over this in the lectures, but it isn't r...
by Kyle Walsh 2J
Thu Nov 12, 2020 3:29 pm
Forum: Dipole Moments
Topic: H-Bonds
Replies: 14
Views: 131

Re: H-Bonds

Hi! Yes, H-bonding occurs when another compound has lone pair of electrons AND when the H atom is already bonded to an N, O, or F atom. The compounds that could have H-bonds are anything that satisfy these requirements. Some examples include molecules like chloroform (CHCl3) and ammonia (NH3) and ov...
by Kyle Walsh 2J
Thu Nov 12, 2020 3:23 pm
Forum: Lewis Structures
Topic: Sapling hw question
Replies: 2
Views: 29

Re: Sapling hw question

Hi! I'm pretty sure that these are just polyatomic ions with set numbers of oxygens that we could be expected to just memorize. I believe nitrite is 2 oxygens, nitrate is 3 oxygens, phosphite is 3 oxygens, and phosphate is 4 oxygens. Hope this helps!
by Kyle Walsh 2J
Thu Nov 12, 2020 1:56 pm
Forum: Ionic & Covalent Bonds
Topic: Textbook 2A17
Replies: 3
Views: 32

Re: Textbook 2A17

Hi! To determine the number of valence electrons, you have to use electron configurations and add the electrons of the outermost shell. For example, for Mn, the electron configuration is [Ar]4s2 3d5. If you turn this into Mn4+, then the electron configuration is [Ar]4s2 3d1, since a charge of 4+ mea...
by Kyle Walsh 2J
Thu Nov 12, 2020 1:38 pm
Forum: Octet Exceptions
Topic: Octet Exceptions
Replies: 2
Views: 19

Re: Octet Exceptions

Hi! So basically there are two types of exceptions to the octet rule, atoms that take less of an octet and atoms that can take more than an octet. The ones that take less than an octet are very situational, but obviously hydrogen and helium are the clearest exceptions, and then other row 2 elements ...
by Kyle Walsh 2J
Fri Nov 06, 2020 12:04 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Oxidation Numbers
Replies: 3
Views: 28

Oxidation Numbers

So I was looking over the Sapling HW, the half that is covered in week 4, and question 9 addresses the oxidation number of a chlorine. I might just be misremembering the terminology, but I don't recall ever learning how to find the oxidation number of an atom. It's probably really simple, but any he...
by Kyle Walsh 2J
Fri Nov 06, 2020 11:46 am
Forum: Student Social/Study Group
Topic: Favorite TV shows
Replies: 189
Views: 1223

Re: Favorite TV shows

I don't know if anybody else has said this already, but Hollywood on Netflix is an absolute must watch. It was created by Ryan Murphy, the same guy who did Glee and the Politician, another solid Netflix show, so you know it's good.
by Kyle Walsh 2J
Fri Nov 06, 2020 11:34 am
Forum: Ionic & Covalent Bonds
Topic: Covalent Character
Replies: 4
Views: 29

Re: Covalent Character

Hi! So the main differences between ionic and covalent bonds include the sharing of electrons, ionic bonds being electrostatic in nature due to charge differences, and solubility. I'm not sure we can entirely answer this until we get deeper into this topic, but yes, I would assume that since electro...
by Kyle Walsh 2J
Fri Nov 06, 2020 11:25 am
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Concept of Polarizeable and Polarizing
Replies: 2
Views: 18

Re: Concept of Polarizeable and Polarizing

Hi! Yes, high polarizability and highly polarizable mean the same thing for an anion. As for effective nuclear charge, yes, the lower the polarizability of an anion, the greater the effective nuclear charge. However, in general for an overall molecule, polarizability is determined by the difference ...
by Kyle Walsh 2J
Fri Nov 06, 2020 11:09 am
Forum: Lewis Structures
Topic: Difference in ionic and covalent Lewis structures
Replies: 9
Views: 94

Difference in ionic and covalent Lewis structures

In today's lecture (11/6), Dr. Lavelle was talking about how you should determine whether a given molecule has covalent or ionic bonds using electronegativity, and then draw it accordingly. This seems to imply there is a difference in how ionic and covalent Lewis structures are drawn, but I thought ...
by Kyle Walsh 2J
Fri Oct 30, 2020 12:37 pm
Forum: Properties of Light
Topic: Sapling Hw #25
Replies: 2
Views: 62

Sapling Hw #25

The problem states: The E.coli bacterium is about 2.4 μm long. Suppose you want to study it using photons of that wavelength or electrons having that de Broglie wavelength. What is the energy E(photon) of the photon? What is the energy E(electron) of the electron? I got the correct answer for the fi...
by Kyle Walsh 2J
Fri Oct 30, 2020 12:23 pm
Forum: Lewis Structures
Topic: Exceptions to the Octet Rule
Replies: 3
Views: 38

Exceptions to the Octet Rule

During today's lecture (10/30), Lavelle had multiple points about how H, He, Li, and Be are all exceptions to the Octet Rule. I vaguely remember this from high school chem, but I don't remember the reasoning at all. Why are they exceptions? Thanks!
by Kyle Walsh 2J
Fri Oct 30, 2020 12:18 pm
Forum: Quantum Numbers and The H-Atom
Topic: Number of Electrons per Shell
Replies: 5
Views: 74

Re: Number of Electrons per Shell

Hi! I believe that in the lecture Dr. Lavelle was referring to using the electron configurations, which are just numbers we have to memorize. s shells take 2 electrons, p shells take 6 electrons, d shells take 10 electrons, and f shells take 14 electrons. I don't believe you can determine the exact ...
by Kyle Walsh 2J
Fri Oct 30, 2020 12:12 pm
Forum: Lewis Structures
Topic: Line in place of paired dots
Replies: 8
Views: 45

Re: Line in place of paired dots

Hi! I think that this is up to the professor, but in general, lines are only used for bonds and lone pairs are represented by pairs of dots. Otherwise it could get a bit confusing.
by Kyle Walsh 2J
Fri Oct 30, 2020 12:09 pm
Forum: Ionic & Covalent Bonds
Topic: Inert vs Noble Gas
Replies: 4
Views: 45

Re: Inert vs Noble Gas

Hi! I believe that in the lecture, both of these terms were used to describe the same group of noble gases. However, in general chemistry the difference is that inert gases can be compound gases, the only requirement being that their outermost electron shell is filled. Noble gases are all purely ele...
by Kyle Walsh 2J
Fri Oct 23, 2020 1:35 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Electrostatic Potential Energy?
Replies: 2
Views: 21

Electrostatic Potential Energy?

So I know that Dr. Lavelle said we won't be responsible for the mathematical side of electrostatic potential energy, but I'm still a bit confused as to the theoretical side. Why is it important at all? Does it relate to bond strength or something that will be covered later? Thanks!
by Kyle Walsh 2J
Fri Oct 23, 2020 1:30 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Lyman vs. Balmer Series
Replies: 5
Views: 42

Re: Lyman vs. Balmer Series

Hi! The Lyman and Balmer series just have different wavelength ranges associated with them, and unfortunately I think that's something we just have to memorize. I believe Lyman is 94-122 nm while Balmer is 410-656 nm. You could also figure out what series it is if a type of light is given, as Lyman ...
by Kyle Walsh 2J
Fri Oct 23, 2020 1:20 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: x,y,z plane
Replies: 2
Views: 34

Re: x,y,z plane

Hi! The x,y,z planes are only used in the context of modelling an orbital in a 3d space. They are purely conceptual, because we don't know the true form of an electron or orbital, so we make 3d models out of their respective wave functions. Whether a part of the "orbital" modelled is in th...
by Kyle Walsh 2J
Fri Oct 23, 2020 1:11 pm
Forum: Significant Figures
Topic: Quick Sig Fig Question with Addition/Subtraction
Replies: 7
Views: 93

Re: Quick Sig Fig Question with Addition/Subtraction

Hi! In my experience, different textbooks and teachers prefer rounding done different ways, but it is always a safe bet to just round at the end.
by Kyle Walsh 2J
Fri Oct 23, 2020 1:09 pm
Forum: Photoelectric Effect
Topic: Dane Worksheet #3
Replies: 4
Views: 38

Re: Dane Worksheet #3

Hi! I believe your method isn't outputting the same answers because since it is an electron, not a photon, you can't use E=hv to determine frequency and then wavelength.
by Kyle Walsh 2J
Fri Oct 23, 2020 12:48 pm
Forum: Einstein Equation
Topic: Usage of E=hv
Replies: 10
Views: 118

Re: Usage of E=hv

Hi! I'm pretty sure that E=hv is a universal equation that works whether the electron is emitted or incoming, but many problems phrase it as an incoming electron because that is how it is perceived to monitoring devices in a lab.
by Kyle Walsh 2J
Thu Oct 15, 2020 3:22 pm
Forum: Quantum Numbers and The H-Atom
Topic: Electron affinity
Replies: 1
Views: 49

Re: Electron affinity

You can find the energy of the incident photons by using the standard energy equation, E=hc/lambda, where Planck's constant is 4.1357E-15 eV/s and the speed of light is 3.00E17 nm/s. Then you just subtract the energy of the ejected electrons from the energy of the incident photons.
by Kyle Walsh 2J
Thu Oct 15, 2020 2:55 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Sapling Wk 2/3 #5
Replies: 2
Views: 51

Sapling Wk 2/3 #5

Hi, I was starting the Sapling hw for this section, and I'm a bit conceptually confused about number 5. The problem is: "The electron in a hydrogen atom is excited to the n=5 shell and emits electromagnetic radiation when returning to lower energy levels. Determine the number of spectral lines ...
by Kyle Walsh 2J
Thu Oct 15, 2020 2:26 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Uncertainty of mass?
Replies: 3
Views: 56

Re: Uncertainty of mass?

Hi! I'm not one hundred percent sure but I don't believe that a question will ask for any other type of uncertainty, as the Heisenberg uncertainty principle is only able to be applied to particles. There are similar principles in physics that can be applied to objects other than particles, but those...
by Kyle Walsh 2J
Thu Oct 15, 2020 2:18 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Spectral Lines / Rydeberg's
Replies: 2
Views: 34

Re: Spectral Lines / Rydeberg's

Hi! I'm pretty sure that emission of energy always means that n2 is going to be 1, because the energy is emitted when the energy level decreases. The energy level increases when energy is being absorbed, and decreases when it's being released, much like exo/endothermic reactions.
by Kyle Walsh 2J
Fri Oct 09, 2020 10:55 am
Forum: Balancing Chemical Reactions
Topic: Types of Chemical Reactions
Replies: 8
Views: 116

Types of Chemical Reactions

In high school chemistry we learned multiple different types of chemical reactions and how to write/balance each one, such as decomposition, combination, single/double replacement, and combustion. I was wondering if it's implied that we should know these already, as it seemed that way for combustion...
by Kyle Walsh 2J
Thu Oct 08, 2020 8:22 pm
Forum: Molarity, Solutions, Dilutions
Topic: Fundamental G.25
Replies: 1
Views: 49

Re: Fundamental G.25

Hi! So for this problem I used the same standard dilution equation as the others, with the small twist being the doubling volume. If you set up M1V1=M2V2, you get the initial molarity as 0.10 M, and the initial volume as 10 mL, or 0.01 L. We're solving for the final molarity so you can leave that be...
by Kyle Walsh 2J
Thu Oct 08, 2020 7:53 pm
Forum: SI Units, Unit Conversions
Topic: #10 in the sapling
Replies: 6
Views: 90

Re: #10 in the sapling

Hi! I totally forgot how to read this stuff too at first lol. Essentially each line has a carbon attached on either end, which is then satisfied by hydrogens. The amount of hydrogens attached is 4 minus however many bonds are connected to the given vertex. So for example, the first diagram with the ...
by Kyle Walsh 2J
Thu Oct 08, 2020 7:41 pm
Forum: Balancing Chemical Reactions
Topic: Sapling Wk1 Q10 Theoretical Yield and Actual Yield
Replies: 4
Views: 75

Re: Sapling Wk1 Q10 Theoretical Yield and Actual Yield

You only need the molar masses and volumes to solve, I'm pretty sure what's given is balanced.
by Kyle Walsh 2J
Thu Oct 08, 2020 5:29 pm
Forum: SI Units, Unit Conversions
Topic: Review HW E23
Replies: 2
Views: 47

Review HW E23

Part A of question E23 on the review HW reads "Calculate the amount (in moles) of (a) Cu2+ ions in 3.00 g of CuBr2". Originally I calculated the mass percentage of Cu, then multiplied that by 3.00 g to find the grams of Cu, and then divided it by the molar mass of Cu to find the moles of C...

Go to advanced search