Search found 86 matches

by Melis Kasaba 2B
Sun Feb 21, 2021 8:32 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Different Standard Reduction Potentials
Replies: 2
Views: 12

Re: Different Standard Reduction Potentials

Generally, ions of the later transition metals have higher reduction potentials, while alkali metal ions have more negative reduction potentials.
by Melis Kasaba 2B
Sun Feb 21, 2021 8:26 pm
Forum: Balancing Redox Reactions
Topic: Salt Bridge Clarification
Replies: 3
Views: 13

Re: Salt Bridge Clarification

In a salt bridge, electrons flow from anode to cathode, which makes the cathode solution more negatively charged since its species are reduced, and the anode solution more positively charged since its species are oxidized.
by Melis Kasaba 2B
Sun Feb 21, 2021 8:22 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: entropy positive value
Replies: 29
Views: 57

Re: entropy positive value

I believe Lavelle said that because the total entropy of the universe is always increasing. Additionally, in an irreversible reaction, entropy always increases. However, there can be a decrease in entropy for a system that is not closed.
by Melis Kasaba 2B
Sun Feb 21, 2021 8:13 pm
Forum: Phase Changes & Related Calculations
Topic: State Property
Replies: 43
Views: 131

Re: State Property

A state property is a property whose value doesn't rely on the path taken to reach that value. Some examples of state properties are internal energy, pressure, temperature, volume, and altitude.
by Melis Kasaba 2B
Sun Feb 21, 2021 8:11 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Q and K
Replies: 35
Views: 67

Re: Q and K

Q is the reaction quotient and K is the equilibrium constant.

K > Q: reaction will proceed forward, reactants --> products
K < Q: reaction will proceed in reverse direction, products --> reactants
Q = K: system is already at equilibrium
by Melis Kasaba 2B
Sun Feb 14, 2021 11:45 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Internal Energy, When Q is zero?
Replies: 4
Views: 10

Re: Internal Energy, When Q is zero?

–q means that heat is being lost from the system and released into the surroundings (exothermic), while a +q indicates that heat is absorbed/required by the system and the reaction is endothermic.
by Melis Kasaba 2B
Sun Feb 14, 2021 11:41 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Entropy
Replies: 27
Views: 83

Re: Entropy

In chemistry, entropy is represented by the capital letter S and it's a measure of the randomness and disorder of molecules. This extensive property depends on the number of particles and is needed to describe the likelihood or probability that the system will be in a particular state. Entropy is a ...
by Melis Kasaba 2B
Sun Feb 14, 2021 11:35 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Kelvin conversion
Replies: 40
Views: 85

Re: Kelvin conversion

On the Constants & Formulas sheet, it says that 0°C = 273.15K, so I think that's the best conversion to use.
by Melis Kasaba 2B
Sun Feb 14, 2021 11:34 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Intensive vs. Extensive Property
Replies: 8
Views: 20

Re: Intensive vs. Extensive Property

Extensive properties rely on the amount of matter being measured in the sample while intensive properties don't. Some examples of extensive properties are mass and volume, while density and color are intensive.
by Melis Kasaba 2B
Sun Feb 14, 2021 11:32 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: HW Question
Replies: 4
Views: 11

Re: HW Question

The change in Gibbs free energy is given by the equation: ΔG = ΔG∘ + RTln(Q). First, you should calculate Q using the partial pressures given. Then, since the values of ΔG∘ and T are given, you can calculate ΔG. For R, remember to use 8.314 J/(mol⋅K) but convert to kJ.
by Melis Kasaba 2B
Sat Feb 06, 2021 12:33 am
Forum: Administrative Questions and Class Announcements
Topic: tips if you're struggling!
Replies: 61
Views: 340

Re: tips if you're struggling!

Thanks for the tips! I personally go to UA sessions because I find it helpful to be held accountable to study and do practice problems and I think it's useful to have someone explain the way to solve problems versus just struggling on my own. I also try to review the material after each week, so by ...
by Melis Kasaba 2B
Sat Feb 06, 2021 12:30 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Postive vs. negative work
Replies: 18
Views: 58

Re: Postive vs. negative work

Work is a measurement of internal energy in chemistry. When work is done ON the system/heat is given to the system, its internal energy increases and the work is positive. If work is done BY the system/heat is given off, its internal energy decreases and the work is negative.
by Melis Kasaba 2B
Fri Feb 05, 2021 8:57 pm
Forum: Student Social/Study Group
Topic: Study routine.
Replies: 51
Views: 99

Re: Study routine.

I think what helps me most is actually practicing problems rather than just reading the textbook. Of course following along the examples in the textbook is useful, but I find the step-up sessions and workshops to be the best because they clearly walk you through the problems and you can ask any ques...
by Melis Kasaba 2B
Fri Feb 05, 2021 8:54 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy increase or decrease?
Replies: 3
Views: 23

Re: Entropy increase or decrease?

Entropy is a measure of the molecular disorder/randomness of a system or a measure of a system's thermal energy per temperature that's not available for doing work. In a system, the total entropy always either increases or remains constant—it never decreases. Entropy increases when a substance is br...
by Melis Kasaba 2B
Fri Feb 05, 2021 7:43 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Combustion = Exothermic
Replies: 23
Views: 78

Re: Combustion = Exothermic

Combustion is always exothermic because it's an oxidation reaction that produces heat. All chemical reactions involve breaking bonds and then making new ones, so if the energy released by the new bonds is greater than the energy needed to break the original bonds.
by Melis Kasaba 2B
Thu Jan 28, 2021 4:49 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium constant meaning
Replies: 2
Views: 15

Re: Equilibrium constant meaning

Like Anna said, J probably refers to a substance given earlier in the problem.
by Melis Kasaba 2B
Thu Jan 28, 2021 4:48 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Choosing R
Replies: 2
Views: 20

Re: Choosing R

The value of the gas constant R depends on the units used for pressure, volume, and temperature in the problem. Usually pressure is the deciding factor based on whether its given in atm, kPa, or mmHg/Torr.
by Melis Kasaba 2B
Thu Jan 28, 2021 4:43 pm
Forum: Phase Changes & Related Calculations
Topic: H and q
Replies: 47
Views: 175

Re: H and q

q is heat, while H is used to describe a change in enthalpy. As we discussed in class, enthalpy is a state function, while heat is focused more on heat released/absorbed from a system.
by Melis Kasaba 2B
Thu Jan 28, 2021 4:39 pm
Forum: Administrative Questions and Class Announcements
Topic: HW Due Date
Replies: 15
Views: 71

Re: HW Due Date

The homework is due this Sunday, which is a bit rough, but as always, we have unlimited attempts on Sapling and the hints/feedback are both very helpful. Additionally, if you look at the outlines, it'll tell you what sections of the textbook correspond to this weeks' topics, which could also come in...
by Melis Kasaba 2B
Thu Jan 28, 2021 4:37 pm
Forum: Student Social/Study Group
Topic: Sapling Week 3-4 Question #5
Replies: 4
Views: 44

Re: Sapling Week 3-4 Question #5

I double-checked your work, and everything looks right except the total enthalpy should be -6449.8.
by Melis Kasaba 2B
Tue Jan 19, 2021 7:21 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: pKa and Ka
Replies: 27
Views: 78

Re: pKa and Ka

pKa = -log Ka

As Lavelle told us p basically means -log() like in pH, pOH, pKa, pKb.

Smaller value of Ka --> larger value of pKa --> weaker acid
by Melis Kasaba 2B
Tue Jan 19, 2021 7:16 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: ICE table values
Replies: 20
Views: 83

Re: ICE table values

You can also just use moles in the ICE table, but then you have to remember to divide these values by L before giving your final answer. I tend to use mol/L just because then I don't have to rely on myself remembering to convert it later. However, I think any concentration unit works, but once again...
by Melis Kasaba 2B
Tue Jan 19, 2021 7:11 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Studying for Midterm #1
Replies: 63
Views: 181

Re: Studying for Midterm #1

Lavelle takes problems from the textbook, so it's very helpful to make sure you understand how to do every single question he assigns. I don't find the Sapling as helpful, but that's probably subjective. It's also important to go to UA sessions since they provide extra problems/practice and can help...
by Melis Kasaba 2B
Tue Jan 19, 2021 7:05 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Comparing pKb Values
Replies: 4
Views: 13

Re: Comparing pKb Values

Yes, it's the same for Kb & pKb.
large Kb value & small pKb--> high level of dissociation, strong base
small Kb value & large pKb --> low level of dissociation, weak base
by Melis Kasaba 2B
Tue Jan 19, 2021 7:00 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm Exams
Replies: 7
Views: 99

Re: Midterm Exams

The format will be the same as last term except the actual exam will take place during class rather than discussion. You do not need a webcam because you can join Zoom on any other device (phone, iPad, etc.) and then take the midterm with Respondus on your laptop. There will most likely be a specifi...
by Melis Kasaba 2B
Fri Jan 15, 2021 1:04 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: lecture 5 question
Replies: 13
Views: 81

Re: lecture 5 question

Yes, Lavelle said that we should memorize the strong acids and bases, and then by knowing those, we can conclude every other acid or base we see is weak. A conjugate base of a Bronsted-Lowry acid is formed after an acid donates a proton. A conjugate acid of a Bronsted-Lowry base is the species forme...
by Melis Kasaba 2B
Fri Jan 15, 2021 12:55 pm
Forum: Administrative Questions and Class Announcements
Topic: Are we covering Buffers?
Replies: 1
Views: 23

Re: Are we covering Buffers?

In Outline 2: Acid and Base Equilibria, it mentions "applying chemical equilibrium and acid-base concepts to environmental and biological examples (e.g., buffers, blood pH))," so I believe we will cover them eventually.
by Melis Kasaba 2B
Fri Jan 15, 2021 12:54 pm
Forum: Student Social/Study Group
Topic: Midterms During Lecture
Replies: 44
Views: 236

Re: Midterms During Lecture

Cooper Kinne 2E wrote:We'll still be in a zoom call with our TA, though, right?

Yes, I believe we're using the same set-up, so Respondus on your laptop and then joining the Zoom call with your TA from another device.
by Melis Kasaba 2B
Fri Jan 15, 2021 12:50 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: q vs k
Replies: 62
Views: 202

Re: q vs k

Q is the reaction quotient and can be used to figure out which direction the reaction will shift in order to reach equilibrium. K > Q: reaction proceeds forward, R --> P. K < Q: reaction proceeds in reverse direction, P --> R. Q = K: system is at equilibrium, no shift to either left or right
by Melis Kasaba 2B
Fri Jan 15, 2021 12:47 pm
Forum: Ideal Gases
Topic: Ice method
Replies: 14
Views: 72

Re: Ice method

ICE stands for Initial, Change, Equilibrium and contains concentrations of molecules in solution in the different stages of a reaction. I contains the initial concentrations for the products and reactants. C represents the change in concentration needed for the reaction to reach equilibrium. It's th...
by Melis Kasaba 2B
Sat Jan 09, 2021 1:25 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: endothermic v endergonic
Replies: 4
Views: 10

Re: endothermic v endergonic

Endothermic & exothermic refer to heat. Endothermic means the reaction requires heat and ΔH > 0. Exothermic means the reaction releases heat and ΔH < 0. Endergonic & Exergonic refer to entropy/free energy. If a reaction is endergonic, this means it's nonspontaneous and requires energy, ΔG > ...
by Melis Kasaba 2B
Sat Jan 09, 2021 1:21 pm
Forum: Ideal Gases
Topic: Kc vs Kp
Replies: 109
Views: 989

Re: Kc vs Kp

Kc and Kp are both equilibrium constants for mixtures of gases, but Kc depends on molar concentrations whereas Kp depends on the partial pressures of gasses inside a closed system.
by Melis Kasaba 2B
Sat Jan 09, 2021 1:18 pm
Forum: Ideal Gases
Topic: reversing reactions
Replies: 83
Views: 437

Re: reversing reactions

The equilibrium constant for a reverse reaction is the reciprocal of the one for the forward reaction, so it would be 1/K.
by Melis Kasaba 2B
Sat Jan 09, 2021 1:16 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K vs. Q
Replies: 53
Views: 207

Re: K vs. Q

Yes, that is correct. Q is the reaction quotient and K is the equilibrium constant. We use Q to figure out which direction a reaction will shift to reach equilibrium. If K > Q, the forward reaction is favored, converting reactants into products. If K < Q, the reverse reaction is favored, converting ...
by Melis Kasaba 2B
Sat Jan 09, 2021 1:13 pm
Forum: Ideal Gases
Topic: Units of Temperature
Replies: 82
Views: 348

Re: Units of Temperature

For the ideal gas law, the temperature should be in Kelvin. In order for gas laws to work, temperature has to be calculated on an absolute scale (Kelvin) rather than an arbitrary scale (Celsius). 0 K is absolute zero, but 0 C is just the melting point of water.
by Melis Kasaba 2B
Tue Dec 15, 2020 2:42 am
Forum: Student Social/Study Group
Topic: Final Exam
Replies: 49
Views: 346

Re: Final Exam

I definitely felt rushed on the last few questions as well, but I'm very grateful that Lavelle decided it was more challenging than intended and added 10 bonus points. I'm just trying to remember that I tried my best and that in the long run, one grade is not a big deal.
by Melis Kasaba 2B
Thu Dec 10, 2020 1:09 pm
Forum: Lewis Acids & Bases
Topic: Lewis vs Bronsted Definition
Replies: 7
Views: 61

Re: Lewis vs Bronsted Definition

Since the Lewis definition focuses on the movement of electrons, you can try to remember that L is for Lewis and E is for electrons (LEwis). Then, once you can remember that, you know that the other definition (Bronsted) involves the donation of protons.
by Melis Kasaba 2B
Thu Dec 10, 2020 1:05 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Calculating H+
Replies: 17
Views: 73

Re: Calculating H+

If you have the pH, you should be able to find [H+], [OH-], and pOH. Here's a helpful chart that tells you what formulas to use:
20140811155915521305.png
by Melis Kasaba 2B
Thu Dec 10, 2020 12:59 pm
Forum: Student Social/Study Group
Topic: Final
Replies: 18
Views: 125

Re: Final

Lavelle has mentioned several times that he gets test problems from the textbook, so I think it's safe to say that most of the problems will be from the textbook or very similar.
by Melis Kasaba 2B
Thu Dec 10, 2020 12:58 pm
Forum: Photoelectric Effect
Topic: Energy levels
Replies: 3
Views: 33

Re: Energy levels

Like Crystal said, it would probably be good to also memorize the infrared (Paschen) series, just in case.
image.png
by Melis Kasaba 2B
Thu Dec 10, 2020 12:55 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR Shapes on Exam
Replies: 3
Views: 61

Re: VSEPR Shapes on Exam

I'd probably say all the ones he brought up in lecture. Here's a helpful chart: [img]
VSEPR%20Geometries.png
[/img]
by Melis Kasaba 2B
Wed Dec 02, 2020 2:57 pm
Forum: Administrative Questions and Class Announcements
Topic: fall 2020 final
Replies: 17
Views: 209

Re: fall 2020 final

The final is on Sunday December 13 from 11:30am-1pm, but international students have the alternative time of 8pm-9:30pm.

https://lavelle.chem.ucla.edu/wp-conten ... hedule.pdf
by Melis Kasaba 2B
Wed Dec 02, 2020 2:55 pm
Forum: Bronsted Acids & Bases
Topic: Why is HF a weak acid?
Replies: 5
Views: 82

Re: Why is HF a weak acid?

You're correct that HCl, HBr, and also HI are strong acids, while HF is weak. It's actually the only hydrohalic acid that isn't strong. It's considered a weak acid because it doesn't completely dissociate into its ions in water. However, very concentrated solutions of HF can behave like a strong aci...
by Melis Kasaba 2B
Wed Dec 02, 2020 2:52 pm
Forum: Naming
Topic: order of ligands [ENDORSED]
Replies: 6
Views: 110

Re: order of ligands [ENDORSED]

Yeah the second image is an error. I believe the book also uses the new IUPAC name convention instead of the old ones that we usually use. You can reference this chart for that though: https://lavelle.chem.ucla.edu/wp-conten ... pounds.pdf
by Melis Kasaba 2B
Wed Dec 02, 2020 2:48 pm
Forum: Hybridization
Topic: Pi Bonds Cannot Rotate
Replies: 23
Views: 178

Re: Pi Bonds Cannot Rotate

For a pi bond, there has to be a parallel orientation of the p orbitals so they overlap. If the bond were to rotate, that would break it.
by Melis Kasaba 2B
Wed Dec 02, 2020 1:05 pm
Forum: Administrative Questions and Class Announcements
Topic: Chem 14A Final
Replies: 21
Views: 199

Re: Chem 14A Final

My TA said it'll be fairly evenly split among things we've done in the course since there's not enough material after midterm 2 to only focus on that.
by Melis Kasaba 2B
Wed Nov 25, 2020 12:40 pm
Forum: General Science Questions
Topic: Finals
Replies: 39
Views: 419

Re: Finals

The final will be cumulative and multiple choice. It'll also be longer than our midterms because we have 1.5 hours instead of 50 minutes.
by Melis Kasaba 2B
Wed Nov 25, 2020 12:37 pm
Forum: Hybridization
Topic: Hybridization Clarification
Replies: 9
Views: 80

Re: Hybridization Clarification

Hybridization occurs when atomic orbitals mix to form a new atomic orbital. This new orbital can hold the same total number of electrons as the old ones, but the properties and energy of it is an average of the original, unhybridized orbitals. The concept of hybridization was created to explain the ...
by Melis Kasaba 2B
Wed Nov 25, 2020 12:33 pm
Forum: Hybridization
Topic: e density
Replies: 30
Views: 169

Re: e density

Yes. A region of e- density can either be considered bonding or non-bonding. e- in a covalent bond are counted as a single region, regardless of whether it's a single, double, or triple bond. Non-bonding regions are the lone pairs (each pair is counted as one non-boding region) on the central atom.
by Melis Kasaba 2B
Wed Nov 25, 2020 12:28 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: coplanar?
Replies: 9
Views: 73

Re: coplanar?

Atoms that lie within the same plane are called coplanar or also periplanar.
by Melis Kasaba 2B
Wed Nov 25, 2020 12:27 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Axial/equatorial
Replies: 4
Views: 27

Re: Axial/equatorial

I believe it depends on bond angle. Bonds with angles of around 90° to the plane are called axial and bonds that only form a small angle compared to the plane are equatorial.
by Melis Kasaba 2B
Tue Nov 17, 2020 12:27 am
Forum: Quantum Numbers and The H-Atom
Topic: London Dispersion Forces
Replies: 7
Views: 68

Re: London Dispersion Forces

London dispersion forces are the weakest type of intermolecular force. I think Lavelle prefers the name dipole-induced dipole interactions because it's more descriptive. Basically, they're a temporary attraction that arises when electrons in two atoms next to each other form temporary dipoles. They ...
by Melis Kasaba 2B
Tue Nov 17, 2020 12:22 am
Forum: Administrative Questions and Class Announcements
Topic: Week 7 Sapling
Replies: 12
Views: 170

Re: Week 7 Sapling

We most likely have a Sapling assignment for next week since the syllabus says Sapling Weekly Online Homework (5 pts per week). I'm sure Lavelle will let us know when it's posted, but he's probably letting us study for the midterm.
by Melis Kasaba 2B
Tue Nov 17, 2020 12:18 am
Forum: Resonance Structures
Topic: Dominant Contribution to Resonance Hybrid
Replies: 4
Views: 54

Re: Dominant Contribution to Resonance Hybrid

A dominant contributor to a resonance hybrid is one that has the lowest energy. Some characteristics that make a structure favorable is having a lot of atoms with complete octets, covalent bonds, and few formal charges. Since structures with lower energy are more stable, that makes them a more favor...
by Melis Kasaba 2B
Tue Nov 17, 2020 12:11 am
Forum: Bond Lengths & Energies
Topic: Higher Melting Point
Replies: 27
Views: 260

Re: Higher Melting Point

CHI3 has a higher melting point than CHF3 because it's a bigger atom. Being larger means that CHI3 has more electrons, and thus a higher polarizability (more easily distortable cloud of electrons), which creates a stronger intermolecular bond, making it harder to melt.
by Melis Kasaba 2B
Tue Nov 17, 2020 12:08 am
Forum: Octet Exceptions
Topic: Exceptions/Expanded Octet
Replies: 1
Views: 21

Re: Exceptions/Expanded Octet

Yes, an expanded octet is one of the exceptions to the octet rule (which I think is why Lavelle likes referring to it as a guideline) because it's when an atom shares more than 8 electrons with its bonding partners. This can be done when an element's valence shell has access to the d-orbitals in the...
by Melis Kasaba 2B
Tue Nov 10, 2020 6:22 pm
Forum: Dipole Moments
Topic: London Dispersion forces
Replies: 7
Views: 34

Re: London Dispersion forces

I don't think there are any exceptions. Dispersion forces exist between all molecules, no matter if they're polar or nonpolar. However, I believe bigger/heavier atoms and molecules might exhibit stronger dispersion forces than smaller/lighter ones.
by Melis Kasaba 2B
Tue Nov 10, 2020 6:19 pm
Forum: Dipole Moments
Topic: Debye
Replies: 2
Views: 22

Re: Debye

The size of a dipole is measured using its electric dipole moment, which is given in the unit debye. 1 debye = 3.34 x 10^-30 Coulomb meters. Lavelle gave the formula (dipole moment) = (charge) x (distance between atoms or bond length). Basically, it's used as a measure of charge difference.
by Melis Kasaba 2B
Tue Nov 10, 2020 6:10 pm
Forum: Dipole Moments
Topic: Ionic Character
Replies: 3
Views: 42

Re: Ionic Character

The ionic character of a bond can be measured in percents and it is customary to say that anything with more than 50% ionic character is "ionic." Although, covalent bonds can still have ionic character. A "higher" ionic character (percent) means that there's more limited electron...
by Melis Kasaba 2B
Tue Nov 10, 2020 4:08 pm
Forum: Bond Lengths & Energies
Topic: Dipole
Replies: 7
Views: 24

Re: Dipole

Molecular dipoles happen when electrons aren't shared equally between atoms in a molecule. This happens when more electronegative atoms pull the bonded electrons closer to themselves. Lavelle also talked about the electric dipole moment which is a way to measure charge difference. Dipole moment = (c...
by Melis Kasaba 2B
Tue Nov 10, 2020 4:04 pm
Forum: Lewis Structures
Topic: Central Atom
Replies: 20
Views: 92

Re: Central Atom

The atom that needs the biggest # of electrons to complete its octet goes in the center. If there's two atoms in the same periodic group, the less electronegative element goes in the center.
by Melis Kasaba 2B
Wed Nov 04, 2020 2:48 pm
Forum: Resonance Structures
Topic: Resonance Structures
Replies: 10
Views: 62

Re: Resonance Structures

I'm pretty sure a resonance structure is just one Lewis structure that can't completely describe the bonding. A resonance hybrid represents the overall delocalization of e– within the molecule by combining multiple possible resonance structures.
by Melis Kasaba 2B
Wed Nov 04, 2020 2:43 pm
Forum: Student Social/Study Group
Topic: Unexpected Result of using Chemistry Communtiy
Replies: 7
Views: 83

Re: Unexpected Result of using Chemistry Communtiy

I wish I had mine memorized, but autofill on my laptop lets me be lazy...
by Melis Kasaba 2B
Wed Nov 04, 2020 2:32 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic v. Covalent Bonds`
Replies: 10
Views: 59

Re: Ionic v. Covalent Bonds`

In ionic bonds, one atom donates an electron to stabilize another atom. This happens between metals and nonmetals that have different electronegativity values from each other. (Electronegativity measures how strongly atoms attract bonding electrons to themselves.) In covalent bonds, the atoms are bo...
by Melis Kasaba 2B
Wed Nov 04, 2020 2:26 pm
Forum: Student Social/Study Group
Topic: Post Midterm Blues
Replies: 71
Views: 652

Re: Post Midterm Blues

I definitely relate, but this was one of our first midterms during our first quarter of college and it's already a super stressful time. I don't think anyone expects people to be thriving right now. I wouldn't beat yourself up about it—it's perfectly fine and beneficial to make mistakes because they...
by Melis Kasaba 2B
Wed Nov 04, 2020 2:22 pm
Forum: Student Social/Study Group
Topic: Favorite TV shows
Replies: 189
Views: 1206

Re: Favorite TV shows

Bones is great! I've also been watching a lot of Criminal Minds recently, but I'd also recommend Euphoria. It's pretty intense, but it doesn't glamorize high school like a lot of other shows and it's produced by Drake which is pretty cool :)
by Melis Kasaba 2B
Mon Oct 26, 2020 3:59 pm
Forum: SI Units, Unit Conversions
Topic: Dimensional Analysis
Replies: 7
Views: 72

Re: Dimensional Analysis

It's also helpful to memorize SI unit prefixes to help with unit conversions, especially since these won't be given to us for tests. I like to use the mnemonic device Good Models Know Donuts Can Make μ (You) Not Petite, which refers to Giga (9), Mega (6), kilo (3), deci (-1), centi (-2), milli (-3),...
by Melis Kasaba 2B
Mon Oct 26, 2020 1:57 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: textbook 1B.5
Replies: 2
Views: 25

Re: textbook 1B.5

The problem says the speed is known to within +/– 1.0 mm/s. This means that the range of possible values (delta v) would be twice that. For example, if the speed was 100 mm/s and it was known within +/– 1.0 mm/s, it could range from 99 mm/s to 101 mm/s, with a difference of 2.0. The 10^–3 comes from...
by Melis Kasaba 2B
Mon Oct 26, 2020 1:45 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Sapling HW Q24
Replies: 1
Views: 20

Re: Sapling HW Q24

Compatible wave patterns must have a whole number of complete wavelengths, so they fit as a standing wave. The wave patterns must be smooth and continuous around the orbit, so that once the ends are attached, there aren't any kinks or gaps in the pattern.
by Melis Kasaba 2B
Mon Oct 26, 2020 1:23 pm
Forum: Administrative Questions and Class Announcements
Topic: Petition to Bring Music Back To Lectures [ENDORSED]
Replies: 34
Views: 555

Re: Petition to Bring Music Back To Lectures [ENDORSED]

Great to have the music again! It definitely helps promote ~good chemistry~ :)
by Melis Kasaba 2B
Mon Oct 26, 2020 1:20 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: finding the region of the electromagnetic spectrum that the wavelength corresponds to
Replies: 3
Views: 34

Re: finding the region of the electromagnetic spectrum that the wavelength corresponds to

605.8 nm falls within the visible region (400-700 nm). My TA confirmed that a diagram of the electromagnetic spectrum won't be provided, so you should know the relative order of the types of radiation and what wavelengths of light correspond to them. She also said we won't need to know the exact bou...
by Melis Kasaba 2B
Mon Oct 19, 2020 12:56 pm
Forum: DeBroglie Equation
Topic: Wave Properties of Electrons
Replies: 4
Views: 37

Re: Wave Properties of Electrons

Diffraction refers to the ways waves act when they hit an obstacle/opening, bending around the corners which causes diffraction patterns. In this case, since electrons passing through the crystal (obstacle) also show diffraction, they must have wave-like properties (in addition to particle propertie...
by Melis Kasaba 2B
Mon Oct 19, 2020 12:49 pm
Forum: Photoelectric Effect
Topic: What is equation is this ?
Replies: 11
Views: 76

Re: What is equation is this ?

C represents the speed of light, which is 3.00 x 10^8 m/s. For light, wavelength (λ), frequency (ƒ), and velocity (v) can all be measured and they fit the equation for waves, where v is velocity or the speed of light (c). So c is used in the equation c = λƒ = 3.00 x 10^8 m/s. This equation can be re...
by Melis Kasaba 2B
Mon Oct 19, 2020 12:39 pm
Forum: DeBroglie Equation
Topic: lecture 8 worked example
Replies: 3
Views: 36

Re: lecture 8 worked example

9.11x10^-31 kg is the electron rest mass. It's a known constant and would be given on a constant/equations sheet on a test.
by Melis Kasaba 2B
Mon Oct 19, 2020 12:34 pm
Forum: Limiting Reactant Calculations
Topic: Study for these types of problems
Replies: 6
Views: 48

Re: Study for these types of problems

I've found Khan Academy to be quite useful. https://www.khanacademy.org/science/chemistry/chemical-reactions-stoichiome/limiting-reagent-stoichiometry/e/limiting_reagent_stoichiometry Also, some of the UAs that teach the peer learning sessions have posted their worksheets to Chemistry Community or i...
by Melis Kasaba 2B
Mon Oct 19, 2020 12:26 pm
Forum: Student Social/Study Group
Topic: How are you studying?
Replies: 203
Views: 1377

Re: How are you studying?

I take detailed notes during lecture and then go back and highlight the key concepts after. I've also watched all the modules and I try to go through the textbook at the same rate as the lectures. I think what's also really helpful is going to the peer learning sessions because the in-depth explanat...
by Melis Kasaba 2B
Mon Oct 12, 2020 1:33 pm
Forum: Properties of Light
Topic: Focus 1B.5
Replies: 3
Views: 33

Re: Focus 1B.5

AnnaNovoselov1G wrote:One eV (electrovolt) is equal to 1.602×10−19 Joules. Good luck!


In this case, since you have the value in keV (140.511 keV), I believe you would use 1 keV = 1.602x10^-16 J.
by Melis Kasaba 2B
Mon Oct 12, 2020 1:28 pm
Forum: Quantum Numbers and The H-Atom
Topic: high intensity light
Replies: 3
Views: 60

Re: high intensity light

If light had only wave properties, then increasing the intensity should eject electrons from the metal because in a classical wave, a more intense wave has a higher amplitude/energy. But in this case, increasing the intensity of light doesn't increase/add to the energy of the individual photons beca...
by Melis Kasaba 2B
Mon Oct 12, 2020 1:21 pm
Forum: Photoelectric Effect
Topic: Solving photoelectric effect questions
Replies: 4
Views: 31

Re: Solving photoelectric effect questions

So does the fact that the work function is in kJ instead of J.mol^1 not apply to this question? It doesn't matter for this part of the question because it's only asking for the kinetic energy. You use the formula E=(1/2)mv^2 which doesn't require the work function. However, for the next question in...
by Melis Kasaba 2B
Mon Oct 12, 2020 1:16 pm
Forum: Properties of Light
Topic: Properties of light
Replies: 3
Views: 47

Re: Properties of light

The answer is wave, particle. In the photoelectric effect, each photon's energy needs to be big enough to cause an electron to be emitted. A photon of light is a particle and so is an electron of the metal. It's an interaction between the two and it supports the particle theory of light.
by Melis Kasaba 2B
Mon Oct 12, 2020 1:04 pm
Forum: Empirical & Molecular Formulas
Topic: Mass Percent Converted to Grams
Replies: 4
Views: 35

Re: Mass Percent Converted to Grams

It helps you easily turn the mass percentages into grams because it's the same number. When you turn these grams into moles, it'll give you the same answer as if you had used the masses for the actual sample because the ratio is the same. But the problem can be more convenient and easier to visualiz...
by Melis Kasaba 2B
Mon Oct 05, 2020 10:12 pm
Forum: Empirical & Molecular Formulas
Topic: Fundamental F. 17
Replies: 6
Views: 79

Re: Fundamental F. 17

I believe the order of elements in a chemical formula follows something called the Hill System. Basically, carbon comes first, then hydrogen, and then the other elements in alphabetical order. If the formula doesn't have carbon, then all the elements, including hydrogen, are listed in alphabetical o...
by Melis Kasaba 2B
Mon Oct 05, 2020 7:30 pm
Forum: Molarity, Solutions, Dilutions
Topic: G7 Clarification
Replies: 4
Views: 70

Re: G7 Clarification

I believe 510. g is how much the aqueous solution with the solute (KNO3) weighs. So you need to calculate how many grams of KNO3 are in the solution and then how many grams of water (since it's an aqueous solution water is the other component). The solution would then be prepared by pouring the calc...
by Melis Kasaba 2B
Mon Oct 05, 2020 1:27 pm
Forum: Administrative Questions and Class Announcements
Topic: Sapling Textbook Access Code
Replies: 10
Views: 94

Re: Sapling Textbook Access Code

Keeryth Sandhu 2J wrote:Does anyone know how long the free trial is?


On the Google Doc that Lavelle gave us, the picture says you can enter this course for 10 days free, but on my Sapling it says you can enter this course for 16 days free.
by Melis Kasaba 2B
Mon Oct 05, 2020 1:03 pm
Forum: Molarity, Solutions, Dilutions
Topic: Molarity and Dilution of a Solution
Replies: 6
Views: 65

Re: Molarity and Dilution of a Solution

First, you have to convert the mass of KCl (55.1g) into moles by dividing it by the molar mass. Then, you divide by the volume (75mL converted into L) to get the initial concentration or molarity of KCl. Then, you manipulate the equation Minitial*Vinitial = Mfinal*Vfinal to solve for Mfinal. Mfinal ...
by Melis Kasaba 2B
Mon Oct 05, 2020 12:56 pm
Forum: Limiting Reactant Calculations
Topic: Limiting Reactant Fundamentals Section M Exercise M.11
Replies: 4
Views: 42

Re: Limiting Reactant Fundamentals Section M Exercise M.11

P4O6 is the formula for phosphorus(III) oxide, so I think the colon is just indicating that what comes after it is the equation for P4O6.

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