Search found 66 matches

by KSong_1J
Sun Jan 26, 2020 10:02 pm
Forum: Phase Changes & Related Calculations
Topic: Focus 4 Homework Questions
Replies: 3
Views: 21

Re: Focus 4 Homework Questions

In regards to what we covered in class,4C goes over the heating curve/the basics of enthalpy and 4D goes over hess’s law so for practice problems I’d say both are good but I’d focus more on 4D!
by KSong_1J
Sun Jan 26, 2020 9:56 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Week 4 Homework
Replies: 11
Views: 35

Re: Week 4 Homework

I think sections 4C and 4D cover all the recent material we’ve done in class so far so I’d do problems from those sections :)
by KSong_1J
Sun Jan 26, 2020 9:06 pm
Forum: Phase Changes & Related Calculations
Topic: Physical or Phase Changes
Replies: 7
Views: 23

Re: Physical or Phase Changes

In all the examples Lavelle has showed in class so far they were given to us so I think the values will be given
by KSong_1J
Sun Jan 26, 2020 9:01 pm
Forum: Phase Changes & Related Calculations
Topic: Class Lecture to Textbook
Replies: 2
Views: 43

Re: Class Lecture to Textbook

Section 4D.4 covers Hess’s Law! 4C and 4D cover pretty much everything we’ve gone over in class so far
by KSong_1J
Sun Jan 26, 2020 8:58 pm
Forum: Phase Changes & Related Calculations
Topic: enthalpy of phase changes
Replies: 8
Views: 26

Re: enthalpy of phase changes

The textbook states that enthalpies of fusion and vaporization are always positive and I’m pretty sure the same goes for the enthalpy of sublimation (since it’s the conversion of a solid to vapor so it’s endothermic)
by KSong_1J
Sun Jan 19, 2020 9:37 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5I.13
Replies: 4
Views: 32

Re: 5I.13

I’m not sure if this is the right way to do it but what I did was look at the Kc values for both and compared them. Since both are diatomic molecules, they’re more stable in the form F2/Cl2 instead of by themselves, so the one that produces more F2/Cl2 is more stable. Since the equation for Cl2 has ...
by KSong_1J
Sun Jan 19, 2020 9:27 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5H.1 and 5H.3?
Replies: 2
Views: 17

Re: 5H.1 and 5H.3?

For 5H.1, when you modify a reaction, the K value is also affected. So for part a, since the reaction was flipped backwards, you take the reciprocal of K (1/41) to get 0.024; for Part b, since the reaction was multiplied by 1/2, you take the square root of K to get 6.4; for Part c, since the reactio...
by KSong_1J
Sun Jan 19, 2020 9:13 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Henderson Hasselbalch Equation
Replies: 3
Views: 12

Re: Henderson Hasselbalch Equation

Dr. Lavelle said that we won’t be using the equation in 14b so I don’t think you need to worry about it!
by KSong_1J
Sun Jan 19, 2020 9:10 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Exo/Endo-thermic Rxns
Replies: 5
Views: 12

Re: Exo/Endo-thermic Rxns

Endothermic reactions absorb energy to create products while exothermic products release energy when creating products. An example that combines this idea with Le Chatelier’s principle is if you raised the temperature in a reaction; if it’s an endothermic reaction, a higher temperature will cause th...
by KSong_1J
Sun Jan 19, 2020 8:54 pm
Forum: General Science Questions
Topic: test 1
Replies: 8
Views: 45

Re: test 1

Test #1 begins on Tuesday, January 21 in our discussion sections and yes it’s chemical equilibrium and acids and bases (basically everything we’ve learned so far)!
by KSong_1J
Sun Jan 12, 2020 7:21 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: increasing N2
Replies: 5
Views: 27

Re: increasing N2

If you increase the N2, then the equilibrium will want to shift towards the right to create more ammonia. Creating more ammonia requires using more N2 and H2, thus the amount of H2 will decrease
by KSong_1J
Sun Jan 12, 2020 7:18 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: "Quick way" part in Lecture
Replies: 7
Views: 40

Re: "Quick way" part in Lecture

If you decrease the volume in the system, then the reaction will favor the direction that has fewer moles of gas (since, according to Le Chatelier’s principle, when stress is applied to a system in equilibrium, the equilibrium will shift to reduce the effect of the stress). By reducing the volume, y...
by KSong_1J
Sun Jan 12, 2020 7:01 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: "Quick way" part in Lecture
Replies: 7
Views: 40

Re: "Quick way" part in Lecture

Did you mean to write something like “if volume decreases and there’s more moles of gas on the left, then the reaction shifts to the right” and “if volume decreases and there’s more moles of gas on the right, then the reaction shifts to the left”?
by KSong_1J
Sun Jan 12, 2020 6:40 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q>K
Replies: 9
Views: 24

Re: Q>K

Q is larger than K in situations where there is more products than reactants, in which case the reverse reaction will be favored so that Q = K
by KSong_1J
Sun Jan 12, 2020 6:38 pm
Forum: Ideal Gases
Topic: partial pressures
Replies: 7
Views: 29

Re: partial pressures

The ratio will be the same because (PO2)^3/(PO3)^2 is the formula for its equilibrium constant, K, which always stays the same whether more moles are added or not
by KSong_1J
Sun Jan 12, 2020 5:07 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kc
Replies: 5
Views: 17

Re: Kc

I think you can use aqueous solutions and gases to solve for Kc but you don’t include solids or liquids
by KSong_1J
Sat Dec 07, 2019 10:09 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Practice Problem
Replies: 2
Views: 23

Re: Practice Problem

According to the textbook (Toolbox 9C.1),if it's not a negatively charged complex, you use iron instead of ferrate (ex. [FCl(OH2)5]+ is a pentaaquachlorido(II) ion
by KSong_1J
Sat Dec 07, 2019 9:54 pm
Forum: Calculating the pH of Salt Solutions
Topic: ph problem
Replies: 2
Views: 32

Re: ph problem

Ka is equal to [H+][A-]/[HA] and, for this equation, you can rewrite it as Ka = [H+]^2/[HA] because H+ and A- have the same concentration. To find the pH, you need to take the negative log of the H+ ions. Since they give you Ka and you know the concentration of the acid, you can just plug them in an...
by KSong_1J
Sat Dec 07, 2019 9:33 pm
Forum: Bronsted Acids & Bases
Topic: Strong Acids and Bases
Replies: 6
Views: 49

Re: Strong Acids and Bases

There's a table in the textbook (Fundamentals J) of the strong acids and bases that is pretty helpful! It's Table J.1 on page F75
by KSong_1J
Sat Dec 07, 2019 9:25 pm
Forum: Bronsted Acids & Bases
Topic: 6C.19
Replies: 2
Views: 29

Re: 6C.19

When it comes to oxoacids with the same number off oxygens attached to the central atom, the greater the electronegativity of the central atom, the stronger the acid. This is due to the fact that a greater electronegativity means it's more electron withdrawing. Therefore, HClO4 is stronger than H3PO...
by KSong_1J
Sat Dec 07, 2019 9:15 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: QUESTION 4 ON MIDTERM
Replies: 1
Views: 30

Re: QUESTION 4 ON MIDTERM

The solutions are on his website! Here's the link: https://lavelle.chem.ucla.edu/wp-conten ... rm_ans.pdf
by KSong_1J
Sun Dec 01, 2019 10:40 pm
Forum: General Science Questions
Topic: Bruincasts
Replies: 9
Views: 120

Re: Bruincasts

I don't think this class has recorded lectures/bruincast. The only recorded lectures he has are the audio-visual focus topics on his website that cover fundamentals and some topics of the quantum world.
by KSong_1J
Sun Dec 01, 2019 10:31 pm
Forum: Student Social/Study Group
Topic: Studying Videos
Replies: 3
Views: 26

Re: Studying Videos

Organic Chemistry Tutor and Professor Dave Explains on Youtube both have great videos for all those topics!
by KSong_1J
Sun Dec 01, 2019 10:29 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Textbook
Replies: 5
Views: 27

Re: Textbook

The textbook covers acids and bases in Fundamentals J and Chapter 6. In Lavelle's learning outcomes it says to look at Fundamentals J, Focus 6A.1-6A.3, 6B.1, 6C.3-6C.4, 6D.3, 6E.1 and Box 6E.1
by KSong_1J
Sun Dec 01, 2019 10:22 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Basic Acids and Bases Help
Replies: 3
Views: 31

Re: Basic Acids and Bases Help

^I agree, Organic Chemistry Tutor is a great resource as well as Professor Dave Explains on Youtube!
by KSong_1J
Sun Dec 01, 2019 10:20 pm
Forum: Bronsted Acids & Bases
Topic: Naming
Replies: 4
Views: 27

Re: Naming

I think we do because it was one of our homework problems (9C.3)
by KSong_1J
Sun Nov 24, 2019 6:25 pm
Forum: Naming
Topic: Polydentate
Replies: 1
Views: 30

Re: Polydentate

A polydentate is basically a ligand that can bind to the central atom at multiple sites (multiple atoms). An example of a monodentate would be H20 (the oxygen makes one bond with the central atom), a bidentate would be oxalate (the two oxygens that are not double bonded to the carbons can each form ...
by KSong_1J
Sun Nov 24, 2019 5:59 pm
Forum: Naming
Topic: Cobalt vs. Cobaltate
Replies: 4
Views: 24

Re: Cobalt vs. Cobaltate

-ate is used if the complex is an anion (is overall negatively charged), so that's when colbatlate would be used. If the complex has an overall positive charge, you would use cobalt.
by KSong_1J
Sun Nov 24, 2019 5:52 pm
Forum: Naming
Topic: Prefixes
Replies: 5
Views: 29

Re: Prefixes

You use those prefixes when a ligand is a polydentate or if it already has a prefix
by KSong_1J
Sun Nov 24, 2019 5:28 pm
Forum: Administrative Questions and Class Announcements
Topic: Lecture
Replies: 3
Views: 22

Re: Lecture

I believe we still have to cover the acids and bases section before the final
by KSong_1J
Sun Nov 24, 2019 5:24 pm
Forum: Naming
Topic: using brackets
Replies: 5
Views: 24

Re: using brackets

You use brackets for anything within the coordination sphere (basically the complex)
by KSong_1J
Sun Nov 17, 2019 10:38 pm
Forum: Student Social/Study Group
Topic: Test 2
Replies: 11
Views: 51

Re: Test 2

I believe it’s everything we learned after the midterm up to/including sigma and pi bonds
by KSong_1J
Sun Nov 17, 2019 10:25 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: bond angles
Replies: 8
Views: 35

Re: bond angles

More lone pairs results in more electron-electron repulsion which pushes the atoms away. This results in smaller bond angles because the atoms move closer together.
by KSong_1J
Sun Nov 17, 2019 10:20 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: vsepr angles
Replies: 10
Views: 47

Re: vsepr angles

Yes you should memorize them for the upcoming test!
by KSong_1J
Sun Nov 17, 2019 10:16 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone Pairs
Replies: 10
Views: 41

Re: Lone Pairs

Lone pairs affect molecular geometry because the electron-electron repulsion causes the atoms to move further away
by KSong_1J
Sun Nov 17, 2019 10:10 pm
Forum: Hybridization
Topic: Test 2
Replies: 11
Views: 71

Re: Test 2

I don’t think hybridization is going to be covered on Test 2
by KSong_1J
Sun Nov 10, 2019 11:39 pm
Forum: Resonance Structures
Topic: Negative Charge
Replies: 3
Views: 16

Re: Negative Charge

You put a negative charge on the atom that’s more likely to gain the electron(s) in a bond!
by KSong_1J
Sun Nov 10, 2019 11:36 pm
Forum: Bond Lengths & Energies
Topic: Test 2 Topics
Replies: 40
Views: 364

Re: Test 2 Topics

I think it’s just everything we learn after the midterm!
by KSong_1J
Sun Nov 10, 2019 11:27 pm
Forum: Student Social/Study Group
Topic: Midterm Grades
Replies: 7
Views: 81

Re: Midterm Grades

I think I remember him saying we get our midterms back on Wednesday!
by KSong_1J
Sun Nov 10, 2019 10:06 pm
Forum: Sigma & Pi Bonds
Topic: Sigma vs Pi
Replies: 11
Views: 51

Re: Sigma vs Pi

You can find sigma bonds in single, double, and triple bonds while pi bonds are only found in double bonds (where there’s one sigma and one pi bond) and triple bonds (one sigma and two pi bonds).
by KSong_1J
Sun Nov 10, 2019 9:39 pm
Forum: Dipole Moments
Topic: Hydrogen Bonds
Replies: 4
Views: 18

Re: Hydrogen Bonds

N, O, and F form hydrogen bonds!
by KSong_1J
Sun Nov 03, 2019 11:46 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic bonds being held together
Replies: 3
Views: 23

Re: Ionic bonds being held together

They’re held together by electrostatic attraction (the attraction between atoms of opposite charges)
by KSong_1J
Sun Nov 03, 2019 11:44 pm
Forum: Photoelectric Effect
Topic: Best way to study for this topic?
Replies: 8
Views: 105

Re: Best way to study for this topic?

Definitely do the homework problems and also search up more problems online if you need more practice! To understand the topic better conceptually I recommend reading the textbook and watching videos about the topic online (the organic chemistry tutor on YouTube has really good ones)
by KSong_1J
Sun Nov 03, 2019 11:30 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configuration
Replies: 3
Views: 28

Re: Electron Configuration

You want to remove electrons from higher energy levels before moving onto lower energy levels, so you’ll want to remove them from the highest orbital. They’re also usually easier to remove because they’re further away from the nucleus
by KSong_1J
Sun Nov 03, 2019 11:26 pm
Forum: Quantum Numbers and The H-Atom
Topic: magnetic quantum number
Replies: 5
Views: 23

Re: magnetic quantum number

The magnetic quantum number describes the number of orbitals within a subshell and the orientation of the orbital; s will have a magnetic quantum number of 0, p can have one between -1 and 1, d can have between -2 and 2, and so on
by KSong_1J
Sun Nov 03, 2019 11:18 pm
Forum: Trends in The Periodic Table
Topic: Midterm Question Regarding Metals, Nonmetals, etc
Replies: 2
Views: 20

Re: Midterm Question Regarding Metals, Nonmetals, etc

I don’t think we’ll specifically asked to identify if the element is a metal, nonmetal, etc. but I think it’s still good information to know because you need it for many things (like naming, bonding, etc)
by KSong_1J
Sun Oct 27, 2019 10:58 pm
Forum: Resonance Structures
Topic: Midterm
Replies: 4
Views: 22

Re: Midterm

Anish Patel 4B wrote:Do you know if this also includes the material from the first test since it was high school stuff?


I think material from the first test is also included in the midterm!
by KSong_1J
Sun Oct 27, 2019 10:55 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm Format
Replies: 11
Views: 114

Re: Midterm Format

I know it's still weeks away but I was wondering, does anyone know about the format of the midterm? Is it comparable to Test 1 but just longer in length? What types of questions will be on it and which units does it cover? Where is the midterm located? Will that be announced closer to the midterm d...
by KSong_1J
Sun Oct 27, 2019 10:50 pm
Forum: Ionic & Covalent Bonds
Topic: Covalent Bonds
Replies: 14
Views: 77

Re: Covalent Bonds

Yes, covalent bonds are only between two nonmetals! If you have a metal-nonmetal bond it's an ionic bond and a metal-metal is a metallic bond.
by KSong_1J
Sun Oct 27, 2019 10:42 pm
Forum: Ionic & Covalent Bonds
Topic: Resonance Structures
Replies: 5
Views: 27

Re: Resonance Structures

I think you have to use the dots to represent the two electrons on the oxygen
by KSong_1J
Sun Oct 27, 2019 10:41 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Advice for studying
Replies: 58
Views: 507

Re: Advice for studying

For studying I definitely recommend reading the textbook chapters (which helps a lot with conceptual understanding of topics), doing all the homework problems, and just searching up youtube videos of topics you don't fully understand!
by KSong_1J
Sun Oct 20, 2019 11:01 pm
Forum: Properties of Light
Topic: Homework 4
Replies: 4
Views: 46

Re: Homework 4

I think we can still do questions under quantum world since it falls under the category of “recently covered material”
by KSong_1J
Sun Oct 20, 2019 10:53 pm
Forum: Student Social/Study Group
Topic: Week 4 HW Problems
Replies: 7
Views: 76

Re: Week 4 HW Problems

I think it can be from both. In the syllabus it says to hand in homework from recently covered material so I believe either should be fine (it also could depend on your discussion section; for example if you had yours on Tuesday, we haven’t really gone over Chemical bonds yet so I don’t think they’d...
by KSong_1J
Sun Oct 20, 2019 10:43 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 1F.19
Replies: 3
Views: 26

Re: 1F.19

Since s-block metals have lower ionization energies, they’re more likely to give away their electrons which makes them more reactive
by KSong_1J
Sun Oct 20, 2019 10:32 pm
Forum: Quantum Numbers and The H-Atom
Topic: Quantum Numbers: Size of An Atom
Replies: 4
Views: 26

Re: Quantum Numbers: Size of An Atom

n is related to the size and energy of the orbital; as n (aka the energy level) increases, the mean distance of an electron from the nucleus increases, which means the radius of the atom gets larger.
by KSong_1J
Sun Oct 20, 2019 10:24 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Writing Electron Configurations
Replies: 2
Views: 22

Re: Writing Electron Configurations

In general, you would follow the order of s, p, d, f but I think there are some special cases in which you don’t follow that order (for example, copper)
by KSong_1J
Sun Oct 13, 2019 10:21 pm
Forum: General Science Questions
Topic: Powerpoint Slides
Replies: 4
Views: 52

Re: Powerpoint Slides

I don’t think he posts his slides, but the audio-visual focus topics do go over what he talks about in class (though they only seem to be available for fundamentals and quantum world).
by KSong_1J
Sun Oct 13, 2019 10:11 pm
Forum: Properties of Electrons
Topic: Photon
Replies: 5
Views: 25

Re: Photon

Photons are basically particles of energy that make up light
by KSong_1J
Sun Oct 13, 2019 10:02 pm
Forum: Properties of Light
Topic: 1B #19
Replies: 1
Views: 16

Re: 1B #19

To calculate the different wavelengths, use de Broglie’s equation (λ = h/mv) and you just search up the mass of the proton and neutron because they’re set values and plug those in for m, plug in 2.75 x 10^5m/s for v, and plug in Planck’s constant for h: Proton: (6.626 x 10^-34Js)/(1.673 x 10^-27kg)(...
by KSong_1J
Sun Oct 13, 2019 9:23 pm
Forum: Photoelectric Effect
Topic: Wavelength, Frequency, and Intensity
Replies: 7
Views: 39

Re: Wavelength, Frequency, and Intensity

Light is made up of photons and the photon’s energy is dependent on its wavelength; longer wavelengths of light have less energy than shorter wavelengths, which is why the shorter wavelengths are able to eject the electrons (since they have more energy and you need to reach a certain threshold to ej...
by KSong_1J
Sun Oct 13, 2019 9:02 pm
Forum: Photoelectric Effect
Topic: Photoelectric Effect
Replies: 3
Views: 31

Re: Photoelectric Effect

No, the surface must be metal to exhibit the photoelectric effect because you have to be able to completely remove the electron in order to achieve the effect. Since metals are able to donate/spare electrons while non-metals can’t, only metals will work.
by KSong_1J
Sun Oct 06, 2019 9:39 pm
Forum: Significant Figures
Topic: Sig Figs
Replies: 3
Views: 22

Re: Sig Figs

Sig figs are basically like a way to round. Khan Academy is a great resource to learn more about the basics of sig figs :)
by KSong_1J
Sun Oct 06, 2019 9:18 pm
Forum: Administrative Questions and Class Announcements
Topic: Specific type of calculator for tests?
Replies: 6
Views: 69

Re: Specific type of calculator for tests?

I think we have to use scientific calculators for tests!
by KSong_1J
Sun Oct 06, 2019 9:15 pm
Forum: Significant Figures
Topic: Reviewing Sig Figs
Replies: 3
Views: 42

Re: Reviewing Sig Figs

For sig fig practice I like using Khan Academy or if you just search up “sig fig practice,” some good websites for practice will pop up (like sciencegeek.net)!
by KSong_1J
Sun Oct 06, 2019 9:10 pm
Forum: Balancing Chemical Reactions
Topic: Fractions
Replies: 20
Views: 188

Fractions

I know this was kind of addressed in a question someone asked earlier but I just wanted to ask if we would be marked down if we left the stoichiometric coefficient as a fraction? I know different professors prefer different things so I just wanted to clarify to see if it would necessarily be seen as...
by KSong_1J
Sun Oct 06, 2019 9:00 pm
Forum: SI Units, Unit Conversions
Topic: Unit Conversions
Replies: 6
Views: 77

Re: Unit Conversions

Hi, An easy way I memorize some of the basic prefixes is “King Henry Died By Drinking Chocolate Milk” K(ilo) H(ecto) D(eca) B(ase) D(eci) C(enti) M(illi). Basically, as you go down the line, the units progressively get smaller (1 kilo = 10,000 of the base or 10^3, 10^2, and so on until you reach Mil...

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