Search found 58 matches

by Karina Jiayu Xu 4E
Sun Mar 17, 2019 12:53 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Test 2 Question 5
Replies: 5
Views: 76

Re: Test 2 Question 5

u guys reply with different answers. did lavelle ever post the solution? where can i find the solution?
by Karina Jiayu Xu 4E
Sat Mar 09, 2019 5:26 pm
Forum: Zero Order Reactions
Topic: initial concentration
Replies: 6
Views: 58

Re: initial concentration

so is it okay to assume infinite concentration of initial reactants?
by Karina Jiayu Xu 4E
Sat Mar 09, 2019 5:25 pm
Forum: Zero Order Reactions
Topic: Zero order
Replies: 10
Views: 91

Re: Zero order

i am also confused about this... what do the different orders actually mean?
by Karina Jiayu Xu 4E
Sat Mar 09, 2019 5:23 pm
Forum: *Electrophiles
Topic: what is going to be on the final? [ENDORSED]
Replies: 12
Views: 531

Re: what is going to be on the final? [ENDORSED]

wait have we already gone over the ochem topics?
by Karina Jiayu Xu 4E
Fri Mar 01, 2019 1:12 am
Forum: Phase Changes & Related Calculations
Topic: reversible processes and equilibrium
Replies: 4
Views: 64

Re: reversible processes and equilibrium

to answer your question, yes
by Karina Jiayu Xu 4E
Fri Mar 01, 2019 1:02 am
Forum: Phase Changes & Related Calculations
Topic: Phase Changes
Replies: 11
Views: 172

Re: Phase Changes

It appeared on the 2019 test so I advise future students to learn it well beforehand.
by Karina Jiayu Xu 4E
Thu Feb 21, 2019 1:17 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: 7th edition 4I. 9
Replies: 2
Views: 41

Re: 7th edition 4I. 9

Calculate using two separate formulas given in lecture then compare the entropy changes
by Karina Jiayu Xu 4E
Thu Feb 21, 2019 1:15 am
Forum: Administrative Questions and Class Announcements
Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
Replies: 179
Views: 5625

Re: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)

This is so helpful. Are the attachments basically study guides?
by Karina Jiayu Xu 4E
Thu Feb 21, 2019 1:13 am
Forum: Ideal Gases
Topic: Reading the textbook [ENDORSED]
Replies: 81
Views: 26217

Re: Reading the textbook [ENDORSED]

Although reading the text book helps, I think simply completing all homework questions and attending lecture and discussion is sufficient to fully understand the course material, to be honest.
by Karina Jiayu Xu 4E
Fri Feb 15, 2019 10:30 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Adding reaction entropies
Replies: 8
Views: 76

Re: Adding reaction entropies

It is allowed because entropy is a state function. A lot of what we are working on are state functions (like enthalpy, gibbs free energy), except for work and heat.
by Karina Jiayu Xu 4E
Fri Feb 15, 2019 10:24 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Midterm Prep Question
Replies: 3
Views: 51

Re: Midterm Prep Question

You calculate he entropies of the change in temperature and the change in pressure separately and then add them up, since entropy is a state function.
by Karina Jiayu Xu 4E
Fri Feb 15, 2019 10:15 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: System and surroundings
Replies: 4
Views: 58

Re: System and surroundings

Recall that the change in entropy of the universe is equal to the sum of the change in entropy of the surrounding and the system. And in a reversible reaction, the total change in entropy in the universe is 0, and thus the change in entropy of the surrounding and the system have to equal.
by Karina Jiayu Xu 4E
Wed Feb 06, 2019 9:54 pm
Forum: Student Social/Study Group
Topic: New to Lavelle
Replies: 32
Views: 541

Re: New to Lavelle

Doing all of the homework problems (not just the 7, but every one listed) helps me the most. His tests are pretty similar to the homework problems sometimes even easier.
by Karina Jiayu Xu 4E
Wed Feb 06, 2019 9:52 pm
Forum: Student Social/Study Group
Topic: Absent on 1/30; in need of notes
Replies: 4
Views: 70

Re: Absent on 1/30; in need of notes

you can ask me for notes :) xuj67497@g.ucla.edu
by Karina Jiayu Xu 4E
Wed Feb 06, 2019 9:51 pm
Forum: Student Social/Study Group
Topic: Note Taking
Replies: 32
Views: 1183

Re: Note Taking

You can also use an ipad to take notes. Goodnotes 4 or 5 are both really good for note taking and organization.
by Karina Jiayu Xu 4E
Sun Feb 03, 2019 3:29 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: What not to count
Replies: 9
Views: 95

Re: What not to count

You should just ignore everything thats not in a gaseous state
by Karina Jiayu Xu 4E
Wed Jan 30, 2019 10:41 pm
Forum: Ideal Gases
Topic: breaking bond - heat released and gained
Replies: 5
Views: 72

Re: breaking bond - heat released and gained

from what i learned in LS i think when u break a bond u release energy (so youre right). For example breaking off a phosphate from ATP will result in energy release.
by Karina Jiayu Xu 4E
Wed Jan 30, 2019 10:21 pm
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student [ENDORSED]
Replies: 96
Views: 29368

Re: Advice from a Medical Student [ENDORSED]

thank you so much!! that was actually very helpful considering how stressful the process is.
by Karina Jiayu Xu 4E
Wed Jan 30, 2019 10:20 pm
Forum: Ideal Gases
Topic: atm vs. bar?
Replies: 23
Views: 289

Re: atm vs. bar?

On the test I used bar and it was fine
by Karina Jiayu Xu 4E
Fri Jan 25, 2019 10:00 pm
Forum: Ideal Gases
Topic: Ideal Gas Law
Replies: 7
Views: 93

Re: Ideal Gas Law

for conversion between concentration and pressure? I'm not really sure.
by Karina Jiayu Xu 4E
Fri Jan 25, 2019 9:53 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Increasing Pressure
Replies: 3
Views: 56

Re: Increasing Pressure

an increase in pressure would shift the reaction towards the side with less moles.
by Karina Jiayu Xu 4E
Sun Jan 20, 2019 8:30 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Is it an acid or a base?
Replies: 8
Views: 101

Re: Is it an acid or a base?

You can also look for any part of the compound that has a strong dipole moment, bc that can usually tell you where an extra hydrogen can go
by Karina Jiayu Xu 4E
Sun Jan 20, 2019 8:20 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: The Conjugate Seesaw
Replies: 13
Views: 126

Re: The Conjugate Seesaw

Because Ka and Kb have inverse relationships since Kw is a constant
by Karina Jiayu Xu 4E
Sun Jan 20, 2019 8:16 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium and Volume
Replies: 2
Views: 35

Re: Equilibrium and Volume

wait why does the first part happen?
by Karina Jiayu Xu 4E
Sat Jan 12, 2019 6:49 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium constant
Replies: 4
Views: 34

Re: Equilibrium constant

More reactants yields more products until K reaches its original value again.
by Karina Jiayu Xu 4E
Sat Jan 12, 2019 6:47 pm
Forum: Ideal Gases
Topic: K and Q
Replies: 7
Views: 72

Re: K and Q

K is used for the exact equilibrium state and Q is used for anytime during the reaction. When they are not exactly the same then the current reaction is leaning one direction or the other.
by Karina Jiayu Xu 4E
Sat Jan 12, 2019 6:45 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Heterogeneous and homogeneous equilibria [ENDORSED]
Replies: 8
Views: 88

Re: Heterogeneous and homogeneous equilibria [ENDORSED]

Is heterogenous equilibria just a reaction at equilibrium that involves more than 1 phase?
by Karina Jiayu Xu 4E
Sat Dec 08, 2018 1:40 pm
Forum: Calculating the pH of Salt Solutions
Topic: 6d11 7th edition
Replies: 2
Views: 64

Re: 6d11 7th edition

Me too. I hope it's not on the final.
by Karina Jiayu Xu 4E
Sat Dec 08, 2018 1:35 pm
Forum: Naming
Topic: confusion name to formula
Replies: 4
Views: 61

Re: confusion name to formula

The "ate" refers to only the anion complex. But the overall charge should always be zero.
by Karina Jiayu Xu 4E
Sat Dec 08, 2018 1:32 pm
Forum: Naming
Topic: order of ligand name
Replies: 5
Views: 98

Re: order of ligand name

I think in class Dr. Lavelle said to just name them in alphabetical order.
by Karina Jiayu Xu 4E
Sat Dec 08, 2018 1:30 pm
Forum: Naming
Topic: naming compounds
Replies: 6
Views: 102

Re: naming compounds

Do we have to memorize the polydentates for the final?
by Karina Jiayu Xu 4E
Sat Dec 08, 2018 1:21 pm
Forum: Amphoteric Compounds
Topic: 7th edition 6A.17
Replies: 3
Views: 68

Re: 7th edition 6A.17

I think you can identify amphoteric compounds by just memorizing them. Basic oxides are always bound to metals, and acidic oxides alway bound to non-metals. But amphoteric oxides are usually formed by the elements in or close to the diagonal line of metalloids.
by Karina Jiayu Xu 4E
Sun Dec 02, 2018 5:53 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: AX2E2
Replies: 14
Views: 175

Re: AX2E2

Because the lone pairs are more negative than an atom, it pushes harder on the two bonded atoms, thus making the angle between them less than 109.5.
by Karina Jiayu Xu 4E
Sun Dec 02, 2018 5:51 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Dipole moment
Replies: 7
Views: 92

Re: Dipole moment

When the electronegativities of two atoms bonded are very different, the molecule will have dipole moment
by Karina Jiayu Xu 4E
Sun Dec 02, 2018 5:49 pm
Forum: Hybridization
Topic: Hybridization of pi bonds
Replies: 3
Views: 62

Re: Hybridization of pi bonds

Hybridized orbitals only occur for sigma bonds. Pi bonds take place in the leftover P orbitals.
by Karina Jiayu Xu 4E
Sun Nov 18, 2018 5:06 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone Pairs
Replies: 8
Views: 104

Re: Lone Pairs

Lone pairs are considered to be more repulsive (more negative) and it pushes on the bound atoms.
by Karina Jiayu Xu 4E
Sun Nov 18, 2018 4:54 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Square Planar vs Tetrahedral
Replies: 8
Views: 102

Re: Square Planar vs Tetrahedral

So does square planar molecules have AX4E2 and tetrahedral just Ax4?
by Karina Jiayu Xu 4E
Sun Nov 18, 2018 4:52 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Angular vs Bent
Replies: 4
Views: 66

Re: Angular vs Bent

They are the same thing. They both describe central molecules with two atoms bound and one pair of lone pair electrons.
by Karina Jiayu Xu 4E
Sun Nov 11, 2018 9:53 pm
Forum: Resonance Structures
Topic: Drawing resonance
Replies: 17
Views: 266

Re: Drawing resonance

Wait how do you know if there will be resonance structures on a molecule?
by Karina Jiayu Xu 4E
Sun Nov 11, 2018 9:41 pm
Forum: Dipole Moments
Topic: Dipole Moments
Replies: 4
Views: 46

Re: Dipole Moments

Basically molecules with atoms that differ largely in terms of electronegativity should have dipole moments
by Karina Jiayu Xu 4E
Sun Nov 11, 2018 9:38 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Stable Condition
Replies: 8
Views: 208

Re: Stable Condition

I might be wrong but I think Dr. Lavelle said that the molecule is the most stable when the FC is equal to 0
by Karina Jiayu Xu 4E
Fri Nov 02, 2018 8:26 pm
Forum: Photoelectric Effect
Topic: Chem Test 2, #5 b
Replies: 4
Views: 124

Re: Chem Test 2, #5 b

I got credit by saying that atoms have discrete energy levels. I hope that helps
by Karina Jiayu Xu 4E
Fri Nov 02, 2018 8:21 pm
Forum: Ionic & Covalent Bonds
Topic: Midterm study
Replies: 7
Views: 197

Re: Midterm study

Is there a face book group chat?
by Karina Jiayu Xu 4E
Fri Nov 02, 2018 8:18 pm
Forum: Ionic & Covalent Bonds
Topic: Non-polar and Polar Covalent Bonds
Replies: 3
Views: 52

Re: Non-polar and Polar Covalent Bonds

If a covalently bonded molecule is symmetrical it is polar.
by Karina Jiayu Xu 4E
Sun Oct 28, 2018 1:24 pm
Forum: Photoelectric Effect
Topic: Work Function
Replies: 14
Views: 290

Re: Work Function

Is the work function the same as the threshold energy?
by Karina Jiayu Xu 4E
Sun Oct 28, 2018 1:22 pm
Forum: Photoelectric Effect
Topic: Test 2
Replies: 16
Views: 291

Re: Test 2

Does anyone know if Test 2 will be curved?
by Karina Jiayu Xu 4E
Sun Oct 28, 2018 1:21 pm
Forum: Photoelectric Effect
Topic: UA practice problem frequency of light
Replies: 3
Views: 247

Re: UA practice problem frequency of light

Can someone explain what a work function is? I think i got that wrong on the test because i thought a work function was work as a function of time.
by Karina Jiayu Xu 4E
Fri Oct 19, 2018 8:57 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Equation
Replies: 6
Views: 117

Re: Equation

Is there a reason why they use pie?
by Karina Jiayu Xu 4E
Fri Oct 19, 2018 8:55 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Nodal Planes [ENDORSED]
Replies: 4
Views: 106

Re: Nodal Planes [ENDORSED]

I think it’s just where you’ll never find electrons
by Karina Jiayu Xu 4E
Fri Oct 19, 2018 8:54 pm
Forum: Properties of Electrons
Topic: Questions about the energy level [ENDORSED]
Replies: 3
Views: 108

Questions about the energy level [ENDORSED]

Can someone explain the relationship between energy level (n) and energy?
I think they’re inversely related but I’m not sure how it works conceptually..
by Karina Jiayu Xu 4E
Sat Oct 13, 2018 9:03 pm
Forum: Balancing Chemical Reactions
Topic: Test 1 and Future Tests
Replies: 5
Views: 152

Re: Test 1 and Future Tests

Anton said to always write all the steps out so if your final answer is incorrect, he can still trace back and give you partial points.
by Karina Jiayu Xu 4E
Sat Oct 13, 2018 9:01 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: diatomic elements
Replies: 12
Views: 368

Re: diatomic elements

Does anyone know what order to put the elements in when writing an empirical formula?
by Karina Jiayu Xu 4E
Sat Oct 13, 2018 8:59 pm
Forum: Significant Figures
Topic: sig fig calculations
Replies: 3
Views: 157

Re: sig fig calculations

Do you use the least number of significant digits from the given values for your answer?
by Karina Jiayu Xu 4E
Fri Oct 05, 2018 12:22 am
Forum: General Science Questions
Topic: Rusty on High School Chem [ENDORSED]
Replies: 113
Views: 34806

Re: Rusty on High School Chem [ENDORSED]

I took regular chemistry in my sophomore year and here I am three years later taking 14A. I've been watching crash course videos, and that has helped a ton.
by Karina Jiayu Xu 4E
Fri Oct 05, 2018 12:09 am
Forum: Significant Figures
Topic: sig figs urgent question!
Replies: 12
Views: 359

Re: sig figs urgent question!

1.001 would have 4 significant figures. As the last post says, it depends on whether there's a decimal or not. For example, 100 has only 1 significant figure, but 100. has 3.
by Karina Jiayu Xu 4E
Fri Oct 05, 2018 12:01 am
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student [ENDORSED]
Replies: 96
Views: 29368

Re: Advice from a Medical Student [ENDORSED]

Asheley thank you so much!
I was wondering when pre-med students should start studying for the MCAT? Also, what kind of chemistry is on the test?

Go to advanced search