Search found 61 matches

by Ashley Fang 2G
Mon Jan 13, 2020 10:03 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Which liquids to use
Replies: 7
Views: 25

Re: Which liquids to use

We never use pure solids (s) or liquids (l) in calculating equilibrium, but we do use gaseous (g) and aqueous (aq) substances. Maybe he was referring to the liquid concentration in the aqueous substance.
by Ashley Fang 2G
Mon Jan 13, 2020 9:38 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Question from discussion section
Replies: 1
Views: 38

Re: Question from discussion section

First find the initial concentrations of A and B by dividing moles of A and B by the overall volume (6L). Then plug this information along with the equilibrium concentration of A into the ICE table. Assuming they give you the equilibrium constant, you should then be able to find x, which will in tur...
by Ashley Fang 2G
Mon Jan 13, 2020 9:32 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Change in Pressure
Replies: 6
Views: 14

Re: Change in Pressure

When the pressure of a system is decreased, a quick way to determine which direction the reaction will shift is seeing which side has the greater number of moles. The side with the greater number of moles will be favored. Conversely, when the pressure of a system is increased, the side with the fewe...
by Ashley Fang 2G
Mon Jan 13, 2020 9:30 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5G.9
Replies: 4
Views: 33

Re: 5G.9

DesireBrown1J wrote:For c, would the 2nd container with 0.50 mol O3 have a larger ratio of PO2/PO3 because it has a greater overall partial pressure?


I'm not completely sure as I think we would need more information in order to calculate the ratio PO2/PO3
by Ashley Fang 2G
Mon Jan 13, 2020 9:26 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K and Q
Replies: 6
Views: 13

Re: K and Q

To add to that, by solving for Q and comparing it to K, you can see what direction the reaction will proceed.
If Q<K, the reaction will proceed to the right (products side).
If Q>K, the reaction will proceed to the left (reactants side).
If Q=K, the reaction is at equilibrium.
by Ashley Fang 2G
Thu Jan 09, 2020 1:47 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Value of Kc and Kp
Replies: 6
Views: 28

Re: Value of Kc and Kp

Bryce Barbee wrote:Can someone please explain to me how to ask a question on Chem Community. I cannot figure it out. Thanks


Go back one page and scroll to the top. You should see a "new topic" button with a star next to it
by Ashley Fang 2G
Thu Jan 09, 2020 1:40 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5G. 3
Replies: 5
Views: 31

Re: 5G. 3

For gases, we can use either pressure or concentration (Kp or Kc), but for aqueous solutions, we can only use concentration to find Kc.
by Ashley Fang 2G
Thu Jan 09, 2020 12:10 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Chemical Activity of a Compound
Replies: 5
Views: 26

Re: Chemical Activity of a Compound

The chemical activity of a compound is equal to [compound]/[compound] ° where ° stands for its standard value. This usually cancels out to equal 1. Therefore, we just leave out the chemical activity of a compound when writing out the Kc equation and just use the values for concentration (ignoring th...
by Ashley Fang 2G
Thu Jan 09, 2020 12:04 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5G.9
Replies: 4
Views: 33

Re: 5G.9

PO2/PO3 will be different because the ratio of the reactant to the product is different at equilibrium point for different amounts of starting reactant.
Only (PO2)^3/(PO3)^2 or (PO3)^2/(PO2)^3 are guaranteed to be the same because they are the equilibrium constant and the inverse of it.
by Ashley Fang 2G
Thu Jan 09, 2020 11:57 am
Forum: Ideal Gases
Topic: Review Ideal Gases
Replies: 6
Views: 50

Re: Review Ideal Gases

Chemmybear also has links to a bunch of resources, strongly recommend!

https://chemmybear.com/
by Ashley Fang 2G
Mon Dec 02, 2019 1:43 am
Forum: Conjugate Acids & Bases
Topic: Strength of Conjugate Acids and Bases
Replies: 3
Views: 29

Re: Strength of Conjugate Acids and Bases

Similarly, conjugate acids of strong bases are weak.
by Ashley Fang 2G
Mon Dec 02, 2019 1:41 am
Forum: Conjugate Acids & Bases
Topic: conjugate acids/bases
Replies: 4
Views: 34

Re: conjugate acids/bases

A conjugate acid is a base with a hydrogen ion added to it.
A conjugate base is what is left over after an acid has donated a proton during a chemical reaction.
by Ashley Fang 2G
Mon Dec 02, 2019 1:34 am
Forum: Polyprotic Acids & Bases
Topic: Polyprotic acids and bases
Replies: 2
Views: 19

Re: Polyprotic acids and bases

Polyprotic acids are acids that can lose more than one proton per molecule in acid-base reactions. Examples: H2SO4, H2CO3 Polyprotic bases are bases that can accept more than one proton per molecule in acid-base reactions. Examples: [SO4]2-, [CO3]2- In titration curves, they will have multiple equiv...
by Ashley Fang 2G
Mon Dec 02, 2019 1:05 am
Forum: Amphoteric Compounds
Topic: Amphoteric Compounds
Replies: 2
Views: 14

Re: Amphoteric Compounds

It can only act as an acid or a base one at a time.
An example would be water either accepting or donating a hydrogen ion.
by Ashley Fang 2G
Mon Dec 02, 2019 1:03 am
Forum: Amphoteric Compounds
Topic: Determining Acidic or Basic
Replies: 2
Views: 18

Re: Determining Acidic or Basic

An amphoteric compound can be either an acid or a base, but only one at a time.
It can either accept or donate a hydrogen ion.
by Ashley Fang 2G
Mon Nov 25, 2019 9:40 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular shape and central atom
Replies: 3
Views: 41

Re: Molecular shape and central atom

Here's a diagram to make it easier to visualize
by Ashley Fang 2G
Mon Nov 25, 2019 9:37 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular shape and central atom
Replies: 3
Views: 41

Re: Molecular shape and central atom

To determine its shape from using VSEPR, you would just have to count the number of bonding pairs and lone pairs it has and match it to its corresponding molecular geometry.
by Ashley Fang 2G
Mon Nov 25, 2019 9:33 am
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: bond order
Replies: 4
Views: 48

Re: bond order

It can also be defined as half of the difference between the number of bonding and antibonding electrons.
by Ashley Fang 2G
Mon Nov 25, 2019 9:31 am
Forum: Hybridization
Topic: Examples of Hybridization
Replies: 2
Views: 22

Re: Examples of Hybridization

Yes, this is because octahedral structures have 6 electron domains
by Ashley Fang 2G
Mon Nov 25, 2019 9:29 am
Forum: Hybridization
Topic: Are terminal atoms hybridized?
Replies: 2
Views: 25

Re: Are terminal atoms hybridized?

In the case of CS2, the S atoms have 1 double bond with C and 2 lone pairs, so it would also have 3 electron domains and yes it would be hybridized to sp2 as well.
As for terminal atoms that are halogens, it just depends again on counting the number of electron domains the atoms have.
by Ashley Fang 2G
Mon Nov 18, 2019 12:21 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7742
Views: 1060730

Re: Post All Chemistry Jokes Here

Think like a proton and be positive!
by Ashley Fang 2G
Mon Nov 18, 2019 12:19 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7742
Views: 1060730

Re: Post All Chemistry Jokes Here

hahaha
by Ashley Fang 2G
Mon Nov 18, 2019 12:18 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7742
Views: 1060730

Re: Post All Chemistry Jokes Here

What kind of dogs do chemists have?

Laboratory retrievers!
by Ashley Fang 2G
Mon Nov 18, 2019 12:15 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Test 2
Replies: 6
Views: 39

Re: Test 2

also it's not cumulative nor will it include hybridization
by Ashley Fang 2G
Mon Nov 18, 2019 12:04 am
Forum: Student Social/Study Group
Topic: Bond Angles
Replies: 6
Views: 38

Re: Bond Angles

I believe notating it as <109.5 degrees is fine, but if asked you should still know that H2O has a smaller bond angle because of its 2 lone pair-lone pair repulsions, compared to just 1 in NH3.
by Ashley Fang 2G
Mon Nov 11, 2019 5:54 pm
Forum: Student Social/Study Group
Topic: Chem 14B
Replies: 10
Views: 84

Re: Chem 14B

I'm taking chem 14B as well next quarter!
But I heard 14BL is better taken with 14C or after 14C if possible because of the level of knowledge you're expected to know.
by Ashley Fang 2G
Mon Nov 11, 2019 5:48 pm
Forum: Dipole Moments
Topic: Dipole Moment
Replies: 6
Views: 33

Re: Dipole Moment

To add to that, the arrow always points to the lowercase delta negative sign, and a line strikes through the arrow at the lowercase delta positive sign (making a cross or a "+" to help you remember it)
by Ashley Fang 2G
Mon Nov 11, 2019 5:30 pm
Forum: Electronegativity
Topic: Formula for Difference
Replies: 7
Views: 48

Re: Formula for Difference

If anything, the electronegativity values will be given if on a test.
The trends are increasing as you go up a column and also to the right across a period.
by Ashley Fang 2G
Mon Nov 11, 2019 5:28 pm
Forum: *Liquid Structure (Viscosity, Surface Tension, Liquid Crystals, Ionic Liquids)
Topic: Bonds vs Shapes [ENDORSED]
Replies: 4
Views: 271

Re: Bonds vs Shapes [ENDORSED]

To add to that, the dipoles can get closer together due to the greater surface area in rod-shaped molecules than spherical-shaped molecules, thus increasing the intermolecular forces.
by Ashley Fang 2G
Mon Nov 11, 2019 5:24 pm
Forum: *Liquid Structure (Viscosity, Surface Tension, Liquid Crystals, Ionic Liquids)
Topic: Polarizability and States
Replies: 3
Views: 44

Re: Polarizability and States

The greater the molecular mass, the greater the electron cloud distortion and polarizability. London dispersion forces tend to be stronger between molecules that are easily polarized. Thus, with a higher intermolecular force, the melting point/boiling point will also tend to be higher because more e...
by Ashley Fang 2G
Tue Nov 05, 2019 12:03 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Why is it 4f14 if there are 15 elements in that row
Replies: 2
Views: 83

Re: Why is it 4f14 if there are 15 elements in that row

Lanthanum is actually the first element of the 5d orbital, cerium through lutetium would be part of the f block
by Ashley Fang 2G
Mon Nov 04, 2019 12:40 am
Forum: Electronegativity
Topic: Electronegativity Ex.
Replies: 2
Views: 22

Re: Electronegativity Ex.

HCl has a greater ionic character than HI because hydrogen and chlorine's electronegativity difference is greater than that of hydrogen and iodine.
Remember that electronegativity increases right across a period and up a group!
by Ashley Fang 2G
Mon Nov 04, 2019 12:34 am
Forum: Lewis Structures
Topic: Drawing Lewis Structures
Replies: 3
Views: 35

Re: Drawing Lewis Structures

Naji Sarsam 4G wrote:2.) The charge of the central atom especially should either be 0 or negative (because it is the most electronegative atom); preferably 0 though


The central atom should be the least* electronegative atom
by Ashley Fang 2G
Mon Nov 04, 2019 12:27 am
Forum: Coordinate Covalent Bonds
Topic: Single, double, and triple bonds
Replies: 6
Views: 42

Re: Single, double, and triple bonds

The greater the electronegativity/electron affinity, the greater the pull on the electrons by the positively charged nucleus. Since fluorine is more electronegative than chlorine, the H-F single bond will be shorter than the H-Cl single bond. And as you increase the # of bonds (double, triple), you ...
by Ashley Fang 2G
Mon Nov 04, 2019 12:16 am
Forum: Lewis Structures
Topic: formal charge
Replies: 4
Views: 31

Re: formal charge

It can be calculated through FC = [# of valence electrons on atom] – [(# of lone pair electrons) + (# of shared electrons)/2]
by Ashley Fang 2G
Mon Oct 28, 2019 12:33 am
Forum: Bond Lengths & Energies
Topic: Chemical Bonds
Replies: 4
Views: 44

Re: Chemical Bonds

Picture yourself on top of a tree: you have high potential energy and are in a very unstable state.
Similarly, atoms don't like having a high potential energy; they'd rather create a bond and be stable at their lowest potential energy state.
by Ashley Fang 2G
Mon Oct 28, 2019 12:27 am
Forum: Lewis Structures
Topic: Choosing the central atom
Replies: 16
Views: 68

Re: Choosing the central atom

Ionization energy increases as you go up a column and to the right of a period. It's the energy required to remove an electron.
by Ashley Fang 2G
Mon Oct 28, 2019 12:23 am
Forum: Electronegativity
Topic: Fluorine's Electronegativity
Replies: 6
Views: 31

Re: Fluorine's Electronegativity

Adding to that, ignoring noble gases, fluorine also has little shielding effect since its electrons are close to the nucleus in the n=2 shell. Thus, the protons in the nucleus have a stronger pull on the electrons than in any other element.
by Ashley Fang 2G
Mon Oct 28, 2019 12:16 am
Forum: Electronegativity
Topic: isoelectronic atoms
Replies: 2
Views: 23

Re: isoelectronic atoms

On the contrary, I think that an atom that is isoelectronic with another atom of a fewer number of protons will attract more electrons, thus be more electronegative. Take for example N and F^2+. Although they both each have 7 electrons, fluorine will obviously attract more electrons because there is...
by Ashley Fang 2G
Mon Oct 28, 2019 12:09 am
Forum: Ionic & Covalent Bonds
Topic: Polarity
Replies: 6
Views: 37

Re: Polarity

Yes! An example of a polar covalent bond would be water (H2O), where most of the negative charge is from the oxygen on one side of the molecule and the positive charge of the hydrogen atoms is on the other side of the molecule. An example of a nonpolar covalent bond would be carbon dioxide (CO2), wh...
by Ashley Fang 2G
Mon Oct 21, 2019 12:22 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7742
Views: 1060730

Re: Post All Chemistry Jokes Here

.
by Ashley Fang 2G
Mon Oct 21, 2019 12:20 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7742
Views: 1060730

Re: Post All Chemistry Jokes Here

Hahahah
by Ashley Fang 2G
Mon Oct 21, 2019 12:15 am
Forum: Photoelectric Effect
Topic: Threshold Energy
Replies: 7
Views: 52

Re: Threshold Energy

I think that "ejected" just means that the electron is released from the atom. The detector that is used to measure the KE of the ejected electron has a slightly positive charge, thus causing it to move.
by Ashley Fang 2G
Mon Oct 21, 2019 12:09 am
Forum: Photoelectric Effect
Topic: Video module Test
Replies: 3
Views: 44

Re: Video module Test

Or, you could use the combined equations of E=hv and c=v(wavelength) to get (wavelength)=hc/E and solve for wavelength!
Hope that helps :)
by Ashley Fang 2G
Mon Oct 21, 2019 12:00 am
Forum: *Shrodinger Equation
Topic: derivation
Replies: 5
Views: 32

Re: derivation

Yupp, his constants and equations sheet can be found on his website or here

https://lavelle.chem.ucla.edu/wp-conten ... ations.pdf
by Ashley Fang 2G
Mon Oct 14, 2019 1:38 am
Forum: Student Social/Study Group
Topic: Study Group Fall 2019
Replies: 32
Views: 1394

Re: Study Group Fall 2019

Count me in! :)
by Ashley Fang 2G
Mon Oct 14, 2019 1:34 am
Forum: Student Social/Study Group
Topic: Grades
Replies: 18
Views: 193

Re: Grades

KayleyW_3L wrote:In addition to wondering when the Test 1 grades will be posted, I am also curious whether there is partial credit on the exams?


I asked my TA and there's definitely partial credit given on exams if you show your work!
by Ashley Fang 2G
Mon Oct 14, 2019 1:32 am
Forum: Student Social/Study Group
Topic: Best Sessions
Replies: 12
Views: 69

Re: Best Sessions

Generally in step-up sessions, what's the usual TA to student ratio and about how much time do they spend with each student trying to understand the concepts?
by Ashley Fang 2G
Mon Oct 14, 2019 1:28 am
Forum: Student Social/Study Group
Topic: Textbook Readings
Replies: 4
Views: 41

Textbook Readings

Do you guys find the textbook readings to be more helpful for studying or other resources such as videos/lectures? I'm asking because I don't know if I'm missing any important information that's covered in the textbook that's not covered in Dr. Lavelle's videos or lectures. I feel like what tends to...
by Ashley Fang 2G
Mon Oct 14, 2019 1:15 am
Forum: Balancing Chemical Reactions
Topic: H 1
Replies: 6
Views: 122

Re: H 1

Another tip is to generally start out balancing the element that shows up the least often in the equation and then work from there, eventually getting to elements in diatomic molecules such as H2 or O2 that stand alone and are easy to balance by themselves (just add a coefficient in front)
by Ashley Fang 2G
Mon Oct 07, 2019 9:01 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7742
Views: 1060730

Re: Post All Chemistry Jokes Here

Hohoho
by Ashley Fang 2G
Mon Oct 07, 2019 9:01 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7742
Views: 1060730

Re: Post All Chemistry Jokes Here

Yes, I am positive!
by Ashley Fang 2G
Mon Oct 07, 2019 9:00 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7742
Views: 1060730

Re: Post All Chemistry Jokes Here

The one true bro
by Ashley Fang 2G
Mon Oct 07, 2019 8:57 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7742
Views: 1060730

Re: Post All Chemistry Jokes Here

Chemistry jokes are sodium funny!
I slapped my neon that one!
by Ashley Fang 2G
Mon Oct 07, 2019 8:30 pm
Forum: Ideal Gases
Topic: Reading the textbook [ENDORSED]
Replies: 132
Views: 76583

Re: Reading the textbook [ENDORSED]

Personally I find that every time I read the textbook, I tend to fall asleep because it's just that long and boring, especially when you're new to the material. What I usually will do however is take notes of the summary and important formulas/equations. Once I have grasped the basic concepts, I wil...
by Ashley Fang 2G
Fri Oct 04, 2019 12:58 am
Forum: Properties of Light
Topic: Speed of Light
Replies: 41
Views: 899

Re: Speed of Light

Speed of light is a constant and will be given during tests/exams.
The link of the constants and equations sheet is on his website but I'll link it here!

https://lavelle.chem.ucla.edu/wp-conten ... ations.pdf
by Ashley Fang 2G
Fri Oct 04, 2019 12:54 am
Forum: Limiting Reactant Calculations
Topic: Reviewing High School Chem Tips
Replies: 10
Views: 64

Re: Reviewing High School Chem Tips

Honestly chemmybear has a lot of great resources for high school chemistry topics.
I also remember watching a lot of Bozeman videos, he explained the topics in a very easy-to-understand way.
Here are the links below!

http://chemmybear.com/
http://www.bozemanscience.com/ap-chemistry/
by Ashley Fang 2G
Fri Oct 04, 2019 12:47 am
Forum: Molarity, Solutions, Dilutions
Topic: Converting Before or After?
Replies: 10
Views: 63

Re: Converting Before or After?

Convert the units first if you're going to be canceling them out with other units. You want to make sure that like units cancel out like units. For example, you would not do 5kg x 1mol/18.02g, you would change the 5kg to 5000g first to make sure you're left with only moles when you cancel out the gr...
by Ashley Fang 2G
Fri Oct 04, 2019 12:35 am
Forum: SI Units, Unit Conversions
Topic: Etext Access for Chem Book
Replies: 3
Views: 53

Re: Etext Access for Chem Book

Hmm I'm not sure about your extext access issue in particular but if you want there's also a free pdf version you could download

https://drive.google.com/file/d/1QBq9rF ... p=drivesdk
by Ashley Fang 2G
Fri Oct 04, 2019 12:13 am
Forum: SI Units, Unit Conversions
Topic: Bond Length
Replies: 5
Views: 61

Re: Bond Length

I believe it's the distance between the nuclei of two bonded atoms in a molecule. It depends on a lot of factors and definitely varies from molecule to molecule. If the bond strength is very high, then typically you'd have a smaller bond length. If the bond strength is weak, then you'd have a longer...

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