Search found 59 matches

by alex_4l
Sun Jan 12, 2020 11:27 pm
Forum: Ideal Gases
Topic: Law of Mass Action
Replies: 3
Views: 31

Re: Law of Mass Action

The Law of Mass Action is the principle that the rate of a chemical reaction is proportional to the masses of the reacting substances. Relating that to chemical equilibrium, the Law states that "if the system is at equilibrium at a given temp, then the following ratio is a constant." It's ...
by alex_4l
Sun Jan 12, 2020 11:18 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5G.9
Replies: 3
Views: 24

Re: 5G.9

Do you want the answers to this or is there some particular part of the problem you don't understand?
by alex_4l
Sun Jan 12, 2020 11:16 pm
Forum: Ideal Gases
Topic: Q vs. K
Replies: 10
Views: 21

Re: Q vs. K

Q and K are similar in the sense that they are calculated the same way with products divided by reactants. They are different however with K being the equilibrium constant and Q being the reaction quotient. Q happens at any time during the reaction and K is the overall equilibrium
by alex_4l
Sun Jan 12, 2020 11:11 pm
Forum: Ideal Gases
Topic: Topics for Test 1
Replies: 14
Views: 63

Re: Topics for Test 1

Also to help with studying if you haven't taken a class with this professor yet, I would suggest doing all the homework problems to those sections, they help a lot!
by alex_4l
Sun Jan 12, 2020 11:10 pm
Forum: Ideal Gases
Topic: Topics for Test 1
Replies: 14
Views: 63

Re: Topics for Test 1

My TA said the test would mainly be on the first two sections on the syllabus, "chemical equilibrium and acid/bases equilibria"
by alex_4l
Sun Dec 08, 2019 8:46 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Really helpful videos!
Replies: 1
Views: 21

Re: Really helpful videos!

Thank you so much! That was actually really informative
by alex_4l
Sun Dec 08, 2019 8:44 pm
Forum: Resonance Structures
Topic: Best Resonance Structure
Replies: 5
Views: 53

Re: Best Resonance Structure

The goal is always to make the charge of each atom in the Lewis Structure to be closest to 0, so the best resonance structure is when the atoms are closest to 0 but if that's not possible just try to get the central atom to 0
by alex_4l
Sun Dec 08, 2019 8:39 pm
Forum: Student Social/Study Group
Topic: Final discussion
Replies: 4
Views: 65

Re: Final discussion

I hated that question it took me so long to remember it from lecture. Will that be more emphasized in 14B?
by alex_4l
Sun Dec 08, 2019 8:33 pm
Forum: Amphoteric Compounds
Topic: Memorization?
Replies: 4
Views: 55

Re: Memorization?

It's always helpful to memorize but I don't think it's necessary
by alex_4l
Sun Dec 08, 2019 8:30 pm
Forum: General Science Questions
Topic: Grades
Replies: 5
Views: 74

Re: Grades

Alexa Hernandez 3k wrote:See your grade on my UCLA, add the pints and then divide by 500 points...


That's what I've been doing and it's been really helpful
by alex_4l
Sun Dec 08, 2019 8:15 pm
Forum: Dipole Moments
Topic: Hydrogen bonds
Replies: 5
Views: 36

Re: Hydrogen bonds

You can also look at the number of lone pairs on N,O or F atoms
by alex_4l
Sun Dec 08, 2019 8:14 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Stronger acid?
Replies: 9
Views: 73

Re: Stronger acid?

In regards to bond strength, HCLO2 stronger because of the types of bonds in the lewis structure (ex: double, single) or because of the bond angles?
by alex_4l
Sun Dec 08, 2019 8:06 pm
Forum: Student Social/Study Group
Topic: Study Tips
Replies: 58
Views: 727

Re: Study Tips

I've been watching youtube videos that pertain to specific topics I'm confused about. Sometimes it's tricky to find really good ones but I find it really helpful to see someone else explain specific topics I need review on since you can rewatch them. this is what helped me the most!! Kaplan videos ...
by alex_4l
Sun Dec 08, 2019 8:04 pm
Forum: Biological Examples
Topic: Cisplatin
Replies: 17
Views: 98

Re: Cisplatin

Cisplatin also does this by replacing something in the guanine molecule with a water molecule so that DNA synthesis cannot occur
by alex_4l
Sun Dec 08, 2019 8:01 pm
Forum: Hybridization
Topic: hybridization
Replies: 5
Views: 36

Re: hybridization

Also an easy trick is just to count the number of electron density areas around an atom. 4 areas is sp^3, 3 areas is sp2, 2 is sp
by alex_4l
Sun Dec 01, 2019 7:38 pm
Forum: Administrative Questions and Class Announcements
Topic: Final Exam
Replies: 3
Views: 34

Re: Final Exam

I'm pretty sure the final will mostly be on new topics we've learned with some fewer questions about the other things we've already been tested on. I would focus studying on new topics and just refresh yourself on the old material
by alex_4l
Sun Dec 01, 2019 7:36 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: The pH Scale
Replies: 7
Views: 57

Re: The pH Scale

My TA discussed the different aspects of pH that I think would be useful to understand for the final
pH -log [H+]
pH -log[OH-]
Ka= acid dissociation constant
Kb= base dissociation constant
PKa= -logKa
Pkb= -logKb
Kw= Ka X Kb (H+ X OH-)
and that pH + pOH will always = 14
by alex_4l
Sun Dec 01, 2019 7:20 pm
Forum: Hybridization
Topic: steric number
Replies: 2
Views: 24

Re: steric number

The steric number is the amount of atoms plus the number of long pairs bonded/attached to the central atom used in VSEPR to determine molecular geometry
by alex_4l
Sun Dec 01, 2019 7:19 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: pH of Weak Acid and Bases
Replies: 4
Views: 26

Re: pH of Weak Acid and Bases

I think you first calculate the pH using -log(10) of either [H+] or [OH-] and then determine if the acid or base is weak or strong. Closer to 7 would be a weak acid (since 1 is the strongest acid) and closer to 7 would be a weak base (since 10 is the strongest base)
by alex_4l
Sun Dec 01, 2019 6:57 pm
Forum: General Science Questions
Topic: Week 10 Classes
Replies: 7
Views: 61

Re: Week 10 Classes

Is our final on the 8th or 9th?
by alex_4l
Sun Nov 24, 2019 9:57 pm
Forum: Biological Examples
Topic: Cisplatin
Replies: 17
Views: 98

Re: Cisplatin

it's a form or chemotherapy to stop the growth of cancer cells, unfortunately it also impacts the healthy cells from multiplying. It usually impacts healthy cells that multiply quickly, such as hair and blood cells.
by alex_4l
Sun Nov 24, 2019 9:52 pm
Forum: Lewis Acids & Bases
Topic: When is an acid considered Bronsted?
Replies: 9
Views: 59

Re: When is an acid considered Bronsted?

Bronstead acids is when the acid is a proton donor and a Lewis acid is an acid that accepts the electron pair
by alex_4l
Sun Nov 24, 2019 9:49 pm
Forum: General Science Questions
Topic: Week 9 HW
Replies: 6
Views: 56

Re: Week 9 HW

I think it's the homework problems in the molecular shape and structure section that involve hybridization (since we didn't have that on test 2) and the last 2 sections of homework problems on the syllabus
by alex_4l
Sun Nov 24, 2019 9:25 pm
Forum: Naming
Topic: Week 9 and Week 10 HW?
Replies: 21
Views: 131

Re: Week 9 and Week 10 HW?

Does that mean that our discussions are cancelled this week?
by alex_4l
Sun Nov 24, 2019 9:24 pm
Forum: Hybridization
Topic: hybridization
Replies: 5
Views: 36

Re: hybridization

Hybridization is basically the concept of mixing atomic orbitals into new hybrid orbitals (these can have new energies, shapes different from the component atomic orbitals) which then make it suitable for the pairing of electrons to form chemical bonds. The regions of electron density = the number o...
by alex_4l
Sun Nov 17, 2019 11:40 pm
Forum: Administrative Questions and Class Announcements
Topic: test 2
Replies: 7
Views: 56

Re: test 2

Does anyone what day the cutoff of lecture material will be?
by alex_4l
Sun Nov 17, 2019 11:37 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 9
Views: 40

Re: Bond Angles

I made a quizlet for the angles in relation to shapes and that has really helped me so far!
by alex_4l
Sun Nov 17, 2019 11:35 pm
Forum: Trends in The Periodic Table
Topic: electron affinity
Replies: 7
Views: 50

Re: electron affinity

electron affinity, ionization energy and electronegativity all follow the same trend of increasing upward and to the right, the only one that's different is size/radius which is downwards and to the left
by alex_4l
Sun Nov 17, 2019 11:17 pm
Forum: Student Social/Study Group
Topic: Study Tips
Replies: 58
Views: 727

Re: Study Tips

Khan academy videos are super helpful! I also go to the Step Up programs that are taught by the TAs as well as office hours which are really beneficial as well. I've also found that just reading through the posts on chemistry community provides a lot of insight on topics that I don't understand or n...
by alex_4l
Sun Nov 10, 2019 9:19 pm
Forum: Octet Exceptions
Topic: incomplete octet
Replies: 6
Views: 51

Re: incomplete octet

You mean like one of the exceptions of a bond with electron deficiency?
by alex_4l
Sun Nov 10, 2019 9:11 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: Test 2
Replies: 6
Views: 41

Re: Test 2

I'm pretty sure that it covers post-midterm information! But does anyone know if the final is cumulative or just topics after test 2?
by alex_4l
Sun Nov 10, 2019 9:03 pm
Forum: Student Social/Study Group
Topic: chem 14b + cehm14bl
Replies: 9
Views: 65

Re: chem 14b + cehm14bl

You don't have to take 14B and 14BL together! I know plenty of people who are taking them different quarters apart. If you're deciding between either 14B/14BL or 14C/14BL I would say 14B/14BL since they're similar topics that would correspond with each other better than two different aspects of chem...
by alex_4l
Sun Nov 10, 2019 9:01 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polar vs covalent
Replies: 7
Views: 31

Re: Polar vs covalent

Adding on to this, if two elements are on opposite sides of one another on the periodic table, they most likely will be ionic due to the size as well since the bigger element would be dominating the bond over the smaller one
by alex_4l
Sun Nov 10, 2019 8:46 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: Fluctuating Dipoles
Replies: 5
Views: 23

Re: Fluctuating Dipoles

I understand the concept of the fluctuating dipole due to the spontaneity of the electrons and their movement. However, how would this impact the way that we write out an example of the dipole on a test or a homework problem? Would it stay the same and we just have to know the concept or would we ha...
by alex_4l
Sun Nov 03, 2019 10:58 pm
Forum: Dipole Moments
Topic: Exceptions for Polarity
Replies: 1
Views: 25

Exceptions for Polarity

Here's some rules for polarity and exceptions of when it's non-polar. Hope this helps! Everything can be considered a polar bond except for two instances 1) carbon and hydrogen bond (not polar mostly just equal sharing of electrons) 2) atom bonded to the identical atom (no difference in electronegat...
by alex_4l
Sun Nov 03, 2019 10:50 pm
Forum: Coordinate Covalent Bonds
Topic: Atom Sharing
Replies: 5
Views: 47

Re: Atom Sharing

Could someone post an example of a coordinate covalent bond and a regular covalent bond?
by alex_4l
Sun Nov 03, 2019 7:38 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal charge purpose
Replies: 40
Views: 1676

Re: Formal charge purpose

On a test, will it specify that we need to calculate the formal charge or should we do it either way just to be sure?
by alex_4l
Sun Nov 03, 2019 7:21 pm
Forum: Properties of Light
Topic: Waves/Particles
Replies: 14
Views: 122

Re: Waves/Particles

Malia Shitabata 3H wrote:So the photons are acting as particles when emitted in the photoelectric effect, but I also wrote in my notes that electrons act as waves. Does it acts as both a wave and a particle or did I misunderstand the lecture?

They can behave as both given the circumstance
by alex_4l
Sun Nov 03, 2019 6:05 pm
Forum: Dipole Moments
Topic: Polarity
Replies: 4
Views: 30

Re: Polarity

Also, if the Lewis Structure contains all the same elements then the molecule is nonpolar, but if there is just one difference it can be polar. For example, if there are 4 Cl attached to a centered Cl, that would have polar bonds but be a nonpolar molecule. But if there are 4 Cl attached to a center...
by alex_4l
Sun Oct 27, 2019 9:29 pm
Forum: Lewis Structures
Topic: Lewis Structure Rules
Replies: 2
Views: 35

Re: Lewis Structure Rules

Follow up, there's 2 things to make sure you check when drawing a Lewis Structure in order to make sure it's correct 1) looking back at total of electrons count to make sure the total has been presented in the structure 2) each atom must have 8 electrons (doesn't matter about single or multiple bond...
by alex_4l
Sun Oct 27, 2019 9:24 pm
Forum: Lewis Structures
Topic: Lewis Structure Rules
Replies: 2
Views: 35

Lewis Structure Rules

Here's some general rules for drawing Lewis Structures! 1) Write the correct skeletal structure for the molecule -hydrogen atoms will always be terminal (outside) -many molecules tend to be symmetrical ***the least electronegative atoms is ALWAYS the central atom 2) calculate the total number of ele...
by alex_4l
Sun Oct 27, 2019 9:02 pm
Forum: Octet Exceptions
Topic: Exceptions
Replies: 10
Views: 435

Re: Exceptions

Going off of that, I know 4 specific chemical structures that have the octet rule (numbers 1/2 are electron deficient exceptions with less than 8 electrons and 3/4 have expanded octets with more than 8 electrons) 1) NO N has 5 electrons, O has 6 electrons which totals in 11 electrons. Usually every ...
by alex_4l
Thu Oct 24, 2019 12:05 pm
Forum: DeBroglie Equation
Topic: Question about Problem done in Discussion
Replies: 2
Views: 152

Re: Question about Problem done in Discussion

I understand the equations and when to use them, I just don't understand why 10 was chosen as the value for V in the last equation and why it wasn't the number we had gotten for it in the earlier equation.
by alex_4l
Sun Oct 20, 2019 6:54 pm
Forum: Properties of Electrons
Topic: Angstrom Conversion
Replies: 12
Views: 102

Re: Angstrom Conversion

Would it be possible for someone to post a worked out example of converting something to angstrom? I just want to make sure I'm doing the conversion correctly, thank you! For example, if you wanted to convert 1.91 meters into Angstroms, you would do 1.91m*(10^-10 Angstroms/1m), which equals 1.91x10...
by alex_4l
Sun Oct 20, 2019 6:17 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Tips for Subshells
Replies: 4
Views: 29

Re: Tips for Subshells

Amina Durrani 3G wrote:Wait, why can you only use a noble gas again? I’m little confused.


It's because those are the only elements on the periodic table that have a complete shell with no valence electrons on the end, so they are the core electron used!
by alex_4l
Sun Oct 20, 2019 6:15 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Tips for Subshells
Replies: 4
Views: 29

Re: Tips for Subshells

This is a table I've used in the past that sort of explains subshell letters in correlation to electron shells, it's super simple but I hope this helps! Shell # of Subshells Letters Specifying Subshells n=4 4 s, p, d, f n=3 3 s, p , d n=2 2 s, p n=1 1 s
by alex_4l
Sun Oct 20, 2019 6:08 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Tips for Subshells
Replies: 4
Views: 29

Tips for Subshells

In class, we had a problem where wrote out the electron configuration for Calcium. Instead of doing the whole electron configuration, we wrote [Ar] 4s^2. A few people next to me were confused about this so I thought I'd explain why. This method is a sort of shortcut for writing out electron configur...
by alex_4l
Sun Oct 20, 2019 5:51 pm
Forum: Properties of Electrons
Topic: Angstrom Conversion
Replies: 12
Views: 102

Re: Angstrom Conversion

Would it be possible for someone to post a worked out example of converting something to angstrom? I just want to make sure I'm doing the conversion correctly, thank you!
by alex_4l
Sun Oct 20, 2019 5:47 pm
Forum: DeBroglie Equation
Topic: Question about Problem done in Discussion
Replies: 2
Views: 152

Question about Problem done in Discussion

In discussion 4C this past week, we did an equation and I was a little confused with one of the steps the question was "green color appears when visible light has a wavelength of 780nm, what will E=,V= and V-=?" for this problem we used E=hc/sigma to get 6.626x10^-34JS x 3x10^8m.s^-1/ 780x...
by alex_4l
Thu Oct 10, 2019 7:20 pm
Forum: Einstein Equation
Topic: Planck's constant
Replies: 9
Views: 127

Re: Planck's constant

This equation also shows that energy is directly proportional to frequency! The equation E=hc/lambda shows that energy is indirectly proportional to wavelength.
by alex_4l
Thu Oct 10, 2019 7:16 pm
Forum: Properties of Electrons
Topic: electron energy [ENDORSED]
Replies: 7
Views: 56

Re: electron energy [ENDORSED]

Just to add on, when an electron goes up a level, let's say from n=2--->n=5, there is a "relaxation" and light emission. The opposite, when an electron goes from n=5--->n=2 there is an "excitation" and energy absorption. An electron can only exist on one orbit or another, not mul...
by alex_4l
Thu Oct 10, 2019 7:03 pm
Forum: Properties of Light
Topic: Waves/Particles
Replies: 14
Views: 122

Re: Waves/Particles

To add on, one of my chemistry professors had a really good explanation for what a photon is: A photon is a discrete bundle of energy (we can think of it as a single packet of light or energy). Light (is a wave) acting as IF it were a particle. The amount of energy carried in the packet depends on t...
by alex_4l
Thu Oct 10, 2019 6:48 pm
Forum: Properties of Light
Topic: Clarification on Frequency
Replies: 8
Views: 86

Re: Clarification on Frequency

Also just to add on! Shorter wavelengths have a higher frequency and a greater energy (this would be things like purple light) Longer wavelengths have a lesser frequency and not as strong of energy (this would be red light) As energy increases, frequency increases since they are proportional to each...
by alex_4l
Thu Oct 10, 2019 6:36 pm
Forum: Limiting Reactant Calculations
Topic: Difference Between Limiting Reagent/ Reactant
Replies: 1
Views: 47

Difference Between Limiting Reagent/ Reactant

I was a little confused on the difference between the limiting reagent and reactant and I figured maybe other people were as well, so I have some reminders of the differences! Limiting Reactant: limiting amount of product that can be made. This is done by looking at the lowest amount you have in ord...
by alex_4l
Thu Oct 03, 2019 12:17 am
Forum: Significant Figures
Topic: General Rules to Help with Sig Figs
Replies: 18
Views: 197

Re: General Rules to Help with Sig Figs

Also, if you end with an answer of let's say-- .00056 and you want to put it in scientific notation, you would want to put that answer in the amount of significant figures of the number in the equation with the least amount of sig figs. So for example: (7.45 x 3) divided by (5.7 x 10^6) 7.45 has thr...
by alex_4l
Thu Oct 03, 2019 12:07 am
Forum: Significant Figures
Topic: General Rules to Help with Sig Figs
Replies: 18
Views: 197

Re: General Rules to Help with Sig Figs

I am confused as to when to apply sig figs. Should I apply them throughout my problem at each step, or just at the end? You apply them at the end with your final answer, don't worry about doing it throughout the problem. In lab with measurements, the last digit is always the estimated one in order ...
by alex_4l
Thu Oct 03, 2019 12:06 am
Forum: Significant Figures
Topic: General Rules to Help with Sig Figs
Replies: 18
Views: 197

Re: General Rules to Help with Sig Figs

Will we be penalized if we use more significant figures than needed? You might be penalized in a lab since it is more important with the measurements, I'm not sure what our professor deems to be okay with for significant figures and how strict it is, but when solving a problem you want your answer ...
by alex_4l
Thu Oct 03, 2019 12:03 am
Forum: Significant Figures
Topic: General Rules to Help with Sig Figs
Replies: 18
Views: 197

Re: General Rules to Help with Sig Figs

@KayleyW_3L
That was a typo on my end! it should be 4 significant figures for number 1, sorry for the confusion :)
by alex_4l
Tue Oct 01, 2019 8:29 pm
Forum: Significant Figures
Topic: General Rules to Help with Sig Figs
Replies: 18
Views: 197

General Rules to Help with Sig Figs

I have a few general rules that help me with counting significant figures, I can give more detailed ones for subtracting, adding, multiplying, etc if anyone needs them. 1) all non zero digits are significant ---example) 52931 has 5 significant figures, as does 17.333 2) interior zeros (ones that are...

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