## Search found 69 matches

Fri Jan 22, 2021 9:46 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: lecture 6 question
Replies: 2
Views: 11

### Re: lecture 6 question

Also the ka or kb must be given for you to set up the ice table. With that given you could solve for x and could get the concentrations of H+ ions, which you would -log to get the ph. Also, if you wanted to find the percent ionization, you would place (x/HA) * 100.
Wed Jan 13, 2021 11:04 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Reaction Quotient
Replies: 10
Views: 465

### Re: Reaction Quotient

The reaction quotient is basically the ratio of the products to reactants not at equilibrium (typically used when something new is added into the reaction). While the equilibrium constant is the ratio of products to reactions at equilibrium, or when the concentrations of products to reactants is con...
Wed Jan 13, 2021 11:01 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Change in volume
Replies: 4
Views: 13

### Re: Change in volume

You could also think of it this way. If there are a lot of people on one side of the room, and there are fewer people on the other side of the room, which side would you choose? More likely the less crowded side, right? This is the same way for gases. When volume decreases there is less space for th...
Wed Jan 13, 2021 10:57 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Change in K (P&T)
Replies: 9
Views: 31

### Re: Change in K (P&T)

The pressure is only important for gases. An increased pressure would favor the side with fewer moles of gases. Whereas temperature affects the equilibrium constant K. I don't know why yet, but he will teach us in the later weeks.
Wed Jan 13, 2021 10:55 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Temperature
Replies: 38
Views: 94

### Re: Temperature

The question would have to say the reaction is endothermic or exothermic, or (what is most probably going to happen) delta H is +, signifying an endothermic reaction, or delta H is negative, signifying an exothermic reaction.
Wed Jan 13, 2021 10:52 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: K in endo and exo when temp. decreases
Replies: 11
Views: 47

### Re: K in endo and exo when temp. decreases

This difference is due to the place where heat is being added in the reaction. Because heat is in the reactants side for endo, when decreased reactants are favored. On the other hand, since heat is on the product's side for exo, when decreased products are favored.
Wed Jan 13, 2021 10:49 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Pressure's effect on concentration
Replies: 4
Views: 13

### Re: Pressure's effect on concentration

The reason for this is because the inert gas is not directly interacting with the reaction to form products or reactants. It is something that is just there.
Wed Jan 06, 2021 11:04 am
Forum: Administrative Questions and Class Announcements
Topic: Sapling access issue
Replies: 5
Views: 16

### Re: Sapling access issue

This means that you have to go to ccle to access sapling. If you go to ccle, you should see a link on the bottom of the site info that says sapling. If you click on that, it shall take you to the sapling page where you click on Lavelle, chem 14b, quarter 2, and use my credit. This then will register...
Wed Jan 06, 2021 11:00 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Textbook Table 5G.2
Replies: 4
Views: 10

### Re: Textbook Table 5G.2

Yeah, I think K is just a general term referring to the equilibrium constant, and Kp and Kc are specific into whether they are calculating for the equilibrium constant based on pressure or concentration.
Wed Jan 06, 2021 10:57 am
Forum: Administrative Questions and Class Announcements
Topic: Chemistry Community Points
Replies: 13
Views: 49

### Re: Chemistry Community Points

Yeah just play it on the safe side and write 50 comments for this quarter.
Wed Jan 06, 2021 10:55 am
Forum: Equilibrium Constants & Calculating Concentrations
Replies: 7
Views: 31

### Re: Quadratic Equations

If one of the positive numbers is greater than the initial conditions, then ignore it. You are basically trying to get positive equilibrium concentrations.
Wed Jan 06, 2021 10:53 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Sapling 10: le chatelier's and reverse reactions
Replies: 5
Views: 43

### Re: Sapling 10: le chatelier's and reverse reactions

Yeah, I think it is a typo. I ignored it and kept 0.494+x, and got the correct answer.
Wed Jan 06, 2021 10:51 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: sapling #2
Replies: 8
Views: 46

### Re: sapling #2

Lesly, I did the same thing you did, and I got a different answer. When I kept your numbers into my calculator I got 0.0234. (0.12^2 x 0.06)/(.192^2)=0.0234.
Wed Jan 06, 2021 10:38 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Audio-Visual Focus-Topic Kp, 65 bars
Replies: 5
Views: 36

### Re: Audio-Visual Focus-Topic Kp, 65 bars

Oh, my bad my problem had different numbers, but yeah you are right. So kp would be (65^2)/(65^2*65).
Wed Jan 06, 2021 10:28 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Audio-Visual Focus-Topic Kp, 65 bars
Replies: 5
Views: 36

### Re: Audio-Visual Focus-Topic Kp, 65 bars

The reaction quotient would be 65\65^2 since the stoichiometric coefficient on the product's side is 1, while the stoichiometric coefficient on the reaction side is 2. So once u calculate that you would compare that to the equilibrium constant to see whether the reaction favors the products or the r...
Wed Jan 06, 2021 10:24 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kc vs Kp
Replies: 4
Views: 35

### Re: Kc vs Kp

So basically Kp and Kc are both equilibrium constants and they don't have any units. The Kp is used when given the partial pressures of the gases, while the Kc is used when given the moles or concentrations of a molecule. The gas equation is not necessary for this concept, but simply put it explains...
Sat Dec 12, 2020 12:42 pm
Forum: Administrative Questions and Class Announcements
Topic: Are all questions on the final multiple choices?
Replies: 29
Views: 145

### Re: Are all questions on the final multiple choices?

Yes, since the format of the final is exactly the same as the midterms. Plus, I think my TA said that there will not be partial credit on this exam, but I don't know for sure.
Sat Dec 12, 2020 12:40 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Calculation OH- sapling
Replies: 4
Views: 21

### Re: Calculation OH- sapling

To find the ph you would do -log[H+]=6.10. Then to find the poH, you would subtract the pH from 14=7.89. Lastly, to find the concentration of [OH], you would do 10^-poH=1.27x10^-8.
Sat Dec 12, 2020 12:36 pm
Forum: Bronsted Acids & Bases
Topic: Textbook Problem J.1 Part C
Replies: 3
Views: 27

### Re: Textbook Problem J.1 Part C

KOH is a strong base since it has OH.
Sat Dec 12, 2020 12:34 pm
Forum: Conjugate Acids & Bases
Topic: Determining whether the predominant species in a reaction is charged or neutral
Replies: 3
Views: 36

### Determining whether the predominant species in a reaction is charged or neutral

For week 10 sapling questions #13 and #14, how do we determine whether the predominant species is neutral or charged. For both of the questions, the reactions were neutral, but both questions had different conditions such as when the ph was greater than the pka for #14 and where the pka was greater ...
Sat Dec 12, 2020 12:21 pm
Forum: Properties of Light
Topic: Wavelength
Replies: 26
Views: 183

### Re: Wavelength

A general rule of thumb is to use m instead of nm for solving for photoelectric effect problems or de brogile problems. However, when you are solving for atomic spectra type of problems, you should be using nm.
Sat Dec 12, 2020 12:18 pm
Forum: Bronsted Acids & Bases
Topic: Determining strong or weak from reaction
Replies: 7
Views: 71

### Re: Determining strong or weak from reaction

I have also been using the sapling chart to determine whether a particular compound was a strong acid/base or weak acid/base, but also another thing that I picked up from the sapling problems was that if the cation of the molecule is from a strong base and the anion is from a weak acid, the molecule...
Sun Dec 06, 2020 12:50 pm
Forum: Naming
Topic: Naming H2O
Replies: 11
Views: 84

### Re: Naming H2O

It's more of a preference than anything. Since O is the electronegative atom, people might write water that way to illustrate that the bonds are occurring from the oxygen rather than the hydrogens.
Sun Dec 06, 2020 12:46 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: pH and pOH
Replies: 6
Views: 45

### Re: pH and pOH

pH is the concentration of H+, while pOH is the concentration of OH-. You could also see that pH is the opposite of poH. So if you are given the pH value and you want to find the pOH value, you subtract pH from 14 to get pOH.
Sun Dec 06, 2020 12:43 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: electronegativity vs bond length for determining acidity
Replies: 4
Views: 30

### Re: electronegativity vs bond length for determining acidity

In this case, the electronegative atom pulls the delocalized electrons, which creates more stability in the anion, which then creates a stronger acid. So even though Br might be a more stable atom, it doesn't make the whole entire molecule stable, and that is what we are looking for in this problem.
Sun Dec 06, 2020 12:40 pm
Forum: Student Social/Study Group
Topic: Studying for Final Exam
Replies: 57
Views: 359

### Re: Studying for Final Exam

I would recommend doing the practice problems in the TB, UA worksheets, and going to the UA review sessions for the topics that you are still confused about.
Sun Dec 06, 2020 12:39 pm
Forum: Dipole Moments
Topic: Dipole canceling
Replies: 13
Views: 79

### Re: Dipole canceling

Yeah nonpolar molecules have dipole movements that are canceled out equally around the central atom.
Sun Nov 29, 2020 12:03 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Methane vs ammonia
Replies: 5
Views: 31

### Re: Methane vs ammonia

The lone pairs distort the shape, making what seems like a tetrahedral structure trigonal pyramidal.
Sun Nov 29, 2020 10:00 am
Forum: Hybridization
Topic: Confusion on certain carbon hybridizations
Replies: 5
Views: 39

### Re: Confusion on certain carbon hybridizations

Hybridizations depends on the number of electron densities surrounding an atom. So in this case, since there are three electron densities surrounding the carbon (2 single bonds and one double bond), the hybridization would be sp2 (3-1=2: subtract the # of electron densities by 1 to get the hybridiza...
Sun Nov 29, 2020 9:51 am
Forum: Formal Charge and Oxidation Numbers
Topic: Lewis acids and bases
Replies: 22
Views: 107

### Re: Lewis acids and bases

Lewis acids accept electrons, while lewis bases donate electrons. Typically, you see cations to be lewis acids, while big molecules such as NH3 to be lewis bases.
Sun Nov 29, 2020 9:48 am
Forum: General Science Questions
Topic: Electron Affinity
Replies: 4
Views: 36

### Re: Electron Affinity

Since noble gases are already stable, they don't need more electrons to be added even if the noble gases have a d orbital.
Tue Nov 24, 2020 5:48 pm
Forum: Administrative Questions and Class Announcements
Replies: 4
Views: 43

In the syllabus, the grade for an A+, A, and A- is not listed. Out of 500, what is an A+, A, and A-?
Sun Nov 22, 2020 11:39 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Sapling HW Smallest Bond Angle
Replies: 4
Views: 38

### Re: Sapling HW Smallest Bond Angle

The more lone pairs there in proximity to a bond, the smaller the bond angle would be.
Sun Nov 22, 2020 11:33 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Polar Characteristics of molecule
Replies: 5
Views: 32

### Re: Polar Characteristics of molecule

Polarity would be a characteristic of ionic bonds since there is a dipole movement, which ionic molecules such as NaCl has with the dipole movement from the Na going to Cl.
Sun Nov 22, 2020 11:30 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Repulsion Strength
Replies: 8
Views: 59

### Re: Repulsion Strength

Lone pairs typically have the highest repulsion since there are no electrons being shared, while bonded pairs typically have the lowest repulsion since the electrons are being shared. Therefore, two lone pairs have the highest repulsion, followed by one lone pair, and bond pairs have the least repul...
Sun Nov 22, 2020 11:26 am
Forum: Resonance Structures
Topic: Valence Electrons [ENDORSED]
Replies: 43
Views: 256

### Re: Valence Electrons[ENDORSED]

Yeah, each column is +1 valence electron, that is until you go to the column that has carbon. Then after carbon, the columns after that go from -3 to 0 formal charge.
Sun Nov 22, 2020 11:24 am
Forum: Student Social/Study Group
Topic: Finals!
Replies: 43
Views: 346

### Re: Finals!

No, I think that final will have content from midterm 1 and midterm 2 equally.
Sun Nov 22, 2020 11:20 am
Forum: Bond Lengths & Energies
Topic: LDF Bond Strength
Replies: 11
Views: 91

### Re: LDF Bond Strength

The bigger the atoms the greater the chance the electrons of the atoms have in interacting with each other, which as a result leads to stronger LDF forces.
Sun Nov 15, 2020 3:13 pm
Forum: Resonance Structures
Topic: Resonance Structures Clarification
Replies: 8
Views: 48

### Re: Resonance Structures Clarification

Yes, you are correct, this is an inherent problem in lewis structures. Because of this problem, formal charges come into place.
Sun Nov 15, 2020 3:10 pm
Forum: Quantum Numbers and The H-Atom
Topic: Effective nuclear charge
Replies: 4
Views: 42

### Re: Effective nuclear charge

An effective nuclear charge is a total pull the nucleus has on electrons accounting for electron repulsions.
Sun Nov 15, 2020 3:07 pm
Forum: Bond Lengths & Energies
Topic: LDF Bond Strength
Replies: 11
Views: 91

### Re: LDF Bond Strength

The larger the atom the more chance individual electrons could interact with each other. As a result, the LDF forces between these electrons is greater.
Sun Nov 15, 2020 3:05 pm
Forum: Electronegativity
Topic: Electronegativity v Electron Affinity
Replies: 4
Views: 39

### Re: Electronegativity v Electron Affinity

Pretty much they are the same thing, but the subtle difference between them is that electronegativity is the pulling power of individual atoms, while electron affinity deals with atoms in a molecule.
Sun Nov 15, 2020 3:01 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Question about Formal Charges
Replies: 5
Views: 20

### Re: Question about Formal Charges

The overall formal charge is the sum of all of the individual formal charges of the atoms in the molecule.
Sun Nov 08, 2020 5:35 pm
Forum: Administrative Questions and Class Announcements
Topic: Taking Bio and Chem simultaneously
Replies: 26
Views: 114

### Re: Taking Bio and Chem simultaneously

Instead of taking bio and chem at the same time, I would recommend completing your GEs, as two science classes could be a lot of work.
Sun Nov 08, 2020 5:33 pm
Forum: Student Social/Study Group
Topic: Studying From Home
Replies: 91
Views: 483

### Re: Studying From Home

I have been practicing daily mindfulness every morning by running in a nearby park. This helped me release all my energy, so once I got home I could concentrate on my school work.
Sun Nov 08, 2020 5:27 pm
Forum: Formal Charge and Oxidation Numbers
Topic: What do we use formal charges for?
Replies: 15
Views: 51

### Re: What do we use formal charges for?

Formal charge is used to accurately map the geometry of a compound, accounting for the bond length and extra electrons on the atoms.
Sun Nov 08, 2020 5:21 pm
Forum: Electronegativity
Topic: periodic table
Replies: 16
Views: 127

### Re: periodic table

An easy way to remember this is to picture ionization energy, electron affinity, and electronegativity as the same thing, and how going across a period from left to right leads to an increase, while when you go from bottom to up a group leads to an increase in IE, EA, and E and vice versa.
Sun Nov 08, 2020 5:18 pm
Forum: Formal Charge and Oxidation Numbers
Topic: formal charge
Replies: 11
Views: 42

### Re: formal charge

Yes since the formal charge is for lewis structures, and lewis structures are made to map the bonds of the atoms in a compound.
Sun Nov 01, 2020 10:12 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Arranging Elements by Electron Affinity
Replies: 6
Views: 38

### Re: Arranging Elements by Electron Affinity

The reason why atoms that have high electron affinity release energy is because they are so attracted to their electrons that if one of the electrons is taken away energy used to hold that atom is released.
Sun Nov 01, 2020 9:11 pm
Forum: DeBroglie Equation
Replies: 21
Views: 129

### Re: Avogadro's Number

Basically use Avogadro's number whenever you are trying to convert to moles or from moles into individual particles of the substance.
Sun Nov 01, 2020 2:32 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: The orbitals
Replies: 8
Views: 67

### Re: The orbitals

You have to know that they are different classification of atoms, meaning the electrons in these atoms are arranged in different ways giving them unique properties. The difference between the 3s and 2s orbital is that the 3s orbital has an extra shell of electrons.
Sun Nov 01, 2020 2:27 pm
Forum: Balancing Chemical Reactions
Topic: Balancing Equations Coefficient Question
Replies: 15
Views: 108

### Re: Balancing Equations Coefficient Question

Yeah I would continue doing the same thing you are doing right now since it is much easier to balance the chemical equation.
Sun Nov 01, 2020 2:24 pm
Forum: Properties of Light
Topic: How to remember what v is in equations
Replies: 46
Views: 261

### Re: How to remember what v is in equations

Depending on the equation I am using, I would try to make sense of how that equation was derived. This then would clarify whether v is frequency or velocity. For example, de Broglie's equation is based on the momentum of the electron so I would think of that v as velocity, while in the speed of ligh...
Mon Oct 26, 2020 3:10 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Writing Out Electron Orbitals
Replies: 2
Views: 32

### Writing Out Electron Orbitals

Why is the 3d orbital lower in energy compared to 4s?
Sat Oct 24, 2020 11:00 pm
Forum: DeBroglie Equation
Topic: De Broglie Equation v. Speed of Light Equation
Replies: 14
Views: 101

### Re: De Broglie Equation v. Speed of Light Equation

Debrogile's equation is used to find the wavelength and momentum of small objects such as electrons, protons, and neutrons, while the speed of light equation is used to find the wavelength and frequency of light.
Sat Oct 24, 2020 10:54 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Amplitude
Replies: 16
Views: 85

### Re: Amplitude

Increasing amplitude increases the number of photons being released, which doesn't change the frequency of the photons since photons are individual particles. So no, increasing amplitude doesn't increase the frequency of the wave.
Sat Oct 24, 2020 10:46 pm
Forum: Student Social/Study Group
Topic: Midterm scratch paper
Replies: 9
Views: 50

### Re: Midterm scratch paper

I don't think the type of scratch paper you use matters. The scratch paper is for you.
Sat Oct 24, 2020 10:44 pm
Forum: Significant Figures
Topic: 40951. 3 Sig Figs
Replies: 5
Views: 60

### Re: 40951. 3 Sig Figs

To be honest I would just use 41000 since you really can't do anything about it.
Sat Oct 24, 2020 10:42 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Advice for studying
Replies: 92
Views: 2073

### Re: Advice for studying

My advice is to do as many practice problems as possible. Do the post-assessment modules, textbook problems, and UA worksheets. However, if you feel good in a topic already, then just move on to practice problems that you are not good at practice those instead. I think somewhere he said that the mid...
Sat Oct 17, 2020 6:22 pm
Forum: Properties of Light
Topic: HW 1a 7b
Replies: 4
Views: 34

### Re: HW 1a 7b

Yes the answer is 150pm. You could check your answers on sapling btw. It's in the homepage of sapling titled Atkins_7e_SSM. Yeah, I would basically plug and chug into that equation.
Sat Oct 17, 2020 6:08 pm
Forum: Administrative Questions and Class Announcements
Topic: Question about Midterms
Replies: 9
Views: 103

### Re: Question about Midterms

Like Sandra said, I'm sure we don't have to memorize any formula's or constants, and we could have a print out of the material. However, what I would recommend using is the periodic table and formulas he has on his class website.
Sat Oct 17, 2020 6:01 pm
Forum: Student Social/Study Group
Topic: How are you studying?
Replies: 203
Views: 1291

### Re: How are you studying?

The way I'm studying for this class is by watching the lectures and doing the textbook problems. If I don't get any of the textbook problems I usually go over them with a study group I'm in. But if you don't have a study group, I would just go to the step up and UA sessions.
Sat Oct 17, 2020 5:57 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: delta E
Replies: 10
Views: 61

### Re: delta E

The minus sign means energy is being released in the form of electromagnetic radiation.
The positive sign means energy is being absorbed in the form of electromagnetic radiation.
Sat Oct 17, 2020 5:55 pm
Forum: Properties of Electrons
Topic: Work function/Threshold Energy
Replies: 19
Views: 91

### Re: Work function/Threshold Energy

Yes they are the same thing. The work function is used to mathematically model the threshold energy.
Mon Oct 05, 2020 4:45 pm
Forum: Significant Figures
Topic: Sig Figs for elements on Periodic table
Replies: 14
Views: 141

### Re: Sig Figs for elements on Periodic table

A good rule of thumb is to use 4 sig figures unless the question states otherwise. Hope this helps :)
Mon Oct 05, 2020 4:41 pm
Forum: Administrative Questions and Class Announcements
Topic: Exams for Chemistry 14A
Replies: 5
Views: 87

### Re: Exams for Chemistry 14A

Idk about the online software we are going to use yet, but I know that they are going to be taken with our TAs.
Mon Oct 05, 2020 4:36 pm
Forum: Administrative Questions and Class Announcements
Topic: Accessing the E-textbook [ENDORSED]
Replies: 103
Views: 7148

### Re: Accessing the E-textbook[ENDORSED]

For this class, I'm pretty sure that you need to get the textbook from the UCLA bookstore.
Mon Oct 05, 2020 4:27 pm
Forum: Molarity, Solutions, Dilutions
Topic: Molar mass for O2 vs O
Replies: 11
Views: 116

### Re: Molar mass for O2 vs O

Yes since Oxygen is a diatomic molecule. So since there are 2 atomic molecules, the molar mass would be 32g.
Mon Oct 05, 2020 3:54 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Determining Molar Mass
Replies: 19
Views: 210

### Re: Determining Molar Mass

If the problem specifically states specifically round to these many significant figures then you have to round, but otherwise you are fine. Hope this helps.

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