Search found 60 matches

by Nare Nazaryan 1F
Sun Jan 19, 2020 10:56 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Le Chatelier's Principle
Replies: 7
Views: 20

Re: Le Chatelier's Principle

It predicts what would happen if a parameter changed and how the reaction would adjust to fixing that change in parameter.
by Nare Nazaryan 1F
Sun Jan 19, 2020 10:54 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: X was ignored
Replies: 27
Views: 77

Re: X was ignored

X was ignored because 0.10 is less than 10^-3, which means it is so small that it would not make a difference to decrease by X; therefore, you only use the 0.10 (think of Dr.Lavelle's example of the million dollars minus $10).
by Nare Nazaryan 1F
Sun Jan 19, 2020 10:50 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q < K
Replies: 16
Views: 42

Re: Q < K

Yes, it is the same because when Q is less than K, there are more reactants than products so the reaction needs to form more products to reach equilibrium.
by Nare Nazaryan 1F
Sun Jan 19, 2020 10:44 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Quadratic Equation
Replies: 8
Views: 24

Re: Quadratic Equation

We use the quadratic equation when equating the values we got from the ICE table (products/reactants) to the given equilibrium constant K, and if X is not smaller than 10^-3.
by Nare Nazaryan 1F
Sun Jan 19, 2020 10:41 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: ICE Tables
Replies: 13
Views: 33

Re: ICE Tables

Because it's a liquid and because it's in excess (as a solvent), it is not included.
by Nare Nazaryan 1F
Sun Jan 12, 2020 11:03 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Homogenous Equilibrium
Replies: 13
Views: 29

Re: Homogenous Equilibrium

It is when all the reactants and products are in the same phase (e.g. gas).
by Nare Nazaryan 1F
Sun Jan 12, 2020 10:57 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Hw for next week
Replies: 19
Views: 59

Re: Hw for next week

I think both are fine since they will both be recent topics; I'm saying this because I took Lavelle for 14A and our TAs were OK with it.
by Nare Nazaryan 1F
Sun Jan 12, 2020 10:55 pm
Forum: Ideal Gases
Topic: Topics on Test 1
Replies: 36
Views: 162

Re: Topics on Test 1

I believe it will be all of "chemical equilibrium" and whatever we get to for "acids and bases" since those are the material for the first two weeks.
by Nare Nazaryan 1F
Sun Jan 12, 2020 10:53 pm
Forum: Ideal Gases
Topic: PV = nRT
Replies: 16
Views: 53

Re: PV = nRT

The P stands for pressure, the V for volume, the n for number of moles, the R is the gas constant, and T is temperature.
by Nare Nazaryan 1F
Sun Jan 12, 2020 10:51 pm
Forum: Ideal Gases
Topic: Understanding Q
Replies: 19
Views: 67

Re: Understanding Q

Yes, solving for Q is the same thing as solving for K in terms of calculations (just that the reaction might not have reached equilibrium yet).
by Nare Nazaryan 1F
Mon Dec 02, 2019 10:40 pm
Forum: Polyprotic Acids & Bases
Topic: Polyprotic Question!
Replies: 12
Views: 817

Re: Polyprotic Question!

Polyprotics have more protons to donate.
by Nare Nazaryan 1F
Mon Dec 02, 2019 10:37 pm
Forum: Bronsted Acids & Bases
Topic: Lecture 12/2
Replies: 3
Views: 23

Re: Lecture 12/2

He said that the conjugate base (anion) of a weak acid will raise the pH of a solution by removing protons from the water and generate -OH.
by Nare Nazaryan 1F
Mon Dec 02, 2019 10:35 pm
Forum: Bronsted Acids & Bases
Topic: Final
Replies: 13
Views: 81

Re: Final

It is most likely cumulative, so anything we have learned can be on it.
by Nare Nazaryan 1F
Mon Dec 02, 2019 10:32 pm
Forum: Bronsted Acids & Bases
Topic: how to identify
Replies: 2
Views: 33

Re: how to identify

Bronsted acids have to donate their hydrogen atom/proton; therefore, NH3 can't be a bronsted acid.
by Nare Nazaryan 1F
Mon Dec 02, 2019 10:24 pm
Forum: Lewis Acids & Bases
Topic: Problem J.9
Replies: 4
Views: 40

Re: Problem J.9

Potassium acetate is produced:

CH3CO2H(aq)+K^+(aq)+OH^-(aq)-->K^+(aq)+CH3CO2^-(aq)+H2O(l)
by Nare Nazaryan 1F
Sun Dec 01, 2019 2:15 pm
Forum: Biological Examples
Topic: EDTA
Replies: 8
Views: 51

Re: EDTA

EDTA is ethylene-diamine-tetra-acetate, and it binds/chelates with cations (metals) in the blood to get rid of them.
by Nare Nazaryan 1F
Sun Dec 01, 2019 2:12 pm
Forum: Biological Examples
Topic: Chemotherapy
Replies: 6
Views: 42

Re: Chemotherapy

Cisplatin is very common for chemotherapy.
by Nare Nazaryan 1F
Sun Dec 01, 2019 2:11 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Oxidation number
Replies: 3
Views: 26

Re: Oxidation number

You just need to take the sum of all the oxidation numbers and then subtract the overall charge from that to get the charge/oxidation number of the transition metal.
by Nare Nazaryan 1F
Sun Dec 01, 2019 2:05 pm
Forum: Properties & Structures of Inorganic & Organic Bases
Topic: Nonmental Oxides as Acids
Replies: 4
Views: 37

Re: Nonmental Oxides as Acids

Yes, CO2 would be an acid in this case.
by Nare Nazaryan 1F
Sat Nov 30, 2019 12:15 pm
Forum: Student Social/Study Group
Topic: Final Jitters
Replies: 97
Views: 19971

Re: Final Jitters

There are many times where anxiety plays a huge factor in a students' performance on an exam, but there are solutions such as studying ahead of time and not cramming for a test, as well as getting enough rest.
by Nare Nazaryan 1F
Sun Nov 24, 2019 9:10 pm
Forum: Naming
Topic: Order in Naming
Replies: 12
Views: 56

Re: Order in Naming

It would be the ligand name (alphabetically), then cation.
by Nare Nazaryan 1F
Sun Nov 24, 2019 9:02 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Ligand
Replies: 10
Views: 53

Re: Ligand

A ligand is a molecule attached to a metal (in biology, usually attached to protein/enzyme).
by Nare Nazaryan 1F
Sun Nov 24, 2019 8:59 pm
Forum: Naming
Topic: Meaning of Cis and Trans
Replies: 11
Views: 51

Re: Meaning of Cis and Trans

Cis means the electronegative atoms are on the same side (e.g. two chlorines), which trans is when they're on opposite sides. Cisplatin works because Guanine can displace two chlorines from one side, vs. two chlorines on opposite sides (trans).
by Nare Nazaryan 1F
Sun Nov 24, 2019 8:56 pm
Forum: Naming
Topic: Oxidation
Replies: 14
Views: 104

Re: Oxidation

The oxidation number/state is the charge that cation/anion has. For example, chlorine's oxidation state would be -1 (chloride).
by Nare Nazaryan 1F
Sun Nov 24, 2019 8:55 pm
Forum: Naming
Topic: Week 9 and Week 10 HW?
Replies: 21
Views: 132

Re: Week 9 and Week 10 HW?

I think we can do it on one sheet of paper and label it week 9 and 10.
by Nare Nazaryan 1F
Wed Nov 13, 2019 10:50 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: Intermolecular forces
Replies: 10
Views: 82

Re: Intermolecular forces

Van der Waals and London interactions are used interchangeably, and refer to induced-dipole induced-dipole interactions. They are the weakest intermolecular force.
by Nare Nazaryan 1F
Wed Nov 13, 2019 10:25 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: Determining Polarity
Replies: 5
Views: 53

Re: Determining Polarity

Yes, the difference in electronegativity should be about 0.5 to be considered polar. Shape also plays a role in terms of the possibility of dipole moments canceling.
by Nare Nazaryan 1F
Wed Nov 13, 2019 10:16 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Tetrahedral VSPER model
Replies: 7
Views: 56

Re: Tetrahedral VSPER model

I believe it is always tetrahedral when 4 bonds surround the central atom, however, lone pairs could also play a role and change the shape.
by Nare Nazaryan 1F
Wed Nov 13, 2019 10:04 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Test 2
Replies: 15
Views: 151

Re: Test 2

It should cover material after the midterm (plus the very last slide he did before the midterm about the different interactions). So I believe that would be last Friday's lecture, today's lecture, and probably this Friday's lecture (I'm not sure about next Monday's). Topics would include dipoles, in...
by Nare Nazaryan 1F
Wed Nov 13, 2019 9:54 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VESPR Model of H2O
Replies: 12
Views: 83

Re: VESPR Model of H2O

H2O would be bent, with oxygen in the center and one hydrogen on the lower left of oxygen and the other on the lower right. This is due to the polarity of water, with the hydrogen atoms having partial positive charge and the dipole arrows being directed toward the oxygen (partial negative charge). O...
by Nare Nazaryan 1F
Sat Nov 09, 2019 9:13 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge
Replies: 9
Views: 67

Re: Formal Charge

If the compound is neutral, you would need all the formal charges to be zero. However, if it has a net charge then one or more atoms might have a negative or positive charge. You want the most electronegative atoms to have a negative charge (oxygen for example), and typically the central atom needs ...
by Nare Nazaryan 1F
Sat Nov 09, 2019 9:09 pm
Forum: Electronegativity
Topic: Periodic Trend
Replies: 13
Views: 74

Re: Periodic Trend

Electronegativity increases as you go across a period and up a group, with flourine being the most electronegative atom (same trend as ionization energy and electron affinity).
by Nare Nazaryan 1F
Sat Nov 09, 2019 9:08 pm
Forum: Bond Lengths & Energies
Topic: Hydrogen Bonding melting point
Replies: 3
Views: 29

Re: Hydrogen Bonding melting point

Hydrogen bonds are very strong, therefore it is difficult to break them. This means it takes a higher melting point to break the bonds.
by Nare Nazaryan 1F
Sat Nov 09, 2019 9:05 pm
Forum: Bond Lengths & Energies
Topic: Bonds
Replies: 2
Views: 38

Re: Bonds

I agree with the above statement. I'd also like to note that hydrogen bonding occurs with the atoms flourine, nitrogen, and oxygen (electronegative atom that would bond with the hydrogen of a different molecule).
by Nare Nazaryan 1F
Sat Nov 09, 2019 9:00 pm
Forum: Dipole Moments
Topic: Polar
Replies: 9
Views: 67

Re: Polar

Polarity depends on electronegativity. The difference of electronegativty between the two atoms signifies whether they will have a positive or negative partial charge.
by Nare Nazaryan 1F
Sun Nov 03, 2019 1:22 pm
Forum: Electronegativity
Topic: Electronegativity
Replies: 9
Views: 52

Re: Electronegativity

905289082 wrote:What is the pattern on the periodic table that we're supposed to memorize for determining electronegativity?


Electronegativity increases as you move up and across the periodic table.
by Nare Nazaryan 1F
Sun Nov 03, 2019 1:19 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge Purpose
Replies: 4
Views: 37

Re: Formal Charge Purpose

When the formal charge is 0, that means that the number of bonds of the atom are balanced with its lone pairs. So yes, it does mean that it is more stable.
by Nare Nazaryan 1F
Sun Nov 03, 2019 1:03 am
Forum: Bond Lengths & Energies
Topic: bond length
Replies: 6
Views: 64

Re: bond length

I believe it is possible, but for now all we need to know is that double bonds are shorter and also stronger than single bonds
by Nare Nazaryan 1F
Sun Nov 03, 2019 12:56 am
Forum: Dipole Moments
Topic: Definition
Replies: 5
Views: 52

Re: Definition

It is pretty much the polarity between atoms, indicated with an arrow pointing toward the negative delta direction.
by Nare Nazaryan 1F
Sun Nov 03, 2019 12:52 am
Forum: Dipole Moments
Topic: Midterm
Replies: 8
Views: 90

Re: Midterm

I think we need to know dipole moments for the midterm, but just not the very last slide he was going over with the specifics.
by Nare Nazaryan 1F
Sun Oct 27, 2019 1:56 pm
Forum: Ionic & Covalent Bonds
Topic: Covalent bonds
Replies: 5
Views: 47

Re: Covalent bonds

As far as we have learned, covalent bonds are only made between nonmetals. However, I did some research and discovered an example of a covalent bond between a metal and nonmetal. Aluminium is a metal but it can bond covalently with chlorine to form aluminium chloride during high temperatures. Alumin...
by Nare Nazaryan 1F
Sun Oct 27, 2019 1:35 pm
Forum: Resonance Structures
Topic: Bond lengths
Replies: 5
Views: 31

Re: Bond lengths

We don't need to know how to find bond lengths; it would be given (in angstroms). Conceptually, we need to know that double bonds are shorter than single bonds.
by Nare Nazaryan 1F
Sun Oct 27, 2019 1:08 pm
Forum: Ionic & Covalent Bonds
Topic: 2A.15
Replies: 4
Views: 30

Re: 2A.15

It's easier for Gallium to lose three electrons to become an octet like Argon, than to gain five electrons to become an octet like Krypton.
by Nare Nazaryan 1F
Sun Oct 27, 2019 1:05 pm
Forum: Ionic & Covalent Bonds
Topic: Cation
Replies: 23
Views: 171

Re: Cation

Cations are positively charged ions since they lose electrons. Anions are negatively charged since they gain electrons. They're important because they help the element form octets.
by Nare Nazaryan 1F
Sun Oct 27, 2019 1:03 pm
Forum: Ionic & Covalent Bonds
Topic: Midterm Topics Covered
Replies: 7
Views: 64

Re: Midterm Topics Covered

I think anything we have covered up until the midterm could possibly be on it. You can also ask Dr. Lavelle just to be sure.
by Nare Nazaryan 1F
Tue Oct 15, 2019 7:18 am
Forum: DeBroglie Equation
Topic: Three Fundamental Equations
Replies: 3
Views: 35

Re: Three Fundamental Equations

It can be a little tricky, but it all depends on what is given. If you are given frequency and need to find wavelength, for example, you can use c=wavelength*frequency and just adjust the equation to what you're trying to solve. Some problems will ask you for an answer after you go through a few dif...
by Nare Nazaryan 1F
Tue Oct 15, 2019 1:55 am
Forum: Einstein Equation
Topic: Einstein Equation
Replies: 4
Views: 49

Re: Einstein Equation

You use E=hv when finding the energy of a photon. In this case, h is Planck's constant and v is frequency.
by Nare Nazaryan 1F
Tue Oct 15, 2019 1:46 am
Forum: Properties of Light
Topic: Homework
Replies: 11
Views: 49

Re: Homework

For this week, the five problems we do have to all come from the "Quantum World." I don't think it matters whether we do more problems from section A or B (etc) than other sections in that unit.
by Nare Nazaryan 1F
Tue Oct 15, 2019 1:43 am
Forum: Properties of Light
Topic: Quantum Unit length
Replies: 2
Views: 15

Re: Quantum Unit length

I'm not positive how much longer we're going to be in this unit, but I have a feeling it might also be next week too, since Professor Lavelle mentioned that this is a lengthy unit. Especially compared to the other topics, this seems more complex.
by Nare Nazaryan 1F
Tue Oct 15, 2019 1:37 am
Forum: Properties of Light
Topic: MidTerms and Finals
Replies: 11
Views: 85

Re: MidTerms and Finals

The midterm and final are going to be outside of class hours. The midterm is scheduled for November 6 from 6-8 pm, and the final is on December 8 from 11:30am-2:30pm. I am not sure where the midterm will be, though.
by Nare Nazaryan 1F
Tue Oct 08, 2019 1:29 am
Forum: Properties of Light
Topic: Posts Per Week
Replies: 6
Views: 67

Re: Posts Per Week

I think that if you post Sunday of week one, it will be counted as week one. The "week" probably starts on Mondays.
by Nare Nazaryan 1F
Tue Oct 08, 2019 1:28 am
Forum: Properties of Light
Topic: Photons
Replies: 7
Views: 56

Re: Photons

Increasing intensity doesn't lead to electrons being emitted, because increasing the intensity only increases the number of photons instead of the energy that each photon has. So in the photoelectric experiment, it's best to see light in terms of photons, since the energy of photons is what helps em...
by Nare Nazaryan 1F
Tue Oct 08, 2019 1:17 am
Forum: Administrative Questions and Class Announcements
Topic: Study Tips/Schedule
Replies: 4
Views: 56

Re: Study Tips/Schedule

I would suggest doing the homework problems so that you get a good range of possible test questions and develop fundamental/conceptual skills to solve problems. You can also look at the lecture notes and online modules, as well as go to peer learning sessions and office hours.
by Nare Nazaryan 1F
Tue Oct 08, 2019 1:14 am
Forum: Administrative Questions and Class Announcements
Topic: Advice from a Medical Student - Part II [ENDORSED]
Replies: 130
Views: 3354

Re: Advice from a Medical Student - Part II [ENDORSED]

HI! Thank you so much for taking time out of your already busy schedule to answer our questions. I'm not sure if someone asked this already, but in terms of medical school, I've always wondered how I'd be able to balance that with family, especially because my ultimate career goal is to become a neu...
by Nare Nazaryan 1F
Tue Oct 08, 2019 12:44 am
Forum: Limiting Reactant Calculations
Topic: Showing Work for Limiting Reactant Calculations on Tests [ENDORSED]
Replies: 68
Views: 1598

Re: Showing Work for Limiting Reactant Calculations on Tests [ENDORSED]

Showing work, even if your final answer is incorrect, will always give you partial credit which is important since the tests are 50 points (roughly 7 points/problem if its 7 questions).
by Nare Nazaryan 1F
Thu Oct 03, 2019 10:49 pm
Forum: Balancing Chemical Reactions
Topic: adding a product
Replies: 6
Views: 50

Re: adding a product

When balancing equations, you want to add stoichiometric coefficients to change the number of MOLES of the compound, not the molecules.
by Nare Nazaryan 1F
Thu Oct 03, 2019 10:46 pm
Forum: Balancing Chemical Reactions
Topic: Combustion
Replies: 12
Views: 116

Re: Combustion

Yes, combustion (and oxidation) involve a compound reacting with oxygen (O2) and producing a certain amount of carbon dioxide (CO2) and water (H2O).
by Nare Nazaryan 1F
Thu Oct 03, 2019 10:40 pm
Forum: Empirical & Molecular Formulas
Topic: Test Materials
Replies: 13
Views: 121

Re: Test Materials

I'm sure we will be given the periodic table and the molecular formulas for compounds (if not asked to find the molecular formula). I am not sure about a formula sheet, but I would definitely recommend memorizing Avogadro's constant since I noticed that we had to use it in a lot of questions from se...
by Nare Nazaryan 1F
Thu Oct 03, 2019 10:33 pm
Forum: Empirical & Molecular Formulas
Topic: Faster way to find molecular formula?
Replies: 3
Views: 48

Re: Faster way to find molecular formula?

I don't think there is a faster way, even though that would make things so much easier. Maybe in the future we will learn a simpler way? I wish I could be of more help.
by Nare Nazaryan 1F
Thu Oct 03, 2019 10:08 pm
Forum: Empirical & Molecular Formulas
Topic: 100 gram Method?
Replies: 9
Views: 94

Re: 100 gram Method?

If you are given the mass percent composition, it's simple to assume that your sample is 100 grams in order to easily convert the mass percent composition, for that certain element, into the mass of that element in grams. That way you can easily calculate the moles of that element using its mass (g)...

Go to advanced search