Search found 100 matches

by TarynD_1I
Sat Mar 14, 2020 5:39 pm
Forum: Zero Order Reactions
Topic: units of k
Replies: 5
Views: 96

Re: units of k

https://users.stlcc.edu/gkrishnan/rateunits.htm
here is a helpful link to organize which units go with each order of reaction!
by TarynD_1I
Sat Mar 14, 2020 5:36 pm
Forum: Ideal Gases
Topic: Kc
Replies: 7
Views: 97

Re: Kc

You'd use concentration of products over reactants for gaseous and aqueous, not liquid and solid.
by TarynD_1I
Sat Mar 14, 2020 5:16 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: pseudo rate law
Replies: 3
Views: 62

Re: pseudo rate law

I believe that the pseudo rate law is essentially increasing all but one of the reactant concentrations, making them basically constant. This makes small changes in the small concentration significant by isolating it.
by TarynD_1I
Sat Mar 14, 2020 5:14 pm
Forum: Administrative Questions and Class Announcements
Topic: Where to find the final exam
Replies: 5
Views: 65

Re: Where to find the final exam

Lavelle is doing the exam through CCLE, so printing out and scanning isn't needed, since it will all be online
by TarynD_1I
Sun Mar 08, 2020 10:11 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Arrhenius Equation Variables
Replies: 4
Views: 56

Re: Arrhenius Equation Variables

PranaviKolla2B wrote:Does the Arrhenius equation simply tell us the effect of temperature on the rate constant?


Yes, the Arrhenius equation is used to measure/calculate what happens to the rate constant (and the rate of the reaction) when a change in temperature occurs.
by TarynD_1I
Sun Mar 08, 2020 10:08 pm
Forum: Balancing Redox Reactions
Topic: Why do we flip E for oxidation?
Replies: 13
Views: 96

Re: Why do we flip E for oxidation?

If using the equation E(cell) = E(cathode) - E(anode) and using reduction values found in the appendix or on the sheet he will give us on the test, then I'm pretty sure that there is no need to flip the anode cell potential value when accounting for oxidation. In this case you would not need to chan...
by TarynD_1I
Sun Mar 08, 2020 9:58 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Temperature
Replies: 4
Views: 31

Re: Temperature

At a higher temperature, it is more likely that moving particles will collide with each other with enough energy to surpass the activation energy barrier. Therefore, the reaction will be faster.
by TarynD_1I
Sun Mar 08, 2020 9:55 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 2 Grades
Replies: 22
Views: 280

Re: Test 2 Grades

You could also check your grades on myucla regularly, since the TA's might input test 2 grades prior to discussion session
by TarynD_1I
Sun Mar 08, 2020 9:53 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Molecularity
Replies: 3
Views: 32

Re: Molecularity

molecularity according to the textbook is the number of reactant molecules, atoms, or ions that take part in a specific elementary reaction.
by TarynD_1I
Sun Mar 01, 2020 10:23 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: salt bridge
Replies: 9
Views: 82

Re: salt bridge

a salt bridge allows the electrons to go from the cathode to the anode to prevent charge buildup
by TarynD_1I
Sun Mar 01, 2020 9:48 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Electrochemical Series
Replies: 5
Views: 46

Re: Electrochemical Series

The electrochemical series is Chapter 6M.2 and basically lays out the relative strengths of oxidizing and reducing agents.
by TarynD_1I
Sun Mar 01, 2020 9:45 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Nernst Equation
Replies: 4
Views: 51

Re: Nernst Equation

I believe we use the Nernst equation to find the cell potential at any point in a reaction
by TarynD_1I
Sun Mar 01, 2020 9:20 pm
Forum: General Science Questions
Topic: Review Sessions for Test 2
Replies: 4
Views: 112

Re: Review Sessions for Test 2

there are no big review sessions by the TA's and UA's but office hours and the step up/workshop sessions in young and covel are very helpful
by TarynD_1I
Sun Mar 01, 2020 9:16 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: first order
Replies: 8
Views: 111

Re: first order

First order reactions has a linear rate and depends on one concentration
by TarynD_1I
Sun Feb 23, 2020 8:18 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagram
Replies: 4
Views: 25

Re: Cell Diagram

My TA explained that cell diagrams look like this:

s | g | aq || aq | g | s

and the electrons go left to right (from the anode to the cathode)
by TarynD_1I
Sun Feb 23, 2020 8:12 pm
Forum: Van't Hoff Equation
Topic: Van't Hoff Equation
Replies: 7
Views: 104

Re: Van't Hoff Equation

I think we use Van't Hoff when trying to calculate how K is affected by a change in temperature
by TarynD_1I
Sun Feb 23, 2020 8:10 pm
Forum: Balancing Redox Reactions
Topic: Balancing redox
Replies: 6
Views: 63

Re: Balancing redox

chari_maya 3B wrote:If it is alkaline, why would you balance it first acidically?


You would have to balance the hydrogens with H+ first in order to balance out the charges, and then cancel the extra protons with OH-
by TarynD_1I
Sun Feb 23, 2020 8:05 pm
Forum: Balancing Redox Reactions
Topic: Balancing Reactions: Acid vs Base
Replies: 3
Views: 46

Re: Balancing Reactions: Acid vs Base

Balancing acidic and alkaline reactions are mostly the same, but balancing alkaline reactions have an additional step. in a basic reaction, after balancing the reaction with protons (H+), you have to also balance out the protons with OH-.
by TarynD_1I
Sun Feb 23, 2020 8:01 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: cell diagram
Replies: 2
Views: 30

Re: cell diagram

My TA explained that cell diagrams look like:

s | g | aq || aq | g | s

where | indicates a phase change and || is a salt bridge

also, the anode is on the left of the salt bridge and cathode is on the right of the salt bridge
by TarynD_1I
Sun Feb 16, 2020 9:28 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Isolated versus closed
Replies: 7
Views: 162

Re: Isolated versus closed

Isolated: does not exchange matter or energy with surroundings
Closed: can exchange energy with surroundings, but not mass
by TarynD_1I
Sun Feb 16, 2020 9:24 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 2
Replies: 11
Views: 139

Re: Test 2

I'm pretty sure it's not cumulative, it probably will be on material from after the midterm, but he'll definitely confirm the topics closer to the test.
by TarynD_1I
Sun Feb 16, 2020 9:19 pm
Forum: Calculating Work of Expansion
Topic: Irreversible and Reversible Expanision
Replies: 9
Views: 183

Re: Irreversible and Reversible Expanision

How can you differentiate when to use -nRlnV2/V1 versus using -PV? I feel like I always get mixed up when I should use which equation. Any tips for knowing which one to use when? https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=160&t=58744&p=221113&hilit=helpful&sid=b6cc45c218434...
by TarynD_1I
Sun Feb 16, 2020 9:16 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Isochoric
Replies: 8
Views: 148

Re: Isochoric

isochoric: constant volume

isobaric: constant pressure

isothermic: constant temperature
by TarynD_1I
Tue Feb 11, 2020 9:38 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: 4H.5
Replies: 4
Views: 105

Re: 4H.5

for b, pentene has more entropy than cyclopentane because cyclopentane is a rigid ring that is not that flexible, while pentene is more flexible (thus having more entropy).
by TarynD_1I
Sun Feb 09, 2020 10:28 pm
Forum: Student Social/Study Group
Topic: Number of Chemistry Community Posts
Replies: 33
Views: 717

Re: Number of Chemistry Community Posts

ashwathinair wrote:Sometimes I post multiple times on the same thread - is this counted as separate posts or as just one?


I think it would count as multiple posts, but for a definite answer I'd ask your TA since they give the credit at the end of the quarter.
by TarynD_1I
Sun Feb 09, 2020 10:26 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Specific Heat Capacity
Replies: 5
Views: 38

Re: Specific Heat Capacity

You use specific heat capacity when trying to find the heat required to raise the temperature of one gram of a substance by 1 degree Celsius.
Molar heat capacity is used to find heat required to raise the temperature of one mole of the substance.
by TarynD_1I
Sun Feb 09, 2020 10:13 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: qp=deltaH
Replies: 6
Views: 66

Re: qp=deltaH

qp is equal to delta h when a system is at constant pressure, so no nonexpansion work is being done.
by TarynD_1I
Sun Feb 09, 2020 10:11 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Strong Acids
Replies: 6
Views: 57

Re: Strong Acids

From what I remember from 14a,
Strong acids include: HCl, HNO3, H2SO4, HBr, HI, HClO4
Strong bases are mostly bases that include OH in the chemical formula (ex: NaOH, KOH)
by TarynD_1I
Sun Feb 09, 2020 10:09 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Cv and Cp
Replies: 3
Views: 22

Re: Cv and Cp

Use Cv when the system is at a constant volume, and Cp when the system is at a constant pressure, I'm pretty sure it'll either be stated in the problem or will be able to be inferred by other info.
by TarynD_1I
Sun Feb 02, 2020 7:35 pm
Forum: Phase Changes & Related Calculations
Topic: State functions
Replies: 7
Views: 82

Re: State functions

State functions can be added or subtracted, which allows us to calculate changes in values of the system
by TarynD_1I
Sun Feb 02, 2020 6:52 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calorimeter vs. Bomb Calorimeter
Replies: 4
Views: 39

Re: Calorimeter vs. Bomb Calorimeter

a regular calorimeter is thermally insulated, while the bomb calorimeter is an insulated container completely immersed in a metal box of water. in addition, a constant pressure calorimeter is used to calculate change in enthalpy, while a bomb calorimeter (constant volume) is used to calculate the ch...
by TarynD_1I
Sun Feb 02, 2020 6:24 pm
Forum: General Science Questions
Topic: Midterm
Replies: 17
Views: 362

Re: Midterm

i'm pretty sure that Dr. Lavelle does not have any past exams in the test bank, but going to the midterm review sessions that he has set up help drastically with understanding concepts or for practicing problems.
by TarynD_1I
Sun Feb 02, 2020 6:21 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ka approximation
Replies: 6
Views: 51

Re: Ka approximation

you would divide the x amount (found using ice table) by the original concentration and multiply by 100. If this percentage is less than 5%, then the approximation is valid.
by TarynD_1I
Wed Jan 29, 2020 1:25 pm
Forum: Calculating Work of Expansion
Topic: Irreversible vs. Reversible Reactions
Replies: 6
Views: 63

Re: Irreversible vs. Reversible Reactions

During reversible reactions, products and reactants are always being made (going back and forth), while in irreversible reactions products can't revert back to what it was as a reactant. I also think that during reversible reactions, the system stays at equilibrium, and during irreversible reactions...
by TarynD_1I
Sun Jan 26, 2020 6:57 pm
Forum: Phase Changes & Related Calculations
Topic: State function
Replies: 4
Views: 32

Re: State function

Heat is not a state function because it is dependent on the path of the reaction, while enthalpy is a state function because it does not depend on the path of the system but is dependent on initial and end results.
by TarynD_1I
Sun Jan 26, 2020 6:53 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Delta U
Replies: 3
Views: 35

Re: Delta U

Delta h is change in enthalpy, while delta u is the change within the internal energy of the system.
by TarynD_1I
Sun Jan 26, 2020 6:49 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Gas Constant
Replies: 13
Views: 82

Re: Gas Constant

The gas constant depends on which measurement that the question uses (J, atm, bar, or torr usually) and it will be on the equations sheet.
by TarynD_1I
Sun Jan 26, 2020 6:42 pm
Forum: Phase Changes & Related Calculations
Topic: work and heat
Replies: 3
Views: 36

Re: work and heat

Work is not a state function because it depends on the path from the initial to final states of the reaction. Heat is not a state function because it depends on the paths of each individual state.
by TarynD_1I
Sun Jan 26, 2020 6:38 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Internal energy = State function
Replies: 4
Views: 36

Re: Internal energy = State function

Internal energy is a state function I believe because it is independent of the path of the process in question. It has different values at each different state of the system.
by TarynD_1I
Sun Jan 19, 2020 8:51 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Exothermic vs. endothermic
Replies: 2
Views: 23

Re: Exothermic vs. endothermic

Think of heat in a endothermic reaction as a reactant (need heat to reaction to proceed) and in a exothermic reaction as a product (reaction produces heat). For exothermic, if K decreases when temperature increases, the reaction shifts to the left, and if K increases when temperature decreases, the ...
by TarynD_1I
Sun Jan 19, 2020 8:25 pm
Forum: General Science Questions
Topic: Acids
Replies: 3
Views: 41

Re: Acids

When referring to Bronsted acids and bases, we refer to proton donors (acids) and proton acceptors (bases).
Lewis acids and bases are electron pair acceptors (acids) and electron pair donors (bases).
by TarynD_1I
Sun Jan 19, 2020 8:21 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K vs Q
Replies: 14
Views: 84

Re: K vs Q

K is the equilibrium constant of an reaction that is already at equilibrium, while Q (reaction quotient) is used when the reaction is not already at equilibrium. Q is also used to show in which direction the reaction shifts (for example, when K>Q, then the reaction shifts to the right).
by TarynD_1I
Sun Jan 19, 2020 8:17 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Not including solids and liquids
Replies: 7
Views: 74

Re: Not including solids and liquids

Solids and liquids are not used in calculating an equilibrium constant, only gasses and aqueous solutions are considered. This is because the activity of the pure solids and liquids are considered to be 1, so it would not affect the equilibrium equation (their concentrations do not change throughout...
by TarynD_1I
Sun Jan 19, 2020 8:14 pm
Forum: *Making Buffers & Calculating Buffer pH (Henderson-Hasselbalch Equation)
Topic: Titration
Replies: 2
Views: 67

Re: Titration

the equivalence point shows where the amount of titrant neutralizes the analyte solution.
by TarynD_1I
Sun Jan 12, 2020 6:26 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Reaction Quotient Q
Replies: 6
Views: 38

Re: Reaction Quotient Q

We use the reaction quotient Q when the reaction is not in equilibrium, to figure out which way the reaction shifts. Use K when the reaction is at equilibrium.
by TarynD_1I
Sun Jan 12, 2020 6:20 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Application of La Chatelier's
Replies: 3
Views: 23

Re: Application of La Chatelier's

You would use Le Chatelier's Principle when the physical parameters of a reaction changes (including temperature, concentration, and pressure). Le Chatelier's basically tells us what happens to the reaction as these changes occur (i.e. if the reaction shifts to the right or the left).
by TarynD_1I
Sun Jan 12, 2020 6:16 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K units
Replies: 3
Views: 25

Re: K units

when calculating for K, the calculation expression is in a ratio, and all of the units cancel each other out. K therefore also has no units.
by TarynD_1I
Sun Jan 12, 2020 6:14 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Calculating K
Replies: 9
Views: 68

Re: Calculating K

Water is not accounted for when calculating for K because it does not affect the equilibrium of the reaction. Pure solids and pure liquids usually do not affect K and are not included in its calculation expression.
by TarynD_1I
Sun Jan 12, 2020 6:09 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Chatelier's Principle
Replies: 7
Views: 62

Re: Chatelier's Principle

Chatelier's Principle is, as Professor Lavelle said in class, chemical reactions adjusting to minimize the effect of change. This change usually refers to changing physical parameters of temperature, pressure, or concentration.
by TarynD_1I
Sun Dec 08, 2019 12:02 am
Forum: Properties & Structures of Inorganic & Organic Bases
Topic: Acidosis
Replies: 2
Views: 92

Re: Acidosis

Respiratory acidosis is a surplus of carbon dioxide in the bloodstream, and since CO2 is acidic, it lowers the pH of blood to be acidic. This happens when a person is suffocating, or not breathing out the CO2 they produce. Therefore, acidosis may be deadly because the pH of blood should not be acidi...
by TarynD_1I
Sat Dec 07, 2019 11:45 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: oxygen in acid strength
Replies: 1
Views: 96

Re: oxygen in acid strength

Acids that contain oxygen are under the "oxoacid" group, which means that the more oxygen atoms that are present, the more acidic the compound is (because of high electronegativity). When comparing two oxoacids, the molecule with a larger number of oxygen atoms would be more acidic. I'm no...
by TarynD_1I
Sat Dec 07, 2019 9:48 pm
Forum: Lewis Structures
Topic: Expanded Octets
Replies: 2
Views: 120

Re: Expanded Octets

Period 3 elements and lower can have an expanded octet because it is able to utilize its d-orbital to also hold electrons.
by TarynD_1I
Sat Dec 07, 2019 9:45 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: resonance in relation to pH
Replies: 2
Views: 58

Re: resonance in relation to pH

I believe that if a molecule has resonance, it has a lower pka, and thus making it more acidic.
by TarynD_1I
Sat Dec 07, 2019 9:36 pm
Forum: Bronsted Acids & Bases
Topic: Strong Acids and Bases
Replies: 6
Views: 163

Re: Strong Acids and Bases

Lyndon gave us this list during his last workshop session:

Strong acids: HCl, HBr, HI, HNO3, H2SO4, HClO4

Strong bases: LiOH, NaOH, KOH, RbOH, ScOH, Ca(OH)2, Sr(OH)2, Ba(OH)2
by TarynD_1I
Sun Dec 01, 2019 8:24 pm
Forum: Bronsted Acids & Bases
Topic: Water as an acid and base
Replies: 7
Views: 88

Water as an acid and base

How does water act as both a Bronsted acid and a base?
by TarynD_1I
Sun Dec 01, 2019 3:48 pm
Forum: Trends in The Periodic Table
Topic: Nitrogen
Replies: 7
Views: 150

Re: Nitrogen

Electron affinity is the likelihood of an atom gaining an electron. Since Nitrogen's 2p shell is has 3 up-spin electrons, making it half full, it would not want to take on another electron because it would make the atom less stable. Half full and completely full subshells are more stable than partia...
by TarynD_1I
Sun Dec 01, 2019 3:42 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Characteristics of a polydentate ligand
Replies: 3
Views: 42

Re: Characteristics of a polydentate ligand

A polydentate ligand has to have more than 2 lewis base sites, for example having more than 2 donor electron pairs that bind to the central atom.
by TarynD_1I
Sun Dec 01, 2019 3:12 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Water
Replies: 5
Views: 54

Re: Water

I think water is considered to be a constant in the equilibrium constant formula (it is considered to be 1) because it shouldn't affect the equilibrium of the reactants.
by TarynD_1I
Sun Dec 01, 2019 2:30 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: What is kA value?
Replies: 5
Views: 71

Re: What is kA value?

kA is the acid dissociation constant, and larger values for kA means that the acid is stronger and dissociates better, while smaller values for kA means that the acid is weaker and does not dissociate as well.
by TarynD_1I
Wed Nov 20, 2019 4:11 pm
Forum: Electronegativity
Topic: electronegativity of hydrogen
Replies: 3
Views: 112

Re: electronegativity of hydrogen

Hydrogen is not very electronegative. In terms of periodic trends, electronegativity goes up as you go up a group as period numbers increase (towards fluorine).
by TarynD_1I
Wed Nov 20, 2019 3:56 pm
Forum: Bond Lengths & Energies
Topic: Boiling Points
Replies: 3
Views: 140

Re: Boiling Points

Why does NO2 have a higher boiling point than N2O? I am confused because NO2 is a radical. NO2 has a higher boiling point because it is more polarizable, which means it has stronger van der waals forces. Since NO2 has more electrons than N2O, it is bigger and more polarizable. I don't think it has ...
by TarynD_1I
Wed Nov 20, 2019 3:47 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shape vs. Geometry
Replies: 5
Views: 84

Re: Molecular Shape vs. Geometry

From what I understand, the geometry is counting up all the areas of electron density, while the shape involves how the areas of electron density from the lone pairs affects the overall shape of the molecule. For example, H20 would have a tetrahedral geometry (because it would have 4 areas of electr...
by TarynD_1I
Wed Nov 20, 2019 3:40 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: Boiling Point
Replies: 7
Views: 97

Re: Boiling Point

I think SO2 would have a higher boiling point because it has more electrons than O3, therefore making it more polarizable. Since it is more polarizable, it has stronger van der waals forces, which take more energy to break, causing SO2 to have a higher boiling point.
by TarynD_1I
Wed Nov 20, 2019 3:32 pm
Forum: Lewis Structures
Topic: XeO2F2 Lewis Structure
Replies: 2
Views: 72

Re: XeO2F2 Lewis Structure

If an element is in the third period or lower, it can have an expanded octet because it can utilize d-orbitals.
by TarynD_1I
Sat Nov 16, 2019 7:25 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Melting Points
Replies: 7
Views: 96

Re: Melting Points

You should probably know which types of bonds are stronger than others, because the stronger the bond, the higher the melting/boiling point. For example, ion-ion being the strongest bond and induced dipole-induced dipole being the weakest.
by TarynD_1I
Sat Nov 16, 2019 7:22 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizability
Replies: 5
Views: 155

Re: Polarizability

You would calculate the difference in electronegativity between the atoms. Polar molecules usually also have a dipole moment, or a difference in partial charges within the molecule.
by TarynD_1I
Sat Nov 16, 2019 7:12 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Definition
Replies: 2
Views: 145

Re: Definition

What exactly is polarizability and how are we supposed to apply it? Like, what is its purpose because I'm kind of confused? Polarizability is how an electron cloud is distorted by an outside electric field. The bigger the atomic radius of an atom, the more polarizable it is because the positive nuc...
by TarynD_1I
Sat Nov 16, 2019 7:01 pm
Forum: Dipole Moments
Topic: Dipole Moment
Replies: 3
Views: 55

Re: Dipole Moment

A dipole moment happens when there is a separation of partial charges within a molecule, which happens when there is a big difference in electronegativity. For example, in H20, there is a dipole moment pointing towards oxygen because oxygen has a much higher electronegativity than hydrogen.
by TarynD_1I
Mon Nov 11, 2019 8:50 pm
Forum: Einstein Equation
Topic: E=hv vs E=pc?
Replies: 7
Views: 250

Re: E=hv vs E=pc?

E=hv is used to find the energy of a photon using Planck's constant and frequency of light.
E=pc is used to find the energy of a photon using the speed of light and the momentum of a photon. I'm pretty sure we only use E=pc when momentum of the photon is provided.
by TarynD_1I
Sun Nov 10, 2019 8:18 pm
Forum: Dipole Moments
Topic: Dipole
Replies: 1
Views: 23

Re: Dipole

You can tell by the difference in electronegativity I think. If one atom in a molecule has a high electronegativity and another atom in the molecule has a low electronegativity, then there is a dipole moment. So basically one side is more positive and one side is more negative. The dipole moment is ...
by TarynD_1I
Sun Nov 10, 2019 8:06 pm
Forum: DeBroglie Equation
Topic: De Broglie Equation Derivation and Use
Replies: 7
Views: 259

Re: De Broglie Equation Derivation and Use

You use de Broglie's equation to find the wavelength of a particle that has resting mass (not light/photons).
by TarynD_1I
Wed Nov 06, 2019 11:39 pm
Forum: Resonance Structures
Topic: resonance hybrid
Replies: 6
Views: 66

Re: resonance hybrid

Lavelle does not expect us to draw the hybrid I think, because he didn't show it in class. So it's preferred that you draw all of the different resonance structures.
by TarynD_1I
Tue Nov 05, 2019 9:25 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Heisenberg Uncertainty in Position
Replies: 4
Views: 159

Re: Heisenberg Uncertainty in Position

I'm pretty sure you'd multiply by 2 to account for both -5 and +5
by TarynD_1I
Mon Nov 04, 2019 4:33 pm
Forum: DeBroglie Equation
Topic: de Broglie vs electromagnetic radiation
Replies: 3
Views: 74

Re: de Broglie vs electromagnetic radiation

You would use de Broglie's to find the wavelength (or describe wave properties) of an object that has resting mass (not light), and you would use E=hv to find the energy of a photon (light).
by TarynD_1I
Sun Nov 03, 2019 8:20 pm
Forum: Lewis Structures
Topic: Resonance Structure
Replies: 4
Views: 59

Re: Resonance Structure

In the review session today on bonding/structures, he told us to either draw all of the resonance structures (and state that there is a hybrid), or to draw the actual hybrid of the structures
by TarynD_1I
Sun Nov 03, 2019 3:32 pm
Forum: Ionic & Covalent Bonds
Topic: Electron Configuration
Replies: 7
Views: 88

Re: Electron Configuration

Yes, because a half filled or a completely filled configuration is more stable than a partially filled.
by TarynD_1I
Sun Nov 03, 2019 3:18 pm
Forum: *Shrodinger Equation
Topic: H ψ = E ψ
Replies: 2
Views: 130

Re: H ψ = E ψ

The H is the Hamiltonian which is just an operator that acts on the ψ. The ψ describes the system mathematically and E is energy. In the review, the problem that was used as an example basically just gave you the H and you had to plug it into the equation and not solve. I think we just have to know...
by TarynD_1I
Sun Nov 03, 2019 1:51 pm
Forum: Trends in The Periodic Table
Topic: Exceptions
Replies: 4
Views: 34

Re: Exceptions

Usually, the electron affinity trend is that EA increases from left to right across the groups, but noble gasses (He, Ne, Ar, etc) have lower EA than the rest of the group.
by TarynD_1I
Sun Nov 03, 2019 1:44 pm
Forum: Lewis Structures
Topic: Lewis Structure for N2O
Replies: 2
Views: 36

Lewis Structure for N2O

Can someone please help walk me through how to draw the lowest energy Lewis Structure for N2O with N as the central atom? (12c on the dino nuggets midterm practice). I was a little confused when they explained it in the review session. Thanks!
by TarynD_1I
Thu Oct 24, 2019 11:16 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Electron Configurations (p-orbital)
Replies: 5
Views: 63

Re: Electron Configurations (p-orbital)

I don't believe that we have to separate px, py, and pz when writing electron configurations. I think Lavelle does it in class to show that each is a different orientation, but when writing configurations on hw or on tests, I haven't been splitting them up.
by TarynD_1I
Thu Oct 24, 2019 10:59 pm
Forum: Ionic & Covalent Bonds
Topic: Electron Affinity
Replies: 5
Views: 83

Re: Electron Affinity

Electron affinity is when an atom (in the gaseous phase) takes on an electron to form an anion (a negative ion). Basically, a neutral charged atom gains an electron, and the electron's negative charge makes the atom's net charge negative. Also, the prompt will probably tell you if the atom is gaseou...
by TarynD_1I
Thu Oct 24, 2019 10:05 pm
Forum: Properties of Electrons
Topic: Anions and Cations
Replies: 4
Views: 77

Re: Anions and Cations

Anions are bigger than their parent atoms because there is more negative electronic charge than positive charge, so there is more electron repulsion. Cations are smaller than their parent atoms because the bigger positive charge from the nucleus makes the attraction of the electrons stronger, thus s...
by TarynD_1I
Thu Oct 24, 2019 9:45 pm
Forum: *Particle in a Box
Topic: TEST 2
Replies: 14
Views: 439

Re: TEST 2

I was advised that the best way to study is by reading the chapters in the book and by doing all of the suggested problems on the syllabus
by TarynD_1I
Tue Oct 22, 2019 10:08 pm
Forum: Einstein Equation
Topic: Used for Photons Only
Replies: 6
Views: 204

Re: Used for Photons Only

E=hv is the equation used to solve for the energy of a particle of light, which is a photon.
by TarynD_1I
Sun Oct 20, 2019 5:14 pm
Forum: Einstein Equation
Topic: When do we use the Einstein Equation?
Replies: 14
Views: 410

Re: When do we use the Einstein Equation?

I'm pretty sure we use E=hv to find the energy of a photon
by TarynD_1I
Fri Oct 18, 2019 10:30 am
Forum: DeBroglie Equation
Topic: Photon Equation
Replies: 4
Views: 90

Re: Photon Equation

Lavelle explained in class that since photons do not have mass (because light doesn't have mass), so they obtain all of their energy from their momentum. So, instead of calculating momentum (p) by multiplying velocity by resting mass, the photon's momentum will probably be given to you in the questi...
by TarynD_1I
Thu Oct 17, 2019 10:46 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Uncertainty Value
Replies: 8
Views: 87

Re: Uncertainty Value

the uncertainty value is 0.2 because the actual value would lie between 2.34 - 2.36.
by TarynD_1I
Thu Oct 17, 2019 9:51 pm
Forum: Photoelectric Effect
Topic: E = pc
Replies: 3
Views: 65

Re: E = pc

I think that you use E = pc when mass is not considered (maybe like a photon, because Lavelle said in class that photons do not have mass, but they have momentum).
by TarynD_1I
Thu Oct 17, 2019 9:45 pm
Forum: Significant Figures
Topic: Tests and Significant Figures
Replies: 6
Views: 216

Re: Tests and Significant Figures

this past test i don't think that the graders took off if you had the wrong amount of significant digits, my TA said he wasn't taking off for sig figs this test
by TarynD_1I
Sun Oct 13, 2019 8:02 pm
Forum: SI Units, Unit Conversions
Topic: knowing how many sig figs to use
Replies: 17
Views: 283

Re: knowing how many sig figs to use

I was recommended to keep as many digits as possible until the very end. This last test, our TA told us that he wasn't placing a heavy emphasis on sig figs so we shouldn't worry about it, but they might start counting it in the future.
by TarynD_1I
Sun Oct 13, 2019 7:57 pm
Forum: Balancing Chemical Reactions
Topic: Writing out equations
Replies: 9
Views: 292

Re: Writing out equations

According to the Hill System, you're supposed to put C carbon first, then Hydrogen, then all the other elements in alphabetical order. But if there is no Carbon the formula, then all the elements are written in alphabetical order.
by TarynD_1I
Thu Oct 10, 2019 11:36 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Test 1 Grading
Replies: 12
Views: 448

Re: Test 1 Grading

the amount of points that each question was worth was put on the test but they do give partial credit if you did the right work but got the wrong answer
by TarynD_1I
Thu Oct 10, 2019 10:39 am
Forum: Empirical & Molecular Formulas
Topic: How to format formulas
Replies: 4
Views: 196

Re: How to format formulas

Usually for the homework problems, when asking for molecular or empirical formulas, the mass percentage composition or the amount in grams of each element is listed out in the order that the resulting compound will be in.
by TarynD_1I
Wed Oct 09, 2019 2:52 pm
Forum: Balancing Chemical Reactions
Topic: Fractions
Replies: 34
Views: 520

Re: Fractions

You should multiply all coefficients to make them whole integers, especially if the question is asking for a molecular or empirical formula.
by TarynD_1I
Sat Oct 05, 2019 10:53 pm
Forum: SI Units, Unit Conversions
Topic: How units of mass effect Scientific notation
Replies: 3
Views: 45

Re: How units of mass effect Scientific notation

10^3 = 1000 while 10^-3= 0.001

When you see a negative, it just means to move the decimal to the left, while a positive exponent means to move the decimal to the right
by TarynD_1I
Thu Oct 03, 2019 9:33 am
Forum: Significant Figures
Topic: rounding in sig figs
Replies: 5
Views: 234

Re: rounding in sig figs

Professor Lavelle also has a link on his website (https://lavelle.chem.ucla.edu/wp-conten ... OUT_SF.pdf) that is really helpful for figuring out sig figs :)
by TarynD_1I
Wed Oct 02, 2019 3:50 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Solubility Rules Memorization ?
Replies: 3
Views: 91

Re: Solubility Rules Memorization ?

For a couple of the examples given in my discussion last week where we were practicing writing out and balancing chemical equations, we weren't given states of matter, but for those questions, it was easier to use context clues to figure it out. It might be a little harder to figure out which reacta...
by TarynD_1I
Wed Oct 02, 2019 3:39 pm
Forum: SI Units, Unit Conversions
Topic: Difference between Chem Community HW and Textbook HW
Replies: 5
Views: 84

Re: Difference between Chem Community HW and Textbook HW

I'm pretty sure that hand-written homework from the textbook is collected at your discussion (except this week) and chemistry community posts are due on Sundays.
by TarynD_1I
Wed Oct 02, 2019 3:29 pm
Forum: Balancing Chemical Reactions
Topic: Combustion [ENDORSED]
Replies: 3
Views: 125

Combustion [ENDORSED]

Just making sure: when writing out combustion reactions, it's implied that we add oxygen as a reagent and CO2 and H20 as products, right?

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