Search found 69 matches

by Samantha Chang 2K
Sun Mar 17, 2019 6:32 pm
Forum: Administrative Questions and Class Announcements
Topic: Picking up the Final
Replies: 2
Views: 35

Re: Picking up the Final

Lavelle said we can pick up our final exam in 3034 Young Hall Week 3 of Spring Quarter!
by Samantha Chang 2K
Tue Mar 12, 2019 10:23 am
Forum: Calculating Work of Expansion
Topic: Reversible vs irreversible
Replies: 6
Views: 93

Re: Reversible vs irreversible

Yes, and remember that an irreversible reaction will always require less work.
by Samantha Chang 2K
Tue Mar 12, 2019 10:22 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: entropy and enthalpy
Replies: 5
Views: 52

Re: entropy and enthalpy

Yes, they are correlated for Gibbs Free energy
by Samantha Chang 2K
Tue Mar 12, 2019 10:21 am
Forum: Administrative Questions and Class Announcements
Topic: Final
Replies: 18
Views: 198

Re: Final

I am guessing the new material will be heavily weighted, but you cannot really predict with Lavelle's tests. It is safe to say that everything is fair game...
by Samantha Chang 2K
Thu Mar 07, 2019 9:47 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: What does unique rate of reaction mean?
Replies: 6
Views: 79

Re: What does unique rate of reaction mean?

The unique rate is a rate of a reaction divided by its stoichiometric coefficient. A unique rate will be the same for each reactant or product but the product will be a negative value.
by Samantha Chang 2K
Thu Mar 07, 2019 9:44 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: What does unique rate of reaction mean?
Replies: 6
Views: 79

Re: What does unique rate of reaction mean?

Very intriguing questing Nathan Tran. I am glad you asked this to further facilitate the conversation of Kinematics.
by Samantha Chang 2K
Tue Mar 05, 2019 9:18 pm
Forum: Ideal Gases
Topic: Water
Replies: 13
Views: 152

Re: Water

Water can be solid, liquid, or gas.
by Samantha Chang 2K
Tue Mar 05, 2019 9:02 pm
Forum: Student Social/Study Group
Topic: Final
Replies: 24
Views: 318

Re: Final

Information about review sessions was sent in a new email :)
by Samantha Chang 2K
Tue Mar 05, 2019 8:59 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Ecell
Replies: 13
Views: 137

Re: Ecell

Ecell=Ecathode-Eanode
by Samantha Chang 2K
Tue Mar 05, 2019 8:57 pm
Forum: Zero Order Reactions
Topic: Half life
Replies: 5
Views: 59

Re: Half life

Half life reactions are just 1st order reactions!
by Samantha Chang 2K
Wed Feb 20, 2019 4:52 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Delta G a state function?
Replies: 23
Views: 188

Re: Delta G a state function?

Free energy is a state function!
by Samantha Chang 2K
Wed Feb 20, 2019 4:49 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: gibbs free energy
Replies: 10
Views: 89

Re: gibbs free energy

If Gibbs Free Energy is negative, it is spontaneous.
by Samantha Chang 2K
Wed Feb 20, 2019 4:46 pm
Forum: Balancing Redox Reactions
Topic: Galvanic cells
Replies: 4
Views: 52

Re: Galvanic cells

The reaction will eventually stop when there are no more ions trading off.
by Samantha Chang 2K
Wed Feb 20, 2019 4:45 pm
Forum: Balancing Redox Reactions
Topic: how to balance
Replies: 5
Views: 49

Re: how to balance

For redox reactions you have to do both, balance, like we learned in high school, and make sure the charges are even.
by Samantha Chang 2K
Wed Feb 20, 2019 4:40 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Anode v. Cathode
Replies: 9
Views: 81

Re: Anode v. Cathode

The anode and the cathode are deemed right and left just as a formality so you can tell where the reactions are taking place. An anode is the oxidation part of the reaction and the cathode contains the reduction part of the reaction.
by Samantha Chang 2K
Wed Feb 20, 2019 2:59 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Spontaneous vs Not Spontaneous
Replies: 7
Views: 57

Re: Spontaneous vs Not Spontaneous

Yes, when delta G is negative it is spontaneous and when delta G is positive it is not spontaneous. When delta. G is 0, it is at equilibrium.
by Samantha Chang 2K
Wed Feb 06, 2019 10:12 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: deltaU=3/2nRdeltaT
Replies: 1
Views: 37

deltaU=3/2nRdeltaT

When do we use this equation to find internal energy? And where does the 3/2 come from for this equation?
by Samantha Chang 2K
Mon Feb 04, 2019 3:07 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Closed and Isolated
Replies: 10
Views: 78

Re: Closed and Isolated

In a closed system, heat can still travel in and out of it, but in an isolated system nothing can affect the internal energy(that is why U=0 for a closed system).
by Samantha Chang 2K
Mon Feb 04, 2019 3:02 pm
Forum: Calculating Work of Expansion
Topic: Work equation
Replies: 2
Views: 38

Re: Work equation

W=-PdeltaV is utilized when pressure IS constant which was shown in lecture through a definite integral because we could factor out the constant of pressure and we are left with the integral dv which just means V2-V1 if we put it into a definite integral. We use the other equation -nRTln(V2/V1) when...
by Samantha Chang 2K
Mon Feb 04, 2019 2:58 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Degeneracy
Replies: 5
Views: 40

Re: Degeneracy

In lecture Lavelle defined degeneracy as the number of ways of achieving a given energy state, and it can help us find entropy.
by Samantha Chang 2K
Wed Jan 23, 2019 9:13 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Initial Q
Replies: 3
Views: 79

Re: Initial Q

I am terrible at explaining, but here is the video I watched: https://www.youtube.com/watch?v=54n1XppP-lA and I got confused with the example at 25:46 when the initial concentrations of the products were not 0.
by Samantha Chang 2K
Wed Jan 23, 2019 8:21 pm
Forum: Phase Changes & Related Calculations
Topic: Endothermic or Exothermic
Replies: 20
Views: 441

Re: Endothermic or Exothermic

Condensations is an exothermic process!
by Samantha Chang 2K
Wed Jan 23, 2019 8:14 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Volume and Le Chatelier's Principle
Replies: 5
Views: 77

Volume and Le Chatelier's Principle

If there are the same number of moles on both sides of the equation and you increase/decrease the volume then does the equation shift to the left or right?
by Samantha Chang 2K
Wed Jan 23, 2019 8:11 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Initial Q
Replies: 3
Views: 79

Initial Q

I was watching a YouTube video, and I got a bit confused on a topic. If you are given initial concentrations and the Kc value, and the Qinitial>Kc then do you switch the x signs for change in molarity when doing the ICE table to find the final equilibrium concentrations? If so, then why?
by Samantha Chang 2K
Wed Jan 16, 2019 6:00 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Expansion...
Replies: 2
Views: 48

Re: Expansion...

Thank you!
by Samantha Chang 2K
Wed Jan 16, 2019 12:46 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Equilibrium in relation to K and Q
Replies: 5
Views: 51

Re: Equilibrium in relation to K and Q

Solving for Q is the same as solving for K. When Q is less than K, forward reaction is favored. When Q is greater than K, reverse reaction is favored.
by Samantha Chang 2K
Wed Jan 16, 2019 12:43 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Exothermic vs. Endothermic Reaction
Replies: 9
Views: 87

Re: Exothermic vs. Endothermic Reaction

We can know if a reaction is endothermic when heat is absorb and in contrast an exothermic reaction is when heat is released. This is how one can environmentally tell if a reaction is exothermic and endothermic. Other than that, I think one has to know if delta H is negative or positive.
by Samantha Chang 2K
Wed Jan 16, 2019 12:39 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Expansion...
Replies: 2
Views: 48

Expansion...

What does it mean when "expansion occurs" on a certain reaction?
by Samantha Chang 2K
Wed Jan 16, 2019 12:36 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Negative pH
Replies: 12
Views: 158

Re: Negative pH

pH can be negative, but in class it the pH utilized will mostly be in the range of 0-14. pH can be negative with super acids!
by Samantha Chang 2K
Wed Jan 16, 2019 12:35 pm
Forum: Ideal Gases
Topic: Water
Replies: 13
Views: 152

Re: Water

A liquid cannot be aqueous, but it can be a solid, liquid, and gas.
by Samantha Chang 2K
Wed Jan 16, 2019 12:34 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 11.43 6th edition
Replies: 4
Views: 53

Re: 11.43 6th edition

When using the ICE box, you can use partial pressure and molarities/concentrations.
by Samantha Chang 2K
Wed Jan 16, 2019 12:27 pm
Forum: Ideal Gases
Topic: Homework for week 2 [ENDORSED]
Replies: 10
Views: 151

Re: Homework for week 2 [ENDORSED]

On an email given Lavelle said homework can be either equilibrium, or acids and bases, or some of both as it is all ‘recently covered material’.
by Samantha Chang 2K
Wed Jan 16, 2019 12:24 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Converting Between Kp and Kc
Replies: 3
Views: 38

Re: Converting Between Kp and Kc

When converting to Kp and Kc, you use the ideal gas law, P=concRT, and you use the concentrations given to find pressure in atm.
by Samantha Chang 2K
Wed Jan 09, 2019 11:20 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K and Kc
Replies: 8
Views: 89

Re: K and Kc

Kc is specifically the molar concentration [P]/[R], and K is just an overall equilibrium constant.
by Samantha Chang 2K
Wed Jan 09, 2019 11:13 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: hw questions - points
Replies: 9
Views: 112

Re: hw questions - points

Homework questions are 7 points a week (70 points per quarter) and the 3 chemistry community posts are 3 points a week (30 points per quarter).
by Samantha Chang 2K
Wed Jan 09, 2019 11:09 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Solids do not have concentrations?
Replies: 3
Views: 46

Re: Solids do not have concentrations?

Yes, you are correct, solids do not have concentration, and neither do pure liquids; therefore, they cannot be used to calculate for K.
by Samantha Chang 2K
Mon Dec 03, 2018 2:49 pm
Forum: Naming
Topic: Regarding the test... [ENDORSED]
Replies: 11
Views: 1467

Regarding the test... [ENDORSED]

Are we going to be tested on naming coordination compounds? There was a little bit of confusion in my UA session because the UA said that Lavelle was supposed to remove naming from the curriculum.
by Samantha Chang 2K
Sun Dec 02, 2018 9:40 am
Forum: Hybridization
Topic: lone pairs
Replies: 20
Views: 166

Re: lone pairs

Yes, a lone pair is considered a region of electron density and therefore you will count it to find hybridization.
by Samantha Chang 2K
Wed Nov 28, 2018 3:58 pm
Forum: Hybridization
Topic: Polar Power
Replies: 5
Views: 67

Re: Polar Power

Thank you!
by Samantha Chang 2K
Tue Nov 27, 2018 11:28 pm
Forum: Hybridization
Topic: Polar Power
Replies: 5
Views: 67

Polar Power

Can someone elaborate what polar power is? And why a high charge and a low volume affect it?
by Samantha Chang 2K
Tue Nov 20, 2018 11:57 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSPER Formula
Replies: 7
Views: 105

Re: VSPER Formula

A stands for the central atom!
by Samantha Chang 2K
Tue Nov 20, 2018 8:51 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR
Replies: 5
Views: 80

Re: VSEPR

Yes!
by Samantha Chang 2K
Tue Nov 20, 2018 8:51 pm
Forum: Hybridization
Topic: Test 3
Replies: 8
Views: 127

Re: Test 3

Yes! Everything that was not covered on the midterm!
by Samantha Chang 2K
Thu Nov 15, 2018 4:45 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Thanksgiving [ENDORSED]
Replies: 14
Views: 249

Re: Thanksgiving [ENDORSED]

Thank you Dr. Lavelle!
by Samantha Chang 2K
Thu Nov 15, 2018 4:13 pm
Forum: Octet Exceptions
Topic: The center atom
Replies: 20
Views: 314

Re: The center atom

The center atom would be oxygen because if you look at the periodic table it has the lowest ionization energy.
by Samantha Chang 2K
Thu Nov 15, 2018 4:00 pm
Forum: Octet Exceptions
Topic: The center atom
Replies: 20
Views: 314

Re: The center atom

The center atom would be oxygen because if you look at the periodic table it has the lowest ionization energy.
by Samantha Chang 2K
Thu Nov 15, 2018 3:59 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge
Replies: 10
Views: 194

Re: Formal Charge

Having a 0 formal charge is most important, unless it is an ion; therefore the formal charge has to be equal to the charge of the ion. Sometimes lewis dot structures can have expanded octet.
by Samantha Chang 2K
Sun Nov 11, 2018 10:54 pm
Forum: Administrative Questions and Class Announcements
Topic: Thanksgiving Wednesday
Replies: 9
Views: 197

Re: Thanksgiving Wednesday

Dr. Lavelle said it depends on if we are behind or ahead.
by Samantha Chang 2K
Sun Nov 04, 2018 9:03 am
Forum: Administrative Questions and Class Announcements
Topic: MIDTERM PRACTICE - Garlic Bread Review Session [ENDORSED]
Replies: 121
Views: 4541

Re: MIDTERM PRACTICE - Garlic Bread Review Session [ENDORSED]

Could someone explain 13c to me? -13c is a Heisenberg Uncertainty Principle problem. The equation for this problem is ΔPΔX=>h/4pi. For this equation we need the mass, the velocity(these two values multipled together are ΔP), and we need ultimately to find ΔX. -We are given the mass which is 2.8 gra...
by Samantha Chang 2K
Sat Nov 03, 2018 12:17 am
Forum: Properties of Light
Topic: 3b on Quantum Test
Replies: 2
Views: 95

3b on Quantum Test

3b) in the second experiment if the same threshold voltage is applied to the mercury lamp(that is now significantly contaminated by atoms with a higher threshold energy) what will happen to the intensity of the light emitted? Will the intensity not be affected? I have a hard time conceptually graspi...
by Samantha Chang 2K
Sat Nov 03, 2018 12:17 am
Forum: Properties of Light
Topic: 3b on Quantum Test
Replies: 1
Views: 87

3b on Quantum Test

3b) in the second experiment if the same threshold voltage is applied to the mercury lamp(that is now significantly contaminated by atoms with a higher threshold energy) what will happen to the intensity of the light emitted? Will the intensity not be affected? I have a hard time conceptually graspi...
by Samantha Chang 2K
Sat Nov 03, 2018 12:13 am
Forum: Quantum Numbers and The H-Atom
Topic: degeneracy of the a 4p orbital
Replies: 9
Views: 218

Re: degeneracy of the a 4p orbital

The degeneracy of a 4p orbital will be 3 because they all have the same energy level.
by Samantha Chang 2K
Sat Nov 03, 2018 12:11 am
Forum: Empirical & Molecular Formulas
Topic: Mass Composition
Replies: 3
Views: 102

Re: Mass Composition

The mass composition percentage has to add up to 100%.
by Samantha Chang 2K
Sat Nov 03, 2018 12:09 am
Forum: Ionic & Covalent Bonds
Topic: Lewis Dot Structures: Ionization Energy
Replies: 6
Views: 89

Re: Lewis Dot Structures: Ionization Energy

Thanks guys! This really helped :)
by Samantha Chang 2K
Sun Oct 28, 2018 9:44 pm
Forum: Ionic & Covalent Bonds
Topic: Lewis Dot Structures: Ionization Energy
Replies: 6
Views: 89

Lewis Dot Structures: Ionization Energy

Why do we choose the atom with the lowest ionization energy as the central atom for Lewis Dot Structures?
by Samantha Chang 2K
Mon Oct 22, 2018 1:09 pm
Forum: Properties of Electrons
Topic: Transitions
Replies: 3
Views: 100

Re: Transitions

The change in energy can be negative(exothermic) or positive(endothermic). In this case the change of energy is exothermic in which energy is released, so the value will be negative.
by Samantha Chang 2K
Thu Oct 18, 2018 7:31 pm
Forum: Properties of Electrons
Topic: eV to J
Replies: 7
Views: 108

Re: eV to J

1eV= 1.6022 x 10^-19Joules
by Samantha Chang 2K
Thu Oct 18, 2018 7:26 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Nodal Planes [ENDORSED]
Replies: 4
Views: 106

Re: Nodal Planes [ENDORSED]

Yes, a nodal plane is in a region of zero electron probability meaning the planes are perpendicular to the internuclear axis. For example, the S orbital has no internuclear axis; therefore, it has no nodal planes.
by Samantha Chang 2K
Sun Oct 14, 2018 2:44 pm
Forum: Significant Figures
Topic: When to round the answers to significant figures
Replies: 11
Views: 267

Re: When to round the answers to significant figures

I would round the answers to the significant figures towards the end because it would provide the most accurate answer. Throughout the problem I would use the most amount of decimal places in order to obtain a precise number until the end.
by Samantha Chang 2K
Thu Oct 11, 2018 8:29 pm
Forum: Properties of Light
Topic: Light
Replies: 9
Views: 135

Re: Light

Amplitude measures the height of each wave and equates to the energy or intensity of the light. The amplitude does not have any effect on the frequency. Wavelength and frequency are inverses of one another, so if one increases the other one decreases. This is based off of the equation c(speed of lig...
by Samantha Chang 2K
Wed Oct 10, 2018 5:00 pm
Forum: Administrative Questions and Class Announcements
Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sundays 4-6pm (Karen) [ENDORSED]
Replies: 135
Views: 25015

Re: DOWNLOAD SESSION WORKSHEETS HERE - Sundays 4-6pm (Karen) [ENDORSED]

Thank you so much Karen! I was looking for more practice problems <3
by Samantha Chang 2K
Sun Oct 07, 2018 5:15 pm
Forum: SI Units, Unit Conversions
Topic: Formula Sheet?
Replies: 6
Views: 109

Re: Formula Sheet?

For this upcoming test, I would memorize the formulas needed, for there are not that many. We will get a periodic table for the molecular masses though.
by Samantha Chang 2K
Wed Oct 03, 2018 7:11 pm
Forum: SI Units, Unit Conversions
Topic: Fundamental Exercises E27
Replies: 3
Views: 87

Re: Fundamental Exercises E27

1. Convert 1Kg H2O to grams
2. Convert the grams of H2O to moles using molar mass of H2O (you can add masses up using the periodic table)
3. Convert the moles to molecules using Avogadro constant (6.022*10^23)
:)
by Samantha Chang 2K
Tue Oct 02, 2018 5:17 pm
Forum: SI Units, Unit Conversions
Topic: Units for the answers
Replies: 2
Views: 54

Re: Units for the answers

Usually the problem indicates what units should be utilized for the answer. If not, stick to your standard metric units of measurement, such as liters, grams, and meters. These are additionally the units employed in most chemistry concepts like molarity and quantum chemistry.
by Samantha Chang 2K
Sun Sep 30, 2018 11:11 am
Forum: Empirical & Molecular Formulas
Topic: Mutiplying by a number
Replies: 3
Views: 84

Re: Mutiplying by a number

Empirical formula represents the relative number of atoms in a molecule, so I would just round up to the nearest whole number if it is that close. I would say that 8.94 and 10.92 are close enough to be rounded up. In the problems that we are given, it is usually apparent whether we need to multiply ...

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