Search found 69 matches
- Sun Mar 17, 2019 6:32 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Picking up the Final
- Replies: 2
- Views: 513
Re: Picking up the Final
Lavelle said we can pick up our final exam in 3034 Young Hall Week 3 of Spring Quarter!
- Tue Mar 12, 2019 10:23 am
- Forum: Calculating Work of Expansion
- Topic: Reversible vs irreversible
- Replies: 6
- Views: 873
Re: Reversible vs irreversible
Yes, and remember that an irreversible reaction will always require less work.
- Tue Mar 12, 2019 10:22 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: entropy and enthalpy
- Replies: 5
- Views: 586
Re: entropy and enthalpy
Yes, they are correlated for Gibbs Free energy
- Tue Mar 12, 2019 10:21 am
- Forum: Administrative Questions and Class Announcements
- Topic: Final
- Replies: 18
- Views: 1953
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...
- Thu Mar 07, 2019 9:49 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: What does unique rate of reaction mean?
- Replies: 6
- Views: 597
Re: What does unique rate of reaction mean?
Indeed Nathan Tran.
- 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: 597
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.
- 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: 597
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.
- Tue Mar 05, 2019 9:18 pm
- Forum: Ideal Gases
- Topic: Water
- Replies: 13
- Views: 1027
Re: Water
Water can be solid, liquid, or gas.
- Tue Mar 05, 2019 9:02 pm
- Forum: Student Social/Study Group
- Topic: Final
- Replies: 24
- Views: 2116
Re: Final
Information about review sessions was sent in a new email :)
- Tue Mar 05, 2019 8:59 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Ecell
- Replies: 13
- Views: 1422
Re: Ecell
Ecell=Ecathode-Eanode
- Tue Mar 05, 2019 8:57 pm
- Forum: Zero Order Reactions
- Topic: Half life
- Replies: 5
- Views: 538
Re: Half life
Half life reactions are just 1st order reactions!
- Wed Feb 20, 2019 4:52 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Delta G a state function?
- Replies: 23
- Views: 2747
Re: Delta G a state function?
Free energy is a state function!
- Wed Feb 20, 2019 4:49 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: gibbs free energy
- Replies: 10
- Views: 856
Re: gibbs free energy
If Gibbs Free Energy is negative, it is spontaneous.
- Wed Feb 20, 2019 4:46 pm
- Forum: Balancing Redox Reactions
- Topic: Galvanic cells
- Replies: 4
- Views: 399
Re: Galvanic cells
The reaction will eventually stop when there are no more ions trading off.
- Wed Feb 20, 2019 4:45 pm
- Forum: Balancing Redox Reactions
- Topic: how to balance
- Replies: 5
- Views: 467
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.
- Wed Feb 20, 2019 4:40 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Anode v. Cathode
- Replies: 9
- Views: 920
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.
- Wed Feb 20, 2019 2:59 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Spontaneous vs Not Spontaneous
- Replies: 7
- Views: 697
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.
- Wed Feb 06, 2019 10:12 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: deltaU=3/2nRdeltaT
- Replies: 1
- Views: 260
deltaU=3/2nRdeltaT
When do we use this equation to find internal energy? And where does the 3/2 come from for this equation?
- Mon Feb 04, 2019 3:07 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Closed and Isolated
- Replies: 10
- Views: 690
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).
- Mon Feb 04, 2019 3:02 pm
- Forum: Calculating Work of Expansion
- Topic: Work equation
- Replies: 2
- Views: 335
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...
- Mon Feb 04, 2019 2:58 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Degeneracy
- Replies: 5
- Views: 510
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.
- Sun Feb 03, 2019 8:03 pm
- Forum: Phase Changes & Related Calculations
- Topic: Week 4 Discussion Notes & Worksheet (2E, 2I, 2K)
- Replies: 3
- Views: 505
Re: Week 4 Discussion Notes & Worksheet (2E, 2I, 2K)
Thanks Joyce!
- Wed Jan 23, 2019 9:13 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Initial Q
- Replies: 3
- Views: 443
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.
- Wed Jan 23, 2019 8:21 pm
- Forum: Phase Changes & Related Calculations
- Topic: Endothermic or Exothermic
- Replies: 20
- Views: 1952
Re: Endothermic or Exothermic
Condensations is an exothermic process!
- 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: 431
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?
- Wed Jan 23, 2019 8:11 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Initial Q
- Replies: 3
- Views: 443
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?
- Wed Jan 16, 2019 6:00 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Expansion...
- Replies: 2
- Views: 218
Re: Expansion...
Thank you!
- 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: 390
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.
- 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: 3163
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.
- Wed Jan 16, 2019 12:39 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Expansion...
- Replies: 2
- Views: 218
Expansion...
What does it mean when "expansion occurs" on a certain reaction?
- 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: 1477
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!
- Wed Jan 16, 2019 12:35 pm
- Forum: Ideal Gases
- Topic: Water
- Replies: 13
- Views: 1027
Re: Water
A liquid cannot be aqueous, but it can be a solid, liquid, and gas.
- Wed Jan 16, 2019 12:34 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 11.43 6th edition
- Replies: 4
- Views: 432
Re: 11.43 6th edition
When using the ICE box, you can use partial pressure and molarities/concentrations.
- Wed Jan 16, 2019 12:27 pm
- Forum: Ideal Gases
- Topic: Homework for week 2 [ENDORSED]
- Replies: 10
- Views: 2947
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’.
- Wed Jan 16, 2019 12:24 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Converting Between Kp and Kc
- Replies: 3
- Views: 208
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.
- Wed Jan 09, 2019 11:20 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K and Kc
- Replies: 8
- Views: 540
Re: K and Kc
Kc is specifically the molar concentration [P]/[R], and K is just an overall equilibrium constant.
- Wed Jan 09, 2019 11:13 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: hw questions - points
- Replies: 9
- Views: 662
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).
- Wed Jan 09, 2019 11:09 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Solids do not have concentrations?
- Replies: 3
- Views: 151
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.
- Mon Dec 03, 2018 2:49 pm
- Forum: Naming
- Topic: Regarding the test... [ENDORSED]
- Replies: 12
- Views: 5683
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.
- Sun Dec 02, 2018 9:40 am
- Forum: Hybridization
- Topic: lone pairs
- Replies: 20
- Views: 1988
Re: lone pairs
Yes, a lone pair is considered a region of electron density and therefore you will count it to find hybridization.
- Wed Nov 28, 2018 3:58 pm
- Forum: Hybridization
- Topic: Polar Power
- Replies: 5
- Views: 450
Re: Polar Power
Thank you!
- Tue Nov 27, 2018 11:28 pm
- Forum: Hybridization
- Topic: Polar Power
- Replies: 5
- Views: 450
Polar Power
Can someone elaborate what polar power is? And why a high charge and a low volume affect it?
- Tue Nov 20, 2018 11:57 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSPER Formula
- Replies: 7
- Views: 777
Re: VSPER Formula
A stands for the central atom!
- Tue Nov 20, 2018 8:52 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Thanksgiving Wednesday Class
- Replies: 19
- Views: 1364
- Tue Nov 20, 2018 8:51 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR
- Replies: 5
- Views: 528
Re: VSEPR
Yes!
- Tue Nov 20, 2018 8:51 pm
- Forum: Hybridization
- Topic: Test 3
- Replies: 8
- Views: 798
Re: Test 3
Yes! Everything that was not covered on the midterm!
- Thu Nov 15, 2018 4:45 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Thanksgiving [ENDORSED]
- Replies: 14
- Views: 1500
Re: Thanksgiving [ENDORSED]
Thank you Dr. Lavelle!
- Thu Nov 15, 2018 4:13 pm
- Forum: Octet Exceptions
- Topic: The center atom
- Replies: 20
- Views: 3162
Re: The center atom
The center atom would be oxygen because if you look at the periodic table it has the lowest ionization energy.
- Thu Nov 15, 2018 4:00 pm
- Forum: Octet Exceptions
- Topic: The center atom
- Replies: 20
- Views: 3162
Re: The center atom
The center atom would be oxygen because if you look at the periodic table it has the lowest ionization energy.
- Thu Nov 15, 2018 3:59 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Formal Charge
- Replies: 10
- Views: 1610
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.
- Sun Nov 11, 2018 10:54 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Thanksgiving Wednesday
- Replies: 9
- Views: 849
Re: Thanksgiving Wednesday
Dr. Lavelle said it depends on if we are behind or ahead.
- Sun Nov 04, 2018 9:03 am
- Forum: Administrative Questions and Class Announcements
- Topic: MIDTERM PRACTICE - Garlic Bread Review Session [ENDORSED]
- Replies: 121
- Views: 17159
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...
- Sat Nov 03, 2018 12:17 am
- Forum: Properties of Light
- Topic: 3b on Quantum Test
- Replies: 2
- Views: 284
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...
- Sat Nov 03, 2018 12:17 am
- Forum: Properties of Light
- Topic: 3b on Quantum Test
- Replies: 1
- Views: 250
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...
- Sat Nov 03, 2018 12:13 am
- Forum: Quantum Numbers and The H-Atom
- Topic: degeneracy of the a 4p orbital
- Replies: 9
- Views: 2098
Re: degeneracy of the a 4p orbital
The degeneracy of a 4p orbital will be 3 because they all have the same energy level.
- Sat Nov 03, 2018 12:11 am
- Forum: Empirical & Molecular Formulas
- Topic: Mass Composition
- Replies: 3
- Views: 370
Re: Mass Composition
The mass composition percentage has to add up to 100%.
- Sat Nov 03, 2018 12:09 am
- Forum: Ionic & Covalent Bonds
- Topic: Lewis Dot Structures: Ionization Energy
- Replies: 6
- Views: 739
Re: Lewis Dot Structures: Ionization Energy
Thanks guys! This really helped :)
- Sun Oct 28, 2018 9:45 pm
- Forum: Ionic & Covalent Bonds
- Topic: Question regarding ionic bonds
- Replies: 9
- Views: 602
- Sun Oct 28, 2018 9:44 pm
- Forum: Ionic & Covalent Bonds
- Topic: Lewis Dot Structures: Ionization Energy
- Replies: 6
- Views: 739
Lewis Dot Structures: Ionization Energy
Why do we choose the atom with the lowest ionization energy as the central atom for Lewis Dot Structures?
- Mon Oct 22, 2018 1:09 pm
- Forum: Properties of Electrons
- Topic: Transitions
- Replies: 3
- Views: 346
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.
- Thu Oct 18, 2018 7:31 pm
- Forum: Properties of Electrons
- Topic: eV to J
- Replies: 7
- Views: 873
Re: eV to J
1eV= 1.6022 x 10^-19Joules
- Thu Oct 18, 2018 7:26 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Nodal Planes [ENDORSED]
- Replies: 4
- Views: 697
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.
- Sun Oct 14, 2018 2:44 pm
- Forum: Significant Figures
- Topic: When to round the answers to significant figures
- Replies: 11
- Views: 2573
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.
- Thu Oct 11, 2018 8:29 pm
- Forum: Properties of Light
- Topic: Light
- Replies: 9
- Views: 862
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...
- 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: 38424
Re: DOWNLOAD SESSION WORKSHEETS HERE - Sundays 4-6pm (Karen) [ENDORSED]
Thank you so much Karen! I was looking for more practice problems <3
- Sun Oct 07, 2018 5:15 pm
- Forum: SI Units, Unit Conversions
- Topic: Formula Sheet?
- Replies: 6
- Views: 553
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.
- Wed Oct 03, 2018 7:11 pm
- Forum: SI Units, Unit Conversions
- Topic: Fundamental Exercises E27
- Replies: 3
- Views: 333
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)
:)
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)
:)
- Tue Oct 02, 2018 5:17 pm
- Forum: SI Units, Unit Conversions
- Topic: Units for the answers
- Replies: 2
- Views: 140
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.
- Sun Sep 30, 2018 11:11 am
- Forum: Empirical & Molecular Formulas
- Topic: Mutiplying by a number
- Replies: 3
- Views: 241
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 ...