Search found 76 matches
- Sat Mar 16, 2019 11:22 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: A in the arrhenius equation
- Replies: 2
- Views: 794
Re: A in the arrhenius equation
I believe A is the collision frequency in the correct orientation.
- Sat Mar 16, 2019 11:12 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Arrhenius equation
- Replies: 2
- Views: 609
Arrhenius equation
How is Enthalpy or delta H related to Activation energy, Ea in the Arrhenius equation?
- Sat Mar 16, 2019 11:10 pm
- Forum: First Order Reactions
- Topic: Graphs/Plots
- Replies: 2
- Views: 544
Re: Graphs/Plots
You should be familiar with the graphs of the rate orders just in case and also Arrhenius equation and just be familiar with labeling them too.
- Sat Mar 16, 2019 8:11 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Slow and Fast step
- Replies: 4
- Views: 732
Slow and Fast step
Are we going to have to identify the slow and fast step or will it be shown on the problems in the final?
- Fri Mar 15, 2019 11:02 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: delta U
- Replies: 4
- Views: 684
Re: delta U
Maria Solis Disc 4C wrote:Internal Energy should always be q+w
Thanks. I see q- w sometimes and that confuses me.
- Fri Mar 15, 2019 10:51 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: delta U
- Replies: 4
- Views: 684
delta U
What is the difference btw delta U= q + w and delta U= q - w?
- Wed Mar 13, 2019 9:39 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Temperature
- Replies: 2
- Views: 468
Re: Temperatutre
I always convert to Kelvin to be safe... There are many instances, such as when you calculate for entropy when you divide two temperatures, and using Celcius here will mess up your ratio and give you an incorrect answer. You also know what to use based on the units and what you need to cancel out.....
- Wed Mar 13, 2019 9:21 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Temperature
- Replies: 2
- Views: 468
Temperature
When do you know to convert Celcius to Kelvin?
- Wed Mar 13, 2019 8:51 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Calculating Temperature
- Replies: 1
- Views: 225
Calculating Temperature
Can someone please explain part (c)?
- Mon Mar 11, 2019 10:11 pm
- Forum: Second Order Reactions
- Topic: half-life for second order
- Replies: 3
- Views: 367
half-life for second order
In the 7th edition textbook, it states "not used" for the equation of half-life of the second order reaction But there are problems, for example, 7b.13 that ask us to calculate the half-life of a second order reaction. I am confused, can someone please clarify this?
- Mon Mar 11, 2019 1:28 am
- Forum: Administrative Questions and Class Announcements
- Topic: Homework week 9
- Replies: 3
- Views: 465
Homework week 9
Do we turn in two homework this wee? That is, do we turn in 14 problems this week ?
- Sun Mar 03, 2019 4:08 pm
- Forum: First Order Reactions
- Topic: First Oder
- Replies: 1
- Views: 265
First Oder
Can someone help me understand 7A.13, 7th edition? Why is the rate first order?
- Sun Mar 03, 2019 3:27 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Large K value
- Replies: 5
- Views: 545
Re: Large K value
If the Ecell° is positive, the reaction is favorable forward which means has K>1
- Mon Feb 25, 2019 6:15 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Test 2
- Replies: 1
- Views: 310
Test 2
Would we be given the standard reduction potential values for the test?
- Sun Feb 24, 2019 2:12 pm
- Forum: Balancing Redox Reactions
- Topic: Which Equation to Flip?
- Replies: 9
- Views: 4662
Re: Which Equation to Flip?
I usually flip the anode equation. Probably that's why the Cu was flipped. Also, the anode equation is being oxidized.
- Sun Feb 24, 2019 1:48 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Platinum
- Replies: 1
- Views: 168
Re: Platinum
I know platinum is used as an oxidation catalyst.
- Sun Feb 24, 2019 1:12 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Test 2
- Replies: 9
- Views: 1054
Re: Test 2
Calculating the equilibrium constant from Gibbs free energy, calculating the free energy of reaction from formation and using van't Hoff equation.
- Sun Feb 24, 2019 12:44 pm
- Forum: Balancing Redox Reactions
- Topic: Oxidation/Reduction
- Replies: 2
- Views: 265
Oxidation/Reduction
How can you identify the species that are being oxidized or reduced?
- Mon Feb 18, 2019 2:59 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: deltaG=0
- Replies: 2
- Views: 311
Re: deltaG=0
The reaction is at equilibrium.
- Sun Feb 17, 2019 7:14 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gibbs free energy?
- Replies: 2
- Views: 298
Re: Gibbs free energy?
One thing that I know Gibbs free determines is the spontaneity of a process.
- Sun Feb 17, 2019 6:42 pm
- Forum: *Free Energy of Activation vs Activation Energy
- Topic: Spontaneous reactions
- Replies: 11
- Views: 4545
Spontaneous reactions
Are exothermic reactions usually spontaneous because energy is released from the system or is there another way to explain it?
- Sat Feb 09, 2019 2:06 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: When to use deltaS=q/t versus deltaS=nRlnV2/V1
- Replies: 2
- Views: 354
Re: When to use deltaS=q/t versus deltaS=nRlnV2/V1
Use deltaS= nRLnV2/V1 when there is a change in entropy of an ideal gas when there is an isothermal expansion from a volume V1 to V2. Use deltaS= q/t when you are trying to find the change in entropy with given heat energy and temp.
- Sat Feb 09, 2019 1:46 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: entropy midterm
- Replies: 2
- Views: 255
Re: entropy midterm
Yes, I think so. Everything from 4f to 4i. Gibbs free energy is 4j so I don't think we need to study that for the midterm.
- Sat Feb 09, 2019 1:44 pm
- Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
- Topic: 4G. 3 7th edition
- Replies: 1
- Views: 227
4G. 3 7th edition
How do I go about this question: Which would have higher molar entropy at T=0, single crystal of BF3 or single crystal of COF2
- Thu Feb 07, 2019 11:27 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm
- Replies: 2
- Views: 379
Midterm
Would we be asked to derive equations and formulas relating to thermodynamics on the midterm? Or should we not worry about that?
- Sat Feb 02, 2019 11:03 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Internal Energy
- Replies: 4
- Views: 327
Re: Internal Energy
1. Start with w: w=-P_{ex}\Delta V 2. Calculate \Delta V \Delta V=1.846L-0.345L=1.501L 3. Convert the given P_{ex} from Torr to atm P_{ex}=750 \textup{ torr } \times \frac{1 \textup{ atm}}{760 \textup{ Torr}}=.99\textup{ atm} 4. Plug into equation for w w=-.99 \times 1.5 =-1.49 \textup{L}\cdot \tex...
- Sat Feb 02, 2019 8:36 pm
- Forum: Phase Changes & Related Calculations
- Topic: Heat
- Replies: 6
- Views: 543
Heat
Would q be negative if heat is absorbed?
- Sat Feb 02, 2019 8:07 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Internal Energy
- Replies: 4
- Views: 327
Internal Energy
Can someone please help me with 4B.5 7th edition?
- Sun Jan 27, 2019 2:28 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Biological Example
- Replies: 1
- Views: 156
Re: Biological Example
I think the example Prof. Lavelle gave in class about why steam burns severely more than liquid is an example of applying enthalpies.
- Sun Jan 27, 2019 2:25 pm
- Forum: Phase Changes & Related Calculations
- Topic: Delta H
- Replies: 11
- Views: 1933
Re: Delta H
Positive delta H means an Endothermic reaction because is greater than 0. Negative delta H is an exothermic reaction because heat is released.
- Mon Jan 21, 2019 10:09 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Conceptual questions
- Replies: 6
- Views: 467
Re: Conceptual questions
Jordan Lo 2A wrote:Is test 1 the entire outline 2? I could be wrong but I don't remember going over polyprotic acids (last couple exercises in 6th edition) or examples (last bullet points under concepts)
I'm not sure. It would be safe to just go over it and know some information about it.
- Sun Jan 20, 2019 9:45 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: amphoteric
- Replies: 2
- Views: 337
amphoteric
Is NH3 amphoteric? I keep getting confused
- Sun Jan 20, 2019 9:32 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Conceptual questions
- Replies: 6
- Views: 467
Conceptual questions
What sort of conceptual questions would be asked on test 1? What concepts do we need to know to explain?
- Fri Jan 18, 2019 12:29 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Weak Acids and Bases
- Replies: 7
- Views: 775
Weak Acids and Bases
If there a way we can easily identify weak acids and bases or should we just memorize the most common ones?
- Fri Jan 18, 2019 10:13 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Le Chatelier's Principle
- Replies: 3
- Views: 319
Le Chatelier's Principle
Can some please explain how to apply Le Chatelier's Principle?
- Tue Jan 15, 2019 12:08 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Test 1
- Replies: 2
- Views: 221
Test 1
Does anyone know what would be covered on test 1 next week?
- Tue Jan 08, 2019 10:10 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Q
- Replies: 6
- Views: 330
Q
Can someone please help me with 5G.11 7th edition?
- Tue Jan 08, 2019 9:39 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 11.7
- Replies: 5
- Views: 437
Re: 11.7
If you are asking about the percentage of X2 molecules that has decomposed at equilibrium, It is the difference between the diatomics at the start and when it reaches equilibrium which is 11-5=6. Divide that by the diatomics at the start = (6/11)*100= 54.5%. I'm not sure but that's how I answered it.
- Sat Dec 08, 2018 9:52 pm
- Forum: Bronsted Acids & Bases
- Topic: Strong base
- Replies: 5
- Views: 729
Re: Strong base
Albert_Luu3K wrote:NaOH is a strong base because it fully dissociates in water. That means there are more OH- ions floating in solution making it more basic.
Does that mean strong acids also fully dissociate in water?
- Sat Dec 08, 2018 9:51 pm
- Forum: Amphoteric Compounds
- Topic: amphoteric
- Replies: 2
- Views: 467
Re: amphoteric
"Not all amphoteric substances are amphiprotic. Although an amphiprotic species must be amphoteric, the converse is not true. For example, the metal oxide ZnO contains no hydrogen and cannot donate a proton. Instead, it is a Lewis acid whose Zn atom accepts an electron pair from the base OH−.&q...
- Mon Nov 26, 2018 10:48 pm
- Forum: Lewis Structures
- Topic: Question 3.45
- Replies: 4
- Views: 303
Re: Question 3.45
Does that mean atoms after row three can? Does this relate to the atomic number?
- Mon Nov 26, 2018 10:42 pm
- Forum: Hybridization
- Topic: Question from textbook
- Replies: 4
- Views: 463
Re: Question from textbook
Because it is T-shaped and T-shaped molecules have sp^3d hybridization.
- Mon Nov 26, 2018 6:24 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 2F3 part B (7th edition)
- Replies: 1
- Views: 113
Re: 2F3 part B (7th edition)
I think we have to give both answers during the test. But make sure to clearly differentiate and state your answers when including resonance structures.
- Mon Nov 26, 2018 11:48 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR
- Replies: 1
- Views: 257
VSEPR
I found this online. I hope it helps!
- Sun Nov 25, 2018 8:54 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Shape of CH2 (2-)
- Replies: 2
- Views: 266
Re: Shape of CH2 (2-)
Because the electron domain of the central atom is 4 and not 2. Someone correct me if I'm wrong.
- Sun Nov 25, 2018 4:17 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Test 3
- Replies: 6
- Views: 556
Test 3
On test 3, would we be asked to name molecular shapes like seesaw, t-shaped, and square planar?
- Sat Nov 24, 2018 10:35 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: van der waals forces
- Replies: 3
- Views: 277
Re: van der waals forces
Van der Waals forces are also known as Dispersion/ induced dipole-induced dipole/ and London interactions. All of these terms describe intermolecular attractions that are always present and attractive. They arise due to fluctuating electron distributions, which results in fluctuating dipoles. These...
- Sat Nov 24, 2018 8:46 pm
- Forum: Hybridization
- Topic: Sigma/Pi Bonds
- Replies: 5
- Views: 356
Re: Sigma/Pi Bonds
Sigma and pi bonds are chemical covalent bonds. Sigma bond has been referred to as the strongest type of covalent bond.
- Sat Nov 24, 2018 8:35 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: van der waals forces
- Replies: 3
- Views: 277
van der waals forces
Can someone please give an overview of van der Waals forces?
- Sat Nov 24, 2018 8:18 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: HW Question 2E.19B
- Replies: 1
- Views: 230
Re: HW Question 2E.19B
I was also confused about that. At first, I even thought the molecule would be linear as a whole. But it makes sense that it is Tetrahedral. It is still confusing though.
- Sat Nov 24, 2018 8:03 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: molecular shape vs molecular geometry
- Replies: 3
- Views: 274
Re: molecular shape vs molecular geometry
Molecular geometry usually includes the lone pair on the central atom. I call this the parent shape. While Molecular shape just describes the shape excluding the lone pair on the central atom. Make sure to differentiate both if or when asked to name shape. An example I like to use is SO2. The molecu...
- Sat Nov 24, 2018 3:59 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone pairs determining shape?
- Replies: 5
- Views: 1630
Re: Lone pairs determining shape?
Just to be on the safe side, I identify each shape as the parent shape and molecular shape. For example, S02 has a parent shape that is trigonal planar because of its lone pair on S but the molecular shape for S02 is bent or angular.
- Sat Nov 24, 2018 3:52 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 4.25 6th edition: Polarity of SF4
- Replies: 4
- Views: 718
Re: 4.25 6th edition: Polarity of SF4
The electronegativity difference between S and F is greater than 0.5, that's why it is Polar.
- Mon Nov 19, 2018 12:22 pm
- Forum: Hybridization
- Topic: Hybridization
- Replies: 1
- Views: 63
Hybridization
During lecture today, C2H4 had a sp^2 hybridization. But when it was expanded, it was 2sp^2 and 2p. I am confused about that.
- Mon Nov 19, 2018 12:18 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Discussion
- Replies: 6
- Views: 692
Discussion
I was wondering; would Tuesday discussion sessions still take place or not?
- Wed Nov 14, 2018 11:34 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR
- Replies: 3
- Views: 385
VSEPR
Is the VSEPR group the names of the shapes of the Lewis structure? I'm so confused.
- Wed Nov 14, 2018 11:32 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angles
- Replies: 3
- Views: 1455
Bond Angles
I know Professor Lavelle mentioned this but do we have to know the bond angles or we just have to guess what it is less than? Also, I'm guessing we have to memorize all the names of shapes right?
- Fri Nov 09, 2018 11:10 am
- Forum: Bond Lengths & Energies
- Topic: Grading
- Replies: 3
- Views: 345
Re: Grading
I don't think there is a grading scale. The total number of points you could get is 500. So just add up all your points at the end of the quarter.
- Fri Nov 09, 2018 11:03 am
- Forum: Lewis Structures
- Topic: Electrons on Least EN Atom
- Replies: 3
- Views: 526
Re: Electrons on Least EN Atom
This is a good video:
https://youtu.be/dNPs-cr_6Bk
https://youtu.be/dNPs-cr_6Bk
- Fri Nov 09, 2018 11:00 am
- Forum: Octet Exceptions
- Topic: octet exceptions
- Replies: 4
- Views: 468
Re: octet exceptions
The first four elements on the periodic table are elements with octet exceptions.
- Wed Oct 31, 2018 12:30 pm
- Forum: Octet Exceptions
- Topic: Octet rule
- Replies: 2
- Views: 204
Re: Octet rule
The octet rule is basically a guideline for bonding which says that elements (with atomic number below 20) should have 4 bonding pairs of electrons (8 e- total - the noble gas configuration). The first 4 elements do not follow this guideline as they do not need 8 e- to reach a noble gas configurati...
- Wed Oct 31, 2018 12:21 pm
- Forum: Lewis Structures
- Topic: D orbital
- Replies: 4
- Views: 401
Re: D orbital
d orbitals can hold up to 10 electrons.
- Wed Oct 31, 2018 12:19 pm
- Forum: Octet Exceptions
- Topic: Octet rule
- Replies: 2
- Views: 204
Octet rule
Can someone please explain the octet rule and why the first 4 atoms on the periodic table don't have it. Thanks !
- Wed Oct 31, 2018 12:16 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Valence Electrons Counting
- Replies: 1
- Views: 187
Re: Valence Electrons Counting
Valence electrons are the outer electrons that are involved in bonding and they hold the highest energy. That's why electrons in the s and p orbitals are valance electrons.
- Sun Oct 21, 2018 3:56 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Test 2
- Replies: 1
- Views: 173
Test 2
What kind of questions would be on the test relating to Atomic Spectra?
- Sun Oct 21, 2018 3:50 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Test On Tuesday
- Replies: 10
- Views: 1014
Re: Test On Tuesday
From what I know, the test will cover the Photoelectric effect, De Broglie wavelength, Heisenberg uncertainty, Atomic spectra, and Quantum numbers.
- Thu Oct 18, 2018 10:49 pm
- Forum: DeBroglie Equation
- Topic: De Broglie
- Replies: 12
- Views: 1398
Re: De Broglie
Also, p=mv. So wavelenght=h/p which is also wavelenght= h/mv.
- Thu Oct 18, 2018 8:21 pm
- Forum: DeBroglie Equation
- Topic: units
- Replies: 3
- Views: 249
Re: units
It depends. Sometimes you would have to use kg*m^2*s^-2 instead of J*s to cancel out and get the right units at the end of your calculations.
- Wed Oct 17, 2018 12:44 pm
- Forum: *Shrodinger Equation
- Topic: Schrodinger's equation
- Replies: 2
- Views: 157
Schrodinger's equation
I just want to clarify. Do we have to know and are we gonna use the schrodinger's equation or not?
- Wed Oct 17, 2018 12:40 pm
- Forum: Properties of Light
- Topic: Mnemonic for em spectrum
- Replies: 2
- Views: 228
Re: Mnemonic for em spectrum
Thanks!
- Wed Oct 17, 2018 12:38 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Difference in orbitals
- Replies: 3
- Views: 336
Re: Difference in orbitals
I don't think you have to worry about the f-orbitals for now. They are more complicated in shape. Just be familiar with s, p and d.
- Thu Oct 11, 2018 8:26 am
- Forum: Properties of Light
- Topic: Wave Model of Light
- Replies: 1
- Views: 130
Re: Wave Model of Light
Electromagnetic radiation is a form of energy that is produced by oscillating electric and magnetic disturbance, or by the movement of electrically charged particles traveling through a vacuum. Electron radiation is released as photons, which are bundles of light energy that travel at the speed of l...
- Thu Oct 11, 2018 8:16 am
- Forum: Properties of Light
- Topic: Photoelectric effect
- Replies: 4
- Views: 203
Photoelectric effect
Does photon have to be greater than work function for photoelectric effect to work?
- Thu Oct 11, 2018 8:10 am
- Forum: Properties of Light
- Topic: Do I need to memorize the Light Spectrum? [ENDORSED]
- Replies: 13
- Views: 900
Re: Do I need to memorize the Light Spectrum? [ENDORSED]
I think we need to. There will be problems were we we need to state the spectrum given the answer we get. There was a similar problem like that on the homework.
- Fri Oct 05, 2018 9:36 am
- Forum: Limiting Reactant Calculations
- Topic: Limiting reagents
- Replies: 12
- Views: 816
Re: Limiting reagents
Okay but during the post assessment, I answered that it cannot have two limiting reactants but the answer was wrong. That's why I'm confused.
- Mon Oct 01, 2018 11:56 am
- Forum: Limiting Reactant Calculations
- Topic: Limiting reagents
- Replies: 12
- Views: 816
Limiting reagents
I watched the video but I'm still not sure. Can a chemical equation have two limiting reagents ?