Search found 64 matches
- Sat Mar 16, 2019 7:47 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: 15.76 6th Edition
- Replies: 1
- Views: 382
15.76 6th Edition
Can someone explain what they did for this problem? I tried to find e^-Ea/RT for each of the activation energies given and compare them but that wasn't the right thing.
- Sat Mar 16, 2019 7:38 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: 15.65 C 6th edition
- Replies: 1
- Views: 258
15.65 C 6th edition
In the solution manual is says that we expect the forward reaction to go up more than the reverse. How do we know this is true?
- Sat Mar 16, 2019 3:07 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Midterm, Question 2.B
- Replies: 3
- Views: 465
Re: Midterm, Question 2.B
Yes it is inverse. It would be 1 over K of the forward reaction.
- Fri Mar 15, 2019 9:31 pm
- Forum: Balancing Redox Reactions
- Topic: Test 2
- Replies: 5
- Views: 499
Re: Test 2
Can someone explain this in terms of oxidizing power and how that differs?
- Fri Mar 15, 2019 10:43 am
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Overall Order
- Replies: 5
- Views: 736
Re: Overall Order
The overall order can help us determine the units of K and figure out which order reaction equation we should use.
- Fri Mar 15, 2019 10:40 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Confirming a Reaction Mechanism
- Replies: 2
- Views: 313
Re: Confirming a Reaction Mechanism
I don't think there's necessarily a way to prove that a mechanism is correct but it can be proved incorrect if the mechanisms do not fit the experimental data.
- Thu Mar 14, 2019 9:30 pm
- Forum: Administrative Questions and Class Announcements
- Topic: lyndon's review?
- Replies: 5
- Views: 881
Re: lyndon's review?
He will probably make a post on chemistry community so just keep an eye out for it!
- Wed Mar 13, 2019 8:45 pm
- Forum: General Rate Laws
- Topic: Rate constant units
- Replies: 3
- Views: 685
Re: Rate constant units
Rate is moles per liter per second
- Wed Mar 13, 2019 8:32 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Catalysts vs Intermediates
- Replies: 4
- Views: 465
Re: Catalysts vs Intermediates
A catalyst is always present as a reactant first, but an intermediate comes up as product first.
- Wed Mar 13, 2019 8:26 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: example
- Replies: 2
- Views: 365
example
In the example he gave in class about the conversion of oxygen to ozone in lower atmosphere using NO(g), would both NO2 and O be an intermediate and NO is the catalyst?
- Mon Feb 25, 2019 8:18 pm
- Forum: Student Social/Study Group
- Topic: Lyndon's workshop
- Replies: 1
- Views: 643
Lyndon's workshop
Hello, if anyone has the answers for Lyndon's review session from week 8 on electrochemistry, please share. It was very full and I couldn't see or hear anything. Thank you. It is greatly appreciated :)
- Mon Feb 25, 2019 7:23 pm
- Forum: Balancing Redox Reactions
- Topic: Friday lecture
- Replies: 1
- Views: 262
Friday lecture
In our notes when we're finding E cell, why is the answer .43V even though we have cathode as .77V and anode as -.34 V? shouldn't it be .77-(-.34)=?
- Wed Feb 13, 2019 11:42 am
- 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: 9.35
- Replies: 2
- Views: 719
9.35
Why does A, the monatomic gas have a larger enthalpy change than a diatomic gas?
- Tue Feb 12, 2019 9:42 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: 9.13
- Replies: 2
- Views: 312
9.13
For change in entropy for change in temperature, why does it use R when the equation for delta S change in temp is delta S=nClnT2/T1?
- Tue Feb 12, 2019 5:14 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Enthalpy of formation
- Replies: 2
- Views: 372
Enthalpy of formation
What other molecules besides O2 and N2 have o enthalpy of formation?
- Tue Feb 12, 2019 4:35 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: 8.45
- Replies: 2
- Views: 323
8.45
How do we know that the delta H given is KJ/ mol? Is it always assumed that it's KJ/mol?
- Tue Feb 05, 2019 5:40 pm
- Forum: Calculating Work of Expansion
- Topic: Work
- Replies: 3
- Views: 423
Work
In the book, it talks about how a gas might push a piston into a vacuum in which no work is being doing. What does it mean by pushing into a vacuum?
- Mon Feb 04, 2019 8:08 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Open vs Closed Systems
- Replies: 4
- Views: 518
Re: Open vs Closed Systems
Hi, it might be helpful to look at question 8.1. They ask you to identify which systems are open, closed, or isolated.
- Mon Feb 04, 2019 6:17 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: reaction constant P
- Replies: 3
- Views: 343
reaction constant P
Why is PdeltaV insignificant if it involves liquids and solids?
- Mon Feb 04, 2019 6:15 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: U
- Replies: 7
- Views: 657
U
What does it mean by U is a state property?
- Mon Feb 04, 2019 6:14 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: positional (residual) entropy
- Replies: 2
- Views: 480
positional (residual) entropy
How does positional (residual) entropy differ from normal entropy?
- Mon Feb 04, 2019 6:13 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: molecules
- Replies: 1
- Views: 295
molecules
In our lecture notes, what does it mean by "molecules in gaseous phase occupy many more states than liquid and solid?"
- Tue Jan 29, 2019 3:02 pm
- Forum: Phase Changes & Related Calculations
- Topic: temperature
- Replies: 3
- Views: 388
temperature
In melting and boiling, why does the temperature of a sample stay constant even though heat is being added?
- Tue Jan 29, 2019 3:00 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: enthalpy
- Replies: 4
- Views: 580
enthalpy
What does it mean by enthalpy is a state function ?
- Tue Jan 22, 2019 5:27 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE chart
- Replies: 2
- Views: 265
Re: ICE chart
Products will always be plus if you start out with no products. If the reaction is going forward, then products will be plus but if the reaction is going backwards, the reactants will be plus.
- Tue Jan 22, 2019 5:24 pm
- Forum: Ideal Gases
- Topic: OH and H3O
- Replies: 10
- Views: 1384
Re: OH and H3O
When you have an acid reacting with water, you'll result in H3O+ because the atom donates an H to water. With bases, you'll get OH- because that atom will take an H from water.
- Tue Jan 22, 2019 5:20 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: autoprotolysis
- Replies: 1
- Views: 555
autoprotolysis
What other examples of autoprotolysis are there besides the example with water? What aspects of autoprotolysis do we need to know for Test 1?
- Thu Jan 17, 2019 10:05 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Question 11.89
- Replies: 1
- Views: 336
Question 11.89
How do we know that the coefficient for A and C is 2 based on the graph that is given?
- Mon Jan 14, 2019 9:31 pm
- Forum: Ideal Gases
- Topic: pressure [ENDORSED]
- Replies: 13
- Views: 1121
pressure [ENDORSED]
Can pressure be changed without changing the volume? If yes, how?
- Thu Jan 10, 2019 1:06 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: H2O
- Replies: 5
- Views: 390
H2O
If water is in gas form, will it be included in the equilibrium equation?
- Thu Jan 10, 2019 12:56 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Keq vs. Kc vs. Kp
- Replies: 3
- Views: 21739
Keq vs. Kc vs. Kp
What is the difference between Keq, Kc, and Kp? Does it matter if we use Keq for Kp since Keq is the general equilibrium constant?
- Mon Jan 07, 2019 7:44 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Ideal Gas Law
- Replies: 1
- Views: 247
Ideal Gas Law
What does R represent in PV=nRT?
- Sat Dec 08, 2018 9:47 pm
- Forum: Amphoteric Compounds
- Topic: amphoteric
- Replies: 2
- Views: 484
amphoteric
If a compound is amphoteric, is it also amphiprotic?
- Sat Dec 08, 2018 7:09 pm
- Forum: Calculating the pH of Salt Solutions
- Topic: pH of acids
- Replies: 13
- Views: 3608
pH of acids
Why does a strong acid have a smaller pH compared to a weak acid that has a higher pH?
- Sat Dec 01, 2018 1:01 pm
- Forum: Lewis Acids & Bases
- Topic: Lewis and Bronsted
- Replies: 8
- Views: 845
Lewis and Bronsted
What's the difference between a Lewis and Bronsted Acid and Base?
- Sat Dec 01, 2018 1:00 pm
- Forum: Naming
- Topic: Roman Numeral
- Replies: 5
- Views: 620
Roman Numeral
Some of the names of molecules have roman numerals. How do we know which ones have roman numerals and what the roman numerals are?
- Sat Dec 01, 2018 12:58 pm
- Forum: Biological Examples
- Topic: Heme structures
- Replies: 1
- Views: 263
Heme structures
Can someone explain exactly what heme structures are or what heme means? Thank you
- Sat Dec 01, 2018 12:57 pm
- Forum: Naming
- Topic: For the Final
- Replies: 1
- Views: 173
Re: For the Final
I assume you have to know the ones that come up in examples a lot, like hydroxide, ammonia, oxide, etc.
- Sat Dec 01, 2018 12:22 pm
- Forum: General Science Questions
- Topic: Final Review
- Replies: 4
- Views: 707
Re: Final Review
Hi! I really enjoy going to Lyndon's workshops. He's super helpful and makes things very easy to understand. 10/10 would recommend :)
- Tue Nov 27, 2018 1:40 pm
- Forum: Hybridization
- Topic: pi bonds
- Replies: 3
- Views: 372
pi bonds
How do we explain pi bonds using hybridization? There was an example from class for C2H4, but I don't understand it.
- Tue Nov 27, 2018 1:29 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: T shaped
- Replies: 6
- Views: 590
Re: T shaped
There is repulsion due to the two lone pairs, therefore they will push the atoms closer together, making a T shape rather than a trigonal planar.
- Tue Nov 27, 2018 1:27 pm
- Forum: Dipole Moments
- Topic: 4.29
- Replies: 3
- Views: 199
4.29
In question 4.29, why does 1 have the largest dipole moment although the distance between the two chlorines is the smallest?
- Tue Nov 27, 2018 1:26 pm
- Forum: Dipole Moments
- Topic: dipole moment
- Replies: 2
- Views: 286
dipole moment
What exactly does the dipole moment tell us and how do we determine whether a dipole moment is large or small?
- Tue Nov 27, 2018 1:24 pm
- Forum: Hybridization
- Topic: hybridization
- Replies: 3
- Views: 448
hybridization
In our notes, professor wrote the hybridization as 2sp, 2sp2, etc but in the the textbook they write it just as sp, sp2, etc.. what is the difference?
- Wed Nov 14, 2018 11:08 pm
- Forum: Dipole Moments
- Topic: Van der Waals
- Replies: 4
- Views: 428
Re: Van der Waals
Yes, all molecules have this bond. In our notes, it states that all dispersion interactions are always present and active and Van der Waals is just another name for dispersion.
- Wed Nov 14, 2018 11:06 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: polar vs nonpolar
- Replies: 6
- Views: 761
polar vs nonpolar
How can we differentiate between a polar and nonpolar molecule?
- Wed Nov 14, 2018 11:05 pm
- Forum: Bond Lengths & Energies
- Topic: Bond Length
- Replies: 9
- Views: 1141
Re: Bond Length
Like others have said, its the average of the lengths. so if you had 2 single bonds and one double bond, you would add all three and divide by 3.
- Wed Nov 14, 2018 4:24 pm
- Forum: Lewis Structures
- Topic: Boron Trifluoride
- Replies: 8
- Views: 838
Boron Trifluoride
In our notes from October 31st, we drew boron trifluoride, but boron only has 6 electrons, why? Don't all elements need 8 electrons?
- Tue Nov 13, 2018 6:57 pm
- Forum: Octet Exceptions
- Topic: octet exceptions
- Replies: 2
- Views: 368
octet exceptions
Can someone explain why some of these atoms have octet exceptions? what makes them different from others?
- Wed Oct 31, 2018 6:56 pm
- Forum: Trends in The Periodic Table
- Topic: Electron affinity
- Replies: 5
- Views: 345
Electron affinity
Can someone explain electron affinity and how it applies to the periodic table?
- Wed Oct 31, 2018 6:54 pm
- Forum: *Black Body Radiation
- Topic: Midterm
- Replies: 4
- Views: 665
Re: Midterm
If there are any black body radiation questions, what might we need to know? Any ideas?
- Wed Oct 31, 2018 6:53 pm
- Forum: *Shrodinger Equation
- Topic: Midterm
- Replies: 6
- Views: 1032
Re: Midterm
What kind of general concepts should we understand in terms of shrodinger's equation? Are there any good examples in the textbook that might be useful?
- Wed Oct 24, 2018 3:58 pm
- Forum: Trends in The Periodic Table
- Topic: Removing 2nd Electron
- Replies: 9
- Views: 802
Re: Removing 2nd Electron
Removing the second electron is more difficult because the atom pulls on the second electron stronger. In the example he gave us, after removing one electron from copper, it became Cu+, therefore the nuclear charge is stronger than Cu.
- Mon Oct 22, 2018 7:03 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Orbitals
- Replies: 2
- Views: 260
Orbitals
Will we need to know the drawings for f- orbital?
- Mon Oct 22, 2018 7:00 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Building- Up Principle
- Replies: 5
- Views: 592
Building- Up Principle
Why is copper [Ar] 3d^10 4s^1, not [Ar] 3d^9 4s^2? Same for chromium which is [Ar] 3d^5 4s^1, not [Ar] 3d^4 4s^2? I remember he mentioned it's so that the element is more stable. What does that mean?
- Wed Oct 17, 2018 6:40 pm
- Forum: *Shrodinger Equation
- Topic: Schrodinger Equation
- Replies: 2
- Views: 458
Schrodinger Equation
I'm very confused. What does the equation actually help us find? Also, what do orbitals have to do with the equation?
- Tue Oct 16, 2018 4:09 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Change in energy
- Replies: 2
- Views: 228
Change in energy
Why is delta E negative when we go from the fourth to the second principal quantum level?
- Tue Oct 16, 2018 3:42 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Planck's Constant
- Replies: 4
- Views: 367
Planck's Constant
When we're using Planck's constant, do we use 6.626 X 10^-34 or 6.63 X 10^-34? Professor switches off between the two in the lecture notes.
- Wed Oct 10, 2018 4:06 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Threshold Energy
- Replies: 4
- Views: 316
Threshold Energy
Can someone explain what threshold energy is and how it is relevant to today's lecture? Thank you.
- Wed Oct 10, 2018 1:09 pm
- Forum: Properties of Light
- Topic: Planck's constant
- Replies: 5
- Views: 528
Re: Planck's constant
E is the energy of the particle or photon, with the units joules.
H is just Planck's constant, which is 6.63 X 10^-34 joules X second.
V is the frequency, with the units Hertz or S^-1.
Energy and frequency are directly proportional, therefore when frequency increases, energy increases.
H is just Planck's constant, which is 6.63 X 10^-34 joules X second.
V is the frequency, with the units Hertz or S^-1.
Energy and frequency are directly proportional, therefore when frequency increases, energy increases.
- Mon Oct 08, 2018 8:40 pm
- Forum: Photoelectric Effect
- Topic: Photoelectric Effect
- Replies: 2
- Views: 183
Photoelectric Effect
Hi, I'm a little confused. When Professor Lavelle explained higher energy in the lecture he did not mean higher intensity correct? A higher intensity would generate more protons but not stronger protons. A higher energy would generate stronger protons. Is my understanding correct or? Also what is th...
- Thu Oct 04, 2018 3:39 pm
- Forum: Empirical & Molecular Formulas
- Topic: How to write empirical/ molecular formulas
- Replies: 3
- Views: 394
How to write empirical/ molecular formulas
How do we know what order to write the empirical or molecular formula in?
For example, F17. In the solution manual they wrote Os before C and H. How would we know that?
For example, F17. In the solution manual they wrote Os before C and H. How would we know that?
- Thu Oct 04, 2018 3:31 pm
- Forum: Significant Figures
- Topic: Molar Mass
- Replies: 5
- Views: 461
Molar Mass
When we're using the molar mass, should we estimate according to how many sig figs are in the problem or do we use the most accurate molar mass we have?
Ex. problem asks to gives 3.45 g. of carbon. Would we use 12.0 or 12.011 for the molar mass?
Ex. problem asks to gives 3.45 g. of carbon. Would we use 12.0 or 12.011 for the molar mass?
- Thu Oct 04, 2018 3:16 pm
- Forum: SI Units, Unit Conversions
- Topic: SI Units
- Replies: 7
- Views: 575
SI Units
Hi! I'm a little confused about the SI unit for mass. In the lecture, professor said that the SI unit for mass was kilograms. When we're writing our answers, do we convert our answers from grams to kilograms? Thank you!