Search found 69 matches
- Sat Mar 16, 2019 7:05 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Catalyst in rate law?
- Replies: 6
- Views: 8283
Catalyst in rate law?
Is having a catalyst in the rate law allowed? Or is it not, like intermediates aren't?
- Sat Mar 16, 2019 6:24 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
- Replies: 179
- Views: 25478
Re: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
For the electrochem worksheet 8d, why don't we include the OH- in the cell diagram?
- Sat Mar 16, 2019 4:29 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Rate determining step & overall rate law
- Replies: 1
- Views: 229
Rate determining step & overall rate law
Does the rate constant k of the exp determined overall rate law equal to the rate-determining step's rate constant? What about when we assume pre-equilibrium?
- Sat Mar 16, 2019 3:54 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Drawing reaction profiles
- Replies: 2
- Views: 326
Re: Drawing reaction profiles
The height of the waves depend on Ea, don't they? (higher = slower, lower = faster)
- Fri Mar 15, 2019 10:38 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: H+ and OH- in cells
- Replies: 1
- Views: 201
H+ and OH- in cells
Do we include H+/OH- in cell diagrams ONLY if they're present in the balanced redox rxn? I'm a bit confused as to when to put them.
- Fri Mar 15, 2019 8:23 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Catalysts
- Replies: 2
- Views: 360
Catalysts
Do catalysts not show up the overall rxn, but can start out in individual mechanism steps - get consumed - then get re-formed? What are the key features that define a catalyst in a rxn mechanism?
- Fri Mar 15, 2019 8:03 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Drawing reaction profiles
- Replies: 2
- Views: 326
Drawing reaction profiles
When drawing profiles, how do we draw the troughs of multiple mechanisms? Don't we have to know whether each step is exo/endothermic, and do we have to know something about stability?
- Tue Mar 12, 2019 6:20 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Unique rate?
- Replies: 7
- Views: 655
Re: Unique rate?
Is the 'unique' of the unique rate indicating that every single rxn has its very own unique rate, like a human fingerprint?
- Tue Mar 12, 2019 6:17 pm
- Forum: General Rate Laws
- Topic: Zero Order Reactions
- Replies: 4
- Views: 404
Re: Zero Order Reactions
So if a reactant's order is zero, its concentration will change linearly regardless of its concentration?
- Tue Mar 12, 2019 6:16 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Intermediates
- Replies: 2
- Views: 330
Intermediates
I'm not sure how to explain what an intermediate is; is it a species that forms during mechanism, but is not in the products nor reactants of the overall rxn? Is there more to this definition?
- Thu Feb 28, 2019 3:19 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: H+, OH-, water
- Replies: 9
- Views: 950
H+, OH-, water
If there are H+ or OH- or water left over from balancing half-rxns, do we have to list them in the cell diagram as well?
- Thu Feb 28, 2019 2:25 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: cell diagram: solids
- Replies: 1
- Views: 213
cell diagram: solids
Why do we not use commas to separate solids undissolved in solution? 7th edition 6L 7c uses a single line instead of a comma; is it because the solid dissolved is not part of the electrode?
- Thu Feb 28, 2019 1:36 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: neutralization redox
- Replies: 1
- Views: 208
neutralization redox
How do we know which rxns to use for neutralization redox rxns? I find it hard to tell which ones I should use. Is there a way to solve these problems in general? I think if I can just know what rxns to use, I could do the rest.
- Thu Feb 28, 2019 1:25 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell diagrams and undissolved solids in solution
- Replies: 1
- Views: 198
Cell diagrams and undissolved solids in solution
How do we know when solids are undissolved in solutions but not acting as electrodes? the I2 is an example, and the 7th edition, 6L #7a is another problem too.
- Tue Feb 26, 2019 4:54 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Porous disk of a concentration cell
- Replies: 2
- Views: 439
Porous disk of a concentration cell
What goes across, if anything does at all, the porous disk of a concentration cell? Do inert anions go across to the more positive side to keep the cell neutral?
- Tue Feb 26, 2019 4:52 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 7th edition 6L. 3(d)
- Replies: 1
- Views: 251
7th edition 6L. 3(d)
Does anyone know what the half-rxns are for this problem and how to solve it?
- Thu Feb 21, 2019 12:30 am
- Forum: Balancing Redox Reactions
- Topic: 6K.3 (d), 7th edition
- Replies: 1
- Views: 255
6K.3 (d), 7th edition
Can someone explain how to balance rxns like these with only one species on reactants or products side?
- Mon Feb 18, 2019 4:26 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Delta G vs. Delta G (degree sign)
- Replies: 4
- Views: 2730
Delta G vs. Delta G (degree sign)
How is the delta G and the standard state delta G (with degree sign) differ? Is the standard state delta G constant for a specific rxn while delta G (w/o the degree) could be different?
- Mon Feb 18, 2019 3:34 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Entropy change: V, P, T
- Replies: 4
- Views: 3002
Entropy change: V, P, T
How does entropy change with volume, pressure, and temperature changes? Basically: what happens to entropy if one of the three factors increases/decreases?
- Tue Feb 12, 2019 2:50 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Internal energy (U) of an isolated system
- Replies: 17
- Views: 2739
Internal energy (U) of an isolated system
If a system is isolated with + amount of energy, will it there be no change even after time passes?
- Mon Feb 11, 2019 12:23 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: le chatelier's principle and continuing rxns
- Replies: 2
- Views: 365
le chatelier's principle and continuing rxns
It says that a way to continue a rxn without adding more reactant is to remove the product, since more reactants will be consumed to form products to minimize the effects of the loss. Isn't this an indefinite way to continue a rxn? At some point you'll run out of reactants to consume, even with Le C...
- Thu Feb 07, 2019 12:51 am
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: 7th edition 4F.7
- Replies: 3
- Views: 384
Re: 7th edition 4F.7
Then is the 5/2R and 3/2R for monoatomic ideal gases a given rule?
- Wed Feb 06, 2019 11:26 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.5 7th edition
- Replies: 1
- Views: 326
4G.5 7th edition
Can someone explain how the cis and trans compounds have different orientations? cis has 12 and trans has 3, and I'm not understanding how we're supposed to obtain the number of orientations. Is it because cis has the two red atoms next to each other while the trans must have them across each other?
- Sun Feb 03, 2019 10:16 pm
- Forum: Calculating Work of Expansion
- Topic: Work sign changes
- Replies: 3
- Views: 401
Work sign changes
Typically if a system is compressed, is the sign for work + and - for expansion?
If so, what's the reason?
If so, what's the reason?
- Thu Jan 31, 2019 3:38 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: 4A.13, 7th ed
- Replies: 1
- Views: 174
4A.13, 7th ed
Does anyone see an error in this problem? I don’t know where the K came from, we only had Celcius to work with.
- Sat Jan 26, 2019 5:27 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Signs in bond enthalpies
- Replies: 4
- Views: 459
Signs in bond enthalpies
When putting signs for bond enthalpies, is it usually + on the reactants side and - on the products sign?
- Sat Jan 26, 2019 5:21 pm
- Forum: Phase Changes & Related Calculations
- Topic: Phase change enthalpy signs
- Replies: 2
- Views: 351
Phase change enthalpy signs
For phase change enthalpies, do we have to change signs for them as well depending on which side of the rxn they're on?
- Fri Jan 25, 2019 12:24 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: K and temp changes
- Replies: 2
- Views: 215
K and temp changes
I know that K changes with temperature but how does it change? Does K increase with temperature or are they inversely related? Or does it depend on case by case?
- Thu Jan 24, 2019 4:14 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: converting between kp and kc
- Replies: 4
- Views: 476
converting between kp and kc
I've been seeing multiple formulas for converting kp to kc - are these just multiple forms of a single formula? Or is there a universal formula for converting kp to kc in any given problem?
- Mon Jan 21, 2019 1:13 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Weak acid and its salt
- Replies: 3
- Views: 238
Weak acid and its salt
In a problem where we have to calculate the pH of a solution of a weak acid + its salt, do we have to take the cations into account? for example the problem in class professor Lavelle told us - the thing with nitrous acid + potassium nitrite. Do we have to take the potassium ions into account? Or do...
- Sat Jan 19, 2019 1:43 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Solving weak acid/base dissociations
- Replies: 4
- Views: 328
Solving weak acid/base dissociations
When we try to solve for the change in concentration (x), I guess the only way to solve it is through using the quadratic equation?
- Thu Jan 17, 2019 2:30 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 7th Edition, 6B.9
- Replies: 1
- Views: 182
7th Edition, 6B.9
Does anyone know how this problem is to be done?
- Mon Jan 14, 2019 2:06 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Changing Temperature
- Replies: 4
- Views: 436
Re: Changing Temperature
I think that's when you increase the heat of the rxn. Does anyone know what happens when the temp is lowered?
- Sat Jan 12, 2019 5:41 pm
- Forum: Ideal Gases
- Topic: When to use and NOT use ideal gases?
- Replies: 1
- Views: 280
When to use and NOT use ideal gases?
Is there a place to not use the ideal gas formula? I heard somewhere that ideal gases may not apply to every case.
- Thu Jan 10, 2019 3:51 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kc, Kp, K
- Replies: 3
- Views: 2828
Kc, Kp, K
What’s the difference between K, Kc, and Kp? The textbook seems like it’s considering K and Kp one and the same.
Also, what does the C in Kc mean?
Also, what does the C in Kc mean?
- Wed Dec 05, 2018 4:21 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polarizing power precedence
- Replies: 1
- Views: 484
Polarizing power precedence
I know for cations of the same row we compare charge and same column we compare atomic radii, but if we're comparing cations of different rows and columns which takes precedence over the other? I had this part of the test wrong.
- Tue Dec 04, 2018 11:37 pm
- Forum: Naming
- Topic: Water as a ligand
- Replies: 5
- Views: 629
Re: Water as a ligand
What about in formulas? I'm not sure when to use H2O or OH2.
- Tue Dec 04, 2018 11:05 pm
- Forum: Naming
- Topic: Water as a ligand
- Replies: 5
- Views: 629
Water as a ligand
If water is a ligand, how do we write it? There seems to be two ways of writing it: H2O and OH2, but I'm not clear on which style applies to which scenario.
- Tue Dec 04, 2018 11:01 pm
- Forum: Naming
- Topic: Anionic ligands
- Replies: 5
- Views: 614
Anionic ligands
It says in the textbook that anionic ligands that end in -ide, -ate, -ite change their endings to -ido, -ato, ito respectively. I don't think this was covered in class; is this something different? When do we use this for?
- Sun Dec 02, 2018 9:35 pm
- Forum: Bronsted Acids & Bases
- Topic: Bronsted vs Lewis
- Replies: 4
- Views: 488
Re: Bronsted vs Lewis
Then can an acid/base be considered Bronsted AND Lewis at the same time?
- Sun Dec 02, 2018 12:45 am
- Forum: Sigma & Pi Bonds
- Topic: Sigma/pi bond: orbitals
- Replies: 1
- Views: 2290
Sigma/pi bond: orbitals
When forming pi or sigma bonds, does it matter which orbitals are used? As in, can only an s & p orbital form sigma and p&p form pi bonds? (it's just a theoretical example)
- Sat Dec 01, 2018 7:57 pm
- Forum: Dipole Moments
- Topic: Dipole moments and resonances
- Replies: 3
- Views: 1075
Dipole moments and resonances
If a molecule's dipole moments cancel out, does this mean that structures with resonance have no net dipole movement? I think that was the case for neutral sulfite (SO3); it has resonance but the real molecule in reality has the bond length equal to the average of the bond lengths of the resonance s...
- Sat Dec 01, 2018 7:19 pm
- Forum: Naming
- Topic: Spaces in naming
- Replies: 2
- Views: 298
Spaces in naming
The lecture notes tell us that there's usually no spacing when naming coordination compounds. Does this mean that writing with spaces in a test will result in loss of points? Also, we add an O to the end of an anion only if it's within the coordination sphere, right?
- Tue Nov 27, 2018 9:54 pm
- Forum: Resonance Structures
- Topic: Bond lengths & number of resonance structures
- Replies: 3
- Views: 661
Bond lengths & number of resonance structures
How does the number of resonance structures determine bond length? Do we end up having more bond lengths to average out?
- Sat Nov 24, 2018 10:54 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Seesaw bond angles
- Replies: 3
- Views: 420
Seesaw bond angles
How many bond angles in a seesaw-shaped structure are 90 degrees wide? I know the structure has both 90 and 120 degree angles but I'm not sure of how many of each are there.
- Sat Nov 24, 2018 10:44 am
- Forum: Sigma & Pi Bonds
- Topic: sigma/pi bonds and resonance
- Replies: 1
- Views: 118
sigma/pi bonds and resonance
If a test asks us to find the number sigma and pi bonds of a molecule that has a resonance structure I assume we have to find the numbers of bonds for each structure to get full credit?
- Thu Nov 22, 2018 2:20 pm
- Forum: Administrative Questions and Class Announcements
- Topic: 14B and 14BL finals
- Replies: 3
- Views: 496
14B and 14BL finals
Is taking 14B and 14BL finals on the same day doable? I'm just asking out of curiosity, please let me know!
- Tue Nov 20, 2018 11:06 pm
- Forum: Hybridization
- Topic: s-character [ENDORSED]
- Replies: 1
- Views: 276
s-character [ENDORSED]
On 7th edition, 2F.15 there's a question about s-character. What's s-character of the hybrid orbitals? Apparently it affects bond angles.
- Sat Nov 17, 2018 12:53 pm
- Forum: Dipole Moments
- Topic: sigma, pi bonds rotation
- Replies: 2
- Views: 143
sigma, pi bonds rotation
How does a sigma or pi bond being able to/unable to rotate influence bonding? Why is it important to note?
- Sat Nov 17, 2018 12:42 pm
- Forum: Dipole Moments
- Topic: Polarity and dipole moment
- Replies: 4
- Views: 536
Polarity and dipole moment
If dipole moments that cancel each other result in nonpolarity does this mean that symmetric atoms and molecules are generally nonpolar?
- Thu Nov 15, 2018 1:53 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR forms
- Replies: 3
- Views: 286
VSEPR forms
Are VSEPR shapes formed so that there's maximum repulsion between atoms?
- Sun Nov 11, 2018 9:30 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: Bond energy value signs
- Replies: 3
- Views: 502
Bond energy value signs
Why are the bond energy signs all negative? They're all attractive forces that result from subtraction but I don't get why they're results of subtraction and why they're negative.
- Tue Nov 06, 2018 8:48 pm
- Forum: Lewis Structures
- Topic: expanded octet
- Replies: 2
- Views: 481
expanded octet
How do you know that an atom has only one additional bond in addition to an octet? is the number of remaining orbitals the way to determine it? (take bromate for example - how do you know it's just 5 bonds on bromine and not 6)
- Tue Nov 06, 2018 7:51 pm
- Forum: Resonance Structures
- Topic: bond lengths of resonant atoms
- Replies: 4
- Views: 575
bond lengths of resonant atoms
How are the bond lengths of resonant atoms (nitrate, nitrite) the same when the resonant structures have different bond lengths?
- Sat Nov 03, 2018 12:39 am
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Test Question 1a
- Replies: 2
- Views: 410
Re: Test Question 1a
Wait, so we have to get the mass of each molecule separately b/c the mass of N2 (14.0067x2) is the molar mass, not the mass of the individual N2 molecule? I also got that question wrong, so I was confused about it
- Fri Nov 02, 2018 1:35 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Filling of Orbitals
- Replies: 3
- Views: 609
Re: Filling of Orbitals
So we just have to follow the periodic table in numerical order? That's not what I remembered - or did I hear something wrong?
- Fri Nov 02, 2018 1:12 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Is electron removed from 3d or 4s first?
- Replies: 5
- Views: 48401
Re: Is electron removed from 3d or 4s first?
Does this mean that generally 4s orbitals will lose electrons before 3d electrons are lost?
- Fri Oct 26, 2018 6:48 pm
- Forum: Trends in The Periodic Table
- Topic: Isoelectronic atoms sizes [ENDORSED]
- Replies: 3
- Views: 542
Isoelectronic atoms sizes [ENDORSED]
How would the size of isoelectronic atoms compare? for example which would be bigger: Ne or Na+? Would this be dependent on nuclear charge?
- Fri Oct 26, 2018 6:42 pm
- Forum: *Particle in a Box
- Topic: Application
- Replies: 4
- Views: 1239
Re: Application
Okay but when do you use the equation for? I never fully understood where to use it (if anyone knows if it explains in the textbook let me know)
- Wed Oct 24, 2018 2:00 am
- Forum: DeBroglie Equation
- Topic: De Broglie wavelengths
- Replies: 3
- Views: 313
De Broglie wavelengths
Are De Broglie wavelengths used for large particles? How do we know when to use the De Broglie equation to get a wavelength? It's confusing when to use the De Broglie or the E=hv equation.
- Thu Oct 18, 2018 6:44 pm
- Forum: *Shrodinger Equation
- Topic: d orbital
- Replies: 1
- Views: 661
d orbital
For one of the d-orbitals (I think dx) why was the orbital a ring again? The rest are in cones so I don't get why dx is a ring
- Thu Oct 18, 2018 6:07 pm
- Forum: *Shrodinger Equation
- Topic: x,y,z notation in schrodinger's equaton
- Replies: 2
- Views: 422
Re: x,y,z notation in schrodinger's equaton
It might have to do with the principal quantum number and orbital number. There's another number that I can't recall right now but they're in the textbook - the notations are n, l, ml.
- Thu Oct 18, 2018 5:56 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Bohr Formula
- Replies: 4
- Views: 459
Re: Bohr Formula
Why do we have to add a negative sign though? is it just an indication of a difference in energy levels?
- Mon Oct 15, 2018 12:39 am
- Forum: Einstein Equation
- Topic: Kinetic energy and e = hv
- Replies: 3
- Views: 453
Kinetic energy and e = hv
If an electron is ejected with zero kinetic energy, what would it look like in real life? How would the electron actually move? Also, if kinetic energy is zero I guess this means that the work function (threshold energy) and hv are equal to each other?
- Thu Oct 11, 2018 1:22 am
- Forum: Photoelectric Effect
- Topic: Work function
- Replies: 7
- Views: 580
Work function
In the lecture, there's a constant reference to 'work function'. What is that, is that the threshold energy with a circle-with-a-line-through-it as a symbol?
- Thu Oct 11, 2018 1:20 am
- Forum: Einstein Equation
- Topic: Spectroscopy experimenting
- Replies: 4
- Views: 356
Spectroscopy experimenting
in a spectroscopy experiment, there are three components: E = hv, work function, and Ek. If the electron has no kinetic energy, does it mean that the electron is detached but doesn't move? How would it look like in real life?
- Sun Oct 07, 2018 9:00 pm
- Forum: Significant Figures
- Topic: Calculating process
- Replies: 5
- Views: 882
Calculating process
Ok so let's say the figures given in a problem are 250.0ml, .0350M, 33g. So would the final answer have to be in 2 sig figs, but we don't round during calculations?
- Thu Oct 04, 2018 6:57 pm
- Forum: SI Units, Unit Conversions
- Topic: HW E9 in textbook
- Replies: 3
- Views: 366
HW E9 in textbook
Can molecules be calculated in moles as well? I thought moles only applied to atoms - or am I mistaken?
- Tue Oct 02, 2018 5:50 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Titrations v Dilutions
- Replies: 2
- Views: 1121
Titrations v Dilutions
Just wondering, what's the difference between titrations and dilutions? I swear I learned it in high school but I just can't remember - I often get confused between the two.