Search found 62 matches
- Sat Mar 16, 2019 12:45 am
- Forum: Second Order Reactions
- Topic: does the order determine molecularity?
- Replies: 7
- Views: 894
does the order determine molecularity?
is the overall order of a reaction the same as its molecularity?
- Sat Mar 16, 2019 12:04 am
- Forum: *Enzyme Kinetics
- Topic: sig figs on the final
- Replies: 2
- Views: 552
sig figs on the final
will we get docked off points if we have incorrect sig figs on the final? On the midterm, sigs figs were not heavily looked at, so is it the same way for the final?
- Fri Mar 15, 2019 11:04 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: writing rate laws: "rate"or "d[A]/dt?"
- Replies: 1
- Views: 245
writing rate laws: "rate"or "d[A]/dt?"
when writing rate laws, is writing them equal to "rate" or "d[A]/dt" the same? (assuming A is a concentration).
- Wed Mar 13, 2019 11:48 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: k1 prime or k-1
- Replies: 1
- Views: 260
k1 prime or k-1
in writing rate constants, do we write "k1 prime" or "k-1"? I've seen both be used in various hw problems, so are they interchangeable?
- Wed Mar 13, 2019 11:46 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
- Replies: 179
- Views: 22916
writing rate laws: "rate"or "d[A]/dt?"
when we write the rate laws, do we write it as "rate=..." or ""d[A]/dt=..."? Specifically in question #3 of the Reaction Mechanisms worksheet, could we replace "d[F]/dt" with "rate"?
- Tue Mar 12, 2019 1:04 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: slow step and fast step
- Replies: 3
- Views: 368
slow step and fast step
why does the slow step not influence the overall rate?
- Thu Mar 07, 2019 12:20 am
- Forum: General Rate Laws
- Topic: 6th edition 15.17 why is c independent of the rate?
- Replies: 1
- Views: 203
6th edition 15.17 why is c independent of the rate?
In question 15.17 of the hw, the solutions say that c is independent of the rate, thus it does not appear in the rate law. How do we determine this from the experiment data?
- Thu Feb 28, 2019 4:06 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 14.13 part d writing half reactions
- Replies: 1
- Views: 172
14.13 part d writing half reactions
in this question of the 6th edition textbook, how do we know that both half reactions proceed towards Au(s)?
- Wed Feb 27, 2019 12:40 am
- Forum: Administrative Questions and Class Announcements
- Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
- Replies: 179
- Views: 22916
Re: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
could someone please explain #8 part a on the electrochemistry worksheet? How do we know that S2O8 2- is reduced and NO is oxidized?
- Sun Feb 24, 2019 5:31 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Positional disorder vs. thermal disorder
- Replies: 2
- Views: 348
Positional disorder vs. thermal disorder
What is the difference between positional disorder and thermal disorder? In homework question 9.85, why is positional disorder dominant?
- Fri Feb 22, 2019 1:10 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: 9.73 part d: if delta S is greater than 0, why is the reaction spontaneous
- Replies: 2
- Views: 1233
9.73 part d: if delta S is greater than 0, why is the reaction spontaneous
If delta S of the reaction is positive, why will the reaction be spontaneous?
- Tue Feb 19, 2019 6:23 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: 9.63 Positive delta G
- Replies: 3
- Views: 618
9.63 Positive delta G
Why are compounds with a positive free energy of formation (delta G) unstable?
- Sat Feb 09, 2019 5:39 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: deltaS=nCvln(t2/t1) what is Cv?
- Replies: 7
- Views: 2749
deltaS=nCvln(t2/t1) what is Cv?
what does the Cv mean in the equation deltaS=nCvln(t2/t1) ? what does it stand for, and when should i use it as opposed to deltaS=nRln(V2/v1)?
- Sat Feb 09, 2019 2:34 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: What is kB in the equation deltaS=kB lnW?
- Replies: 1
- Views: 174
What is kB in the equation deltaS=kB lnW?
What does the kB in the equation deltaS=kB lnW mean? Is it a constant that we memorize? If it is, will it be given in the constants and equations sheet on the midterm?
- Sat Feb 09, 2019 1:58 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: 355
When to use deltaS=q/t versus deltaS=nRlnV2/V1
In what circumstances should I use the equation of change in entropy deltaS=q/t versus deltaS=nRlnV2/V1? I don’t know when I should use which equation.
- Fri Feb 08, 2019 12:22 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: How to know which gas constant to use
- Replies: 2
- Views: 300
How to know which gas constant to use
When should I use R=8.314 versus using R= 8.206 * 10^-2 ?
- Fri Feb 08, 2019 11:51 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: q=deltaH under constant pressure
- Replies: 1
- Views: 190
q=deltaH under constant pressure
Why is q=deltaH under constant pressure? What is the reasoning behind it?
- Fri Feb 08, 2019 11:36 am
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: 8.49
- Replies: 1
- Views: 231
8.49
In this homework question, how do we know that the temperature is at 298K? It does not explicitly mention the temperature in the question, so how are we supposed to know that?
- Sun Feb 03, 2019 11:04 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Hess's Law depends on enthalpy as a state function
- Replies: 3
- Views: 1031
Hess's Law depends on enthalpy as a state function
Why does Hess's law depend on the fact that enthalpy is a state property?
- Sun Feb 03, 2019 11:01 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: deriving the work equation: -P*deltaV
- Replies: 2
- Views: 261
deriving the work equation: -P*deltaV
Will we be required to derive the work equation (-P*deltaV) for the midterm?
- Sun Feb 03, 2019 10:58 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Internal energy
- Replies: 5
- Views: 532
Re: Internal energy
Internal energy is a state property. It is found by adding q (heat) and w (work).
- Fri Jan 25, 2019 12:33 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: autoprotolysis on Test 1?
- Replies: 2
- Views: 264
autoprotolysis on Test 1?
Will autoprotolysis of water be tested on Test 1? If so, is solving for (using ICE boxes) autoprotolysis equations the same as for regular neutralization equations?
- Fri Jan 25, 2019 12:24 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: increasing pressure, what happens to concentration?
- Replies: 10
- Views: 2428
increasing pressure, what happens to concentration?
Why is it that when we increase pressure, the reaction favors the side with less moles of gas?
- Fri Jan 25, 2019 12:22 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE BOX and coefficients
- Replies: 4
- Views: 764
Re: ICE BOX and coefficients
the coefficient in front of the molecule is multiplied to x when you fill out the change values in the ICE box. For example, if a molecule has the coefficient 2, it would change by +/- 2x.
- Tue Jan 22, 2019 12:08 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: when to ignore the second ionization constant
- Replies: 3
- Views: 1093
when to ignore the second ionization constant
In 12.81, the answer says that since Ka2 << Ka1, the second ionization can be ignored. What is the criteria to knowing when the second ionization is very small?
- Tue Jan 22, 2019 12:04 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: What does Kc have to be less than for you to estimate?
- Replies: 3
- Views: 286
Re: What does Kc have to be less than for you to estimate?
if Kc<10^-3, then you can use the approximation and ignore x in the denominator
- Wed Jan 16, 2019 8:57 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 6th edition 11.69
- Replies: 1
- Views: 115
6th edition 11.69
On number 11.69, the question asks: Consider the equilibrium CO + H20 >> CO2 +H2. If the partial pressure of CO2 is increased, what happens to the partial pressure of H2? The answer says that increasing the partial pressure of CO2 will create more reactants, thus decreasing the partial pressure of H...
- Thu Jan 10, 2019 12:10 pm
- Forum: Ideal Gases
- Topic: use
- Replies: 8
- Views: 244
Re: use
The partial pressure equation is used to convert a gas from units of atm or bar to moles per liter. It is useful when we have a Kc value instead of Keq.
- Thu Jan 10, 2019 12:05 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Why Would Equilibrium cause death in humans?
- Replies: 3
- Views: 3122
Re: Why Would Equilibrium cause death in humans?
I think that this would mean no dynamic equilibrium would be happening inside humans, as in no cellular processes would be occurring, because reactants have ceased becoming products and vice versa.
- Mon Jan 07, 2019 4:28 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 11.13 Reaction Quotient [ENDORSED]
- Replies: 3
- Views: 228
11.13 Reaction Quotient [ENDORSED]
In question 11.13 in the textbook, it asks to find the reaction quotient. Is reaction quotient the same as equilibrium constant?
- Sat Dec 08, 2018 3:50 pm
- Forum: Naming
- Topic: adding "ion" at the end of a name
- Replies: 4
- Views: 412
adding "ion" at the end of a name
When we name a coordination complex with a charge (positive or negative), do we need to add the word "ion" at the end?
- Sat Dec 08, 2018 10:35 am
- Forum: Naming
- Topic: using prefix "mono"
- Replies: 2
- Views: 322
using prefix "mono"
When would you use the prefix "mono" when naming coordination compounds?
- Sat Dec 08, 2018 10:34 am
- Forum: Amphoteric Compounds
- Topic: Amphiprotic and Amphoteric
- Replies: 1
- Views: 405
Amphiprotic and Amphoteric
What is an example of a molecule that is amphoteric but not amphiprotic, and what makes it that way?
- Sun Dec 02, 2018 12:35 am
- Forum: Lewis Acids & Bases
- Topic: Strong acids and strong bases
- Replies: 5
- Views: 451
Strong acids and strong bases
Are strong acids and strong bases always completely ionized in water?
- Sun Dec 02, 2018 12:32 am
- Forum: Naming
- Topic: endings in naming
- Replies: 3
- Views: 168
Re: endings in naming
I believe we add "o" to the end of an anion. Cyanide is an anion, so it is named as cyano.
- Sun Dec 02, 2018 12:29 am
- Forum: Lewis Acids & Bases
- Topic: bronsted acid vs. lewis acid
- Replies: 4
- Views: 463
bronsted acid vs. lewis acid
can a molecule be a bronsted acid and a lewis acid at the same time?
- Mon Nov 26, 2018 5:50 pm
- Forum: Hybridization
- Topic: electron occupying unhybridized orbital
- Replies: 2
- Views: 207
electron occupying unhybridized orbital
why does an electron prefer to occupy an unhybridized orbital before spin pairing in a hybridized orbital?
- Mon Nov 26, 2018 5:48 pm
- Forum: Hybridization
- Topic: Pi bonds
- Replies: 2
- Views: 395
Pi bonds
Why is it that sigma bonds allow rotation, while pi bonds do not?
- Mon Nov 26, 2018 5:46 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Cis and Trans
- Replies: 3
- Views: 432
Cis and Trans
What is the difference between a cis and trans molecule?
- Sun Nov 18, 2018 11:40 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sundays 4-6pm (Karen) [ENDORSED]
- Replies: 135
- Views: 38504
Re: DOWNLOAD SESSION WORKSHEETS HERE - Sundays 4-6pm (Karen) [ENDORSED]
Hello Karen! If you went over any notes (wrote stuff on the board) on Sunday, could you please send those notes? Thank you so much!
- Sun Nov 18, 2018 11:37 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: vsper structures
- Replies: 3
- Views: 405
vsper structures
what does it mean when a lone pair is in the axial or equitorial plane?
- Sun Nov 18, 2018 11:35 pm
- Forum: Sigma & Pi Bonds
- Topic: sigma and pi bonds
- Replies: 2
- Views: 174
sigma and pi bonds
what is the difference between a sigma and pi bond?
- Sun Nov 18, 2018 11:32 pm
- Forum: Ionic & Covalent Bonds
- Topic: Intra vs Intermolecular forces
- Replies: 9
- Views: 16464
Re: Intra vs Intermolecular forces
Intramolecular forces are stronger than intermolecular forces, because the attractions that hold compounds together are stronger than the attractions between molecules.
- Wed Nov 14, 2018 10:49 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Molecular Shape
- Replies: 4
- Views: 342
Re: Molecular Shape
An octahedral vsepr shape can be visualized as two square pyramids with their bases pressed together to form a sort of diamond shape with 8 sides.
- Sat Nov 10, 2018 2:33 pm
- Forum: Ionic & Covalent Bonds
- Topic: localized e- def
- Replies: 2
- Views: 213
Re: localized e- def
Delocalized electrons are electrons that are involved in resonance structures. For example, benzene, C6H6, has three delocalized double bonds, meaning that the three double bonds can be placed in different areas.
- Sat Nov 10, 2018 2:30 pm
- Forum: Resonance Structures
- Topic: Drawing resonance structures
- Replies: 5
- Views: 717
Re: Drawing resonance structures
You would need to draw all the possible resonance structures, because resonance is a blend of structures with the same arrangement atoms, but just with different arrangements of electrons.
- Sat Nov 10, 2018 2:28 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sundays 4-6pm (Karen) [ENDORSED]
- Replies: 135
- Views: 38504
Re: DOWNLOAD SESSION WORKSHEETS HERE - Sundays 4-6pm (Karen) [ENDORSED]
Hi Karen! Will you still be holding a workshop this Sunday (over Veteran's Day weekend)?
- Sun Nov 04, 2018 5:37 pm
- Forum: Ionic & Covalent Bonds
- Topic: Naming Ionic Compounds
- Replies: 5
- Views: 460
Re: Naming Ionic Compounds
My TA told me that we would not need to name ionic compounds, that they would be given on the exam.
- Sun Nov 04, 2018 5:36 pm
- Forum: Trends in The Periodic Table
- Topic: Electron Affinity
- Replies: 3
- Views: 344
Re: Electron Affinity
Electron affinity is the energy that is released when an electron is added to a neutral atom. It increases diagonally upward and to the right of the periodic table.
- Sun Nov 04, 2018 5:33 pm
- Forum: Lewis Structures
- Topic: HOCO Lewis structure
- Replies: 1
- Views: 104
Re: HOCO Lewis structure
I think it's because with the way the formal charges turn out, this configuration is more stable.
- Fri Oct 26, 2018 11:27 pm
- Forum: Lewis Structures
- Topic: Periodic Table Trends
- Replies: 3
- Views: 307
Re: Periodic Table Trends
I agree that there shouldn't be any exceptions to periodic table trends. Generally, ionization energy decreases down a group and increases across a period. Electron affinity is highest for elements in the top right corner of the periodic table.
- Fri Oct 26, 2018 11:24 pm
- Forum: General Science Questions
- Topic: Midterm studying
- Replies: 10
- Views: 1418
Re: Midterm studying
I think that going to the peer learning sessions are very helpful. I have gone to quite a few over the past few weeks, and the UA's have helped me understand the material better! Also listening to other students' questions is very useful too.
- Fri Oct 26, 2018 11:22 pm
- Forum: Trends in The Periodic Table
- Topic: Ionization Energy and Electron Affinity
- Replies: 9
- Views: 1808
Re: Ionization Energy and Electron Affinity
Ionization energy is the energy needed to remove an electron from an atom in the gas phase. The further an electron is from the nucleus, the easier it is to remove. Ionization energies tend to decrease down a group (because of shielding from shells) and increase across a period (because greater attr...
- Sat Oct 20, 2018 3:58 pm
- Forum: Properties of Light
- Topic: 3 Posts on Chemistry Community [ENDORSED]
- Replies: 5
- Views: 442
Re: 3 Posts on Chemistry Community [ENDORSED]
How do you make a New Post on Chemistry Community? I only know how to post replies.
- Sat Oct 20, 2018 3:56 pm
- Forum: Photoelectric Effect
- Topic: Work Function
- Replies: 16
- Views: 766
Re: Work Function
Is the unit of work function Joules, or Joules per photon?
- Sat Oct 20, 2018 3:54 pm
- Forum: Trends in The Periodic Table
- Topic: s, p, d, f
- Replies: 16
- Views: 4272
Re: s, p, d, f
On Test 2, would we be required to draw the different types of orbitals or identify various diagrams of orbitals?
- Thu Oct 11, 2018 6:00 pm
- Forum: Photoelectric Effect
- Topic: Empirical Equation
- Replies: 4
- Views: 392
Re: Empirical Equation
Is work function the same thing as threshold energy?
- Thu Oct 11, 2018 5:53 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Heisenberg
- Replies: 5
- Views: 425
Re: Heisenberg
Heisenberg indeterminacy is the principle that the measurement process influences the outcome. For example, light (photons) shined on an electron will change the pathway of the electron and cause uncertainty in its distance.
- Thu Oct 11, 2018 5:47 pm
- Forum: Properties of Electrons
- Topic: Series and Wavelengths
- Replies: 2
- Views: 205
Re: Series and Wavelengths
For each of the series, the principal quantum number for the lower energy is different. For the Lyman series, the lower energy level is n=1. For the Balmer series, the lower energy level is n=2. For the Paschen series, the lower energy level is n=3.
- Wed Oct 03, 2018 11:40 pm
- Forum: Limiting Reactant Calculations
- Topic: Combustion Analysis? [ENDORSED]
- Replies: 7
- Views: 405
Re: Combustion Analysis? [ENDORSED]
Dr. Lavelle gave an interesting method of how to think about combustion: eating food + breathing in oxygen --> breathe out CO2 + H20. Hope this analogy helps!
- Tue Oct 02, 2018 6:48 pm
- Forum: SI Units, Unit Conversions
- Topic: Formula Units: Molecules or Atoms
- Replies: 5
- Views: 442
Re: Formula Units: Molecules or Atoms
I'm confused about what exactly are formula units too. On problem E9 part b, the answer is written in terms of atoms as formula units, but isn't MgSO4 * 7H2O a molecule?
- Mon Oct 01, 2018 1:48 pm
- Forum: SI Units, Unit Conversions
- Topic: Homework Grading Clarification [ENDORSED]
- Replies: 8
- Views: 878
Re: Homework Grading Clarification [ENDORSED]
Yes, we are turning in 7 problems for homework. However, even though we are only turning in 7 problems, Lavelle encourages us to do as many homework problems as possible so that we understand the material fully. (: