Search found 62 matches

by Josephine Lu 4L
Sat Mar 16, 2019 12:45 am
Forum: Second Order Reactions
Topic: does the order determine molecularity?
Replies: 2
Views: 105

does the order determine molecularity?

is the overall order of a reaction the same as its molecularity?
by Josephine Lu 4L
Sat Mar 16, 2019 12:04 am
Forum: *Enzyme Kinetics
Topic: sig figs on the final
Replies: 2
Views: 108

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?
by Josephine Lu 4L
Fri Mar 15, 2019 11:04 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: writing rate laws: "rate"or "d[A]/dt?"
Replies: 1
Views: 34

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).
by Josephine Lu 4L
Wed Mar 13, 2019 11:48 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: k1 prime or k-1
Replies: 1
Views: 43

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?
by Josephine Lu 4L
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: 6698

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"?
by Josephine Lu 4L
Tue Mar 12, 2019 1:04 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: slow step and fast step
Replies: 3
Views: 45

slow step and fast step

why does the slow step not influence the overall rate?
by Josephine Lu 4L
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: 33

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?
by Josephine Lu 4L
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: 38

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)?
by Josephine Lu 4L
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: 6698

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?
by Josephine Lu 4L
Sun Feb 24, 2019 5:31 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Positional disorder vs. thermal disorder
Replies: 2
Views: 54

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?
by Josephine Lu 4L
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: 49

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?
by Josephine Lu 4L
Tue Feb 19, 2019 6:23 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: 9.63 Positive delta G
Replies: 3
Views: 133

9.63 Positive delta G

Why are compounds with a positive free energy of formation (delta G) unstable?
by Josephine Lu 4L
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: 118

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)?
by Josephine Lu 4L
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: 50

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?
by Josephine Lu 4L
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: 60

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.
by Josephine Lu 4L
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: 52

How to know which gas constant to use

When should I use R=8.314 versus using R= 8.206 * 10^-2 ?
by Josephine Lu 4L
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: 41

q=deltaH under constant pressure

Why is q=deltaH under constant pressure? What is the reasoning behind it?
by Josephine Lu 4L
Fri Feb 08, 2019 11:36 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: 8.49
Replies: 1
Views: 35

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?
by Josephine Lu 4L
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: 65

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?
by Josephine Lu 4L
Sun Feb 03, 2019 11:01 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: deriving the work equation: -P*deltaV
Replies: 2
Views: 48

deriving the work equation: -P*deltaV

Will we be required to derive the work equation (-P*deltaV) for the midterm?
by Josephine Lu 4L
Sun Feb 03, 2019 10:58 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Internal energy
Replies: 5
Views: 91

Re: Internal energy

Internal energy is a state property. It is found by adding q (heat) and w (work).
by Josephine Lu 4L
Fri Jan 25, 2019 12:33 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: autoprotolysis on Test 1?
Replies: 2
Views: 50

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?
by Josephine Lu 4L
Fri Jan 25, 2019 12:24 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: increasing pressure, what happens to concentration?
Replies: 10
Views: 181

increasing pressure, what happens to concentration?

Why is it that when we increase pressure, the reaction favors the side with less moles of gas?
by Josephine Lu 4L
Fri Jan 25, 2019 12:22 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ICE BOX and coefficients
Replies: 4
Views: 57

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.
by Josephine Lu 4L
Tue Jan 22, 2019 12:08 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: when to ignore the second ionization constant
Replies: 3
Views: 69

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?
by Josephine Lu 4L
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: 54

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
by Josephine Lu 4L
Wed Jan 16, 2019 8:57 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6th edition 11.69
Replies: 1
Views: 35

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...
by Josephine Lu 4L
Thu Jan 10, 2019 12:10 pm
Forum: Ideal Gases
Topic: use
Replies: 8
Views: 89

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.
by Josephine Lu 4L
Thu Jan 10, 2019 12:05 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Why Would Equilibrium cause death in humans?
Replies: 3
Views: 77

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.
by Josephine Lu 4L
Mon Jan 07, 2019 4:28 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 11.13 Reaction Quotient [ENDORSED]
Replies: 3
Views: 73

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?
by Josephine Lu 4L
Sat Dec 08, 2018 3:50 pm
Forum: Naming
Topic: adding "ion" at the end of a name
Replies: 4
Views: 72

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?
by Josephine Lu 4L
Sat Dec 08, 2018 10:35 am
Forum: Naming
Topic: using prefix "mono"
Replies: 2
Views: 47

using prefix "mono"

When would you use the prefix "mono" when naming coordination compounds?
by Josephine Lu 4L
Sat Dec 08, 2018 10:34 am
Forum: Amphoteric Compounds
Topic: Amphiprotic and Amphoteric
Replies: 1
Views: 133

Amphiprotic and Amphoteric

What is an example of a molecule that is amphoteric but not amphiprotic, and what makes it that way?
by Josephine Lu 4L
Sun Dec 02, 2018 12:35 am
Forum: Lewis Acids & Bases
Topic: Strong acids and strong bases
Replies: 5
Views: 71

Strong acids and strong bases

Are strong acids and strong bases always completely ionized in water?
by Josephine Lu 4L
Sun Dec 02, 2018 12:32 am
Forum: Naming
Topic: endings in naming
Replies: 3
Views: 58

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.
by Josephine Lu 4L
Sun Dec 02, 2018 12:29 am
Forum: Lewis Acids & Bases
Topic: bronsted acid vs. lewis acid
Replies: 4
Views: 81

bronsted acid vs. lewis acid

can a molecule be a bronsted acid and a lewis acid at the same time?
by Josephine Lu 4L
Mon Nov 26, 2018 5:50 pm
Forum: Hybridization
Topic: electron occupying unhybridized orbital
Replies: 2
Views: 44

electron occupying unhybridized orbital

why does an electron prefer to occupy an unhybridized orbital before spin pairing in a hybridized orbital?
by Josephine Lu 4L
Mon Nov 26, 2018 5:48 pm
Forum: Hybridization
Topic: Pi bonds
Replies: 2
Views: 86

Pi bonds

Why is it that sigma bonds allow rotation, while pi bonds do not?
by Josephine Lu 4L
Mon Nov 26, 2018 5:46 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Cis and Trans
Replies: 3
Views: 55

Cis and Trans

What is the difference between a cis and trans molecule?
by Josephine Lu 4L
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: 28260

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!
by Josephine Lu 4L
Sun Nov 18, 2018 11:37 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: vsper structures
Replies: 3
Views: 78

vsper structures

what does it mean when a lone pair is in the axial or equitorial plane?
by Josephine Lu 4L
Sun Nov 18, 2018 11:35 pm
Forum: Sigma & Pi Bonds
Topic: sigma and pi bonds
Replies: 2
Views: 56

sigma and pi bonds

what is the difference between a sigma and pi bond?
by Josephine Lu 4L
Sun Nov 18, 2018 11:32 pm
Forum: Ionic & Covalent Bonds
Topic: Intra vs Intermolecular forces
Replies: 9
Views: 468

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.
by Josephine Lu 4L
Wed Nov 14, 2018 10:49 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shape
Replies: 4
Views: 54

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.
by Josephine Lu 4L
Sat Nov 10, 2018 2:33 pm
Forum: Ionic & Covalent Bonds
Topic: localized e- def
Replies: 2
Views: 55

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.
by Josephine Lu 4L
Sat Nov 10, 2018 2:30 pm
Forum: Resonance Structures
Topic: Drawing resonance structures
Replies: 5
Views: 219

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.
by Josephine Lu 4L
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: 28260

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)?
by Josephine Lu 4L
Sun Nov 04, 2018 5:37 pm
Forum: Ionic & Covalent Bonds
Topic: Naming Ionic Compounds
Replies: 5
Views: 80

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.
by Josephine Lu 4L
Sun Nov 04, 2018 5:36 pm
Forum: Trends in The Periodic Table
Topic: Electron Affinity
Replies: 3
Views: 83

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.
by Josephine Lu 4L
Sun Nov 04, 2018 5:33 pm
Forum: Lewis Structures
Topic: HOCO Lewis structure
Replies: 1
Views: 29

Re: HOCO Lewis structure

I think it's because with the way the formal charges turn out, this configuration is more stable.
by Josephine Lu 4L
Fri Oct 26, 2018 11:27 pm
Forum: Lewis Structures
Topic: Periodic Table Trends
Replies: 3
Views: 45

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.
by Josephine Lu 4L
Fri Oct 26, 2018 11:24 pm
Forum: General Science Questions
Topic: Midterm studying
Replies: 10
Views: 352

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.
by Josephine Lu 4L
Fri Oct 26, 2018 11:22 pm
Forum: Trends in The Periodic Table
Topic: Ionization Energy and Electron Affinity
Replies: 9
Views: 390

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...
by Josephine Lu 4L
Sat Oct 20, 2018 3:58 pm
Forum: Properties of Light
Topic: 3 Posts on Chemistry Community [ENDORSED]
Replies: 5
Views: 98

Re: 3 Posts on Chemistry Community [ENDORSED]

How do you make a New Post on Chemistry Community? I only know how to post replies.
by Josephine Lu 4L
Sat Oct 20, 2018 3:56 pm
Forum: Photoelectric Effect
Topic: Work Function
Replies: 16
Views: 193

Re: Work Function

Is the unit of work function Joules, or Joules per photon?
by Josephine Lu 4L
Sat Oct 20, 2018 3:54 pm
Forum: Trends in The Periodic Table
Topic: s, p, d, f
Replies: 16
Views: 340

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?
by Josephine Lu 4L
Thu Oct 11, 2018 6:00 pm
Forum: Photoelectric Effect
Topic: Empirical Equation
Replies: 4
Views: 72

Re: Empirical Equation

Is work function the same thing as threshold energy?
by Josephine Lu 4L
Thu Oct 11, 2018 5:53 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Heisenberg
Replies: 5
Views: 102

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.
by Josephine Lu 4L
Thu Oct 11, 2018 5:47 pm
Forum: Properties of Electrons
Topic: Series and Wavelengths
Replies: 2
Views: 56

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.
by Josephine Lu 4L
Wed Oct 03, 2018 11:40 pm
Forum: Limiting Reactant Calculations
Topic: Combustion Analysis? [ENDORSED]
Replies: 7
Views: 150

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!
by Josephine Lu 4L
Tue Oct 02, 2018 6:48 pm
Forum: SI Units, Unit Conversions
Topic: Formula Units: Molecules or Atoms
Replies: 5
Views: 103

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?
by Josephine Lu 4L
Mon Oct 01, 2018 1:48 pm
Forum: SI Units, Unit Conversions
Topic: Homework Grading Clarification [ENDORSED]
Replies: 7
Views: 227

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. (:

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