Search found 106 matches

by Tiffany_Chen 2K
Wed Mar 11, 2020 1:01 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Catalysts vs. Intermediates
Replies: 8
Views: 22

Re: Catalysts vs. Intermediates

Intermediates will not show up in the final product, catalysts will as it is not degraded.
by Tiffany_Chen 2K
Wed Mar 11, 2020 1:00 pm
Forum: Administrative Questions and Class Announcements
Topic: ENDGAME Review Session
Replies: 71
Views: 1808

Re: ENDGAME Review Session

Thank you for an awesome two quarters! Best of luck in your future endeavors :)
by Tiffany_Chen 2K
Wed Mar 11, 2020 12:59 pm
Forum: Student Social/Study Group
Topic: turning in the final
Replies: 2
Views: 23

Re: turning in the final

Lavelle should update us soon (hopefully). Might be an online test, or we have to scan it in by a certain time?
by Tiffany_Chen 2K
Wed Mar 11, 2020 12:58 pm
Forum: Administrative Questions and Class Announcements
Topic: test 2 return
Replies: 6
Views: 78

Re: test 2 return

Your TA should email you with details!
by Tiffany_Chen 2K
Wed Mar 11, 2020 12:55 pm
Forum: Administrative Questions and Class Announcements
Topic: Earthquake FINAL REVIEW SESSION
Replies: 11
Views: 374

Re: Earthquake FINAL REVIEW SESSION

Yesss, we love a student-run review session! ^Trustworthy source :)
by Tiffany_Chen 2K
Tue Mar 03, 2020 10:25 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Galvanic cells
Replies: 6
Views: 30

Re: Galvanic cells

Yes and electrons will flow from anode to cathode! Thus, a positive cell potential for reaction to be spontaneous.
by Tiffany_Chen 2K
Tue Mar 03, 2020 10:24 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Ions
Replies: 2
Views: 9

Re: Ions

NO3 is generally used as a salt bridge. OH- is added when the redox is in a basic solution (to balance oxygens).
by Tiffany_Chen 2K
Tue Mar 03, 2020 10:23 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Cell Potential and Work/Free Energy
Replies: 2
Views: 30

Re: Cell Potential and Work/Free Energy

Additionally, cell potential would be the maximum energy available to do work.
by Tiffany_Chen 2K
Tue Mar 03, 2020 10:21 am
Forum: Balancing Redox Reactions
Topic: MnO4-
Replies: 5
Views: 32

Re: MnO4-

Oxygen has a -2 charge for each atom, given a total of -8 charge. Since the overall molecule is -1, Mn will have to be +7.
by Tiffany_Chen 2K
Tue Mar 03, 2020 10:20 am
Forum: Balancing Redox Reactions
Topic: Oxidation/Reduction
Replies: 17
Views: 69

Re: Oxidation/Reduction

Ruby Richter 2L wrote:When adding reactions and in the final state how do you determine what physical state everything is in?


You should be able to tell the states given the half reactions. Soluble compounds can also form (from reactant solids).
by Tiffany_Chen 2K
Thu Feb 27, 2020 3:46 pm
Forum: Balancing Redox Reactions
Topic: OH- in Basic Solutions
Replies: 6
Views: 31

Re: OH- in Basic Solutions

Think of it like this: for the reducing agent (so the reactant is being oxidized), it will be positively charged after losing electrons. Thus, you can add OH- to balance out the positive charge.
by Tiffany_Chen 2K
Thu Feb 27, 2020 3:45 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: log and ln in Nernst
Replies: 8
Views: 48

Re: log and ln in Nernst

Either would work, log is typically used as it is more useful in calculating pH.
by Tiffany_Chen 2K
Thu Feb 27, 2020 3:44 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: How to tell which is anode/cathode based on standard reduction potentials E
Replies: 5
Views: 18

Re: How to tell which is anode/cathode based on standard reduction potentials E

The more positive E(red) will be at the cathode, so you can find E(ox) of the other half reaction by reversing the given E(red) value. Then add them to find the overall reaction cell potential.
by Tiffany_Chen 2K
Thu Feb 27, 2020 3:42 pm
Forum: General Science Questions
Topic: Test 2
Replies: 16
Views: 119

Re: Test 2

Last page of thermochemistry, and all of electrochemistry!
by Tiffany_Chen 2K
Thu Feb 27, 2020 3:42 pm
Forum: Balancing Redox Reactions
Topic: Oxidation number of Ozone
Replies: 10
Views: 60

Re: Oxidation number of Ozone

Oxidation number would be 0 as the overall charge of O3 is 0.
by Tiffany_Chen 2K
Thu Feb 20, 2020 8:25 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: converting T to kelvin
Replies: 21
Views: 136

Re: converting T to kelvin

If the question asks for the answer to be in specific units, don't forget to convert at the end. For thermodynamics, usually celsius/kelvin can be interchangeable due to the same difference.
by Tiffany_Chen 2K
Thu Feb 20, 2020 8:23 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Anode and Cathode
Replies: 14
Views: 233

Re: Anode and Cathode

Anode: site of oxidation, cathode: site of reduction.
by Tiffany_Chen 2K
Thu Feb 20, 2020 8:22 pm
Forum: Balancing Redox Reactions
Topic: Oxidation number of Ozone
Replies: 10
Views: 60

Re: Oxidation number of Ozone

How do you find oxidation numbers? Group one would be +1, group two would be +2, group seventeen would be -1. Neutral compounds would have a total oxidation number of 0, so you can usually figure out individual oxidation numbers of atoms from knowing one atom out of the compound (E.g. CrCl3, Cl has...
by Tiffany_Chen 2K
Thu Feb 20, 2020 5:19 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Adiabatic systems
Replies: 11
Views: 60

Re: Adiabatic systems

Yep, as no heat transfer will occur (isolated system).
by Tiffany_Chen 2K
Thu Feb 20, 2020 5:18 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Second law of thermodynamics
Replies: 6
Views: 46

Re: Second law of thermodynamics

Entropy in the natural world is always increasing, if the reaction is reversible, entropy would then equal 0.
by Tiffany_Chen 2K
Wed Feb 12, 2020 10:20 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: entropy at equilibrium
Replies: 3
Views: 31

Re: entropy at equilibrium

At equilibrium, deltaS(total)=0. Thus, deltaS(sys) will have the opposite relationship to deltaS(surr). Any entropy change will be the only entropy change to the system (as deltaS(surr) will only reflect the exact opposite of deltaS(sys)).
by Tiffany_Chen 2K
Wed Feb 12, 2020 9:59 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Irreversible Expansion
Replies: 7
Views: 66

Re: Irreversible Expansion

In the opposite way of thinking, reversible expansions are where there is an infinitesimal amount of changes to the system, thus allowing the system to be reversible. Irreversible expansions are typically a huge, sudden change that will take an equally large amount of energy to reverse (which is mos...
by Tiffany_Chen 2K
Wed Feb 12, 2020 9:56 pm
Forum: Calculating Work of Expansion
Topic: Constant pressure in a calorimeter
Replies: 3
Views: 37

Re: Constant pressure in a calorimeter

Adding on, for a regular calorimeter, it is constant pressure (air can diffuse in and out). Bomb calorimeter, it is constant volume as it's a sealed container, thus you would use Cv.
by Tiffany_Chen 2K
Wed Feb 12, 2020 9:37 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Joules or KJ?
Replies: 14
Views: 82

Re: Joules or KJ?

Just make sure the constants you use (e.g. R), will match the units you want. Really depends on what the question asks for.
by Tiffany_Chen 2K
Wed Feb 12, 2020 9:34 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Spontaneous
Replies: 23
Views: 108

Re: Spontaneous

When deltaG (free energy available to do work) is negative!
by Tiffany_Chen 2K
Sat Feb 08, 2020 10:40 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: Perfect Crystal
Replies: 3
Views: 12

Re: Perfect Crystal

For the third law, "entropy reaches a constant value (0 for perfect crystals) when temperature approaches 0 K". 0 K would indicate the material is only present in one possible micro-state/position.
by Tiffany_Chen 2K
Sat Feb 08, 2020 10:38 pm
Forum: Calculating Work of Expansion
Topic: Irreversible vs. reversible work
Replies: 2
Views: 11

Re: Irreversible vs. reversible work

Think of area under the curve, reversible work will have a gradual decrease in temperature, giving more area. For irreversible reactions (where pressure is constant after a force is exerted), the area will be just a box (recall the diagram from class).
by Tiffany_Chen 2K
Sat Feb 08, 2020 10:37 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: q rev
Replies: 9
Views: 50

Re: q rev

Heat for a reversible equation is qrev. Reversible equations are when the equation is at equilibrium.
by Tiffany_Chen 2K
Sat Feb 08, 2020 10:35 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Boltzmann Equation
Replies: 3
Views: 25

Re: Boltzmann Equation

Yep, in terms of molecular states the Boltzmann equation will be useful for calculating entropy (statistical). The other equation for entropy is good for thermodynamics as a whole.
by Tiffany_Chen 2K
Sat Feb 08, 2020 10:34 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs free energy
Replies: 4
Views: 37

Re: Gibbs free energy

Really depends on specific values (using the equation). We should cover the +/- conditions post midterms. For entropy, you can think of the second law, where spontaneity and increase in entropy relates (-deltaG corresponds with spontaneous reactions).
by Tiffany_Chen 2K
Thu Jan 30, 2020 2:31 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Negative pH
Replies: 9
Views: 47

Re: Negative pH

For very strong acids, their pH will be extremely low and can thus create a negative outcome using the log equation.
by Tiffany_Chen 2K
Thu Jan 30, 2020 2:28 pm
Forum: Ideal Gases
Topic: Inert Gas
Replies: 12
Views: 48

Re: Inert Gas

For problems, inert gases will not show up in the equation (thus adding it will not shift equilibrium).
by Tiffany_Chen 2K
Thu Jan 30, 2020 2:26 pm
Forum: Ideal Gases
Topic: non ideal gases
Replies: 8
Views: 46

Re: non ideal gases

Any gas that exhibits intermolecular forces and takes up volume.
by Tiffany_Chen 2K
Thu Jan 30, 2020 2:24 pm
Forum: Calculating Work of Expansion
Topic: Irreversible vs. Reversible Reactions
Replies: 6
Views: 53

Re: Irreversible vs. Reversible Reactions

A reversible reaction would not increase the entropy of the system or surroundings, as it maintains a thermodynamic equilibrium. A irreversible system is most common, as it takes the reaction away from equilibrium (then energy will need to be put in to reverse the system).
by Tiffany_Chen 2K
Thu Jan 30, 2020 2:13 pm
Forum: Phase Changes & Related Calculations
Topic: Units
Replies: 16
Views: 80

Re: Units

Agreeing with the above comments, here is also the proof:

K=C+273.15
K1-K2=C+273.15-(C+273.15)
K1-K2=C1-C2
by Tiffany_Chen 2K
Mon Jan 20, 2020 1:34 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Adding a catalyst
Replies: 7
Views: 37

Re: Adding a catalyst

In addition, remember that only temperature will change the reaction's equilibrium constant. A catalyst will only speed up the reaction for equilibrium to be reached more quickly.
by Tiffany_Chen 2K
Mon Jan 20, 2020 1:33 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Pressure changes
Replies: 5
Views: 20

Re: Pressure changes

No shift in reaction will occur if there are equal moles on both sides.
by Tiffany_Chen 2K
Mon Jan 20, 2020 1:32 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Summary of Le Chatelier
Replies: 5
Views: 31

Re: Summary of Le Chatelier

Chemical equilibriums will shift accordingly to minimize stressors. In lecture, we covered stressors such as concentration, pressure, and heat.
by Tiffany_Chen 2K
Mon Jan 20, 2020 1:30 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5 percent rule
Replies: 2
Views: 17

Re: 5 percent rule

Both, if the ionization percentage is less than 5%, this justifies in approximating x as 0.
by Tiffany_Chen 2K
Mon Jan 20, 2020 1:30 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: pH sig figs
Replies: 9
Views: 34

Re: pH sig figs

For your final answer (if asked for pH), you want to have the least number of sig figs for the value past the decimal point. E.g. you are given 0.015M of something and that is the least number of sig figs. Your answer would be need two sig figs past the decimal point, e.g. 3.00
by Tiffany_Chen 2K
Mon Jan 20, 2020 12:43 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: X approx check
Replies: 2
Views: 14

Re: X approx check

I would just to be safe! You can check using percent ionization too, if the percent ionization is <5%, then x approximation is justified.
by Tiffany_Chen 2K
Mon Jan 13, 2020 5:28 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: "Quick way" part in Lecture
Replies: 7
Views: 56

Re: "Quick way" part in Lecture

Look at PV=nRT but rearranged into P=((n/V)*RT) or P=conc*RT. For example, volume is halfed ->> n will double. You can then recalculated Qc and compare this to Kc to determine which way the reaction will go.
by Tiffany_Chen 2K
Mon Jan 13, 2020 5:21 pm
Forum: Ideal Gases
Topic: Kc and Kp
Replies: 5
Views: 30

Re: Kc and Kp

The question should indicate which one to use. Though all reactants/products can be in gas form, we can still look and compare their concentrations (Kc).
by Tiffany_Chen 2K
Mon Jan 13, 2020 5:19 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Reaction Quotient
Replies: 11
Views: 51

Re: Reaction Quotient

Reaction quotient is used to determine whether the equation is at equilibrium (so compare to the K value). If not, we can predict which direction the reaction needs to favor in order to reach the equilibrium rate for both sides.
by Tiffany_Chen 2K
Mon Jan 13, 2020 5:15 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: The Value of Kw
Replies: 3
Views: 19

Re: The Value of Kw

Yes, increasing temperature will increase the value of Kw as the autoprotolysis of water is endothermic (so increasing heat will lead to formation of more products).
by Tiffany_Chen 2K
Mon Jan 13, 2020 5:12 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Autoprotolysis of water endo or exo?
Replies: 4
Views: 20

Re: Autoprotolysis of water endo or exo?

If you think of the reverse reaction (2H2+O2->2H2O), energy is released to form the covalent bonds of water. Thus the reverse is exothermic, while the forward reaction (protonation of H2O) is endothermic.
by Tiffany_Chen 2K
Mon Jan 06, 2020 6:28 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Calculating Kc
Replies: 4
Views: 53

Re: Calculating Kc

Solids and liquids will hold relatively constant volume, thus you can technically "cancel" them out when putting products over reactants to find Kc.
by Tiffany_Chen 2K
Mon Jan 06, 2020 6:24 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Writing Equilibrium Constant Labels
Replies: 4
Views: 46

Re: Writing Equilibrium Constant Labels

Kc is used for concentrations (M), which can be gases or aqueous molecules, Kp uses partial pressures of gases. Question should be clear on which one to use.
by Tiffany_Chen 2K
Mon Jan 06, 2020 6:21 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K threshold
Replies: 2
Views: 39

Re: K threshold

If K=10^-3 or greater, full calculations using the quadratic equation should be used
by Tiffany_Chen 2K
Mon Jan 06, 2020 6:19 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: H3O and OH
Replies: 5
Views: 58

Re: H3O and OH

Anything gas or aqueous should be included. Solvents (l) or solids will not be including in calculating Kc/Kp.
by Tiffany_Chen 2K
Mon Jan 06, 2020 6:16 pm
Forum: Ideal Gases
Topic: ICE Table Variables
Replies: 6
Views: 65

Re: ICE Table Variables

Yes, using variables will aid you in calculating different parts of the Kc equilibrium. You will use the quadratic equation to solve for the 'x', then apply to the reactant or product.
by Tiffany_Chen 2K
Wed Dec 04, 2019 12:43 pm
Forum: Administrative Questions and Class Announcements
Topic: MARSHMALLOW- FINAL REVIEW SESSION [ENDORSED]
Replies: 111
Views: 4361

Re: MARSHMALLOW- FINAL REVIEW SESSION [ENDORSED]

For #31 should the name be ...nickel(III) ion? The complex has a 2+ charge.
by Tiffany_Chen 2K
Mon Dec 02, 2019 9:31 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Hydronium concentration = 1.5M, negative ph?
Replies: 3
Views: 34

Re: Hydronium concentration = 1.5M, negative ph?

Nyari Muchaka_Discussion 4A wrote:pH cannot be negative, it exists between 0-14.


But taking the -log[1.5]=-0.176, do we just assume it as positive? Or basically very close to 0 I guess.
by Tiffany_Chen 2K
Mon Dec 02, 2019 9:16 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Oxalate and CO3 2- as a polydentate
Replies: 3
Views: 36

Re: Oxalate and CO3 2- as a polydentate

For d), oxalate is bidentate as there will be two double bonds (these won't bind to the metal as the pi bonds restrict rotation, thus only 2 of the single bonded oxygens can bind at once).
by Tiffany_Chen 2K
Mon Dec 02, 2019 9:11 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Carbonate Ion
Replies: 2
Views: 29

Re: Carbonate Ion

Resonance structure, one structure has two double bonds (leading to monodentate), one structure has one double bond (so two available oxygens, bidentate).
by Tiffany_Chen 2K
Mon Dec 02, 2019 9:08 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Hydronium concentration = 1.5M, negative ph?
Replies: 3
Views: 34

Hydronium concentration = 1.5M, negative ph?

But the book converts the -0.176 ph into a positive number. Why is that?
by Tiffany_Chen 2K
Mon Dec 02, 2019 8:52 pm
Forum: Conjugate Acids & Bases
Topic: Acids and Bases in solution
Replies: 1
Views: 38

Re: Acids and Bases in solution

CH3COO- is the conjugate base of acetic acid (as it is a proton acceptor (takes in H+ from H2O, leaving OH-, which creates the basic solution)).
by Tiffany_Chen 2K
Mon Dec 02, 2019 8:49 pm
Forum: Amphoteric Compounds
Topic: 6A.17
Replies: 4
Views: 75

Re: 6A.17

Metal oxides generally form basic oxides, while nonmetal oxides generally form acidic oxides. Sulfur is a nonmetal thus will be acidic. Amphoteric oxides (shown in class) can react as both an acid or base to form a salt and water.
by Tiffany_Chen 2K
Mon Nov 25, 2019 8:32 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: ETDA formula - acetate or acetic acid end?
Replies: 1
Views: 53

ETDA formula - acetate or acetic acid end?

I've seen EDTA under two names - ethylenediaminetetra acetic acid and ethylenediaminetetra acetato . Which one is correct? Additionally, I've seen structures with hydrogens attached to the acetate ends and structures without (so there is a negative charge)––all under the name of EDTA. I thought acet...
by Tiffany_Chen 2K
Mon Nov 25, 2019 12:55 pm
Forum: Naming
Topic: Di-, Tri-, Tetra- vs Bis-, Tris-, Tetrakis-
Replies: 11
Views: 69

Re: Di-, Tri-, Tetra- vs Bis-, Tris-, Tetrakis-

You would also use the prefix if the ligand is polydentate, and there are more than one of the ligands (so no di-dien).
by Tiffany_Chen 2K
Mon Nov 25, 2019 12:53 pm
Forum: Sigma & Pi Bonds
Topic: sigma and pi bonds
Replies: 19
Views: 166

Re: sigma and pi bonds

Yes, the first bond would be a sigma bond, followed by a pi bond for each additional bond. For example, for a sp hybridization (triple bond), there would be one sigma bond and two pi bonds (using the two empty 2p orbitals).
by Tiffany_Chen 2K
Mon Nov 25, 2019 12:51 pm
Forum: Naming
Topic: 9C #5
Replies: 3
Views: 47

Re: 9C #5

Polydentate means the number of donor groups a ligand can bound to the transition metal. E.g. EDTA is hexadentate, as there are 4 oxygens and 2 nitrogens available to bind to the TM.
by Tiffany_Chen 2K
Mon Nov 25, 2019 12:49 pm
Forum: Trends in The Periodic Table
Topic: Electronegativity
Replies: 9
Views: 85

Re: Electronegativity

Yes! Also recall ionization energy is the energy need to remove a valence electron, and electron affinity is the energy released when an electron is bound to a neutral atom in gas phase.
by Tiffany_Chen 2K
Mon Nov 25, 2019 12:46 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Forming Chelating Complexes: HW 9C.7
Replies: 1
Views: 39

Re: Forming Chelating Complexes: HW 9C.7

I found this post to be helpful (viewtopic.php?t=764). I believe if the ligand is polydentate and will form a "claw" structure when binding to the same transition metal, it can be categorized as a chelate.
by Tiffany_Chen 2K
Mon Nov 18, 2019 2:50 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bonds in VSEPR
Replies: 11
Views: 73

Re: Bonds in VSEPR

Think of the bonding regions as regions of electron density (triple/double bonds are each considered one region, same for single bonds).
by Tiffany_Chen 2K
Mon Nov 18, 2019 2:49 pm
Forum: Bond Lengths & Energies
Topic: Interaction Potential Energy
Replies: 2
Views: 58

Re: Interaction Potential Energy

No calculations, but understand the concept, which is that greater distance will lead to a PE of 0 (no interaction), and greater polarizability of the two atoms will lead to a more negative PE (as there is a negative sign in front of the equation, and negative PE is favored).
by Tiffany_Chen 2K
Mon Nov 18, 2019 2:46 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: seesaw
Replies: 1
Views: 23

Re: seesaw

Yes! The bond angles between the equatorial atoms will actually be less than 120 degrees, as well as less than 90 degree angle between the axial atoms and equatorial atoms.
by Tiffany_Chen 2K
Mon Nov 18, 2019 2:41 pm
Forum: Hybridization
Topic: hybridization 1st number
Replies: 3
Views: 21

Re: hybridization 1st number

For example, in carbon, hybridization would occur in 2s/2p orbitals (as these electrons are used in creating hybrid orbitals). Both 2sp or sp would work (2sp is just more specific as it gives the quantum number).
by Tiffany_Chen 2K
Sat Nov 16, 2019 3:06 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: Dipole-dipole in H2SeO4
Replies: 3
Views: 47

Re: Dipole-dipole in H2SeO4

I think because oxygen is much more electronegative than Se, it exerts a greater pull on the electrons and pulls out. The dipoles may not cancel out because there are multiple resonances of H2SeO4. For example, if the OH and O are not symmetrically bonded to the Se (like an O across and O and an OH...
by Tiffany_Chen 2K
Sat Nov 16, 2019 1:34 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: Dipole-dipole in H2SeO4
Replies: 3
Views: 47

Dipole-dipole in H2SeO4

Why would there be dipole forces for molecules of H2 and SeO4? Aren't they both nonpolar?

Update: the question asks for the entire molecule of H2SeO4, makes more sense!
by Tiffany_Chen 2K
Thu Nov 14, 2019 10:09 pm
Forum: Dipole Moments
Topic: For which of the following molecules will dipole–dipole inter- actions be important
Replies: 2
Views: 32

Re: For which of the following molecules will dipole–dipole inter- actions be important

The shape would be tetrahedral - try drawing it out with different atoms on top (the polar vectors would not cancel due to the shape, no matter if H or Cl is the top atom).
by Tiffany_Chen 2K
Thu Nov 14, 2019 10:06 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Test 2
Replies: 11
Views: 94

Re: Test 2

Definitely get started on homework from Outline 4, also review the intermolecular forces.
by Tiffany_Chen 2K
Thu Nov 14, 2019 10:03 pm
Forum: Lewis Structures
Topic: Oxygen
Replies: 9
Views: 114

Re: Oxygen

Can you give an example? It depends on the formal charge/molecule.
by Tiffany_Chen 2K
Thu Nov 14, 2019 10:02 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2E21
Replies: 2
Views: 32

Re: 2E21

The molecular shape for N2H4 would be trigonal pyramidal as it is A34E1. The general rule for that shape is that bond angles are less than 109.5, 107 is exact and obtained from experimental data (so less than 109.5 degrees would work as the answer, the book is just exact).
by Tiffany_Chen 2K
Thu Nov 14, 2019 9:53 pm
Forum: Limiting Reactant Calculations
Topic: A different way
Replies: 8
Views: 156

Re: A different way

I would say that's the most efficient and clearest way to do limiting reactant problems for this class.
by Tiffany_Chen 2K
Tue Nov 05, 2019 7:31 pm
Forum: Electronegativity
Topic: Homework Question 2D.5 Part a
Replies: 2
Views: 35

Re: Homework Question 2D.5 Part a

Chlorine is more electronegative than iodine (atomic trends). The difference in electronegativity between HCl will then be greater than HI, therefore ionic character is more expressed in HCl.
by Tiffany_Chen 2K
Tue Nov 05, 2019 7:28 pm
Forum: Resonance Structures
Topic: 2C.5 c
Replies: 1
Views: 46

Re: 2C.5 c

I guess that would qualify as resonance (https://commons.wikimedia.org/wiki/File ... nce-2D.png), but in this case we are looking for radicals, and the structure itself (either one) would be stable.
by Tiffany_Chen 2K
Tue Nov 05, 2019 5:48 pm
Forum: Photoelectric Effect
Topic: binding energy
Replies: 3
Views: 88

Re: binding energy

Yes, it refers to threshold energy (energy to remove the e- from the metal surface).
by Tiffany_Chen 2K
Tue Nov 05, 2019 5:47 pm
Forum: Lewis Structures
Topic: Lewis Structure HClO3
Replies: 2
Views: 38

Re: Lewis Structure HClO3

I think it has to do with HClO3 being a strong acid, thus ClO3 would be a structure, and the remaining hydrogen would be bonded to an oxygen (as H+ will dissociate in water to form H3O+, leaving ClO3-).
by Tiffany_Chen 2K
Mon Nov 04, 2019 1:13 pm
Forum: Administrative Questions and Class Announcements
Topic: Class on Wednesday?
Replies: 2
Views: 44

Class on Wednesday?

Do we have lecture on Wednesday?
by Tiffany_Chen 2K
Tue Oct 29, 2019 4:46 pm
Forum: Administrative Questions and Class Announcements
Topic: Do Midterm Review Sessions Repeat Topics?
Replies: 4
Views: 43

Re: Do Midterm Review Sessions Repeat Topics?

There should be a couple more review sessions, including an in-depth one on Sunday.
by Tiffany_Chen 2K
Tue Oct 29, 2019 4:43 pm
Forum: Resonance Structures
Topic: Bond Order
Replies: 2
Views: 26

Re: Bond Order

You would take the number of bonds of that molecule (after drawing the lewis structure) divided by the number of bond groups (e.g. NO3 would have 4 bonds/3 bond groups = bond order of 1.33). The higher the bond order means the electrons are more tightly attracted, thus a greater stability.
by Tiffany_Chen 2K
Tue Oct 29, 2019 4:39 pm
Forum: Resonance Structures
Topic: resonance vs resonance hybrid
Replies: 2
Views: 25

Re: resonance vs resonance hybrid

Resonance structure is where the placement of the double or triple bond alternates, while a resonance hybrid structure would take in the average of the resonance structures for that molecule to display the a more realistic electronic structure.
by Tiffany_Chen 2K
Tue Oct 29, 2019 4:35 pm
Forum: Ionic & Covalent Bonds
Topic: 2A.5 (d-block configurations)
Replies: 4
Views: 34

Re: 2A.5 (d-block configurations)

So Cu is one of the d-block exceptions, where it would be more stable (symmetric distribution of electrons) to fill all of the 3d block (as 4s is technically higher in energy) first, before moving on to the next energy level.
by Tiffany_Chen 2K
Tue Oct 29, 2019 4:33 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge
Replies: 4
Views: 41

Re: Formal Charge

I would say perform formal charge calculations to structures where you are uncertain of the middle atom (such as OHCl, where formal charges can determine whether O or Cl would be in the middle).
by Tiffany_Chen 2K
Tue Oct 22, 2019 7:23 pm
Forum: Student Social/Study Group
Topic: Video Module For New Material
Replies: 4
Views: 96

Re: Video Module For New Material

Does he have modules for each unit/focus?
by Tiffany_Chen 2K
Tue Oct 22, 2019 7:23 pm
Forum: Trends in The Periodic Table
Topic: 1F.1 Atomic Radius Differences
Replies: 3
Views: 30

Re: 1F.1 Atomic Radius Differences

There are definitely exceptions further along the periodic table, but as long as you follow the general trend/reasoning used for upper elements you should be good (exceptions except for those mentioned in class should not be tested).
by Tiffany_Chen 2K
Tue Oct 22, 2019 7:18 pm
Forum: Trends in The Periodic Table
Topic: Effective Nuclear Charge
Replies: 7
Views: 46

Re: Effective Nuclear Charge

For atomic radius: let's say we are going from right to left across a period. The effective nuclear charge would increase, as the number of protons increase but the number of inner electrons stay the same. Thus, the nucleus will have a higher hold on the outer electrons, decreasing the atom's radius.
by Tiffany_Chen 2K
Tue Oct 22, 2019 7:15 pm
Forum: Trends in The Periodic Table
Topic: Ionization Energies Trend
Replies: 5
Views: 38

Re: Ionization Energies Trend

Ionization energy is the energy required to remove an electron from an atom in gas phase. Going across a period, you are increasing the number of photos while the number of shielding electrons (inner electrons) stay constant. So there will be an increase of effective nuclear charge, a tighter hold o...
by Tiffany_Chen 2K
Tue Oct 22, 2019 7:13 pm
Forum: Einstein Equation
Topic: Lecture Question!
Replies: 5
Views: 95

Re: Lecture Question!

I believe the electron will absorb the exact needed energy to go up an energy level, and the excess energy will be released.
by Tiffany_Chen 2K
Sat Oct 19, 2019 11:24 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Uncertainty Value
Replies: 8
Views: 55

Re: Uncertainty Value

Arianna Perea 3H wrote:What happens if the uncertainty is less than h/4pi?


The best scenario would be equal to h/4pi.
by Tiffany_Chen 2K
Sat Oct 19, 2019 11:07 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Unit for Avogadro's Number
Replies: 10
Views: 174

Re: Unit for Avogadro's Number

Avogadro’s number can be towards any unit, as long as it’s represented as 6.022*10^23unit/mol.
by Tiffany_Chen 2K
Sat Oct 19, 2019 9:37 pm
Forum: Properties of Light
Topic: light
Replies: 5
Views: 72

Re: light

Yes, and we can use the speed of light as a basis to compare our calculations to.
by Tiffany_Chen 2K
Sat Oct 19, 2019 9:36 pm
Forum: *Shrodinger Equation
Topic: Wave functions
Replies: 9
Views: 85

Re: Wave functions

Hey just asking what the wave functions represent exactly, and will we have to know actual numeric values for the functions? They represent a mathematical probability of finding electrons. Just know that the (wave function)^2 gives you a positive graph, with peaks being places with high electron de...
by Tiffany_Chen 2K
Sat Oct 19, 2019 9:32 pm
Forum: DeBroglie Equation
Topic: 25.
Replies: 4
Views: 62

Re: 25.

905385366 wrote:I was looking at the solutions manual and the value for h is not planks constant (6.626x10-34) but some other value. Can somebody explain why it is different?


The value given should be h/4pi, which is used in Heisenberg's indeterminacy equation.
by Tiffany_Chen 2K
Thu Oct 10, 2019 11:37 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Photoelectric Effect
Replies: 4
Views: 70

Re: Photoelectric Effect

Intensity of the light relates back to how scientists previously thought light could only behave as a wave, thus the thinking of how increasing the intensity of the light (wave amplitude) would increase the energy needed to eject the electrons. However, this model failed and led to the particle mode...
by Tiffany_Chen 2K
Thu Oct 10, 2019 11:22 am
Forum: Significant Figures
Topic: Do we use molar mass ?
Replies: 8
Views: 79

Re: Do we use molar mass ?

Try to take at least 2 or 3 values past the decimal point when using molar mass of elements. Also try not to round until the final answer to be exact as possible.
by Tiffany_Chen 2K
Thu Oct 10, 2019 11:20 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Using Heisenberg Uncertainty Eq. and finding energy per photon
Replies: 1
Views: 987

Re: Using Heisenberg Uncertainty Eq. and finding energy per photon

You can use the uncertainty in velocity that was found and plug into the E=1/2mv^2 to find the uncertainty in kinetic energy. The units for that would be J/e, so you can then convert to moles by multiplying Avogadro's number.
by Tiffany_Chen 2K
Thu Oct 10, 2019 11:18 am
Forum: Properties of Light
Topic: Hydrogen Atoms for White Light
Replies: 3
Views: 25

Re: Hydrogen Atoms for White Light

Hydrogen only has one electron, as compared to other elements where removal of one electron will lead to electron-electron repulsions (likewise the Rydberg equation only works for Hydrogen). I think Lavelle was describing how you can use other elements if you remove all but one electron.
by Tiffany_Chen 2K
Tue Oct 08, 2019 4:50 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Test 1 [ENDORSED]
Replies: 107
Views: 3252

Re: Test 1 [ENDORSED]

Just make sure to bring a non-graphing calculator!

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