Search found 106 matches
- Wed Mar 11, 2020 1:01 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Catalysts vs. Intermediates
- Replies: 8
- Views: 819
Re: Catalysts vs. Intermediates
Intermediates will not show up in the final product, catalysts will as it is not degraded.
- Wed Mar 11, 2020 1:00 pm
- Forum: Administrative Questions and Class Announcements
- Topic: ENDGAME Review Session
- Replies: 71
- Views: 5404
Re: ENDGAME Review Session
Thank you for an awesome two quarters! Best of luck in your future endeavors :)
- Wed Mar 11, 2020 12:59 pm
- Forum: Student Social/Study Group
- Topic: turning in the final
- Replies: 2
- Views: 313
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?
- Wed Mar 11, 2020 12:58 pm
- Forum: Administrative Questions and Class Announcements
- Topic: test 2 return
- Replies: 6
- Views: 589
Re: test 2 return
Your TA should email you with details!
- Wed Mar 11, 2020 12:55 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Earthquake FINAL REVIEW SESSION
- Replies: 11
- Views: 1033
Re: Earthquake FINAL REVIEW SESSION
Yesss, we love a student-run review session! ^Trustworthy source :)
- Tue Mar 03, 2020 10:25 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Galvanic cells
- Replies: 6
- Views: 454
Re: Galvanic cells
Yes and electrons will flow from anode to cathode! Thus, a positive cell potential for reaction to be spontaneous.
- Tue Mar 03, 2020 10:24 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Ions
- Replies: 2
- Views: 169
Re: Ions
NO3 is generally used as a salt bridge. OH- is added when the redox is in a basic solution (to balance oxygens).
- 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: 239
Re: Cell Potential and Work/Free Energy
Additionally, cell potential would be the maximum energy available to do work.
- Tue Mar 03, 2020 10:21 am
- Forum: Balancing Redox Reactions
- Topic: MnO4-
- Replies: 5
- Views: 354
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.
- Tue Mar 03, 2020 10:20 am
- Forum: Balancing Redox Reactions
- Topic: Oxidation/Reduction
- Replies: 17
- Views: 1068
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).
- Thu Feb 27, 2020 3:46 pm
- Forum: Balancing Redox Reactions
- Topic: OH- in Basic Solutions
- Replies: 6
- Views: 416
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.
- 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: 474
Re: log and ln in Nernst
Either would work, log is typically used as it is more useful in calculating pH.
- 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: 319
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.
- Thu Feb 27, 2020 3:42 pm
- Forum: General Science Questions
- Topic: Test 2
- Replies: 16
- Views: 937
Re: Test 2
Last page of thermochemistry, and all of electrochemistry!
- Thu Feb 27, 2020 3:42 pm
- Forum: Balancing Redox Reactions
- Topic: Oxidation number of Ozone
- Replies: 10
- Views: 673
Re: Oxidation number of Ozone
Oxidation number would be 0 as the overall charge of O3 is 0.
- Thu Feb 20, 2020 8:25 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: converting T to kelvin
- Replies: 46
- Views: 3189
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.
- Thu Feb 20, 2020 8:23 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Anode and Cathode
- Replies: 14
- Views: 919
Re: Anode and Cathode
Anode: site of oxidation, cathode: site of reduction.
- Thu Feb 20, 2020 8:22 pm
- Forum: Balancing Redox Reactions
- Topic: Oxidation number of Ozone
- Replies: 10
- Views: 673
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...
- Thu Feb 20, 2020 5:19 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Adiabatic systems
- Replies: 14
- Views: 769
Re: Adiabatic systems
Yep, as no heat transfer will occur (isolated system).
- 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: 441
Re: Second law of thermodynamics
Entropy in the natural world is always increasing, if the reaction is reversible, entropy would then equal 0.
- Wed Feb 12, 2020 10:20 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: entropy at equilibrium
- Replies: 3
- Views: 229
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)).
- Wed Feb 12, 2020 9:59 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Irreversible Expansion
- Replies: 7
- Views: 419
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...
- Wed Feb 12, 2020 9:56 pm
- Forum: Calculating Work of Expansion
- Topic: Constant pressure in a calorimeter
- Replies: 3
- Views: 272
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.
- Wed Feb 12, 2020 9:37 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Joules or KJ?
- Replies: 14
- Views: 2486
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.
- Wed Feb 12, 2020 9:34 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Spontaneous
- Replies: 23
- Views: 1112
Re: Spontaneous
When deltaG (free energy available to do work) is negative!
- 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: 61
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.
- Sat Feb 08, 2020 10:38 pm
- Forum: Calculating Work of Expansion
- Topic: Irreversible vs. reversible work
- Replies: 2
- Views: 95
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).
- Sat Feb 08, 2020 10:37 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: q rev
- Replies: 9
- Views: 269
Re: q rev
Heat for a reversible equation is qrev. Reversible equations are when the equation is at equilibrium.
- Sat Feb 08, 2020 10:35 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Boltzmann Equation
- Replies: 3
- Views: 80
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.
- Sat Feb 08, 2020 10:34 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Gibbs free energy
- Replies: 4
- Views: 217
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).
- Thu Jan 30, 2020 2:31 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Negative pH
- Replies: 9
- Views: 265
Re: Negative pH
For very strong acids, their pH will be extremely low and can thus create a negative outcome using the log equation.
- Thu Jan 30, 2020 2:28 pm
- Forum: Ideal Gases
- Topic: Inert Gas
- Replies: 12
- Views: 632
Re: Inert Gas
For problems, inert gases will not show up in the equation (thus adding it will not shift equilibrium).
- Thu Jan 30, 2020 2:26 pm
- Forum: Ideal Gases
- Topic: non ideal gases
- Replies: 8
- Views: 413
Re: non ideal gases
Any gas that exhibits intermolecular forces and takes up volume.
- Thu Jan 30, 2020 2:24 pm
- Forum: Calculating Work of Expansion
- Topic: Irreversible vs. Reversible Reactions
- Replies: 6
- Views: 331
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).
- Thu Jan 30, 2020 2:13 pm
- Forum: Phase Changes & Related Calculations
- Topic: Units
- Replies: 16
- Views: 746
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
K=C+273.15
K1-K2=C+273.15-(C+273.15)
K1-K2=C1-C2
- 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: 248
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.
- 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: 196
Re: Pressure changes
No shift in reaction will occur if there are equal moles on both sides.
- 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: 279
Re: Summary of Le Chatelier
Chemical equilibriums will shift accordingly to minimize stressors. In lecture, we covered stressors such as concentration, pressure, and heat.
- Mon Jan 20, 2020 1:30 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5 percent rule
- Replies: 2
- Views: 44
Re: 5 percent rule
Both, if the ionization percentage is less than 5%, this justifies in approximating x as 0.
- Mon Jan 20, 2020 1:30 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: pH sig figs
- Replies: 9
- Views: 387
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
- Mon Jan 20, 2020 12:43 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: X approx check
- Replies: 2
- Views: 173
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.
- 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: 163
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.
- Mon Jan 13, 2020 5:21 pm
- Forum: Ideal Gases
- Topic: Kc and Kp
- Replies: 5
- Views: 234
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).
- Mon Jan 13, 2020 5:19 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Reaction Quotient
- Replies: 11
- Views: 250
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.
- Mon Jan 13, 2020 5:15 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: The Value of Kw
- Replies: 3
- Views: 127
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).
- Mon Jan 13, 2020 5:12 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Autoprotolysis of water endo or exo?
- Replies: 4
- Views: 534
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.
- Mon Jan 06, 2020 6:28 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Calculating Kc
- Replies: 4
- Views: 110
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.
- Mon Jan 06, 2020 6:24 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Writing Equilibrium Constant Labels
- Replies: 4
- Views: 145
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.
- Mon Jan 06, 2020 6:21 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K threshold
- Replies: 2
- Views: 143
Re: K threshold
If K=10^-3 or greater, full calculations using the quadratic equation should be used
- Mon Jan 06, 2020 6:19 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: H3O and OH
- Replies: 5
- Views: 147
Re: H3O and OH
Anything gas or aqueous should be included. Solvents (l) or solids will not be including in calculating Kc/Kp.
- Mon Jan 06, 2020 6:16 pm
- Forum: Ideal Gases
- Topic: ICE Table Variables
- Replies: 6
- Views: 250
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.
- Wed Dec 04, 2019 12:43 pm
- Forum: Administrative Questions and Class Announcements
- Topic: MARSHMALLOW- FINAL REVIEW SESSION [ENDORSED]
- Replies: 115
- Views: 11835
Re: MARSHMALLOW- FINAL REVIEW SESSION [ENDORSED]
For #31 should the name be ...nickel(III) ion? The complex has a 2+ charge.
- 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: 240
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.
- Mon Dec 02, 2019 9:16 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Oxalate and CO3 2- as a polydentate
- Replies: 3
- Views: 295
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).
- Mon Dec 02, 2019 9:11 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Carbonate Ion
- Replies: 2
- Views: 110
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).
- 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: 240
Hydronium concentration = 1.5M, negative ph?
But the book converts the -0.176 ph into a positive number. Why is that?
- Mon Dec 02, 2019 8:52 pm
- Forum: Conjugate Acids & Bases
- Topic: Acids and Bases in solution
- Replies: 1
- Views: 91
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)).
- Mon Dec 02, 2019 8:49 pm
- Forum: Amphoteric Compounds
- Topic: 6A.17
- Replies: 4
- Views: 359
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.
- Mon Nov 25, 2019 8:32 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: ETDA formula - acetate or acetic acid end?
- Replies: 1
- Views: 214
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...
- Mon Nov 25, 2019 12:55 pm
- Forum: Naming
- Topic: Di-, Tri-, Tetra- vs Bis-, Tris-, Tetrakis-
- Replies: 11
- Views: 895
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).
- Mon Nov 25, 2019 12:53 pm
- Forum: Sigma & Pi Bonds
- Topic: sigma and pi bonds
- Replies: 27
- Views: 1555
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).
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.
- Mon Nov 25, 2019 12:49 pm
- Forum: Trends in The Periodic Table
- Topic: Electronegativity
- Replies: 9
- Views: 453
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.
- Mon Nov 25, 2019 12:46 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Forming Chelating Complexes: HW 9C.7
- Replies: 1
- Views: 120
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.
- Mon Nov 18, 2019 2:50 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bonds in VSEPR
- Replies: 11
- Views: 574
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).
- Mon Nov 18, 2019 2:49 pm
- Forum: Bond Lengths & Energies
- Topic: Interaction Potential Energy
- Replies: 2
- Views: 254
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).
- Mon Nov 18, 2019 2:46 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: seesaw
- Replies: 1
- Views: 81
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.
- Mon Nov 18, 2019 2:41 pm
- Forum: Hybridization
- Topic: hybridization 1st number
- Replies: 3
- Views: 248
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).
- 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: 393
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...
- 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: 393
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!
Update: the question asks for the entire molecule of H2SeO4, makes more sense!
- 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: 190
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).
- Thu Nov 14, 2019 10:06 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Test 2
- Replies: 11
- Views: 493
Re: Test 2
Definitely get started on homework from Outline 4, also review the intermolecular forces.
- Thu Nov 14, 2019 10:03 pm
- Forum: Lewis Structures
- Topic: Oxygen
- Replies: 9
- Views: 708
Re: Oxygen
Can you give an example? It depends on the formal charge/molecule.
- Thu Nov 14, 2019 10:02 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 2E21
- Replies: 2
- Views: 94
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).
- Thu Nov 14, 2019 9:53 pm
- Forum: Limiting Reactant Calculations
- Topic: A different way
- Replies: 8
- Views: 803
Re: A different way
I would say that's the most efficient and clearest way to do limiting reactant problems for this class.
- Tue Nov 05, 2019 7:31 pm
- Forum: Electronegativity
- Topic: Homework Question 2D.5 Part a
- Replies: 2
- Views: 91
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.
- Tue Nov 05, 2019 7:28 pm
- Forum: Resonance Structures
- Topic: 2C.5 c
- Replies: 1
- Views: 118
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.
- Tue Nov 05, 2019 5:48 pm
- Forum: Photoelectric Effect
- Topic: binding energy
- Replies: 3
- Views: 366
Re: binding energy
Yes, it refers to threshold energy (energy to remove the e- from the metal surface).
- Tue Nov 05, 2019 5:47 pm
- Forum: Lewis Structures
- Topic: Lewis Structure HClO3
- Replies: 2
- Views: 178
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-).
- Mon Nov 04, 2019 1:13 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Class on Wednesday?
- Replies: 2
- Views: 100
Class on Wednesday?
Do we have lecture on Wednesday?
- Tue Oct 29, 2019 4:46 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Do Midterm Review Sessions Repeat Topics?
- Replies: 4
- Views: 153
Re: Do Midterm Review Sessions Repeat Topics?
There should be a couple more review sessions, including an in-depth one on Sunday.
- Tue Oct 29, 2019 4:43 pm
- Forum: Resonance Structures
- Topic: Bond Order
- Replies: 2
- Views: 90
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.
- Tue Oct 29, 2019 4:39 pm
- Forum: Resonance Structures
- Topic: resonance vs resonance hybrid
- Replies: 2
- Views: 142
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.
- Tue Oct 29, 2019 4:35 pm
- Forum: Ionic & Covalent Bonds
- Topic: 2A.5 (d-block configurations)
- Replies: 4
- Views: 155
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.
- Tue Oct 29, 2019 4:33 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Formal Charge
- Replies: 4
- Views: 197
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).
- Tue Oct 22, 2019 7:23 pm
- Forum: Student Social/Study Group
- Topic: Video Module For New Material
- Replies: 4
- Views: 205
Re: Video Module For New Material
Does he have modules for each unit/focus?
- Tue Oct 22, 2019 7:23 pm
- Forum: Trends in The Periodic Table
- Topic: 1F.1 Atomic Radius Differences
- Replies: 3
- Views: 233
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).
- Tue Oct 22, 2019 7:18 pm
- Forum: Trends in The Periodic Table
- Topic: Effective Nuclear Charge
- Replies: 7
- Views: 201
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.
- Tue Oct 22, 2019 7:15 pm
- Forum: Trends in The Periodic Table
- Topic: Ionization Energies Trend
- Replies: 5
- Views: 185
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...
- Tue Oct 22, 2019 7:13 pm
- Forum: Einstein Equation
- Topic: Lecture Question!
- Replies: 5
- Views: 191
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.
- Sat Oct 19, 2019 11:24 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Uncertainty Value
- Replies: 8
- Views: 206
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.
- Sat Oct 19, 2019 11:07 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Unit for Avogadro's Number
- Replies: 10
- Views: 2146
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.
- Sat Oct 19, 2019 9:37 pm
- Forum: Properties of Light
- Topic: light
- Replies: 5
- Views: 233
Re: light
Yes, and we can use the speed of light as a basis to compare our calculations to.
- Sat Oct 19, 2019 9:36 pm
- Forum: *Shrodinger Equation
- Topic: Wave functions
- Replies: 9
- Views: 306
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...
- Sat Oct 19, 2019 9:32 pm
- Forum: DeBroglie Equation
- Topic: 25.
- Replies: 4
- Views: 169
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.
- Thu Oct 10, 2019 11:37 am
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Photoelectric Effect
- Replies: 4
- Views: 182
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...
- Thu Oct 10, 2019 11:22 am
- Forum: Significant Figures
- Topic: Do we use molar mass ?
- Replies: 8
- Views: 221
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.
- 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: 1042
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.
- Thu Oct 10, 2019 11:18 am
- Forum: Properties of Light
- Topic: Hydrogen Atoms for White Light
- Replies: 3
- Views: 77
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.
- Tue Oct 08, 2019 4:50 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Test 1 [ENDORSED]
- Replies: 107
- Views: 16840
Re: Test 1 [ENDORSED]
Just make sure to bring a non-graphing calculator!