Search found 107 matches
- Wed Mar 11, 2020 9:37 am
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Observed and experimental rate
- Replies: 1
- Views: 193
Re: Observed and experimental rate
Observed rate is the rate that an experiment would find, the experimental rate is the rate we would expect (such as the rate of the slow step). These rates always equal one another but it may not look like they do. When this happens you have to look at the equilibrium constant of the previous faster...
- Wed Mar 11, 2020 9:34 am
- Forum: Administrative Questions and Class Announcements
- Topic: Final
- Replies: 5
- Views: 379
Re: Final
He hasn't specified but from the sounds of it, it may be flexible.
- Tue Mar 10, 2020 5:35 pm
- Forum: Administrative Questions and Class Announcements
- Topic: ENDGAME Review Session
- Replies: 71
- Views: 5464
Re: ENDGAME Review Session
Thank you so much for all your help! I know it may be a lot to ask but I really would appreciate it if you could livestream or record a review session. They help me so much for the exam
- Tue Mar 10, 2020 5:30 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Angular dependence
- Replies: 2
- Views: 248
Re: Angular dependence
Do you mean the lower the activation energy the greater k and the higher the activation energy the smaller k is?
- Tue Mar 10, 2020 5:29 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Situation for Lecture, Discussion, and Final
- Replies: 3
- Views: 331
Re: Situation for Lecture, Discussion, and Final
Also, does anyone know if review sessions will still be held?
- Wed Mar 04, 2020 9:08 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: platinum
- Replies: 2
- Views: 225
Re: platinum
It's because the solid on the anode side is iodine which is not a metal. You need a solid metal to conduct electricity and thus allow for the movement of electrons
- Wed Mar 04, 2020 9:02 pm
- Forum: Balancing Redox Reactions
- Topic: Oxidation number
- Replies: 5
- Views: 310
Re: Oxidation number
This goes back to Chem14A. You can find an elements oxidation level by looking at the periodic table. For examples, group 1 elements like to lose one electron so they are +1, and halogens like to gain one electron so they are typically -1. But when you are dealing with a compound with multiple eleme...
- Wed Mar 04, 2020 8:58 pm
- Forum: Balancing Redox Reactions
- Topic: confusing homework question
- Replies: 4
- Views: 375
Re: confusing homework question
It's because the whole point of your solid electrode is that it can conduct electricity (movement of electrons) which only metals can effectively do. So will you do have a solid, iodine cannot be the electrode because it is not a metal
- Wed Mar 04, 2020 8:57 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Calculating cell potential of an electrode
- Replies: 2
- Views: 225
Re: Calculating cell potential of an electrode
I would always check what is spontaneous because that will help you to confirm the cathode and anode
- Wed Mar 04, 2020 8:55 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: cell diagrams
- Replies: 1
- Views: 150
Re: cell diagrams
If it is part of the reaction yes, because a compound can be both oxidizing and reducing in a concentration cell
- Thu Feb 27, 2020 9:36 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell Diagrams
- Replies: 3
- Views: 231
Re: Cell Diagrams
You include H+ ions if they don't cancel out in the final balanced redox reaction. I don't see why it would not be the same for water as well
- Wed Feb 26, 2020 6:09 pm
- Forum: Balancing Redox Reactions
- Topic: balancing in acidic solutions
- Replies: 4
- Views: 364
Re: balancing in acidic solutions
Use H+ for acidic solutions and OH- for basic :)
- Wed Feb 26, 2020 6:08 pm
- Forum: Balancing Redox Reactions
- Topic: common oxidation numbers
- Replies: 3
- Views: 270
Re: common oxidation numbers
Also consider electronegativity when dealing with multiple group 5, 6 ,7 elements such as oxygen and sulfur. While both prefer gaining two electrons, oxygen is more electronegative so if the two were to react S would likely be +6 rather than -2
- Wed Feb 26, 2020 6:06 pm
- Forum: Balancing Redox Reactions
- Topic: common oxidation numbers
- Replies: 3
- Views: 270
Re: common oxidation numbers
You can reference the periodic table and see what elements have however many electrons and whether they would prefer to gain or lose a specific number of electrons to fulfill the octet rule.
- Wed Feb 26, 2020 6:05 pm
- Forum: Balancing Redox Reactions
- Topic: 6L.3 d)
- Replies: 1
- Views: 199
Re: 6L.3 d)
I believe it because you know the anode is an oxidation. And since you only have O2 and H+ for the anode the only reasonable reaction you can make were oxidation occurs would be having 2H2O --> 4H+ + 2OH- + 4e-. And same for reduction in the cathode. Since you only have OH- and O2 the only reasonabl...
- Wed Feb 26, 2020 10:59 am
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: log or ln
- Replies: 6
- Views: 475
Re: log or ln
You want to use log when dealing with pH and [H+] [OH-] concentrations
- Sat Feb 22, 2020 6:14 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 2976286
Re: Post All Chemistry Jokes Here
What was Avogadro's favorite sport?
Golf, because he always got a mole-in-one!
Golf, because he always got a mole-in-one!
- Sat Feb 22, 2020 6:00 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Textbook progress
- Replies: 3
- Views: 268
Re: Textbook progress
I had the same question, but I believe we may have completed it, or at the very least through 6N (I think we covered 6O too though)
- Sat Feb 22, 2020 5:58 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell diagrams
- Replies: 2
- Views: 191
Re: Cell diagrams
I think you have to assume that both half reactions are interacting with water because water is the only solvent we use in redox reactions in regards to this class
- Sat Feb 22, 2020 5:54 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Using an inert electrode
- Replies: 2
- Views: 190
Re: Using an inert electrode
I was a bit curious about that question too. The best reason I can come up with is that the solid included in the reaction is a product, not a reactant. Therefore it can't serve as the electrode initially because it hasn't been produced yet, so you have to have an inert electrode to initiate the rea...
- Sat Feb 22, 2020 5:52 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 6L.7
- Replies: 1
- Views: 219
Re: 6L.7
Ag(s) doesn't have a positive charge because it is not interacting with another element and therefore cannot be gaining or losing an electron
- Tue Feb 11, 2020 5:09 pm
- Forum: Calculating Work of Expansion
- Topic: delta U for an ideal gas expansion
- Replies: 3
- Views: 208
Re: delta U for an ideal gas expansion
Thanks, if we were told that a gas expansion is isothermal, do you think that we should assume it's an ideal gas if not specified (so that we can use the fact that delta U=0)? Yeah I believe so! But I don't think whether or not it is an ideal gas influences delta U = 0. I'm pretty sure that stateme...
- Tue Feb 11, 2020 5:06 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Change in enthalpy (4C.3)
- Replies: 1
- Views: 174
Re: Change in enthalpy (4C.3)
For constant pressure q = delta H not delta S. So you would use delta S = q/T or delta H / T (you may also be able to use delta S = -n R ln (V2/V1)?
For constant volume you also still use q/T but couldn't use S = -n R ln (V2/V1)
If the system is isothermal use delta S = n C ln (T2/T1)
For constant volume you also still use q/T but couldn't use S = -n R ln (V2/V1)
If the system is isothermal use delta S = n C ln (T2/T1)
- Tue Feb 11, 2020 5:02 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: S = q/T
- Replies: 5
- Views: 312
Re: S = q/T
Yep! If you have changing temperature then you use delta S = n C ln (T2/T1)
- Tue Feb 11, 2020 5:00 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: reversible expansion vs. irreversible free expansion
- Replies: 2
- Views: 349
Re: reversible expansion vs. irreversible free expansion
The only real difference is how the work was done. In an irreversible reaction the expansion occurs instantaneously, where as in a reversible reaction the expansion occurs over infinitely small expansions.
- Tue Feb 11, 2020 4:54 pm
- Forum: Calculating Work of Expansion
- Topic: reversible vs irreversible expansions
- Replies: 2
- Views: 112
Re: reversible vs irreversible expansions
Then it's based on your conditions regarding the system. Is there constant pressure? How about constant temperature? etc.
- Tue Feb 11, 2020 4:51 pm
- Forum: Calculating Work of Expansion
- Topic: delta U for an ideal gas expansion
- Replies: 3
- Views: 208
Re: delta U for an ideal gas expansion
Because isothermal means energy/heat and matter cannot leave or enter the system, therefore the internal energy of the system (delta U) is constant
- Wed Feb 05, 2020 7:36 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: 4F.7
- Replies: 2
- Views: 146
Re: 4F.7
I don't have my homework on me right now but on thing I messed up on was using the wrong R, check your units and make sure everything cancels and you get the correct units. Different R's have different units
- Wed Feb 05, 2020 7:29 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Reversible and Irreversible
- Replies: 3
- Views: 187
Re: Reversible and Irreversible
Because for infinitesimally small expansion, work must be done and equilibrium must be regained. This repeats over and over and this creates a decreasing curve where as irreversible expansion occurs immediately so work occurs instantly only once and equilibrium is only regained once (this creates a ...
- Wed Feb 05, 2020 7:24 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Entropy as three steps
- Replies: 2
- Views: 155
Re: Entropy as three steps
You have to cool it because in order to vaporize you must be at 100C. So first you have to increase the temperature to 100, then vaporize, then reduce the temp back down to 85degrees in order to satisfy the question
- Wed Feb 05, 2020 7:22 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm
- Replies: 7
- Views: 241
Re: Midterm
Not that I am aware of but usually they email the class when they do
- Mon Feb 03, 2020 5:07 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Advice from a Medical Student - Part II [ENDORSED]
- Replies: 298
- Views: 244716
Re: Advice from a Medical Student - Part II [ENDORSED]
Thank you so much for posting a part 2! I was so excited to see it. I was wondering how you found opportunities (work, internships, volunteering, really any experience). As you probably are well aware pre-med programs at UCLA are tough to get into especially as a first year. Do you have any tips or ...
- Thu Jan 30, 2020 9:41 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Enthalpy at Constant Pressure
- Replies: 2
- Views: 124
Re: Enthalpy at Constant Pressure
I believe it just means that its a closed system (like a piston) so while volume may change the pressure will never change because the system can expand and contract
- Thu Jan 30, 2020 9:38 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 4E.7
- Replies: 1
- Views: 160
Re: 4E.7
Thats because you only need to break:
1 O-H (463kJ/mol) and 1 C=C (612kJ/mol)
And you form:
1 C-H -1(412) 1 C-O -1(360kJ/mol) and 1 C-C -1(348kJ/mol)
Add that all up and you get -45kJ/mol
1 O-H (463kJ/mol) and 1 C=C (612kJ/mol)
And you form:
1 C-H -1(412) 1 C-O -1(360kJ/mol) and 1 C-C -1(348kJ/mol)
Add that all up and you get -45kJ/mol
- Tue Jan 28, 2020 10:35 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Enthalpies
- Replies: 4
- Views: 213
Re: Enthalpies
Standard reaction enthalpy is the enthalpy of the P and R at their most stable point. Standard enthalpy of formation is the summation of all the R and P standard reaction enthalpy [I think but I may have messed this up]
- Tue Jan 28, 2020 10:27 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 4E.5, 4E.7
- Replies: 7
- Views: 568
Re: 4E.5, 4E.7
4E.5
3(837)kJ/mol - 6(518)kJ/mol = -597 kJ/mol
4E.7
a)
1(944)kJ/mol + 3(158)kJ/mol - 6(270)kJ/mol = -202kJ/mol
b)
1(463)kJ/mol + 1(612)kJ/mol - 1(412)kJ/mol - 1(360)kJ/mol - 1(348)kJ/mol = -45kJ/mol
c)
1(412)kJ/mol + 1(242)kJ/mol - 1(338)kJ/mol - 1(431)kJ/mol = -115 kJ/mol
Hope this helps!
3(837)kJ/mol - 6(518)kJ/mol = -597 kJ/mol
4E.7
a)
1(944)kJ/mol + 3(158)kJ/mol - 6(270)kJ/mol = -202kJ/mol
b)
1(463)kJ/mol + 1(612)kJ/mol - 1(412)kJ/mol - 1(360)kJ/mol - 1(348)kJ/mol = -45kJ/mol
c)
1(412)kJ/mol + 1(242)kJ/mol - 1(338)kJ/mol - 1(431)kJ/mol = -115 kJ/mol
Hope this helps!
- Mon Jan 27, 2020 10:54 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Homework sections
- Replies: 7
- Views: 275
Re: Homework sections
Actually I think its 4E and maybe 4D, I'm pretty sure Lavelle said we are going backwards
- Wed Jan 22, 2020 3:01 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: state property
- Replies: 5
- Views: 108
Re: state property
Because the total enthalpy you end with is not dependent on the process you took to get to that point (like if I boil a pot of water and tell you it initially was 80 degrees and now its 150 degrees. You would tell me the temperature increased by 70 degrees, you wouldn't need to know how long I boile...
- Wed Jan 22, 2020 2:57 pm
- Forum: Phase Changes & Related Calculations
- Topic: phase transitions
- Replies: 3
- Views: 101
Re: phase transitions
Because the more energy provided the more the substance starts to become the next phase, but this energy must go to maintaining that phase so increasing heat won't increase temperature until the substance has completely achieved the next phase
- Wed Jan 22, 2020 2:49 pm
- Forum: Phase Changes & Related Calculations
- Topic: Heat curve for water
- Replies: 2
- Views: 107
Re: Heat curve for water
Ok so this might be hard to explain without the picture but basically while converting a liquid to a gas, by increasing the heat you don't actually change the temperature of the substance itself because all that extra heat is being used to hold the newly developing phase. Temperature of a substance ...
- Wed Jan 22, 2020 2:43 pm
- Forum: Phase Changes & Related Calculations
- Topic: - and + H values
- Replies: 5
- Views: 141
Re: - and + H values
Because delta H = enthalpy of final(or product) - enthalpy of initial(or reactant). Exothermic reactions release energy, therefore the enthalpy of the product is less than the enthalpy of the reactants. A small number - a bigger number results in a negative value for delta H. And vice versa for endo...
- Wed Jan 22, 2020 2:41 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: approximation
- Replies: 5
- Views: 164
Re: approximation
Basically if K is less than 10^3, meaning that the acid/base barely disassociates, then we can assume that the dissociation affects the initial condition of your acid/base so little that it's insignificant. This means that when calculating your x, or the change in concentration, instead of have your...
- Thu Jan 16, 2020 11:13 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Tips for Test
- Replies: 23
- Views: 1066
Re: Tips for Test
I really like Lydon's (spelt his name wrong) workshop on Monday's in Covel. He gives you a worksheet and eventually the answers and it usually covers most (if not all) the material on the test
- Thu Jan 16, 2020 11:12 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Checking Answers
- Replies: 1
- Views: 123
Re: Checking Answers
If your dealing with acids and bases you can always plug your x back into your equation or convert your answer back into pKa, pH, etc to see if your answer makes sense
- Thu Jan 16, 2020 11:10 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Changes in K and Q
- Replies: 2
- Views: 157
Re: Changes in K and Q
K changes in terms of temperature but not by increasing/decreasing the concentration of your products or reactants. Q just tells you what direction you reaction is moving (forward/reverse) as it approaches equilibrium or K.
- Thu Jan 16, 2020 11:07 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Textbook clarification: weak acids and bases
- Replies: 3
- Views: 112
Re: Textbook clarification: weak acids and bases
So because it is a very weak acid/base it only dissociates by a small concentration. Therefore, since your KA or B is [products] / [reactants] and only a small concentration will dissociate into the product, Ka or B is a very small number divided by a much bigger number which = a very small number :...
- Tue Jan 14, 2020 5:09 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5G 9 HW C VS. D AND E
- Replies: 2
- Views: 156
Re: 5G 9 HW C VS. D AND E
basically the only thing the remains unchanged in the equilibrium constant, and since d is the equilibrium constant and e is the reciprocal, they won't change. And while c does have products/reactants, it lacks the correct exponents so a change in concentration of a reactant or product would result ...
- Sun Jan 12, 2020 8:37 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kp vs Kc usage
- Replies: 5
- Views: 136
Re: Kp vs Kc usage
If it's talking about gases used Kp for partial pressure. If it's talking about aqueous solutions use Kc for concentration.
- Sun Jan 12, 2020 8:36 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Reaction Quotient
- Replies: 11
- Views: 274
Re: Reaction Quotient
It really doesn't have a ton of application in real-life scenarios so you really just need to understand it as it applies to the homework
- Sun Jan 12, 2020 8:34 pm
- Forum: Ideal Gases
- Topic: The Laws
- Replies: 7
- Views: 190
Re: The Laws
So far Lavelle has only really touched on PV=nRT
- Fri Jan 10, 2020 10:05 am
- Forum: Administrative Questions and Class Announcements
- Topic: Discussion 1J with TA Kevin?
- Replies: 2
- Views: 201
Re: Discussion 1J with TA Kevin?
I would check your assigned TA again, there may have been a change the morning of.
- Wed Jan 08, 2020 4:34 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: changing K
- Replies: 4
- Views: 167
Re: changing K
I believe so because both variable uses [products]/[reactants] so I would assume the trends are the same
- Thu Dec 05, 2019 12:29 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Rydberg Equation use
- Replies: 2
- Views: 277
Re: Rydberg Equation use
If you get the right answer no but if you don't get the right answer you may not get as many partial credit points that you would if you did it Lavelle's way
- Thu Dec 05, 2019 12:27 pm
- Forum: Lewis Acids & Bases
- Topic: 6.13
- Replies: 1
- Views: 144
Re: 6.13
I believe it is because it reacts with water?
- Thu Dec 05, 2019 12:25 pm
- Forum: Naming
- Topic: Homework week 9
- Replies: 1
- Views: 95
Re: Homework week 9
I think I'd still with 6A and 6B to be safe and reserve 6C and 6D (maybe a little of 6B) for HW 10
- Thu Dec 05, 2019 12:23 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Listing quantum numbers
- Replies: 3
- Views: 273
Re: Listing quantum numbers
I doubt so but if you know the book lists from - to + it wouldn't hurt to mimic it! Also it may confuse you when looking at what planes (x,y,z) your orbital is in but I don't think he really expects us to know that anyways
- Thu Dec 05, 2019 12:21 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Strength of Acids
- Replies: 2
- Views: 82
Re: Strength of Acids
For Binary acids: Across a period: more polar the HA bond the stronger the acid (weak bonds) Down a group: the weaker the HA bond the stronger the acid (so greater atomic diameter means a weak bond which means a stronger acid) For OxoAcids: The more O bonded to the central atom the stronger the acid...
- Thu Dec 05, 2019 12:18 pm
- Forum: Properties & Structures of Inorganic & Organic Bases
- Topic: Strength of bases
- Replies: 5
- Views: 462
Re: Strength of bases
It's all about how strongly a base will bond with a H+ so I recommend looking at what characteristics (such as EN and size) will affect it
- Thu Dec 05, 2019 12:17 pm
- Forum: Naming
- Topic: amine or ammine
- Replies: 2
- Views: 118
Re: amine or ammine
And while they are different you won't (at least according to my TA) won't be docked an entire point for it
- Sun Dec 01, 2019 10:43 pm
- Forum: General Science Questions
- Topic: Friday Lecture Week 10
- Replies: 3
- Views: 285
Re: Friday Lecture Week 10
Lavelle said in an email that we finish the syllabus Wednesday and start lecture that same day. So I'd assume Friday is also review :)
- Sun Dec 01, 2019 10:42 pm
- Forum: General Science Questions
- Topic: Review in General
- Replies: 4
- Views: 353
Re: Review in General
I first use the outlines Lavelle provides us. Then I do practice problems and for things I forgot I create a quizlet. Then it's just more practice problems in the areas I struggle in
- Sun Dec 01, 2019 10:41 pm
- Forum: Hybridization
- Topic: 2F.7
- Replies: 2
- Views: 173
Re: 2F.7
What I do first is draw the lewis structures. The number of electron dense regions corresponds with the hybridization orbital. For hybridization orbitals it go s, p1, p2, p3, d1, d2, d3, d4, d5 and so on (I believe)
- Sun Dec 01, 2019 10:39 pm
- Forum: General Science Questions
- Topic: test taking nervousness
- Replies: 19
- Views: 991
Re: test taking nervousness
I have the same problem especially in this class. What I'm trying to do is not hyping up the test. Just view as it as an opportunity to prove your knowledge where you will earn as many points as possible as opposed to thinking about the points you may lose.
- Sun Dec 01, 2019 10:06 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Chelating Ligands
- Replies: 2
- Views: 214
Re: Chelating Ligands
I believe by polydenate it means the ligand can form three of more chelated rings
- Mon Nov 25, 2019 6:26 pm
- Forum: Naming
- Topic: Naming in Fundamentals J (acids and bases)
- Replies: 2
- Views: 92
Naming in Fundamentals J (acids and bases)
So I know Lavelle has discussed naming in terms of ligands but do we need to know the names for acids and bases? I only ask because in fundamentals J questions 7 and 9 the questions gives us compounds such as phosphoric acid and phosphate and we are asked to write the balanced chemical equations. Do...
- Sun Nov 24, 2019 2:09 pm
- Forum: Sigma & Pi Bonds
- Topic: Orbital overlap
- Replies: 4
- Views: 297
Re: Orbital overlap
Ramneet Sandhu 3D wrote:A head-on overlap is formed by sigma bonds. Pi bonds are able to form side-to-side overlaps.
Which is why sigma bonds are stronger than pie bonds
- Fri Nov 22, 2019 12:27 pm
- Forum: Student Social/Study Group
- Topic: Study Tips
- Replies: 58
- Views: 4292
Re: Study Tips
Flash Cards (especially with things that require memorization such as molecular shape) and I like making outlines of sections so I know what I need to know and can test myself to find out what I need to focus on (I pull a lot from Lavelle's outlines and my own notes)
- Fri Nov 22, 2019 12:25 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Removing Non-Axis Atoms First
- Replies: 4
- Views: 373
Re: Removing Non-Axis Atoms First
It helps to picture the molecule and look at how many other angles a lone pair will affect in each region
- Wed Nov 20, 2019 12:02 pm
- Forum: Sigma & Pi Bonds
- Topic: Why are sigma bonds stronger than pi bonds?
- Replies: 6
- Views: 363
Re: Why are sigma bonds stronger than pi bonds?
Because in a sigma bond the orbitals can overlap to a greater extent where as with pie bonds they are overlapping indirectly which means they can't overlap as much as sigma bond. The more they over lap, the stronger the pull
- Wed Nov 20, 2019 11:59 am
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: Ion-dipole vs Hydrogen Bonding
- Replies: 2
- Views: 279
Re: Ion-dipole vs Hydrogen Bonding
Yes, ion-dipole interactions are stronger than hydrogen bonds because the ion has a greater charge
- Tue Nov 19, 2019 6:55 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Memorization of Molecular Shapes
- Replies: 1
- Views: 195
Re: Memorization of Molecular Shapes
This isn't quite what you are asking for but I'm memorizing them by imaging the electron density shape then removing atoms and replace them with lone pairs. Then you can picture what the molecule looks like and make it easier to identify its shape. For shapes not consisting of lone pairs, I'm memori...
- Fri Nov 15, 2019 5:05 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR Formula Exceptions
- Replies: 6
- Views: 427
Re: VSEPR Formula Exceptions
I don't believe Lavelle has mentioned any so in terms of his class, I don't think you have to worry
- Fri Nov 15, 2019 5:04 pm
- Forum: Dipole Moments
- Topic: Xenon
- Replies: 4
- Views: 325
Re: Xenon
I think he mentioned something about how since xenon has a low electronegativity, its electrons are more easily distorted by atoms with stronger electronegativity, like fluorine. Exactly! But he was careful to add that this cannot occur with some noble gases, specifically He and Ne, and only at ext...
- Fri Nov 15, 2019 5:02 pm
- Forum: Hybridization
- Topic: 2F.13
- Replies: 2
- Views: 228
Re: 2F.13
If you would please give us the actual question. Then I think more people would be able to help! :)
- Fri Nov 15, 2019 5:00 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Molecular Shape v Electron Geometry
- Replies: 4
- Views: 340
Re: Molecular Shape v Electron Geometry
It basically considering how the number of atoms bonded to the central atom will affect it's shape and how the number of electron dense regions (so bonded atom AND lone pairs) affect the bond angles of the initial shape. These two factors ultimately determine the shape of the molecule
- Fri Nov 15, 2019 4:58 pm
- Forum: Ionic & Covalent Bonds
- Topic: Types of Covalent Bonds
- Replies: 4
- Views: 289
Re: Types of Covalent Bonds
Polar bonds are stronger than non-polar bonds due to their dipole movements. As for coordinate covalent compounds I am not sure
- Fri Nov 08, 2019 10:58 am
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm --> Final Concepts
- Replies: 3
- Views: 222
Re: Midterm --> Final Concepts
The final is cumulative. Even if it wasn't though, a lot of the concepts we are going to learn will likely build off of topics and concepts we learned pre-midterm.
- Fri Nov 08, 2019 9:48 am
- Forum: Lewis Structures
- Topic: Midterm grades
- Replies: 26
- Views: 1348
Re: Midterm grades
Does anyone know the class average on the midterm from last year?
- Wed Nov 06, 2019 10:15 am
- Forum: SI Units, Unit Conversions
- Topic: units for Equations Sheet
- Replies: 2
- Views: 223
Re: units for Equations Sheet
I always like to remind myself of the units for J before doing a calculation because for most, if not all, equations the values you use for mass should be in kilograms, distance should be in meters, and time should be in seconds
- Wed Nov 06, 2019 10:10 am
- Forum: Lewis Structures
- Topic: Line Drawings Outline 3
- Replies: 2
- Views: 144
Re: Line Drawings Outline 3
I think he is referring to the common way in which people write lewis structures for organic compounds where they leave out H atoms because it is implied? I think he just wants use to be comfortable with them and be able to understand what they imply
- Wed Nov 06, 2019 10:07 am
- Forum: Octet Exceptions
- Topic: Expanded Octet
- Replies: 2
- Views: 121
Re: Expanded Octet
Basically you are going to first fulfill the octet rule for all the atoms in the compound. I personally like to add my extra lone pairs to the central atom in order to form the expanded octet first then check the formal charge for each of the atoms. That way you know if you need double or triple bonds
- Fri Nov 01, 2019 1:17 am
- Forum: Ionic & Covalent Bonds
- Topic: Electronegativity
- Replies: 7
- Views: 236
Re: Electronegativity
If Lavelle does give us a question asking us to compare the electronegativity between two elements he will have to provide us a periodic table with the corresponding electronegativity values or the values in general
- Fri Nov 01, 2019 1:15 am
- Forum: Resonance Structures
- Topic: Delocalization vs. Resonance
- Replies: 8
- Views: 2904
Re: Delocalization vs. Resonance
Delocalization just represents a compound's typical behavior of dispersing charges to exterior elementsNatalie Benitez 1C wrote:So in terms of delocalization can we say this occurs when atoms form bonds with each other because in a way they are spreading out their electrons through sharing them?
- Fri Nov 01, 2019 1:13 am
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Bohr Frequency Condition, Electrons
- Replies: 2
- Views: 211
Re: Bohr Frequency Condition, Electrons
Just mean that when an electron drops from a certain energy level to another, that electron releases certain energy or light due to the conservation of energy. That light or energy can be calculated Exactly, which is why this change in energy is often represented by a negative value because it's th...
- Fri Nov 01, 2019 1:12 am
- Forum: *Black Body Radiation
- Topic: Will this concept be tested
- Replies: 8
- Views: 1160
Re: Will this concept be tested
Black bodies won't be tested
- Fri Nov 01, 2019 1:11 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Electron Config for Pd versus Nickel
- Replies: 2
- Views: 981
Re: Electron Config for Pd versus Nickel
I don't know why specifically in this case this occurs, but Lavelle mentioned that the greater the period the more exceptions to our basic rules.
- Thu Oct 24, 2019 1:53 pm
- Forum: DeBroglie Equation
- Topic: Help with the concept of De Broglie's
- Replies: 8
- Views: 832
Re: Help with the concept of De Broglie's
705198479 wrote:what is the formula for wavelength ?
Wavelength = Speed of Light / Frequency
- Thu Oct 24, 2019 1:49 pm
- Forum: Ionic & Covalent Bonds
- Topic: Cation
- Replies: 23
- Views: 1615
Re: Cation
Also cations and anions have positive/negative charges that can affect the orientation of a molecule (think of water) and affect what molecules they may be attracted too.
- Thu Oct 24, 2019 1:47 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ionic v.covalent bonds
- Replies: 7
- Views: 320
Re: Ionic v.covalent bonds
Yep! With that being said you can use the periodic table to determine what bond two elements will likely make
- Thu Oct 24, 2019 1:45 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: HW question
- Replies: 3
- Views: 141
Re: HW question
You're correct! It's actually an error in the textbook. Lavelle has the explanation under the tab "Solution Manual Errors 7th Edition". With that being said, because Δv = 10.0 m.s-1 then answer is actually Δx = 6.7 x 10-37 m
- Wed Oct 23, 2019 7:46 pm
- Forum: Lewis Structures
- Topic: Number of valence electrons
- Replies: 3
- Views: 159
Re: Number of valence electrons
I believe we are covering this either Friday or next week in class!
- Wed Oct 16, 2019 9:19 pm
- Forum: *Shrodinger Equation
- Topic: Electron Spin
- Replies: 2
- Views: 195
Re: Electron Spin
Electron spin is just the direction in which the electron rotates (there are two options: up [+1/2] and down [-1/2]). You can almost think of an electron as the earth rotating around the sun, while the Earth rotates around the sun on its orbit in also rotates on its axis. As for what determines the ...
- Wed Oct 16, 2019 9:10 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Stern and Gerlach
- Replies: 5
- Views: 243
Re: Stern and Gerlach
The stern and Gerlach experiment basically consisted of emitted a beam of the same element through a magnetic field and rather than all the atoms continuing on a straight path, some of the electrons curved upwards and the others downwards. Because the n,l, and m(l) variables were all the same it mea...
- Tue Oct 15, 2019 9:30 pm
- Forum: DeBroglie Equation
- Topic: Calculating Wavelength
- Replies: 5
- Views: 278
Re: Calculating Wavelength
So first you need to calculate the wavelength of both the proton and electrons with there respective mass. The formula you would use in this case would be: wavelength = h (planck's constant) / (mass x velocity). You kind find in the back of the book that the mass of a proton is (1.673 x 10^-27)kg an...
- Tue Oct 15, 2019 9:21 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Rydbergs Equation
- Replies: 3
- Views: 144
Re: Rydbergs Equation
Lavelle also wanted to emphasized how we are subtracting the lower energy level from the higher energy level (such as n=2 - n=1), and how the positive value is expressed as emitted light at unique frequencies, which in emphasized by using his formula.
- Tue Oct 15, 2019 9:17 pm
- Forum: Properties of Light
- Topic: Defraction patters
- Replies: 3
- Views: 263
Re: Defraction patters
Yes both light and electrons have wave like properties. As for defraction, it refers to the wave nature of both electrons and light. Lavelle used the example in class of a filter with holes in it and if you shine a beam of electrons/light through the filter the detector on the other side will detect...
- Wed Oct 09, 2019 11:36 am
- Forum: Photoelectric Effect
- Topic: Quantum
- Replies: 5
- Views: 275
Re: Quantum
It's like Lavelle described in lecture, we assume water flowing from a facet in continuous but when we zoom in and reduce the flow, eventually gaps begin to form because you're not going to have half a water molecule so to be quantized refers to minimal whole values (n = 1,2,3...)
- Wed Oct 09, 2019 11:32 am
- Forum: Balancing Chemical Reactions
- Topic: How to write reactions for tests
- Replies: 5
- Views: 211
Re: How to write reactions for tests
You most likely won't but if you know the state it won't hurt you to include it!
- Wed Oct 09, 2019 11:31 am
- Forum: Properties of Electrons
- Topic: Changes in Orbitals
- Replies: 3
- Views: 75
Re: Changes in Orbitals
I had a similar question. I am assuming that because the orbital changes so does both n and the energy so to calculate the energy difference you would use the formulas provided in today's lecture? (I believe we go over orbitals later in this unit so hopefully it will make more sense then)
- Wed Oct 09, 2019 11:27 am
- Forum: Student Social/Study Group
- Topic: Atomic Spectra: Energy Levels
- Replies: 3
- Views: 144
Atomic Spectra: Energy Levels
So after sitting through Wednesday's lecture regarding the Atomic Spectra, I just was wondering if all questions regarding the topic would be mainly focused on calculating the change of energy when an electron moves from say n=2 to n=1. Or is there another large part I am missing? Thanks guys!