Search found 105 matches
- Sun Mar 14, 2021 2:11 pm
- Forum: Student Social/Study Group
- Topic: How do you deal with burnout?
- Replies: 144
- Views: 13261
Re: How do you deal with burnout?
not doing homework in my bed and forcing myself to wake up early definitely help
- Sun Mar 14, 2021 2:09 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Final Grades
- Replies: 19
- Views: 1465
Re: Final Grades
ok thanks !
- Sun Mar 14, 2021 2:08 pm
- Forum: Student Social/Study Group
- Topic: Note Taking
- Replies: 145
- Views: 15397
Re: Note Taking
I always take hand written notes because I find the muscle memory helps me to remember more equations and important phrases.
- Sun Mar 14, 2021 2:07 pm
- Forum: General Science Questions
- Topic: No Lavelle Chem 14C?
- Replies: 68
- Views: 4342
Re: No Lavelle Chem 14C?
If the lectures are live and recorded does anyone know if we are required to attend?
- Sun Mar 14, 2021 2:05 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Final Grades
- Replies: 19
- Views: 1465
Re: Final Grades
do you guys remember if there is a curve?
- Sun Mar 07, 2021 3:42 pm
- Forum: Student Social/Study Group
- Topic: Final Study Tips!
- Replies: 38
- Views: 2132
Re: Final Study Tips!
I make a packet out of all of the recommended syllabus problems and work through it the week before =
- Sun Mar 07, 2021 3:41 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: what does E notch tell us compared to the E of a cell?
- Replies: 8
- Views: 327
Re: what does E notch tell us compared to the E of a cell?
E˚cell is under standard conditions while Ecell can have varying conditons. Ecell = E˚cell - RT ln(Q)
- Sun Mar 07, 2021 3:40 pm
- Forum: Zero Order Reactions
- Topic: Overall order of the reaction
- Replies: 45
- Views: 1756
Re: Overall order of the reaction
Sum the order of each reactant to get the overall reaction order
- Sun Mar 07, 2021 3:37 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Isolated Systems
- Replies: 15
- Views: 813
Re: Isolated Systems
It is theoretical because it is so difficult to actually create perfect conditions. I think the bomb calorimeter is a real isolated system but I am unsure how close it is to perfect.
- Sun Mar 07, 2021 3:36 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Ecell vs. E˚cell
- Replies: 2
- Views: 213
Re: Ecell vs. E˚cell
You can use the equation Ecell = E˚cell - RT ln(Q) where Q is the concentrations of your substances.
- Sun Feb 28, 2021 2:49 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Meaning of K
- Replies: 55
- Views: 3711
Re: Meaning of K
K can either stand for Kelvin or the equilibrium constant, which should be fairly easy to distinguish. The Boltzman constant is the other k I can think of appearing, but it's lowercase and often has a B subscript. Be careful with kB for the Boltzman constant and KB for an equilibrium constant consid...
- Sun Feb 28, 2021 2:46 pm
- Forum: Student Social/Study Group
- Topic: Final
- Replies: 63
- Views: 3071
Re: Final
I usually make all of the practice problems that Dr. Lavelle puts on the syllabus into a packet, and treat it like an open note midterm to gauge how much I know and what areas I'm lacking in. It also helps with muscle memory of repeated problems on the exam.
- Sun Feb 28, 2021 2:45 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Calculating equilibrium constant
- Replies: 11
- Views: 603
Re: Calculating equilibrium constant
Standard equilibrium constants for the half reactions are always written in a favorable direction. When you combine the half reactions, one usually is flipped to balance the electron transfer on each side, so you will have to flip its sign.
- Sun Feb 28, 2021 2:44 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: n in ∆G = -nFE
- Replies: 80
- Views: 3859
Re: n in ∆G = -nFE
This refers to the moles of electrons that are being transferred in the reaction. To find this, you can write out the half reactions for each molecule, and then make sure you take into account coefficients in the equation if necessary.
- Mon Feb 22, 2021 12:49 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Nernst Equation @ equilibrium
- Replies: 6
- Views: 349
Re: Nernst Equation @ equilibrium
from here if you know E° you can then solve for the equilibrium constant (K) with logK= (nE°)/(0.0592V)
- Mon Feb 22, 2021 12:48 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Nernst Equation @ equilibrium
- Replies: 6
- Views: 349
Re: Nernst Equation @ equilibrium
yes exactly!
- Mon Feb 22, 2021 12:47 pm
- Forum: Student Social/Study Group
- Topic: We made it through Midterm 2!
- Replies: 71
- Views: 3531
Re: We made it through Midterm 2!
congrats on surviving midterm 2
- Mon Feb 22, 2021 12:47 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Spontaneous process
- Replies: 4
- Views: 221
Re: Spontaneous process
A spontaneous reaction always has a -ΔG, and since ΔG = -nFE, when there is a spontaneous reaction there will be a +E value for those negative symbols to cancel out.
- Mon Feb 22, 2021 12:45 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Units for delta G
- Replies: 31
- Views: 1803
Re: Units for delta G
the moles will cancel between n (mol) and F (C/mol) so it will be in kJ
- Mon Feb 22, 2021 12:44 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: n in NFE
- Replies: 64
- Views: 3008
Re: n in NFE
n is the moles of electrons transferred in the reaction.
- Sun Feb 14, 2021 9:30 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Sapling Question 6
- Replies: 5
- Views: 329
Re: Sapling Question 6
For this one you should solve for two ΔS values and sum them.
1. ΔS = nRln(V2/V1)
2. ΔS = Cv ln(T2/T1)
Before adding make sure you multiply the second value by the number of moles in the equation.
1. ΔS = nRln(V2/V1)
2. ΔS = Cv ln(T2/T1)
Before adding make sure you multiply the second value by the number of moles in the equation.
- Sun Feb 14, 2021 9:28 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: What's the difference between delta G and delta G°
- Replies: 7
- Views: 16329
Re: What's the difference between delta G and delta G°
ΔG = ΔG° + -RTln(Q)
The degrees on the delta G means that this is the standardized value.
The degrees on the delta G means that this is the standardized value.
- Sun Feb 14, 2021 9:27 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: G° vs G
- Replies: 30
- Views: 2449
Re: G° vs G
ΔG = ΔG° + -RTln(Q)
The degrees on the delta G means that this is the standardized value.
The degrees on the delta G means that this is the standardized value.
- Sun Feb 14, 2021 9:26 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Sapling week 5/6 #20
- Replies: 14
- Views: 2079
Re: Sapling week 5/6 #20
I had the same problem, just make sure the inequalities are on the bottom and spontaniety is on the top!
- Sun Feb 14, 2021 9:25 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: qrev vs q
- Replies: 21
- Views: 1902
Re: qrev vs q
Qrev is the Q of the reverse reaction, which is used for entropy. They're both heat transfer values.
- Sun Feb 14, 2021 9:24 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Sapling Week 5/6 HW 18
- Replies: 11
- Views: 478
Re: Sapling Week 5/6 HW 18
I am doing all of these steps and am still getting it wrong and don't know why. Can anyone help with C2H2(g) + 2H2(g) --> C2H6 ??
- Sun Feb 07, 2021 11:38 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Cv vs. Cp
- Replies: 4
- Views: 241
Re: Cv vs. Cp
Cv is the specific heat at a constant volume, and Cp is the specific heat at a constant pressure.
Since solids and liquids can't change volumes, we know for all that Cp = Cv.
Since solids and liquids can't change volumes, we know for all that Cp = Cv.
- Sun Feb 07, 2021 11:37 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Delta U
- Replies: 6
- Views: 270
Re: Delta U
ΔU refers to the change in the internal energy of a system.
This is the effect that the heat/work done on the system has on its initial internal energy state.
This is the effect that the heat/work done on the system has on its initial internal energy state.
- Sun Feb 07, 2021 11:35 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Liquids and Solids
- Replies: 7
- Views: 325
Re: Liquids and Solids
Only gasses can change volumes, so for solids and liquids Cp = Cv.
- Sun Feb 07, 2021 11:34 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Lecture wk5, Wednesday Question
- Replies: 2
- Views: 123
Re: Lecture wk5, Wednesday Question
I'm quite positive that the Boltzman Constant is always 1.3806 × 10-23 m^2 kg /s^2 K, it isn't dependent on the molecules you're dealing with.
- Sun Feb 07, 2021 11:31 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Different R Constants
- Replies: 14
- Views: 695
Different R Constants
I am confused on when to use which value for the gas constant: R = 8.3145 J/mol·K. and R= 0.08204 liter·atm/mol·K.
Can anyone help?
Can anyone help?
- Sat Jan 30, 2021 2:10 pm
- Forum: Student Social/Study Group
- Topic: Worried About MT 1 Grades
- Replies: 39
- Views: 1631
Re: Worried About MT 1 Grades
I felt the same way when I BOMBED the first 14A midterm, but it happens to everyone so don't get down on yourself...just study harder every time you think you can do better...because you can. All that matters is you do your best. I believe in you!
- Sat Jan 30, 2021 2:08 pm
- Forum: Phase Changes & Related Calculations
- Topic: reaction shifts
- Replies: 18
- Views: 690
Re: reaction shifts
Increasing temp in an exothermic reaction will shift to the left, meaning it favors reactants.
Increasing temp in an endothermic reaction will shift to the right, meaning it favors products.
Increasing temp in an endothermic reaction will shift to the right, meaning it favors products.
- Sat Jan 30, 2021 2:06 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: How Does Temperature Affect the Equilibrium Constant?
- Replies: 25
- Views: 21864
Re: How Does Temperature Affect the Equilibrium Constant?
In an exothermic reaction:
Increasing temperature will favor the reactants
Decreasing temperature will favor the products
In an endothermic reaction:
Increasing temperature will favor the products
Decreasing temperature will favor the reactants
Increasing temperature will favor the reactants
Decreasing temperature will favor the products
In an endothermic reaction:
Increasing temperature will favor the products
Decreasing temperature will favor the reactants
- Sat Jan 30, 2021 2:04 pm
- Forum: Phase Changes & Related Calculations
- Topic: when to assume x is insignificant
- Replies: 86
- Views: 6417
Re: when to assume x is insignificant
When the equilibrium constant is less than 10^-4 in your ICE table, you can assume that x is negligent in K calculations.
- Sat Jan 30, 2021 2:03 pm
- Forum: Student Social/Study Group
- Topic: Motivation
- Replies: 39
- Views: 1748
Re: Motivation
I fill in every single assignment and test on the syllabus in a planner at the start of the quarter so that my schedule is already written out for me when each week begins. Having a schedule and mapping everything out definitely helped.
- Sun Jan 24, 2021 10:59 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 4.31 text [ENDORSED]
- Replies: 2
- Views: 194
Re: 4.31 text [ENDORSED]
a) to find out whether the reaction is endothermic or exothermic, take the ΔH°f(products) - ΔH°f(reactants). If you get a positive value, it is endothermic, and if negative it is exothermic.
b) now use these conditions to solve for ΔH (unsure about how exactly to do this step).
b) now use these conditions to solve for ΔH (unsure about how exactly to do this step).
- Sun Jan 24, 2021 10:57 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sapling Week 2 Question 3
- Replies: 6
- Views: 397
Re: Sapling Week 2 Question 3
rather than approximating, make an ICE table, and use the Ka value and equation to solve for your x value.
Then, take [H+]/[HA] at equilibrium x 100% for percent ionization.
Then, take [H+]/[HA] at equilibrium x 100% for percent ionization.
- Sun Jan 24, 2021 10:55 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 4D.15 Question
- Replies: 2
- Views: 406
Re: 4D.15 Question
ΔH° = ΔH°f(products) - ΔH°f(reactants).
So for this, combine the ΔH°f for your products and reactants, and subtract for overall reaction enthalpy.
So for this, combine the ΔH°f for your products and reactants, and subtract for overall reaction enthalpy.
- Sun Jan 24, 2021 10:52 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: hw question #5
- Replies: 2
- Views: 169
Re: hw question #5
to solve for OH-, make sure you are using an ICE table to solve for x from the Kb equation.
- Sun Jan 24, 2021 10:51 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bond Enthalpy on Midterm
- Replies: 3
- Views: 96
Re: Bond Enthalpy on Midterm
I am unsure, but in my TA Reid Wilson discussion slides from week 3, there is a table from the textbook (4D.1).
- Sun Jan 24, 2021 10:47 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sapling Acids/base equilibrium #5
- Replies: 2
- Views: 94
Re: Sapling Acids/base equilibrium #5
From the pH, you can solve for pOH because pH + pOH = 14.
From there, you can make an ICE table, and solve for your x with the Kb equation.
From there, you can make an ICE table, and solve for your x with the Kb equation.
- Fri Jan 15, 2021 5:24 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Predominant Species
- Replies: 3
- Views: 231
Re: Predominant Species
The predominant species is just the strongest species present I believe.
- Fri Jan 15, 2021 5:23 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Week 2 HW
- Replies: 8
- Views: 413
Re: Week 2 HW
Once you know the pH you can subtract this from 14 to get the pOH. Then, by doing 10^(-pOH) you will get [OH-]
- Fri Jan 15, 2021 5:21 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Classifying Salts
- Replies: 2
- Views: 62
Re: Classifying Salts
A salt will be basic if it contains the conjugate base of a weak acid
A salt will be acidic if it contains the conjugate acid of a weak base.
A salt will be acidic if it contains the conjugate acid of a weak base.
- Fri Jan 15, 2021 5:19 pm
- Forum: Calculating the pH of Salt Solutions
- Topic: Sapling Week 2 (Question 5)
- Replies: 1
- Views: 147
Re: Sapling Week 2 (Question 5)
I wouldn't approximate, but rather set up an ICE table using another variable as the initial concentration. If you do 10^(-pOH) you will get an x value for your table. Then you can use the x and Kb to solve for an initial concentration, which you can use to set up the percent ionization equation. I ...
- Fri Jan 15, 2021 5:12 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: the different Ks
- Replies: 7
- Views: 3421
Re: the different Ks
Ka = [H+] [A-] / [HA] -> formula for the acidity constant of equilibrium, where HA is an acid and A- is it's conjugate base Kb = [BH+] [OH-] / [B] -> formula for the basicity constant of equilibrium, where B is a base and BH is it's conjugate acid Kw = [H3O+] [OH-] -> this is the formula for equilib...
- Sun Jan 10, 2021 1:59 pm
- Forum: Ideal Gases
- Topic: Inert Gas
- Replies: 20
- Views: 571
Re: Inert Gas
An inert gas would be one that does not affect the outcome of the reaction. For instance, if you added Cl2 to a reaction that does not involve Cl2 and will not react with it, the same exact concentration of CL2 would be in the reactants as well as the products, only changing the volume and thus the ...
- Sun Jan 10, 2021 1:57 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: I in ICE Chart
- Replies: 11
- Views: 422
Re: I in ICE Chart
If you are given the initial concentration for products, then the reactants could be zero for initial concentration if you are asked to find the concentration of the reactants.
- Sun Jan 10, 2021 1:55 pm
- Forum: Ideal Gases
- Topic: Kc vs Kp
- Replies: 109
- Views: 4414
Re: Kc vs Kp
When the problem contains all gases, you can use Kp if the pressure measurements are given. If you are given measurements for concentration rather than pressure, however, it is okay to use Kc.
- Wed Jan 06, 2021 4:02 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: names for reaction quotient Q
- Replies: 19
- Views: 497
Re: names for reaction quotient Q
They can all be calculated in the same way as you would calculate K with products over reactants. The difference between them is that Q is general, Qc is concentration specific, and Qp is partial pressure specific. Just as is with K, Kp, Kc. To calculate Qp or Qc, you would need to use the appropria...
- Wed Jan 06, 2021 3:59 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Lecture 2 Ex) 1.5mol PCl5
- Replies: 2
- Views: 123
Lecture 2 Ex) 1.5mol PCl5
"1.50 mol PCl5 is placed in a 500ml reaction vessel and decomposes at 250°C to form PCL3 and CL2. Kc= 1.80, all 3 compounds are gases at 250°C." Lavelle ended the second lecture today with this example and I have been trying to solve it, but am stuck on if I should be calculating Qc or Qp,...
- Wed Dec 16, 2020 2:37 pm
- Forum: Student Social/Study Group
- Topic: Grades
- Replies: 29
- Views: 1186
Re: Grades
Grades are saturday for the Final I believe! I would assume quarter grades would follow soon after.
- Wed Dec 16, 2020 2:36 pm
- Forum: Student Social/Study Group
- Topic: 14B Groupme
- Replies: 12
- Views: 745
14B Groupme
Does anyone know if there is a Groupme for 14B next quarter yet? I was thinking that would be a good way to stay on top of chem and study/review so that I don't forget everything before 14B starts.
- Wed Dec 16, 2020 2:34 pm
- Forum: Lewis Acids & Bases
- Topic: Acids & Bases
- Replies: 9
- Views: 746
Re: Acids & Bases
A Bronstead Acid, or just an acid, is a species that can donate a proton. A Lewis Acid is a species that accepts an electron pair.
A Bronstead Base, or just a base, is a species that accepts a proton. A Lewis Base is one that donates an electron pair.
A Bronstead Base, or just a base, is a species that accepts a proton. A Lewis Base is one that donates an electron pair.
- Wed Dec 16, 2020 2:32 pm
- Forum: Student Social/Study Group
- Topic: Anxiety
- Replies: 109
- Views: 6971
Re: Anxiety
Make some tea and tidy up your room! Or change study locations every so often. Keeping a fresh scenery is important especially when you're stuck at home.
- Sun Dec 06, 2020 3:25 pm
- Forum: Naming
- Topic: Prefixes for parts outside of Coordination Compound
- Replies: 7
- Views: 350
Re: Prefixes for parts outside of Coordination Compound
I believe it is that it would be "dichloride" if the two chlorides were binding to the same central atom, but since they are not inside the brackets and thus not both binding to the same central atom these are just referred to as "chloride".
- Sun Dec 06, 2020 3:22 pm
- Forum: Bronsted Acids & Bases
- Topic: bronsted vs. lewis acid
- Replies: 10
- Views: 383
Re: bronsted vs. lewis acid
Bronsted is concerned with proton presence/movement, and Lewis is concerned with electron presence/movement. I have found it helpful to remember that every Bronsted Base is a Lewis Base and every Bronsted Acid is a Lewis Acid, but these trends DONT work in reverse.
- Sun Dec 06, 2020 3:17 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone Pair Locations
- Replies: 6
- Views: 407
Re: Lone Pair Locations
Lone pairs have significant stronger repulsion strength, so they occupy a larger region of electron density as they push down on other surrounding bonds to push away from themselves and thus the other bonds become closer together, reducing bond angles and forming a bent shape.
- Sun Dec 06, 2020 3:10 pm
- Forum: Lewis Acids & Bases
- Topic: lewis vs bronsted
- Replies: 8
- Views: 562
Re: lewis vs bronsted
Bronsted defines based on proton characteristics and movement, while Lewis focuses on electron movement and characteristic.
- Sun Nov 29, 2020 11:59 pm
- Forum: Resonance Structures
- Topic: Stable Resonance Structures
- Replies: 4
- Views: 310
Re: Stable Resonance Structures
I know that for resonance structures you must determine which has the most stable formal charge, to ensure that this is the most stable atom. I am not sure of what else.
- Sun Nov 29, 2020 11:58 pm
- Forum: Bond Lengths & Energies
- Topic: London Dispersion Forces
- Replies: 5
- Views: 323
Re: London Dispersion Forces
Yes, more bonds would make London Dispersion Forces stronger, because a heavier atom with more bonds will have electrons extending further from the nucleus with a weaker connection, so they can temporarily form dipole connections.
- Sun Nov 29, 2020 11:55 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Rings and cyclic structures
- Replies: 2
- Views: 111
Re: Rings and cyclic structures
A ring or cyclic structure is a combination of the resonance structure arrangements of double or triple bonds in a circular formation (C6H6 for example). I hope that helps!
- Sun Nov 29, 2020 11:53 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: Sigma and Pi Bonds
- Replies: 33
- Views: 1581
Re: Sigma and Pi Bonds
I don't believe there is a specific order in which these bonds need to be numbered, however one must be sigma and any remaining must be pi bonds.
- Sun Nov 29, 2020 11:49 pm
- Forum: Octet Exceptions
- Topic: Which Elements have Expanded Octets
- Replies: 4
- Views: 351
Re: Which Elements have Expanded Octets
Do you know if we will need to know only specific ones or the trick to determine the elements with expanded octets for the final exam? Because I am still unsure how to determine this.
- Sun Nov 22, 2020 9:01 pm
- Forum: Bond Lengths & Energies
- Topic: Melting Point
- Replies: 12
- Views: 589
Re: Melting Point
Melting points increase as the intermolecular strength of the atom increases. The more forces acting upon the nucleus to hold the atom together, the more energy required to break these.
- Sun Nov 22, 2020 8:55 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Molecular Shape of Large Molecules
- Replies: 3
- Views: 68
Re: Molecular Shape of Large Molecules
To find the shape with more than one central atom, separate the large molecule into pieces by each of the central atoms. Then, after determining the shape of each portion, you combine these to describe the overall shape of the molecule.
I hope that helps !
I hope that helps !
- Sun Nov 22, 2020 8:52 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone Pair E-
- Replies: 47
- Views: 1819
Re: Lone Pair E-
Yes, each lone pair counts as its own region of electron density.
- Sun Nov 22, 2020 8:51 pm
- Forum: Bond Lengths & Energies
- Topic: Higher Melting Point
- Replies: 28
- Views: 2527
Re: Higher Melting Point
It has a higher melting point because it has more electrons, making it a larger molecule with more electronegative forces acting upon it, making it more difficult to break the bonds.
- Sun Nov 22, 2020 8:50 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Incorrect Lewis Structure
- Replies: 3
- Views: 220
Re: Incorrect Lewis Structure
I'm pretty sure that it's because the number of regions of electron densities doesn't change when you draw different resonance structures. I am also confused by this because in the SO3 ^2- example in lecture, one structure had all single bonds and 4 regions of e- density, while the other structure ...
- Sun Nov 22, 2020 8:47 pm
- Forum: Lewis Structures
- Topic: Electron Density
- Replies: 14
- Views: 605
Re: Electron Density
Electron density refers to the probability that an atom would be found in any given region of an orbital. And to answer your second question, I believe that any area where an electron could be found would be considered a region of electron density. Does electron density also contribute to the polar...
- Sun Nov 22, 2020 8:29 pm
- Forum: Student Social/Study Group
- Topic: Big Sad: Midterm 2
- Replies: 86
- Views: 5472
Re: Big Sad: Midterm 2
I totally feel you. I thought I had the first midterm in the bag....and i definitely did not.
Also felt like I had concepts for this midterm down and thought it was easier than the last... but I'm praying that the same thing doesn't happen. Scared for my grade.
Also felt like I had concepts for this midterm down and thought it was easier than the last... but I'm praying that the same thing doesn't happen. Scared for my grade.
- Sun Nov 22, 2020 8:27 pm
- Forum: Hybridization
- Topic: Shape of Hybrid Orbital
- Replies: 5
- Views: 380
Re: Shape of Hybrid Orbital
sp orbitals have a linear shape
sp2 orbitals have a trigonal planer shape
sp3 orbitals have a tetrahedral shape
sp3d orbitals have a trigonal bi- pyramidal shape
sp3d2 orbitals have octahedral or square bi-pyramid shape
Hope this helps!
sp2 orbitals have a trigonal planer shape
sp3 orbitals have a tetrahedral shape
sp3d orbitals have a trigonal bi- pyramidal shape
sp3d2 orbitals have octahedral or square bi-pyramid shape
Hope this helps!
- Sun Nov 22, 2020 8:24 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Extra Credit
- Replies: 11
- Views: 608
Extra Credit
Are there any extra credit opportunities offered for this course?
I am concerned since we cannot make up Chemistry Community posts if we miss the hard midnight deadline, and because the midterms have been more difficult than I had expected.
I am concerned since we cannot make up Chemistry Community posts if we miss the hard midnight deadline, and because the midterms have been more difficult than I had expected.
- Sun Nov 22, 2020 8:22 pm
- Forum: Student Social/Study Group
- Topic: post midterm 2
- Replies: 27
- Views: 1097
Re: post midterm 2
I thought this midterm was much easier than the last...however I thought the first midterm was fairly doable ... and really did not do well.
Does anyone know when the grades will be released?
Does anyone know when the grades will be released?
- Sun Nov 22, 2020 8:12 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Linear Strucutres
- Replies: 6
- Views: 300
Re: Linear Strucutres
Linear structures should have bonds of 180 degrees
- Sun Nov 22, 2020 8:11 pm
- Forum: General Science Questions
- Topic: # of chem posts
- Replies: 27
- Views: 1685
Re: # of chem posts
jasmineculilap_2J wrote:You need 5 posts per week, so 35 posts are needed.
Do general questions and jokes count? Or strictly chemistry material?
- Sun Nov 22, 2020 8:10 pm
- Forum: General Science Questions
- Topic: # of chem posts
- Replies: 27
- Views: 1685
Re: # of chem posts
Summer_Corona 3F wrote:By this Sunday you should have 35 posts.
If we missed a week can we make extra posts in the next week to make up for it?
- Sun Nov 22, 2020 8:08 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: shape, structure
- Replies: 4
- Views: 143
Re: shape, structure
I am not really sure...but what may help is to know the structures that go with different VSEPR notations...because if molecules have the same VSEPR structure they have the same shape.
Ex: CH4 and CCl4 are both notated as AX4...which always has a tetrahedral shape.
I hope that helps somewhat !
Ex: CH4 and CCl4 are both notated as AX4...which always has a tetrahedral shape.
I hope that helps somewhat !
- Sun Nov 22, 2020 8:05 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3049881
Re: Post All Chemistry Jokes Here
Why do chemists like nitrates so much?
They're cheaper than day rates!
They're cheaper than day rates!
- Sun Nov 22, 2020 8:05 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3049881
Re: Post All Chemistry Jokes Here
What's the dullest element? Bohrium!
- Sun Nov 22, 2020 8:04 pm
- Forum: Sigma & Pi Bonds
- Topic: Pi bonds and Sigma bonds
- Replies: 3
- Views: 245
Re: Pi bonds and Sigma bonds
I don't exactly know the theory but... sigma bond: when 2 orbitals with 1 electron each interact end to end ... that is on their internuclear axes. these bonds are also cylindrically symmetric. pi bond: when 2 orbitals with 1 electron each interact side to side. These also occur in any case where th...
- Sun Nov 22, 2020 7:56 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: polarity of trans-dichlorethene
- Replies: 4
- Views: 154
Re: polarity of trans-dichlorethene
Yes, however since the Chlorines are on opposite sides the dipole moments cancel in terms of direction. It is different for cis-dichlorethene because the Chlorines are on the same side, so their dipole moments do not cancel. Hope that helps !!
- Sun Nov 22, 2020 7:53 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Thanksgiving
- Replies: 26
- Views: 1158
Re: Thanksgiving
I believe we will still have them seeing as they are pre recorded.
Also will there be discussions on thursday or friday?
Also will there be discussions on thursday or friday?
- Sun Nov 22, 2020 7:48 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: memorizing molecular shapes
- Replies: 3
- Views: 182
Re: memorizing molecular shapes
Will Dr. Lavell be telling us which ones we should memorize for the final then or should we assume all?
- Sun Nov 22, 2020 7:46 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lecture 20 Example 2
- Replies: 1
- Views: 92
Lecture 20 Example 2
I am confused as to how we are supposed to find the structure of SO3 ^-2 One resonance structure with all single bonds has a lone pair in a 4th region of electron density, however with a double bond there are only 3 regions. Why is it that it is still trigonal pyramidral instead of trigonal planar ....
- Mon Nov 16, 2020 3:35 pm
- Forum: Octet Exceptions
- Topic: Xenon Textbook 2C.11
- Replies: 2
- Views: 126
Xenon Textbook 2C.11
This is probably a simple answer ... but I forget why Xe is allowed to have 12 valence e- in molecules.
What makes Xe and As and other elements like this able to have more than 8 valence e- ?
What makes Xe and As and other elements like this able to have more than 8 valence e- ?
- Sun Nov 15, 2020 6:48 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Textbook 1E.19
- Replies: 1
- Views: 139
Textbook 1E.19
This problem asks for the ground state of listed ions.
I am confused as to why Sb^(3+) = [Kr]4d^10 5s^2, while Sn^(4+) = [Kr]4d^10...is this because 5s would be filled after 4d?
I am confused as to why Sb^(3+) = [Kr]4d^10 5s^2, while Sn^(4+) = [Kr]4d^10...is this because 5s would be filled after 4d?
- Sun Nov 15, 2020 6:43 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Textbook 1E.23
- Replies: 4
- Views: 414
Re: Textbook 1E.23
Hi! Correct me if I'm wrong, but I think you have confused unpaired electrons with valence electrons. Since Ga, Ge, As, Se, and Br are all p-block elements, the number of unpaired electrons for each element respectively is 1,2,3,2,1. If you are looking for the number of valence electrons for each e...
- Sun Nov 15, 2020 6:42 pm
- Forum: Ionic & Covalent Bonds
- Topic: Textbook 2A.23
- Replies: 1
- Views: 67
Textbook 2A.23
"On the basis of the expected charges on the monatomic ions, give the chemical formula of each of the following compounds: (a) magnesium arsenide; (b) indium(III) sulfide; (c) aluminum hydride; (d) hydrogen telluride; (e) bismuth(III) fluoride."
Can someone explain a, b, and e please?
Can someone explain a, b, and e please?
- Sun Nov 15, 2020 6:39 pm
- Forum: Ionic & Covalent Bonds
- Topic: Textbook 2A.5
- Replies: 4
- Views: 190
Textbook 2A.5
Can someone please explain how to find the ground-state e- configurations for Bi^(3+) and P^(3-)?
- Sun Nov 15, 2020 6:34 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Textbook 1E.23
- Replies: 4
- Views: 414
Textbook 1E.23
The question reads: "The elements Ga, Ge, As, Se, and Br lie in the same period in the periodic table. Write the electron configuration expected for the ground-state atoms of these elements and predict how many unpaired electrons, if any, each atom has. Seeing as these all go across the period ...
- Sun Nov 15, 2020 6:28 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Textbook 1E.25
- Replies: 1
- Views: 107
Textbook 1E.25
The textbook question reads: "Give the notation for the valence-shell configuration (including the outermost d-electrons) of (a) the alkali metals; (b) Group 15 elements; (c) Group 5 transition metals; (d) the “coinage” metals (Cu, Ag, Au)." I know how to give a notation for a single atom,...
- Wed Nov 04, 2020 3:02 pm
- Forum: Trends in The Periodic Table
- Topic: Nuclear Charge
- Replies: 6
- Views: 200
Re: Nuclear Charge
The atomic radius decreases because of the increasing amount of protons in the nucleus, which creates a more polar charge and pulls electrons closer to the nucleus in their orbit due to increased stability.
- Wed Nov 04, 2020 3:00 pm
- Forum: Lewis Structures
- Topic: Coordinate Covalent Bonds & Lewis Acid-base Reactions
- Replies: 6
- Views: 373
Re: Coordinate Covalent Bonds & Lewis Acid-base Reactions
I know that a Lewis Acid is an atom that can accept a pair of electrons, and a Lewis Base is an atom that can donate a pair of electrons. For instance, F + BF3 --> BF4 is a Lewis Acid-Lewis Base reaction, creating an acid-base adduct. I am unsure if we need to label these concepts in our Lewis Struc...
- Wed Nov 04, 2020 2:54 pm
- Forum: Ionic & Covalent Bonds
- Topic: Electron spin in bonds
- Replies: 8
- Views: 412
Re: Electron spin in bonds
Forgive me if I am wrong, but isn't spin a constant property of the electron or am I completely missing something. I believe youre right in that it is a constant property of an electron...meaning it always has some sort of spin. I think this spin can change depending on bonding, but I also think th...
- Wed Nov 04, 2020 2:53 pm
- Forum: Ionic & Covalent Bonds
- Topic: Electron spin in bonds
- Replies: 8
- Views: 412
Re: Electron spin in bonds
I also have a question. If they cannot change spin, then does that inhibit what kinds of atoms are able to bond together? I am actually not sure ... I am also wondering this. I thought this just depended on the kind of bond, so a borrowed or shared electron would fall into place in terms of spin wi...
- Wed Nov 04, 2020 2:49 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Lecture O Formal Charge Ex
- Replies: 4
- Views: 293
Lecture O Formal Charge Ex
In lecture when Prof. Lavell was calculating the individual formal charges of S and O in SO4 I was very confused by the FC of the Oxygen in the molecule.Can someone explain how he did that ?
- Wed Nov 04, 2020 2:45 pm
- Forum: Resonance Structures
- Topic: Resonance Structures
- Replies: 10
- Views: 390
Re: Resonance Structures
Yes! A resonance structure can be any of the possible structures (ex: In C6H6 there are 2 resonance structures bc of double bond placement. A resonance hybrid is the combination of all of these structures (ex: in C6H6 the diagram with the circle in the middle represents the resonance of those placem...
- Wed Oct 21, 2020 5:12 pm
- Forum: Photoelectric Effect
- Topic: Sapling 2 Problem 3
- Replies: 5
- Views: 92
Sapling 2 Problem 3
Why is it that when we are given an energy of E, frequency of v, and wavelength of λ,
E=100 while λ and v are not altered when applied to 100 photons??
E=100 while λ and v are not altered when applied to 100 photons??