Search found 107 matches
- Mon Mar 15, 2021 2:35 pm
- Forum: General Rate Laws
- Topic: Factors Affecting k
- Replies: 83
- Views: 4543
Re: Factors Affecting k
The rate constant, k, just like the equilibrium constant, K, is affected by a temperature change.
- Mon Mar 15, 2021 2:33 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Reaction Quotient Predictions
- Replies: 6
- Views: 405
Re: Reaction Quotient Predictions
If Q>K, then the reaction will progress towards the reactants since more products formed. If Q<K, the reaction will progress towards the products since there are more reactants present.
- Mon Mar 15, 2021 2:29 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: The Slowest Step
- Replies: 6
- Views: 417
Re: The Slowest Step
The slowest step is typically given to you. If you are given a diagram, the slow step would be the one with the greatest activation energy.
- Mon Mar 15, 2021 2:27 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Saying Thank You to Dr. Lavelle
- Replies: 490
- Views: 513587
Re: Saying Thank You to Dr. Lavelle
Dear Dr. Lavelle,
Thank you for an amazing quarter! I know this has been a challenging year for all of us, but you were able to keep me motivated and engaged. I learned so much from you, which I am forever grateful for. Thanks again for everything, and have a great spring break!
Thank you for an amazing quarter! I know this has been a challenging year for all of us, but you were able to keep me motivated and engaged. I learned so much from you, which I am forever grateful for. Thanks again for everything, and have a great spring break!
- Sat Mar 13, 2021 7:54 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Value of N
- Replies: 24
- Views: 1083
Re: Value of N
n is the number of electrons that are transferred in a redox reaction. Make sure you balance your redox reactions before plugging in a value for n in the Nernst equation.
- Sat Mar 13, 2021 7:48 pm
- Forum: *Enzyme Kinetics
- Topic: Catalyst vs Intermediate
- Replies: 12
- Views: 794
Re: Catalyst vs Intermediate
Intermediates are produced in one step and later used in another step to help the reaction progress. Catalysts, on the other hand, are introduced into reactions to lower the activation energy and speed up the reaction.
- Sat Mar 13, 2021 7:31 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Chemistry Community Posts
- Replies: 10
- Views: 553
Re: Chemistry Community Posts
Our chemistry-related posts will most likely remain here, and I believe that we will still have access to our accounts, which I like since one day, years into the future, I would love to log back in and reminisce about my college days (sounds corny, I know haha).
- Sat Mar 13, 2021 7:24 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Anode and Cathode
- Replies: 25
- Views: 1213
Re: Anode and Cathode
Yes, the anode is where oxidation occurs (loss of electrons), and the cathode is where reduction occurs (gaining of electrons). Thus, the electrons will always flow from the anode to the cathode.
- Sat Mar 13, 2021 7:22 pm
- Forum: Zero Order Reactions
- Topic: zero order
- Replies: 47
- Views: 1769
Re: zero order
For a zero-order reaction, the rate of the reaction is independent of the concentration of the reactants.
- Sun Mar 07, 2021 10:56 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Final Exam Time
- Replies: 47
- Views: 2085
Re: Final Exam Time
The final is on March 14th from 9:30 AM -11 AM.
- Sun Mar 07, 2021 10:54 pm
- Forum: General Rate Laws
- Topic: Intermediates
- Replies: 17
- Views: 1444
Re: Intermediates
Intermediates cannot be in the rate law because they are produced in one reaction and then used up in another reaction. Thus, when looking for the reaction's overall rate, the intermediates ending up canceling each other out since they are on opposite sides.
- Sun Mar 07, 2021 10:46 pm
- Forum: Zero Order Reactions
- Topic: When to use each order
- Replies: 19
- Views: 1068
Re: When to use each order
When the plot of [A] vs. time is linear, then it is zero-order. When the plot of ln[A] vs. time is linear, then it is first-order. When the plot 1/[A] vs. time is linear, then it is second-order.
- Sun Mar 07, 2021 10:43 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K
- Replies: 33
- Views: 1249
Re: K
Kc is the equilibrium constant for molar concentrations, whereas K is a more general equilibrium constant.
- Sun Mar 07, 2021 10:41 pm
- Forum: Ideal Gases
- Topic: gas constant R
- Replies: 18
- Views: 1590
Re: gas constant R
As long as the units cancel and you end up with the correct unites you are looking for, then it does not matter.
- Sun Feb 28, 2021 11:14 pm
- Forum: Ideal Gases
- Topic: K and Q
- Replies: 57
- Views: 3068
Re: K and Q
Q is the reaction quotient, which is the ratio of products to reactants that are not at equilibrium. In contrast, K is the equilibrium constant, which is also the ratio of products to reactants, but they have already reached equilibrium.
- Sun Feb 28, 2021 11:11 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: n in ∆G = -nFE
- Replies: 80
- Views: 3816
Re: n in ∆G = -nFE
n is the number of moles of electrons that are being transferred after balancing the redox reaction.
- Sun Feb 28, 2021 11:08 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: Molar Entropy
- Replies: 10
- Views: 1045
Re: Molar Entropy
The higher the atomic number, the greater the number of microstates, which increases the disorder.
- Sun Feb 28, 2021 11:06 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: work
- Replies: 21
- Views: 869
Re: work
When work is done on the system, the work is positive, but when the system does work, the work is negative.
- Sun Feb 28, 2021 11:03 pm
- Forum: *Electrophiles
- Topic: Anode vs Cathode
- Replies: 16
- Views: 1380
Re: Anode vs Cathode
The anode is where oxidation occurs (releasing electrons), whereas the cathode is where reduction occurs (the gaining of electrons). I don't really know of a mnemonic that could help you easily differentiate between the two.
- Sun Feb 21, 2021 8:07 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Q and K
- Replies: 40
- Views: 2635
Re: Q and K
If Q>K, then there are more products present than is needed for equilibrium; thus, the reaction will proceed to the reactants until equilibrium is established. If Q<K, then there are more reactants present than is needed for equilibrium to be established; thus, the reaction will proceed towards the ...
- Sun Feb 21, 2021 8:02 pm
- Forum: Balancing Redox Reactions
- Topic: cool acronym
- Replies: 25
- Views: 1429
Re: cool acronym
I also learned this acronym in AP chem, haha! It honestly is very helpful.
- Sun Feb 21, 2021 7:53 pm
- Forum: Student Social/Study Group
- Topic: Post Midterm 2 De-stressing
- Replies: 92
- Views: 6113
Re: Post Midterm 2 De-stressing
To be honest, I usually just take a nap after a stressful midterm/week. It helps me recharge and be prepared for the next week.
- Sun Feb 21, 2021 7:52 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Hfus
- Replies: 9
- Views: 1089
Re: Hfus
You would use delta H fusion when you are dealing with a phase change from a solid to a liquid.
- Sun Feb 21, 2021 7:50 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Which R Values to use
- Replies: 22
- Views: 8091
Re: Which R Values to use
When you are dealing with the ideal gas law, PV=nRT, you would use 0.08206 since its units are (atm)(L)/(mol)(K). This matches every aspect of the ideal gas law. However, it depends on the units you are given. For instance, one of the R values is 8.314 J/(K)(mol). This is typically used when you are...
- Sun Feb 14, 2021 9:54 pm
- Forum: Calculating Work of Expansion
- Topic: U, q, w
- Replies: 11
- Views: 782
Re: U, q, w
Delta U = q + w, delta U being the change in internal energy, q being the heat added or released from the system, and w is the work the system does. When q = 0, then you are dealing with an isothermal system, meaning delta U = 0 and therefore, q = -w. When the system does not work due to constant vo...
- Sun Feb 14, 2021 9:42 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Adding Equations
- Replies: 16
- Views: 757
Re: Adding Equations
Whenever you are dealing with state properties such as enthalpy and entropy, you can add every process and calculation conducted. This is because it does not matter what path the system undertook. All we care about is the final and initial states.
- Sun Feb 14, 2021 9:40 pm
- Forum: Administrative Questions and Class Announcements
- Topic: cc update
- Replies: 23
- Views: 1079
Re: cc update
Dr. Lavelle usually updates them after every midterm, so the chem community posts will most likely be updated soon since our 2nd midterm is coming up.
- Sun Feb 14, 2021 9:38 pm
- Forum: Calculating Work of Expansion
- Topic: negative vs positive work
- Replies: 21
- Views: 892
Re: negative vs positive work
When the system is compressed, work is positive, but when the system expands, work is negative since it is doing work by pushing against external pressure.
- Sun Feb 14, 2021 9:33 pm
- Forum: Student Social/Study Group
- Topic: Fav Shows of the Moment
- Replies: 115
- Views: 26872
Re: Fav Shows of the Moment
Attack on Titan and Jujutsu Kaisen! Highly recommend both!
- Sun Feb 07, 2021 3:39 pm
- Forum: Phase Changes & Related Calculations
- Topic: H and q
- Replies: 47
- Views: 1534
Re: H and q
Heat, which is not a state function, is denoted by q, while enthalpy, which is a change in heat at constant pressure, is a state function, and thus, it is denoted by delta H.
- Sun Feb 07, 2021 3:36 pm
- Forum: Phase Changes & Related Calculations
- Topic: Endothermic v. Exothermic
- Replies: 139
- Views: 10309
Re: Endothermic v. Exothermic
Exothermic reactions are a release in heat and, thus, they have a negative value associated with them. An absorption in energy/heat is an endothermic process, and, therefore, it will always be positive.
- Sun Feb 07, 2021 3:31 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Chem Community Grade Error
- Replies: 15
- Views: 622
Re: Chem Community Grade Error
Dr. Lavelle included this week in the grading, but don’t worry, once you complete your posts for this week, it will automatically update. As long as you have 50 posts by the end of the quarter, you’ll be fine.
- Sun Feb 07, 2021 3:26 pm
- Forum: Phase Changes & Related Calculations
- Topic: Vapor vs gas
- Replies: 121
- Views: 8944
Re: Vapor vs gas
Vapor and gas are the same thing.
- Sun Feb 07, 2021 3:26 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Can heat capacities be negative?
- Replies: 52
- Views: 13523
Re: Can heat capacities be negative?
Heat capacity cannot be negative because it is the amount of energy required to raise a substance's temperature by 1 degree Celsius.
- Sun Jan 31, 2021 11:19 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Taking the Anti-Log
- Replies: 37
- Views: 2441
Re: Taking the Anti-Log
To go from pKa or pKb to Ka or Kb, you would do 10^-(pKa or pKb).
- Sun Jan 31, 2021 11:17 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Water as a Reactant
- Replies: 9
- Views: 355
Re: Water as a Reactant
Just like everyone has been saying, you would assume it is a liquid unless stated otherwise. Also, since liquid water is in large excess in a reaction, it is disregarded from the equilibrium constant.
- Sun Jan 31, 2021 11:14 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: pKa and conjugate base
- Replies: 4
- Views: 274
Re: pKa and conjugate base
The larger the pKa, the weaker the acid and the weaker the acid, the stronger is its conjugate base.
- Sun Jan 31, 2021 11:11 pm
- Forum: Ideal Gases
- Topic: Exo vs Endothermic
- Replies: 40
- Views: 2260
Re: Exo vs Endothermic
Endothermic is when heat is absorbed, so there is sufficient energy to break the bonds within a molecule. Exothermic, on the other hand, is when energy is released, which typically occurs when bonds are being formed. You would know it is exothermic for this reaction because it appears to be a combus...
- Sun Jan 31, 2021 11:04 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: is HClO3 weak or strong? [ENDORSED]
- Replies: 49
- Views: 3974
Re: is HClO3 weak or strong? [ENDORSED]
HClO3 is a strong acid.
- Sun Jan 24, 2021 9:35 pm
- Forum: Ideal Gases
- Topic: Bars to atm [ENDORSED]
- Replies: 41
- Views: 1705
Re: Bars to atm [ENDORSED]
Dr. Lavelle said that we should assume 1 bar=1 atm since they are relatively close in amount to be considered equivalent in our calculations.
- Sun Jan 24, 2021 9:33 pm
- Forum: Student Social/Study Group
- Topic: Study Strategies
- Replies: 31
- Views: 1083
Re: Study Strategies
Do as many practice problems as you can, read the textbook, review your notes, and attend review sessions. Hope this helps :)
- Sun Jan 24, 2021 9:30 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: When to use ICE box
- Replies: 23
- Views: 775
Re: When to use ICE box
You would use the ICE box when you are given an initial concentration of a weak acid or base, and you are trying to calculate the equilibrium concentration of both the products and the reactants.
- Sun Jan 24, 2021 9:28 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sapling #2 Week 2
- Replies: 5
- Views: 223
Re: Sapling #2 Week 2
You have to check if and see if it truly is negligible or not. The way you do that is by calculating the percentage protanated or deprotonated. If the percentage is less than 5%, it is fine to disregard the x in the denominator in your calculation. However, if it is greater than 5%, you will have to...
- Sun Jan 24, 2021 9:23 pm
- Forum: Phase Changes & Related Calculations
- Topic: Steam
- Replies: 33
- Views: 1802
Re: Steam
Steam burns at 100 degrees Celcius are more severe than water burns at 100 degrees Celcius because you have to consider the amount of energy required for the phase change. Thus, when steam begins to condense when it touches a colder surface, you have to add the energy released from the phase change ...
- Sun Jan 17, 2021 11:11 pm
- Forum: Phase Changes & Related Calculations
- Topic: Determining Stronger Acids
- Replies: 18
- Views: 657
Re: Determining Stronger Acids
The smaller the pKa, the stronger the acid. Also, the greater the Ka, the stronger the acid.
- Sun Jan 17, 2021 11:09 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Q and K
- Replies: 46
- Views: 1561
Re: Q and K
Q is the reaction quotient, which is essentially the ratio of products to reactants of a reaction that is not at equilibrium. K, on the other hand, is the equilibrium constant, which is the ratio of products to reactants at equilibrium. You can relate Q to K to find out which direction the reaction ...
- Sun Jan 17, 2021 11:06 pm
- Forum: Student Social/Study Group
- Topic: Chemistry Community Posts
- Replies: 22
- Views: 849
Re: Chemistry Community Posts
You have to complete 5 posts every week for a total of 50 posts by the end of the quarter.
- Sun Jan 17, 2021 11:05 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Units to know
- Replies: 11
- Views: 499
Re: Units to know
You should also know atmospheres and torr (1 atm=760 torr) when dealing with partial pressures.
- Sun Jan 17, 2021 11:02 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Ka vs. Kb
- Replies: 30
- Views: 4914
Re: Ka vs. Kb
Ka is the acidity constant, whereas Kb is the basicity constant. They are both solved in the same way: [P]/[R]. You would use them whenever a question asks for you to solve for the equilibrium constant or you are trying to calculate the equilibrium concentration of a reactant or product that is pres...
- Sun Jan 17, 2021 10:58 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: C in ICE Box
- Replies: 19
- Views: 648
Re: C in ICE Box
Whatever is reacting to form something else will be the negative one. That is because as the reaction proceeds, the reactant's concentration will begin to decrease while the product(s) it is forming will be increasing. That is why it would be positive for products, and for reactants, it would be neg...
- Sun Jan 10, 2021 11:08 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: change in K
- Replies: 22
- Views: 813
Re: change in K
Temperature is the only factor that affects K. For instance, if you are dealing with an endothermic reaction, and you increase the temperature, the system will try to offset this increase in temperature by shifting towards the products. This will cause the product's concentration to increase and, th...
- Sun Jan 10, 2021 11:01 pm
- Forum: Ideal Gases
- Topic: T variable in pv=nrt [ENDORSED]
- Replies: 38
- Views: 1548
Re: T variable in pv=nrt [ENDORSED]
When dealing with the ideal gas law, you must always use kelvin for temperature.
- Sun Jan 10, 2021 10:56 pm
- Forum: Ideal Gases
- Topic: Kc vs Kp
- Replies: 109
- Views: 4376
Re: Kc vs Kp
When you are given the concentration of the reactants and products, you use Kc. However, if you are given the partial pressures of the reactants and products, you would use Kp.
- Sun Jan 10, 2021 10:51 pm
- Forum: Ideal Gases
- Topic: Non-Ideal gases?
- Replies: 26
- Views: 883
Re: Non-Ideal gases?
Pretty sure we will be only dealing with ideal gasses in this course.
- Sun Jan 10, 2021 10:50 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K vs. Q
- Replies: 53
- Views: 1920
Re: K vs. Q
Correct. Whenever you take the ratio of the concentration (or partial pressure) of products over reactants when it is not at equilibrium, you are solving for Q, the reaction quotient. If the reaction is at equilibrium, then the ratio of products to reactants is the equilibrium constant, K.
- Sun Jan 10, 2021 10:46 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: H2O
- Replies: 44
- Views: 1896
Re: H2O
You only include H2O in the equilibrium constant if it is a gas. If it is a solid or a liquid, you do not include it.
- Thu Dec 17, 2020 3:13 am
- Forum: General Science Questions
- Topic: 14B enrollment
- Replies: 9
- Views: 818
Re: 14B enrollment
Yes. Dr. Lavelle has designed this course to flow smoothly, with every new topic covered being built upon the previous topics discussed. Since we ended with an introduction to acids and bases in Chem 14A, I believe we will begin with a more detailed explanation of acids and bases in Chem 14B.
- Thu Dec 17, 2020 3:07 am
- Forum: *Titrations & Titration Calculations
- Topic: Polyprotic Acids and Bases
- Replies: 4
- Views: 3141
Re: Polyprotic Acids and Bases
Polyprotic acids are acids that are able to be deprotonated more than once. For instance, H2SO4: 1) H2SO4 + H2O ----> HSO4^- + H+ 2) HSO4^- + H20 ----> SO4^2- + H+.
- Thu Dec 17, 2020 3:01 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Textbook problem 9C.9
- Replies: 4
- Views: 279
Re: Textbook problem 9C.9
Coordination numbers are the number of ligands that are attached to the central metal cation. These are only for the ligands within the coordination sphere. Since [NiCl4] has 4 ligands attached to the central metal cation, then it has a coordination number of 4. [Ag(NH3)2] has two, thus, it has a co...
- Thu Dec 17, 2020 2:57 am
- Forum: Lewis Acids & Bases
- Topic: Lewis vs Bronsted
- Replies: 20
- Views: 1064
Re: Lewis vs Bronsted
Lewis acids and bases deal with electrons, whereas Bronsted acids and bases deal with protons. A Lewis acid is any atom that can accept a pair of electrons from a lewis base, forming a coordinate covalent bond. A Bronsted acid is a compound that is able to release a proton (H+). A Bronsted base is a...
- Thu Dec 17, 2020 2:54 am
- Forum: General Science Questions
- Topic: Passing Grade
- Replies: 34
- Views: 1863
Re: Passing Grade
50% of all the points you can earn (250/500) would give you a C-, which is considered a passing grade.
- Sun Dec 06, 2020 10:53 pm
- Forum: Bronsted Acids & Bases
- Topic: Strong & Weak Acid
- Replies: 6
- Views: 199
Re: Strong & Weak Acid
The longer the bond, the stronger the acid. This is because longer bonds are weaker in strength, and thus, are easier to deprotonate.
- Sun Dec 06, 2020 10:43 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: Ligands
- Replies: 9
- Views: 460
Re: Ligands
The number of ligands is the number of lewis bases (electron-pair donors) attached to the central metal cation. This would also be the coordination number for the coordination compound.
- Sun Dec 06, 2020 10:39 pm
- Forum: Significant Figures
- Topic: When should I start looking at sig figs?
- Replies: 31
- Views: 1390
Re: When should I start looking at sig figs?
I always do all the calculations first, and then I look for sig figs at the very end. This allows my answer to be as accurate as possible, with very minimal to no rounding error.
- Sun Dec 06, 2020 10:37 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polarity
- Replies: 7
- Views: 204
Re: Polarity
Yes, if the molecule has polar bonds, but the dipole moments cancel, it would be a nonpolar molecule.
- Sun Dec 06, 2020 10:32 pm
- Forum: Student Social/Study Group
- Topic: How are you?
- Replies: 154
- Views: 12367
Re: How are you?
Stressed. Studying for finals and finishing up remaining assignments has been exhausting. I cannot wait for break.
- Sun Nov 29, 2020 11:39 pm
- Forum: Significant Figures
- Topic: 40. versus 40
- Replies: 23
- Views: 1524
Re: 40. versus 40
Correct.
- Sun Nov 29, 2020 11:36 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: Polarity
- Replies: 16
- Views: 716
Re: Polarity
Lone pairs do not automatically make a molecule polar. Only if the lone pairs are located in one particular section of the molecule (thus, they're not canceling each other) will the molecule be polar.
- Sun Nov 29, 2020 11:32 pm
- Forum: Resonance Structures
- Topic: Resonance
- Replies: 11
- Views: 634
Re: Resonance
Certain resonance structures have a more stable formal charge since they are closer to 0. Structures with the least amount of formal charge tend to be the most stable, and thus, they are the resonance structures that contribute the most to the molecular structure.
- Sun Nov 29, 2020 11:14 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: polar v nonpolar molecules
- Replies: 30
- Views: 2312
Re: polar v nonpolar molecules
Polar molecules are molecules that have dipoles that do not cancel. Nonpolar molecules have dipoles that do cancel. Also, if there are differences in electronegativity because the atoms bound to the central atom are not uniform, then it will be a polar molecule.
- Sun Nov 29, 2020 11:11 pm
- Forum: Hybridization
- Topic: Lecture #23
- Replies: 13
- Views: 636
Re: Lecture #23
Yes, since it is a resonance structure, they are delocalized.
- Sun Nov 29, 2020 11:09 pm
- Forum: Student Social/Study Group
- Topic: Tips for Staying Focused
- Replies: 64
- Views: 3576
Re: Tips for Staying Focused
I usually make a plan for the day that I follow. For example, I have to study for chem from time X to time Y, and only after I completed this schedule, will I take a break. I also like to put my phone away, so I don't get distracted if I get a call or a text.
- Sun Nov 22, 2020 5:36 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angles
- Replies: 21
- Views: 662
Re: Bond Angles
Bond angles are not calculated. They are experimentally determined.
- Sun Nov 22, 2020 5:31 pm
- Forum: Bond Lengths & Energies
- Topic: electron repulsion
- Replies: 15
- Views: 741
Re: electron repulsion
Repulsion occurs between lone pairs and bonding pairs. However, the strength of the repulsions are different: lone pair-lone pair repulsion > lone pair-bonding pair repulsions > bonding pair-bonding pair repulsions.
- Sun Nov 22, 2020 5:28 pm
- Forum: Coordinate Covalent Bonds
- Topic: Hydrogen bonds
- Replies: 20
- Views: 1187
Re: Hydrogen bonds
Carbon and Hydrogen have similar electronegativities, and thus, have a small electronegativity difference. However, since Fluorine, Oxygen, and NItrogen are more electronegative than Carbon, there is a greater electronegativity difference. This is why hydrogen bonds are only present in bonds with Ni...
- Sun Nov 22, 2020 5:21 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Thanksgiving
- Replies: 26
- Views: 1148
Re: Thanksgiving
I believe we may still have lectures on our break. We had one during Veterans day, so I don't see why this would be any different.
- Sun Nov 22, 2020 5:18 pm
- Forum: Student Social/Study Group
- Topic: Big Sad: Midterm 2
- Replies: 86
- Views: 5450
Re: Big Sad: Midterm 2
Don't stress about it too much. There is still a lot of time left for you to make up for any bad score. Keep your head up. You got this!
- Sun Nov 15, 2020 8:10 pm
- Forum: Lewis Structures
- Topic: Drawing Lewis Structures on Midterm
- Replies: 31
- Views: 1021
Re: Drawing Lewis Structures on Midterm
When drawing Lewis Structures, you should always draw the most stable and plausible structure, which would be the one with the least amount of formal charge.
- Sun Nov 15, 2020 8:08 pm
- Forum: Ionic & Covalent Bonds
- Topic: D orbitals
- Replies: 3
- Views: 156
Re: D orbitals
Since it is an exception, Ag has an electron configuration of [Kr]4d^10 5s^1 (it is more stable to have all the d orbitals paired than having 4 paired orbitals and 1 unpaired orbital). Thus. for Ag^+1, the electron configuration would be [Kr]4d^10 since we are removing an electron from the valence s...
- Sun Nov 15, 2020 7:46 pm
- Forum: General Science Questions
- Topic: Midterm #2
- Replies: 11
- Views: 514
Re: Midterm #2
We will be tested on the material we did not cover in outline 2 and all of the material in outline 3.
- Sun Nov 15, 2020 7:40 pm
- Forum: Lewis Structures
- Topic: Confusions with Expanded Octets in Period 3
- Replies: 2
- Views: 132
Re: Confusions with Expanded Octets in Period 3
Elements in the 3p block can have expanded octets because in the n=3 shell, there are s,p, and d orbitals present (n=3 l=2). The presence of empty d-orbitals allows for expanded octets since they can hold additional electrons.
- Sun Nov 15, 2020 7:35 pm
- Forum: Resonance Structures
- Topic: Formal Charge
- Replies: 11
- Views: 471
Re: Formal Charge
The most stable structure would be the one with the atoms having a formal charge closest to 0. Also, you should always make sure that the most electronegative atom holds the negative formal charge since it is the most capable of holding the electrons. If the most electronegative atom has a + formal ...
- Tue Nov 10, 2020 3:44 am
- Forum: Lewis Structures
- Topic: Central Atom
- Replies: 20
- Views: 621
Re: Central Atom
The least electronegative atom will go in the center.
- Sun Nov 08, 2020 10:14 pm
- Forum: Student Social/Study Group
- Topic: Chemistry Among Us
- Replies: 43
- Views: 2065
Re: Chemistry Among Us
I am not trying to die, so I would help shut off the reactor.
- Sun Nov 08, 2020 10:11 pm
- Forum: Electronegativity
- Topic: Noble Gases
- Replies: 40
- Views: 12532
Re: Noble Gases
No, they are omitted. This is due to noble gases having a full octet. A full octet means that the element or compound is not reactive. If these full octet elements were to add an electron, it would require energy and, thus, the electron affinity for it would be negative.
- Sun Nov 08, 2020 10:06 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Effective Nuclear Charge
- Replies: 2
- Views: 146
Re: Effective Nuclear Charge
As you move across the periodic table, you are increasing in the number of protons in the nucleus. This increase in the number of protons causes the effective nuclear charge to increase since the more protons there are, the greater the pull on the electrons.
- Sun Nov 08, 2020 9:59 pm
- Forum: Student Social/Study Group
- Topic: Mid-quarter Check in
- Replies: 67
- Views: 3163
Re: Mid-quarter Check in
I'm doing alright. A little stressed here and there, and I barely have any time to relax :(. But overall, I am still hanging in there...at least for now.
- Sun Nov 01, 2020 8:18 pm
- Forum: Empirical & Molecular Formulas
- Topic: Empirical formula question
- Replies: 16
- Views: 1308
Re: Empirical formula question
When calculating empirical formulas, you will have to have them as whole numbers. Thus, when calculating empirical formulas, you would have to multiply every single element in a way that gets rid of any fraction.
- Sun Nov 01, 2020 8:14 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Writing Electronic Configurations
- Replies: 8
- Views: 221
Re: Writing Electronic Configurations
It depends on what the question is asking. If the question asks for the long hand electron configuration, you will write every aspect of that element's electron configuration. If it asks for the shorthand, you will write the noble gas that is right above the element you are writing the electron conf...
- Sun Nov 01, 2020 8:10 pm
- Forum: Photoelectric Effect
- Topic: Participation points
- Replies: 16
- Views: 642
Re: Participation points
I believe the TAs check the date and time you make a post. Therefore, to receive all 5 points for a week, you would have to make sure you make 5 posts before midnight every Sunday.
- Sun Nov 01, 2020 8:08 pm
- Forum: DeBroglie Equation
- Topic: Avogadro's Number
- Replies: 21
- Views: 1548
Re: Avogadro's Number
Avogadro's number is 6.022 x 10^23, and you would use it when looking for formula units, atoms, photons, and any particle (just not moles or grams).
- Sun Nov 01, 2020 8:02 pm
- Forum: Properties of Light
- Topic: Is c always the speed of light?
- Replies: 92
- Views: 4931
Re: Is c always the speed of light?
Yes, c will always be the speed of light. It is constant, after all. The reason why it is a constant is due to the inverse relationship between wavelength and frequency. Whenever you double wavelength, you are halving the frequency, and when you multiply these two values together, you will always ob...
- Sun Oct 25, 2020 5:59 pm
- Forum: Student Social/Study Group
- Topic: Midterm Prep
- Replies: 15
- Views: 559
Re: Midterm Prep
I'm not sure about the number of problems in the midterm, but I know how to prep. The best way to prep would be to read from the textbook and do as many practice problems as possible. This will allow you to apply your knowledge and gain practice on how to tackle particular problems. I hope this help...
- Sun Oct 25, 2020 5:55 pm
- Forum: Properties of Light
- Topic: Balmer or Lyman Series
- Replies: 9
- Views: 258
Re: Balmer or Lyman Series
If you are given a wavelength that is less than 400nm, then you would use the Lyman series (n=1) because the Lyman series absorbs or emits energy in the UV region. However, if you are dealing with the visible region, you would use the Balmer series (n=2).
- Sun Oct 25, 2020 5:53 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Electron Density Distribution
- Replies: 8
- Views: 374
Re: Electron Density Distribution
The electron density distribution is the arrangement of electrons within an orbital. It is essentially the probability of finding an electron at a particular position in the (wave function)^2. If you are at a peak or a trough, you will have a high probability of finding an electron. However, if you ...
- Sun Oct 25, 2020 5:47 pm
- Forum: Empirical & Molecular Formulas
- Topic: Dealing with Diatomic Elements
- Replies: 14
- Views: 1299
Re: Dealing with Diatomic Elements
Since it gives you nitrogen by itself, it would be N2, but you would have to convert moles of N2 to N when dealing with empirical formulas.
- Sun Oct 25, 2020 5:43 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Emitting a Photon
- Replies: 9
- Views: 245
Re: Emitting a Photon
Whenever an excited electron falls back down to its ground state, it will emit photons that release energy. This electron can continuously release photons at every energy level until it has reached its ground state, where the electron becomes relaxed.
- Sun Oct 18, 2020 8:33 pm
- Forum: SI Units, Unit Conversions
- Topic: unit conversions
- Replies: 24
- Views: 1151
Re: unit conversions
When doing conversions, I usually use 10^x (x being all real numbers). This simplifies my conversions since I do not have to waste my time writing out the full value.
- Sun Oct 18, 2020 8:29 pm
- Forum: Significant Figures
- Topic: sig fig
- Replies: 20
- Views: 990
Re: sig fig
I usually change my sig figs at the very end to ensure that my calculations are as close to the real value as possible. If you keep rounding midway, your answer begins to deviate from the final actual value.
- Sun Oct 18, 2020 8:25 pm
- Forum: SI Units, Unit Conversions
- Topic: studying tactics
- Replies: 8
- Views: 164
Re: studying tactics
1)Attend as many sessions as possible. This will allow you to get extra practice problems, not in the textbook nor the Chem 14A website. Also, they go over how to do them, so if you are ever stuck, they explain the problems step-by-step. 2) Do as many practice problems as you can. It is common that ...