Search found 102 matches
- Sat Mar 13, 2021 11:05 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing Basic vs. Acidic Reactions
- Replies: 3
- Views: 344
Re: Balancing Basic vs. Acidic Reactions
A tip that I found useful for basic solutions is to find however many Oxygens you need on one side, and add double that many OH- to the same side. Then to balance it, add that number of H2O to the other side. (so for ex, if the left side has 2 oxygens and the right has 1 oxygen, you would add 2 oh- ...
- Sat Mar 13, 2021 10:36 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: porous disk
- Replies: 7
- Views: 434
Re: porous disk
Hi! So basically a porous disc is just a membrane that allows the anions of a cell to transfer directly between solutions, whereas a salt bridge uses a salt. For example, a porous disc allows the direct transference of Cl- ions, while a salt bridge requires NaCl to transfer the Cl-. As far as I can...
- Sat Mar 13, 2021 10:24 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell Diagrams
- Replies: 8
- Views: 432
Re: Cell Diagrams
I believe that as long as the anode is on the left and the cathode is on the right, and the electrodes are on the outsides it should be correct :)
- Sat Mar 13, 2021 10:21 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: porous disk
- Replies: 7
- Views: 434
porous disk
Hi! Can someone please explain the difference between a porous disc and a salt bridge and what differences they have on the cell?
- Sat Mar 13, 2021 9:55 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: tb 6.53
- Replies: 1
- Views: 188
tb 6.53
Can someone explain the textbook q 6.53 part c? I'm confused as to why adding NaOH to the cathode compartment would decrease the cell potential. Is it because the NaOH reacts with some of the Cr+3 making the concentration less?
- Sat Mar 13, 2021 7:11 pm
- Forum: Student Social/Study Group
- Topic: General tips/hints
- Replies: 5
- Views: 384
General tips/hints
Hi! I was just curious as to what topics everyone had a hard time with, and what hints or tips you found that helped you out. Goodluck on all your finals!
- Sun Mar 07, 2021 11:05 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Activation Energy and Enthalpy
- Replies: 4
- Views: 2848
Re: Activation Energy and Enthalpy
I believe this is because enthalpy is a state function and depends on the bonds in products and reactants, whereas activation energy is how much energy is needed for the reaction to occur, which can change. Even with a change in activation energy, the reactants and products remain the same, so the e...
- Sun Mar 07, 2021 10:55 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Determining The Favored Side of an Equilibrium Product
- Replies: 12
- Views: 1266
Re: Determining The Favored Side of an Equilibrium Product
I'm not fully sure if this is what you're asking, but to find the direction of the reaction we have to compare the Q value to K. If Q is bigger than K then it shifts to the left (because it is measured by products/reactants, and a number bigger than K would mean there are more products), and if Q is...
- Sun Mar 07, 2021 10:48 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing redox reactions
- Replies: 5
- Views: 328
Re: Balancing redox reactions
Because it's in a basic environment you can have OH- left over but not H+. You can add OH- to both sides to make the H+ into water and then just have OH- on the other side which is ok because it's in a basic solution!
- Sun Mar 07, 2021 9:21 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell Notation
- Replies: 5
- Views: 433
Re: Cell Notation
I was wondering this too. I read somewhere that as you read it from left to right your eyes move in the direction of electron flow, so I was thinking this might have something to do with it because the electrons move into the aqueous solution to the other aqueous solution. Not sure if this is right ...
- Sun Mar 07, 2021 9:00 pm
- Forum: Student Social/Study Group
- Topic: How do you deal with burnout?
- Replies: 144
- Views: 16824
Re: How do you deal with burnout?
It has been extremely difficult for me to stay motivated as well, which is pretty normal during times like these. I've noticed something that helps me is not being too hard on myself when I don't get as much work done as I hoped, because when I am it discourages me from working again and puts me in ...
- Sun Feb 28, 2021 10:55 pm
- Forum: *Electrophiles
- Topic: Anode vs Cathode
- Replies: 16
- Views: 1488
Re: Anode vs Cathode
I remember it by Oxidation occurs at the Anode (they both start with vowels) and Reduction occurs at the Cathode (both start with consonants)
- Sun Feb 28, 2021 10:51 pm
- Forum: Balancing Redox Reactions
- Topic: Sapling Week 7/8 question 5
- Replies: 2
- Views: 185
Re: Sapling Week 7/8 question 5
This one took me a while too, and it was a lot of trial and error for me. First I used the trick that says whatever side needs more oxygen atoms, add two times that number of OH- molecules, and then on the other side, add 1x that number of H2O molecules. Then I split it into the half reactions and b...
- Sun Feb 28, 2021 10:44 pm
- Forum: Balancing Redox Reactions
- Topic: Sapling 3
- Replies: 2
- Views: 291
Re: Sapling 3
One thing that helped me with this problem is the hint that said something along the lines of take the number of oxygen molecules you need on the one side, and add 2x that number of OH- molecules to that side, then add 1x that number of H2O molecules to the other side. Then write out the half reacti...
- Sun Feb 28, 2021 9:14 pm
- Forum: Balancing Redox Reactions
- Topic: Finding the bets oxidizing agent
- Replies: 1
- Views: 175
Re: Finding the bets oxidizing agent
I was confused on that too and initially thought the same thing, but I think it's whichever one is most electronegative is the best oxidizing agent.
- Sun Feb 28, 2021 9:12 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Sapling Week 7/8 question 15
- Replies: 6
- Views: 427
Re: Sapling Week 7/8 question 15
First you have to find E°cell using the table (Ecathode-Eanode), and with that value you have to use the Nernst equation and plug in the values and that should give you the answer
- Sun Feb 21, 2021 11:27 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: State functions
- Replies: 18
- Views: 933
Re: State functions
I saw something to remember some of them which is PVT HUGS (pressure volume temp, enthalpy, internal energy, Gibbs energy, and entropy), might not be all of them but the hugs part helps me remember.
- Sun Feb 21, 2021 11:23 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Favorable and Unfavorable
- Replies: 4
- Views: 794
Re: Favorable and Unfavorable
When reactants go from higher energy states to lower energy states, they are more stable, so it is favorable and doesn't require an input of energy. Those that are unfavorable require energy to put the products at a higher energy state than the reactants.
- Sun Feb 21, 2021 11:19 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: fun way to remember anode and cathode
- Replies: 16
- Views: 2681
Re: fun way to remember anode and cathode
I think I remember my hs chem teacher saying something like the Cathode is the (paw)sitive side of the salt bridge because cats have paws :)
- Sun Feb 21, 2021 11:11 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cathode/Anode
- Replies: 3
- Views: 200
Re: Cathode/Anode
I just try to see which side the electricity moves into, and that's the anode, also usually the positive side, and which side the electricity moves out of which is the cathode. Wherever the metal loses electrons is the anode side.
- Sun Feb 21, 2021 11:06 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Standard Conditions
- Replies: 8
- Views: 433
Re: Standard Conditions
My first thought is that you would assume T=25 degrees celsius, because as someone mentioned earlier, it's for the standard state, but I'm not entirely sure.
- Sun Feb 14, 2021 11:57 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: rearranging equation
- Replies: 3
- Views: 204
Re: rearranging equation
The part that I mess up on is forgetting negatives, and what helps me with this is using a lot of parentheses. This helps me group things together and helps when having to divide to isolate a variable.
- Sun Feb 14, 2021 11:51 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Sampling #19
- Replies: 2
- Views: 174
Re: Sampling #19
Hi! First you would solve for Q using the pressures given, taking the coefficients into consideration. Then you would use the equation delta G = delta G (standard state) +RT In (Q) and then solve for delta G, hope this helps!
- Sun Feb 14, 2021 11:35 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: HW Question
- Replies: 4
- Views: 357
Re: HW Question
First you have to find Q, by using the pressures given, and remember to take the constant into consideration. Then you use the equation Delta G = delta g (standard state) + RT In(Q) and solve for delta G.
- Sun Feb 14, 2021 11:28 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Phase Changes of Delta H and Delta S
- Replies: 3
- Views: 2057
Re: Phase Changes of Delta H and Delta S
I was confused about this too, but the way that I thought about it was that if something goes to a higher energy state, like liquid to gas, it takes energy so H is positive. Delta S also increases because at higher energy levels, it can occupy more possible arrangements, meaning a higher delta S.
- Sun Feb 14, 2021 11:20 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Week 5/6 sapling 17
- Replies: 3
- Views: 525
Week 5/6 sapling 17
Hi, I thought I understood how to do this problem, but I can’t get the right answer for delta S and delta G. Can someone explain the steps or discuss possible mistakes? Calculate the standard enthalpy, entropy, and Gibbs free energy at 298 K for the given reaction, using the data in the table of the...
- Mon Feb 08, 2021 1:12 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Temperature Scale
- Replies: 3
- Views: 160
Re: Temperature Scale
Celsius and Kelvin both change at the same rate, because Kelvin is just Celsius+273. So a +1 change in celsius corresponds to a +1 change in Kelvin.
- Mon Feb 08, 2021 12:40 am
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: week 5/6 sapling #8
- Replies: 1
- Views: 67
week 5/6 sapling #8
Can someone explain how to do this problem please? The molar heat capacity for carbon monoxide at constant volume is CV, m=20.17 J/(K·mol). A 13.00 L fixed-volume flask contains CO(g) at a pressure of 7.00kPa and a temperature of 25.0 °C. Assuming that carbon monoxide acts as an ideal gas and that i...
- Mon Feb 08, 2021 12:33 am
- Forum: Administrative Questions and Class Announcements
- Topic: Tips for Concentrating during a test
- Replies: 31
- Views: 1354
Re: Tips for Concentrating during a test
I have a very hard time concentrating during tests, but it helps me to write down the problems I'm having a hard time with and go back to them later, eat a good meal before starting, and most importantly take a break from studying 30 mins to an hour before. I also had a hard time remaining focused w...
- Mon Feb 08, 2021 12:22 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: How is Cv and Cp related to each other? Is there a specific equation that can relate them to each other?
- Replies: 3
- Views: 315
Re: How is Cv and Cp related to each other? Is there a specific equation that can relate them to each other?
Cp is the molar specific heat capacity at a constant pressure for an ideal gas, and Cv is the molar specific heat capacity at a constant volume so when you set the equations equal to each other I believe you get Cp= Cv+R
- Mon Feb 08, 2021 12:11 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: DeltaE vs DeltaU
- Replies: 13
- Views: 626
Re: DeltaE vs DeltaU
I don't believe that there is any difference between the two, or at least I haven't found any.
- Mon Feb 01, 2021 12:46 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bond enthalpy method
- Replies: 10
- Views: 402
Re: Bond enthalpy method
Standard enthalpies of formation are most accurate, then Hess's Law, and then bond enthalpies. I think it's because it's just based on averages, but I'm not fully sure.
- Mon Feb 01, 2021 12:38 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: bomb calorimeter vs regular calorimeter
- Replies: 3
- Views: 139
Re: bomb calorimeter vs regular calorimeter
I'm not sure of exactly what we need to know, but bomb calorimeters keep the system at a constant volume, and don't let it expand even if more moles of gas are produced.
- Mon Feb 01, 2021 12:31 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: sapling #7 week3
- Replies: 3
- Views: 198
sapling #7 week3
Can someone please review the steps for this problem? Just want to make sure I'm doing it right.
Calculate the standard enthalpy change for the reaction at 25 degrees C.
MgCl2(s)+H2O(l)⟶MgO(s)+2HCl(g)
Calculate the standard enthalpy change for the reaction at 25 degrees C.
MgCl2(s)+H2O(l)⟶MgO(s)+2HCl(g)
- Mon Feb 01, 2021 12:15 am
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Sapling 11 week 3/4
- Replies: 2
- Views: 237
Re: Sapling 11 week 3/4
I believe you would use the q=c*m*delta T equation, but hopefully someone can confirm.
- Mon Feb 01, 2021 12:06 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Calculating Bond Enthalpies
- Replies: 4
- Views: 276
Re: Calculating Bond Enthalpies
Hi, to calculate bond enthalpies you take the enthalpy of formation of reactants - the enthalpies of formation of the products. It's important to keep track of any negatives so maybe a problem is arising because of that; I sometimes have issues with these problems as well.
- Sun Jan 24, 2021 11:34 pm
- Forum: Student Social/Study Group
- Topic: Exam Duration
- Replies: 7
- Views: 329
Re: Exam Duration
If it's structured similar to how 14A was last quarter, there should be an extra 5 or so minutes to check our setups and equation sheets, and to take any technology errors into consideration. Additionally last quarter some TA's opened the zoom a few minutes early to make sure everything worked right...
- Sun Jan 24, 2021 11:30 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Temperature Given in Problems
- Replies: 6
- Views: 207
Re: Temperature Given in Problems
Hi, I've been kind of confused about this too. I was just thinking that they give us the temperature so we can assume the phases of the given substances are gasses so we can include them in the calculation, but I'm not 100% sure. Hopefully someone else known for sure!
- Sun Jan 24, 2021 11:25 pm
- Forum: Phase Changes & Related Calculations
- Topic: weak/strong bases and acids
- Replies: 7
- Views: 471
Re: weak/strong bases and acids
I just memorized the list of strong acids and bases and anything that is not on that list I consider to be weak and that has worked best for me.
- Sun Jan 24, 2021 11:18 pm
- Forum: Student Social/Study Group
- Topic: Preferred UA sessions?
- Replies: 1
- Views: 137
Re: Preferred UA sessions?
I've found Justins (Thursdays at 12 I believe) to be very helpful!
- Sun Jan 24, 2021 11:15 pm
- Forum: Phase Changes & Related Calculations
- Topic: when to assume x is insignificant
- Replies: 86
- Views: 7705
Re: when to assume x is insignificant
Hi, I was confused about this too, but I remember Dr. Lavelle saying that if the equilibrium constant is under 1x10^-3 then you can assume that the change is insignificant, but I've read that 1x10^-4 is more accurate. It can be assumed to be insignificant if it is less than this and doesn't change t...
- Sun Jan 17, 2021 9:43 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: how to get molarity
- Replies: 8
- Views: 430
Re: how to get molarity
Hi! Because the question gives you the number in moles/liter (written as mol/L^-1) it already tells you the molarity, so you can just use the values they give.
- Sun Jan 17, 2021 9:39 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sapling Week 1 #5
- Replies: 8
- Views: 601
Re: Sapling Week 1 #5
It's important to remember that if a reaction is reversed, the k value will be the inverse of the value shown, and if it is multiplied by a certain value (like 3 of one equation) then that k value is raised to that power. Once you get those values you multiply them together and that should give you ...
- Sun Jan 17, 2021 9:14 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Week 1 Sapling #5
- Replies: 3
- Views: 142
Re: Week 1 Sapling #5
The important thing for this problem is to remember that if the reaction goes backwards then the k value is the inverse, and if it is multiplied by a certain number, then the value is raised to the power of that number. Other than that it's pretty much just matching up the equations to where the rea...
- Sun Jan 17, 2021 9:09 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sapling Week 1 #9
- Replies: 4
- Views: 449
Re: Sapling Week 1 #9
I had trouble with this one too, and ended up with a negative value at first as well. First you have to find the Kc values based on the values they gave you at equilibrium, but when you set up the ice chart the initial value for the NO is the new value they gave, not the one at equilibrium. The chan...
- Sun Jan 17, 2021 7:29 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ice tables
- Replies: 7
- Views: 458
ice tables
Does anyone have any tips for using ice tables? I know all the steps and what to put under each category, but I find myself making mistakes sometimes and any help would be appreciated!
- Sat Jan 09, 2021 10:09 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Products and Equilibrium
- Replies: 5
- Views: 366
Re: Products and Equilibrium
This just means that the products are lower in energy than the reactants, so it makes it more favorable for there to be more products than reactants.
- Sat Jan 09, 2021 10:06 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Q and K
- Replies: 13
- Views: 513
Re: Q and K
Yes, that's correct. Q can be used to see which direction the reaction will go to reach equilibrium. If Q<K it will proceed forward, but if Q>K it will go backwards and form more reactants.
- Sat Jan 09, 2021 10:04 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Concentration
- Replies: 12
- Views: 721
Re: Concentration
I believe concentrations can't be negative because they measure how much of a substance is present. So if there was none of something, then the concentration would just be 0, not anything in the negatives.
- Sat Jan 09, 2021 10:00 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kc and Kp
- Replies: 3
- Views: 225
Re: Kc and Kp
That's what I have written too, with delta n being the sum of the coefficients of the product minus the sum of the coefficients of the reactants.
- Sat Jan 09, 2021 9:57 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: pressure and concentration
- Replies: 3
- Views: 236
Re: pressure and concentration
When the pressure changes, this usually affects the volume as well, and as Dr. Lavelle said, it's not necessarily the pressure that changes the concentration, it's the change in volume. Concentration can be written as moles over volume, so if the volume increases (and pressure decreases), the concen...
- Sun Dec 13, 2020 1:26 am
- Forum: Student Social/Study Group
- Topic: Study methods
- Replies: 7
- Views: 408
Re: Study methods
Next quarter I'm definitely going to go to more of the UA sessions because those were super helpful. The hardest part about online learning for me is just staying on top of my work, so I'd try to do the textbook problems more ahead of time to prevent getting behind.
- Sun Dec 13, 2020 1:21 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polarity and Bond Angle
- Replies: 2
- Views: 243
Re: Polarity and Bond Angle
For memorizing the angles, shapes that have 4 regions like tetrahedral and trigonal pyramidal are going to have angles of 109.5 or similar, because of the 4 regions, so I just remember that 4 means 109.5. Shapes that have 3 regions on the same plane like trigonal planar are going to be 120 because 3...
- Sun Dec 13, 2020 12:41 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: About electron configurations positive ions of elements in the 4p period (Based on Cu and Cr)
- Replies: 2
- Views: 310
Re: About electron configurations positive ions of elements in the 4p period (Based on Cu and Cr)
I believe after removing all the p orbital electrons you remove the s orbital electrons next and then the d orbital but I'm not fully sure, hopefully someone else can confirm.
- Sun Dec 13, 2020 12:30 am
- Forum: Bronsted Acids & Bases
- Topic: HClO3 Strong Acid
- Replies: 4
- Views: 580
Re: HClO3 Strong Acid
I had this question too. I was thinking that it was a strong acid but that note confused me so I'm not 100% sure.
- Sat Dec 12, 2020 10:02 pm
- Forum: Hybridization
- Topic: hybrid orbitals
- Replies: 4
- Views: 232
hybrid orbitals
When naming hybrid orbitals do we have to put the orbital number before it? Like does we have to specify that it's 2sp^3 or is it just sp^3 for example.
- Sun Dec 06, 2020 9:38 pm
- Forum: Naming
- Topic: Naming a compound
- Replies: 10
- Views: 3554
Re: Naming a compound
I also have a hard time naming the compounds, but I've heard that just practicing a lot and memorizing as well as you can can help in becoming faster at it.
- Sun Dec 06, 2020 9:29 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Detrmining Shape from coordination numbers
- Replies: 6
- Views: 475
Re: Detrmining Shape from coordination numbers
If I'm understanding it correctly, the coordination number is roughly how many attachments can be found on the central atom. So if the coordination number is 4, the geometries that include 4 attachments would be most commonly used.
- Sun Dec 06, 2020 9:24 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Coordination Number
- Replies: 5
- Views: 437
Re: Coordination Number
To simplify it, I just think of the coordination number as how many atoms or other molecules are connected to the central atom. In this case the 5 NH3 molecules are connected and the 1 SO4 molecule is connected, so total there are 6, making the coordination number 6.
- Sun Dec 06, 2020 9:20 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: angles Q.21 2E
- Replies: 3
- Views: 202
Re: angles Q.21 2E
He mentioned this in lecture, but I believe we don't need to memorize the exact number, just that it's slightly less than 109.5.
- Sun Dec 06, 2020 9:16 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Coordination Number
- Replies: 4
- Views: 232
Re: Coordination Number
This might be oversimplifying it, but I just remember that each en contributes 2 to the coordination number and each edta contributes 6 to the coordination number. I think we just have to memorize it but correct me if I'm wrong!
- Sun Dec 06, 2020 9:09 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Determining Oxidation Numbers
- Replies: 6
- Views: 517
Re: Determining Oxidation Numbers
I have some trouble with this too, but normally I just think of it like an equation! Each atom has its own charge, and the molecule as a whole has a charge, and the sum of the charges of the atoms needs to equal the charge of the molecule. Normally all the atoms except the one you're looking for has...
- Mon Nov 30, 2020 4:57 am
- Forum: Resonance Structures
- Topic: Stable Resonance Structures
- Replies: 4
- Views: 342
Re: Stable Resonance Structures
As of what we've learned so far I think the biggest thing to look at is the formal charge if the question doesn't give you any more info. The structure with the least number of formal charges is most stable. I also believe that the structure with the least separation of formal charge is more stable ...
- Mon Nov 30, 2020 4:50 am
- Forum: Lewis Structures
- Topic: Sapling #20
- Replies: 7
- Views: 307
Re: Sapling #20
Hi, I think that because it's the same element with the same electronegativity that's on all the sides, it cancels out. I was kind of confused on whether or not the charges would affect the polarity too but I don't think it does because then it would seem to be polar.
- Mon Nov 30, 2020 4:44 am
- Forum: Resonance Structures
- Topic: finding resonance structures
- Replies: 5
- Views: 552
finding resonance structures
Hi, I sometimes struggle with finding the resonance structures for certain molecules, does anyone have any tricks that help you easily make all the structures?
- Sun Nov 29, 2020 1:15 am
- Forum: Sigma & Pi Bonds
- Topic: pi bonds
- Replies: 16
- Views: 1220
pi bonds
Hi! Does anyone have any tips for better visualizing how pi bonds work? I understand the basics but I'm having a hard time picturing them. Thank you!
- Sun Nov 22, 2020 11:44 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: bond angle tips
- Replies: 10
- Views: 715
bond angle tips
Does any one have any tips for remembering the bond angles or is it just somethings that needs to be memorized as is?
- Sun Nov 22, 2020 11:36 pm
- Forum: *Liquid Structure (Viscosity, Surface Tension, Liquid Crystals, Ionic Liquids)
- Topic: determining viscosity
- Replies: 11
- Views: 2648
Re: determining viscosity
Without doing an experiment, you can compare viscosities by looking at the IMF's of the substances. If a substance has high IMF's they will be closer together and more viscous. If it has low IMF's, the molecules won't be as attracted to each other and farther apart, so it will be less viscous.
- Sun Nov 22, 2020 11:32 pm
- Forum: Lewis Structures
- Topic: Octet Rule
- Replies: 17
- Views: 1183
Re: Octet Rule
I have this issue a lot too, but I know that the octet rule can be defied for certain elements. In some cases, the d orbitals can accept electrons as well, which allows some elements like sulfur and chlorine to have more than 8. I'm not sure what the exact rules for this are, but hopefully someone e...
- Sun Nov 22, 2020 11:08 pm
- Forum: Trends in The Periodic Table
- Topic: Exceptions to Trends in atomic radius
- Replies: 3
- Views: 2104
Re: Exceptions to Trends in atomic radius
I have read that Sb is slightly larger than Sn, but I'm not sure if this is true because I can't seem to find any more information on it
- Sun Nov 22, 2020 11:01 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ionic and Covalent Bonds
- Replies: 7
- Views: 501
Re: Ionic and Covalent Bonds
If you know how the electron is being shared, or if it's being given up and given to the other atom that's another way to tell if it's polar covalent or ionic, but mostly it's looking at the electronegativities or what kind of elements it's between (like metal or nonmetal).
- Sun Nov 15, 2020 11:03 pm
- Forum: Lewis Structures
- Topic: expanded octets
- Replies: 2
- Views: 163
expanded octets
Can someone please explain how we know when an atom will use the expanded octet? I know which atoms can I just get confused on knowing when it will use it if at all. Thank you!
- Sun Nov 15, 2020 9:59 pm
- Forum: Ionic & Covalent Bonds
- Topic: Between 1.5 and 2
- Replies: 3
- Views: 142
Re: Between 1.5 and 2
I believe that if the electronegativity difference is more than 1.7 it will be an ionic bond and .5-1.7 is a polar bond, so for the lewis structure for an ionic bond you would draw the two ions separate, and for the polar bonds it would be the normal lewis structure. I'm not 100% sure though so hope...
- Sun Nov 15, 2020 9:26 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: polar vs nonpolar
- Replies: 3
- Views: 185
Re: polar vs nonpolar
First look at whether the bonds are polar or not by looking at electronegativity, and if there are no polar bonds then the molecule is non polar. If there are polar bonds, look at the arrangement of the molecule and if it is not symmetrical, then the molecule is polar. I have a hard time with this t...
- Sun Nov 15, 2020 9:19 pm
- Forum: Lewis Structures
- Topic: Sapling 9
- Replies: 8
- Views: 410
Re: Sapling 9
For formal charge the most probable structures are the ones with the least amount of formal charges on the individual atoms (as long as it still adds up to the total charge), and for bond length, it says that experimentally it was found that the bond length was 144 which is close to 140, the bond le...
- Sun Nov 15, 2020 1:00 am
- Forum: Lewis Structures
- Topic: Lewis structure based on oxidation #
- Replies: 2
- Views: 134
Lewis structure based on oxidation #
Hi! Can someone please explain how to find which lewis structure is best based on the oxidation number of the central atom? (like number 9 on sapling) Thank you!
- Sun Nov 08, 2020 11:11 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Explaining Electron Configuration
- Replies: 4
- Views: 187
Re: Explaining Electron Configuration
I think of it as counting up the number of electrons in an element. The metals on the left side of the periodic table have electrons in the s orbital (1s^1, 1s^2, 2s^1, 2s^2...) and these can only go up to _s^2. The 6 groups on the right side are the p orbital and the exponent can go up to 6 because...
- Sun Nov 08, 2020 10:50 pm
- Forum: Resonance Structures
- Topic: formal charge
- Replies: 5
- Views: 206
Re: formal charge
Yes, I believe the formal charges should add up the charge of the molecule as a whole. I think certain atoms are more likely to be negative or positive based on their electronegativities, but I don't know if chlorine for example would always have to be negative, even though it usually is because it ...
- Sun Nov 08, 2020 10:16 pm
- Forum: Trends in The Periodic Table
- Topic: Ionization and electron affinity
- Replies: 6
- Views: 462
Re: Ionization and electron affinity
Ionization energy is the amount of energy that is required to remove an electron, and more specifically the least bound electron to the atom. Elements that only have one valence electron have lower ionization energies because removing the one electron would make it have a full outer shell. As you mo...
- Sun Nov 08, 2020 10:08 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Pz Py Pz
- Replies: 5
- Views: 322
Re: Pz Py Pz
They represent the different orientations of the electrons in the atom. They are the different orbitals in the p subshell, so basically the three different positions of those electrons.
- Sun Nov 08, 2020 10:05 pm
- Forum: Electronegativity
- Topic: polyatomic ions
- Replies: 4
- Views: 243
Re: polyatomic ions
I believe it comes down to the electronegative of the atoms, so it depends on which you're looking at. The more electronegative it is compared to the atoms it is bonded to the more likely it is to follow the trends seen on the periodic table, (like oxygen having a -2 charge).
- Sun Nov 08, 2020 9:58 pm
- Forum: Lewis Structures
- Topic: nitrate lewis structure
- Replies: 7
- Views: 1093
Re: nitrate lewis structure
Hi! I believe this is because it would cause nitrogen to have 5 bonds, the two double bonds and a single bond, which wouldn't be very stable.
- Sun Nov 08, 2020 6:08 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Electron Configuration for Ions
- Replies: 1
- Views: 98
Re: Electron Configuration for Ions
Hi Stella! I had this question too. I've been doing what the UA said and starting from the previous noble gas, but I'm not sure if both are correct or if one is preferred.
- Mon Nov 02, 2020 12:02 am
- Forum: Student Social/Study Group
- Topic: How to relax
- Replies: 168
- Views: 28181
Re: How to relax
Usually I just watch tv or workout, (which isn't very relaxing sometimes), but I've been trying to do yoga recently and it's pretty fun!
- Mon Nov 02, 2020 12:00 am
- Forum: SI Units, Unit Conversions
- Topic: Converting equations
- Replies: 16
- Views: 906
Re: Converting equations
Hi, I come across this problem a lot too, but it helps me to write out each equation with units every step of the way, without skipping steps. Hope it helps!
- Sun Nov 01, 2020 11:46 pm
- Forum: DeBroglie Equation
- Topic: sapling homework
- Replies: 4
- Views: 353
sapling homework
Can someone please explain how to start this problem? The incident radiation had a wavelength of 1064 nm, and the ejected electrons were found to have an energy of 0.137 eV. The electron affinity is the difference in energy between the incident photons and the energy of the ejected electrons. Determ...
- Sun Nov 01, 2020 6:13 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: electrons in an atom
- Replies: 2
- Views: 209
electrons in an atom
Can someone please explain how to find the number of electrons in an Atom based on the Quantum number? I'm getting stuck on what the l means and how it factors into how many electrons there are. Thank you!
- Sun Nov 01, 2020 5:00 pm
- Forum: Student Social/Study Group
- Topic: Favorite TV shows
- Replies: 277
- Views: 42647
Re: Favorite TV shows
I've been watching Lucifer on Netflix! Really funny, gets interesting and I think another season is coming out soon!
- Sun Oct 25, 2020 10:49 pm
- Forum: Photoelectric Effect
- Topic: Photoelectric Effect-Work Function
- Replies: 4
- Views: 276
Re: Photoelectric Effect-Work Function
This has been confusing me too, but I believe work function is the energy needed to remove an electron from a surface, and this energy must match the energy of the photon for the electron to be removed. I think the problem has to give you the work function if you are supposed to use it, or if you kn...
- Sun Oct 25, 2020 10:42 pm
- Forum: Properties of Electrons
- Topic: Circular Standing Wave
- Replies: 2
- Views: 204
Re: Circular Standing Wave
I'm not sure if this is what you're asking, but I believe an electron cannot be in between energy levels, if it doesn't have enough energy it will just remain at the lower energy level. Not too sure about the circular standing wave I was curious about that too.
- Sun Oct 25, 2020 10:22 pm
- Forum: Ionic & Covalent Bonds
- Topic: Covalent Bonds
- Replies: 9
- Views: 393
Re: Covalent Bonds
Hydrogen bonds are the weakest, and I believe ionic bonds tend to be stronger than covalent because of the different charges on the ions and the electronegativity differences, except when placed in water or some solution covalent bonds are stronger.
- Sun Oct 25, 2020 9:56 pm
- Forum: Einstein Equation
- Topic: Sapling hw #7
- Replies: 2
- Views: 135
Sapling hw #7
Hi! I had a question of one of the problems from sapling which is, suppose the typical work function of the metal is roughly 4.170×10−19 J. Calculate the maximum wavelength in angstroms of the radiation that will eject electrons from the metal. What would be the first step to solve this? I tried loo...
- Sun Oct 18, 2020 11:30 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Notetaking and Organization
- Replies: 7
- Views: 308
Re: Notetaking and Organization
Since most of the topics relate to each other in some way, I've just been compiling everything into one document. I make sure I label everything appropriately so it is easy to find later on. The only thing that helps me retain information better is repetition and practice so I go over my notes multi...
- Sun Oct 18, 2020 11:21 pm
- Forum: Properties of Electrons
- Topic: Energy per Photon
- Replies: 7
- Views: 242
Re: Energy per Photon
If I understand your question and the topic correctly, then the energy required to remove an electron would be the lowest the energy of the photon could be. So if the photon is going to remove the electron it must have the same or more energy than the required energy. I'm not sure if you can assume ...
- Sun Oct 18, 2020 11:16 pm
- Forum: Einstein Equation
- Topic: Particles with mass
- Replies: 5
- Views: 172
Re: Particles with mass
Adding onto what everyone else said, because photons have no mass, they get all their energy from their momentum. Which is why light is never at rest if I'm correct.
- Sun Oct 18, 2020 11:07 pm
- Forum: Properties of Light
- Topic: Intensity vs amplitude
- Replies: 6
- Views: 378
Re: Intensity vs amplitude
From what I've read as well, intensity is the square of the amplitude so they are proportional but not the same thing. They are both related to the amount of energy a wave has.
- Sun Oct 18, 2020 11:01 pm
- Forum: Properties of Electrons
- Topic: Energy levels
- Replies: 8
- Views: 471
Re: Energy levels
The gaps become smaller as energy levels increase because the farther away from the nucleus the electrons are the less the pull from the protons is. So the farther away the electron is the less energy is needed, so the gaps decreases.
- Sun Oct 11, 2020 4:01 pm
- Forum: SI Units, Unit Conversions
- Topic: Unit Conversion Tips
- Replies: 5
- Views: 311
Re: Unit Conversion Tips
When converting units it makes it easier for me to write them all out as fractions so I can see and make sure the appropriate ones cancel out. That way I can easily see which units go where. I usually convert before calculating but am not sure if it can be done after as well.
- Sun Oct 11, 2020 3:23 pm
- Forum: Empirical & Molecular Formulas
- Topic: Molecular Formula
- Replies: 3
- Views: 227
Re: Molecular Formula
You have to find the molar mass of the empirical formula and the molar mass of the molecular formula and then find the ratio between them. Then you multiply that by the number of atoms in the empirical formula. So if the molar mass of the molecular formula is 3x as much as the molar mass of the empi...
- Sun Oct 11, 2020 3:18 pm
- Forum: SI Units, Unit Conversions
- Topic: Conversion Factors
- Replies: 6
- Views: 205
Re: Conversion Factors
I believe he mentioned that on tests we will be given conversion factors and some formulas but I could be mistaken.