Search found 112 matches
- Sat Mar 13, 2021 7:36 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Concentration Equations
- Replies: 2
- Views: 214
Concentration Equations
I know that we use the concentration equations, like E = Enaught - RT/nF ln Q for concentration cells. I was wondering if they can be used for Galvanic cells as well or are they exclusive to concentration cells?
- Fri Mar 12, 2021 9:41 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Chemical Kinetics Review session with TA
- Replies: 4
- Views: 293
Re: Chemical Kinetics Review session with TA
I would definitely email a TA and see if they had worksheets or if it was just a general review. You could also search Chemistry Community or CCLE to see if they posted their worksheets on there.
- Fri Mar 12, 2021 9:38 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Sapling #7
- Replies: 4
- Views: 322
Re: Sapling #7
Your answer seems to be right. It could be a rounding error, with you rounding up when sapling wants you to go to the first decimal place?
- Fri Mar 12, 2021 9:33 pm
- Forum: General Rate Laws
- Topic: Intermediate
- Replies: 59
- Views: 3869
Re: Intermediate
An intermediate is a compound that is produced in a reaction and then subsequently used up in a later step of the reaction. So, it is not present in the products or the reactants but is both created and used up over the course of the reaction.
- Fri Mar 12, 2021 9:32 pm
- Forum: Second Order Reactions
- Topic: Determining slow step
- Replies: 22
- Views: 1210
Re: Determining slow step
You can tell if a reactant is part of the slow step if it is present in the overall rate law, as that only includes the reactants in the slow step.
- Fri Mar 12, 2021 9:31 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: About k
- Replies: 26
- Views: 2978
Re: About k
In regards to equilibrium, a large k value will tell us that at equilibrium, there will be a larger amount of products formed in comparison to reactants. In the case of kinetics, a large k value tells us that the reaction is proceeding at a fast rate.
- Tue Mar 09, 2021 12:26 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Catalysts and Rate Constants
- Replies: 4
- Views: 517
Re: Catalysts and Rate Constants
It does affect the rate constants as catalysts decrease the activation energy, increasing rate constant as seen through the Arrhenius equation. As Ea decreases, the overall value of k increases, meaning that a catalyst will increase the rate constant.
- Sun Mar 07, 2021 6:59 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: nernst equation
- Replies: 20
- Views: 851
Re: nernst equation
The n value represents the number of electrons transferred in the redox reaction! So, if you balance the two half-reactions to make sure that an equal number of electrons are being transferred, that number of electrons is the value you would input for n.
- Sun Mar 07, 2021 6:56 pm
- Forum: Administrative Questions and Class Announcements
- Topic: lectures
- Replies: 22
- Views: 1128
Re: lectures
I believe we are done with new material after Wednesday's lecture and that Friday's lecture is a general review. From last quarter, I would agree that studying the information from previous midterms is very important.
- Sun Mar 07, 2021 6:55 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: intermediates in a reaction
- Replies: 8
- Views: 1594
Re: intermediates in a reaction
It isn't a guarantee that there will be an intermediate, but it is highly likely for most reactions. You can tell if it is an intermediate if the compound does not show up in the overall balanced equation and is created in one step and used up in another step.
- Sun Mar 07, 2021 6:53 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Reaction Mechanism Checking
- Replies: 3
- Views: 527
Re: Reaction Mechanism Checking
Usually, if the mechanism follows both of the steps outlined, it is most likely to be correct. However, it is not a tried and true method as there could be other mechanisms that also follow both steps and could equally be the correct mechanism for the reaction. So, to know if it is actually the reac...
- Sun Mar 07, 2021 6:51 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: molecularity
- Replies: 4
- Views: 263
Re: molecularity
Molecularity is defined as the number of individual molecules involved in an elementary step of a reaction. The rate law follows from molecularity, as the number of molecules involved in the step defines the step's rate law. So, for example, if you had a step that was A + A, it would have a molecula...
- Sun Feb 28, 2021 9:39 pm
- Forum: Balancing Redox Reactions
- Topic: Determining which molecule is the oxidizing agent
- Replies: 49
- Views: 1971
Re: Determining which molecule is the oxidizing agent
Yes! The oxidizing agent is the molecule that is reduced and is oxidizing another molecule. Vice versa, the reducing agent is the molecule being oxidized and reducing something else.
- Sun Feb 28, 2021 9:36 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Moles in ΔG = -nFE
- Replies: 45
- Views: 4113
Re: Moles in ΔG = -nFE
The moles, or n, refers to the number of electrons transferred in the balanced reaction.
- Sun Feb 28, 2021 9:33 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: anode vs. cathode
- Replies: 12
- Views: 740
Re: anode vs. cathode
The anode is on the left and is oxidized while the cathode is on the right and is reduced. So, find which molecules are being oxidized/reduced and you'll find the cathode and anode of the reaction.
- Sun Feb 28, 2021 9:32 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing Reactions
- Replies: 22
- Views: 1122
Re: Balancing Reactions
I dont think the order of the reactants or products matters much, as long as each is on the correct side of the equation it should work.
- Sun Feb 28, 2021 9:30 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Sapling #9
- Replies: 4
- Views: 305
Re: Sapling #9
Double-check your cell potentials to make sure you're using the right ones! Otherwise, your steps are right.
- Sat Feb 20, 2021 7:22 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Adiabatic
- Replies: 26
- Views: 1204
Re: Adiabatic
Adiabatic means no heat is exchanged between the system and its surroundings.
- Sat Feb 20, 2021 7:22 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Free Energy
- Replies: 49
- Views: 2138
Re: Free Energy
A state function only depends on the final and initial values, it doesn't care about the "path" taken to get there. Free energy is a state function because it follows these restrictions.
- Sat Feb 20, 2021 7:20 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Delta G and G naught
- Replies: 46
- Views: 4656
Re: Delta G and G naught
Delta G naught is the standard reaction Gibbs free energy. If the reaction is not occurring at standard conditions, then regular gibbs free energy is used, which takes into account variations in the temperature, pressure, and anything else.
- Sat Feb 20, 2021 7:15 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Entropy related to Enthalpy
- Replies: 20
- Views: 1001
Re: Entropy related to Enthalpy
It's referencing Gibbs Free Energy! This shows that delta G = delta H - T delta S
- Sat Feb 20, 2021 7:14 pm
- Forum: Student Social/Study Group
- Topic: Post Midterm 2 De-stressing
- Replies: 92
- Views: 7495
Re: Post Midterm 2 De-stressing
I'm going to be talking with my friends and catching up on all the hw for the week :D
- Sat Feb 20, 2021 7:13 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Delta U and Delta H
- Replies: 12
- Views: 4654
Re: Delta U and Delta H
Delta U = Delta H + w, since delta H = q at a constant pressure.
- Sun Feb 14, 2021 3:10 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Temperature and K
- Replies: 21
- Views: 1192
Re: Temperature and K
Temperature can be measured in Kelvin if that is the K you are talking about. If you are talking about the equilibrium constant, k then changes in temperature will change the equilibrium constant for the reaction. If the reaction is endothermic, adding heat will shift the direction towards the produ...
- Sun Feb 14, 2021 3:06 pm
- Forum: Student Social/Study Group
- Topic: Fav Shows of the Moment
- Replies: 115
- Views: 48703
Re: Fav Shows of the Moment
I love to binge New Girl. I've watched it like 10 times!
- Sun Feb 14, 2021 3:05 pm
- Forum: General Science Questions
- Topic: Sapling HW Week 5&6 Question #7
- Replies: 5
- Views: 2310
Re: Sapling HW Week 5&6 Question #7
The enthalpy for the reaction is given by the heater, which is running at 500 W (J/s). So, you would convert the W into J by multiplying by the 4.02 minutes over which each compound boils, as that would reference the time in which the compound is vaporized. This is the enthalpy in the reaction. Then...
- Sun Feb 14, 2021 2:54 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: Sapling Week 5/6 Q#8
- Replies: 5
- Views: 374
Re: Sapling Week 5/6 Q#8
I think it is important to note that two different heat capacities are given, and as we do not know how to use both in the same equation, it can be assumed that you would need to take it in steps. Also, as it is a heating and vaporization problem, the process of doing two things would probably indic...
- Sun Feb 14, 2021 2:50 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm 2 Content
- Replies: 18
- Views: 756
Re: Midterm 2 Content
The midterm covers up until Friday, 2/12's lecture. So, the lectures during the midterm week do not count towards the midterm and, as it is not cummulative, nothing covered in the previous midterm will show up as well.
- Sun Feb 14, 2021 2:48 pm
- Forum: Administrative Questions and Class Announcements
- Topic: cc update
- Replies: 23
- Views: 1251
Re: cc update
I think Dr. Lavelle mentioned that he has to put in the points manually, so it isn't an accurate reflection until he updates them. Just wait it out!
- Sun Feb 14, 2021 2:48 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Can We Review our Exams?
- Replies: 69
- Views: 3485
Re: Can We Review our Exams?
I would assume that the same format would follow from 14A where the TA's could go over your exam questions with you. You would have to go to a TA's office hours and ask them to see if they'll go over your midterm with you.
- Wed Feb 03, 2021 10:22 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: U and E
- Replies: 7
- Views: 232
Re: U and E
U and E are extensive properties! They depend on the number of molecules are in the system.
- Wed Feb 03, 2021 10:18 pm
- Forum: Calculating Work of Expansion
- Topic: Negative Work
- Replies: 30
- Views: 1314
Re: Negative Work
When work is being done to a system, the work will be positive and if work is being done by the system, the work will be negative.
- Wed Feb 03, 2021 10:16 pm
- Forum: Ideal Gases
- Topic: Exo vs Endothermic
- Replies: 40
- Views: 2540
Re: Exo vs Endothermic
Since forming bonds requires energy and breaking bonds loses energy, you can determine if it's exo or endothermic based on if bonds are being created or destroyed. If a bond is being created, it probably is endothermic because making a bond requires energy, and if a bond is being broken, it is proba...
- Wed Feb 03, 2021 10:11 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Solving for Cubic Equations
- Replies: 13
- Views: 1149
Re: Solving for Cubic Equations
You can make x negligible for any equation where the k value is very small. It is not limited to just cubic equations.
- Wed Feb 03, 2021 10:10 pm
- Forum: Ideal Gases
- Topic: Chem BL
- Replies: 107
- Views: 8612
Re: Chem BL
I am definitely thinking about taking BL next quarter, simply because I wanted to learn all of the 14B material before diving straight in. I am wondering if taking it with Chem 14C is a good idea though, because of how hard Organic Chemistry is supposed to be. Also, having an online lab seems diffic...
- Sat Jan 30, 2021 11:42 pm
- Forum: General Science Questions
- Topic: Careless Mistakes
- Replies: 54
- Views: 3830
Re: Careless Mistakes
Honestly, the only way to improve this is to slow down and double-check everything you are doing very thoroughly. You should also be thinking about what your calculator outputs and if it makes sense for the scenario as a whole, and if it doesn't then look through and see what mistake you could have ...
- Sat Jan 30, 2021 11:40 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: perfect system
- Replies: 20
- Views: 855
Re: perfect system
It means that the heat of the object's surroundings is equivalent to the heat of the object. So if the object lost energy to its surroundings, the surroundings would gain that same amount of energy.
- Sat Jan 30, 2021 11:38 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: change in celsius = change in kelvin
- Replies: 22
- Views: 7996
Re: change in celsius = change in kelvin
Kelvin is a Celsius plus 273. So, for every one-unit increase in Celsius, there will be a one-unit increase in Kelvin as well.
- Sat Jan 30, 2021 11:37 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: steam causing burns
- Replies: 40
- Views: 1402
Re: steam causing burns
Yes! When the steam touches something cooler, in this case, your skin, it condensates and therefore loses all the energy it gained in order to become and transferring it into your skin. This would cause you a much more severe burn in comparison to just water at 100 degrees, as it is also releasing a...
- Sat Jan 30, 2021 11:35 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Clarification about Solids & Liquids for Le Chateliers Principle
- Replies: 7
- Views: 1872
Re: Clarification about Solids & Liquids for Le Chateliers Principle
Yes! Since solids and liquids are not included in the k constant, changing their concentrations should not have an impact on the equilibrium of a system. However, remember to look out for aqueous solutions, because if the volume of the solvent is increased by a lot then it is possible that the conce...
- Sun Jan 24, 2021 7:51 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: pH of weak acid
- Replies: 9
- Views: 438
Re: pH of weak acid
We can assume that x is insignificant usually when Ka < 10^-4, or when x is less than 5% of the initial amount of the acid/base. We can assume x is insignificant because it is so small it will barely impact the overall concentration of the acid.
- Sun Jan 24, 2021 7:49 pm
- Forum: Phase Changes & Related Calculations
- Topic: Salt
- Replies: 19
- Views: 739
Re: Salt
Salts can be acidic, basic, or neutral. If there is a salt with a cation from a strong base and an anion from a weak acid, the salt will be basic as the anion will draw a proton from water, forming OH- ions. If there is a salt with a cation from a weak base and an anion from a strong acid, the salt ...
- Sun Jan 24, 2021 7:44 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Diatomic Molecules
- Replies: 6
- Views: 435
Re: Diatomic Molecules
I believe that any molecule with two atoms is considered diatomic. The diatomic elements are those that can form diatomic molecules with themselves.
- Sun Jan 24, 2021 7:10 pm
- Forum: Student Social/Study Group
- Topic: Favorite Music
- Replies: 113
- Views: 12283
Re: Favorite Music
I like listening to lowfi music or sometimes I use the instrumental versions of songs I like!
- Sun Jan 24, 2021 7:09 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: How to tell if a salt is acidic, basic or neutral
- Replies: 7
- Views: 1290
Re: How to tell if a salt is acidic, basic or neutral
You have to look at the ions it is composed of! If the salt is made of a cation of a strong base and the anion of a weak acid, the salt itself would make the solution basic as the anion would steal a proton from water and leave OH- behind. In contrast, if it is made of a cation of a weak base and th...
- Sat Jan 16, 2021 6:16 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: sapling homework #2
- Replies: 5
- Views: 301
Re: sapling homework #2
You can get the equilibrium value of O2, as you know the moles of O2 at equilibrium and the volume of the container. Using the moles of O2 at equilibrium, you can use stoichiometry to find the moles of SO2 and SO3 present at equilibrium in the reaction. When you have those values, you can divide the...
- Sat Jan 16, 2021 6:12 pm
- Forum: Ideal Gases
- Topic: Kc vs. Kp
- Replies: 71
- Views: 2731
Re: Kc vs. Kp
You're right that solving for Kc and Kp is the same. Kp uses partial pressures while Kc uses concentrations. If you want to convert between the pressure to the concentration you can use PV = nRT, as n/V is concentration.
- Sat Jan 16, 2021 6:10 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: hw question #3
- Replies: 10
- Views: 572
Re: hw question #3
You can multiply both sides by (0.7 -x)^2 to remove the denominator and then expand each expression to create an equality. Afterward, you can move all the terms to one side and set the equation equal to zero. All that's left is to solve using the quadratic equation or even graphing out the equation ...
- Sat Jan 16, 2021 6:07 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: pH of Weak Acids
- Replies: 11
- Views: 473
Re: pH of Weak Acids
I think you need to remember that pH is just a measure of the H3O+ concentration in the solution, so when you dissolve the acids in the solution, it measures how many H3O+ ions are in the solution afterward. However, this is very relative with different concentrations of acids, weak or strong. The m...
- Sat Jan 16, 2021 6:05 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: HW Question
- Replies: 8
- Views: 379
Re: HW Question
Hi! So you're just supposed to play around with the equations and their k constants to find the k constant of the original equation. Personally, I inversed the N2(g)+3H2(g)↽−−⇀2NH3(g) equation, which would mean that you would inverse the k constant by doing 1/k. Then, I used I2(g)↽−−⇀2I(g) and multi...
- Sat Jan 09, 2021 10:17 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Q and K
- Replies: 13
- Views: 507
Re: Q and K
Yes, that is correct. K is just Q when the products are at equilibrium, so you can use Q as a measure of determining which way the reaction will move. When K>Q, the reaction will shift towards the products, and if K< Q, the reaction will shift towards the reactants.
- Sat Jan 09, 2021 10:15 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Concentration
- Replies: 12
- Views: 721
Re: Concentration
Concentrations cannot be negative because it is defined by moles/L. As it is impossible to have a negative number of moles or a negative number of L, the concentration must be positive.
- Sat Jan 09, 2021 10:13 pm
- Forum: Student Social/Study Group
- Topic: New Year Resolutions?
- Replies: 54
- Views: 3013
Re: New Year Resolutions?
I want to start working out a bit more as well as journaling my days so I remember the things that I did in the future!
- Sat Jan 09, 2021 10:12 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sapling Week 1 #6
- Replies: 6
- Views: 258
Re: Sapling Week 1 #6
I agree with what was said above, you cubed the 1.75 when it should be squared!
- Sat Jan 09, 2021 10:11 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Lecture Format
- Replies: 22
- Views: 893
Re: Lecture Format
I think it follows the same format as 14A where the lectures were recorded and posted under the media tab on CCLE. I assume we would be informed via email if anything was synchronous!
- Sat Jan 09, 2021 9:55 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Sapling Problem: Used non-UCLA email address for previous quarter
- Replies: 5
- Views: 312
Re: Sapling Problem: Used non-UCLA email address for previous quarter
I would agree with using chrome! It seems that sapling just operates better with chrome than any other browser so maybe use it instead.
- Sat Dec 12, 2020 10:24 pm
- Forum: Calculating the pH of Salt Solutions
- Topic: weak acid/base and pH
- Replies: 9
- Views: 776
Re: weak acid/base and pH
Yep! This happens cuz weak acids have pH's lower than 7 and weak bases have pH's over 7, so they usually will be lowering or raising the pH.
- Sat Dec 12, 2020 10:20 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: pKa and pH
- Replies: 2
- Views: 518
Re: pKa and pH
I think you should know that if the pKa < pH, then the majority of atoms in the solution will be charged for acids. However, if the pKa > pH, then the majority of atoms in the solution will be neutral, for acids. The inverse is true for bases. Also, you should know that the pKa value being low indic...
- Sat Dec 12, 2020 10:17 pm
- Forum: General Science Questions
- Topic: bond angles
- Replies: 3
- Views: 246
Re: bond angles
Yes, you can just say less than or slightly less than to indicate the bond angles. I don't think we are expected to know exactly the angles of the bonds in the presence of lone pairs.
- Sat Dec 12, 2020 10:14 pm
- Forum: Hybridization
- Topic: hybrid orbitals
- Replies: 4
- Views: 232
Re: hybrid orbitals
It just depends on the level of specification you want! If you wanna tell the energy level as well as the hybridization of the orbital, you would put the 2. But sp^3 is equally correct if you are not specifying the energy level.
- Sat Dec 12, 2020 10:13 pm
- Forum: Naming
- Topic: Cobalt vs Cobaltate
- Replies: 16
- Views: 1176
Re: Cobalt vs Cobaltate
You add the -ate to the TM when the charge of the coordination compound is negative to signal that the compound is negative. If the charge is neutral or positive, you will leave it as the metal, like cobalt.
- Sat Dec 05, 2020 7:14 pm
- Forum: Naming
- Topic: Order of Ligands/naming
- Replies: 28
- Views: 1234
Re: Order of Ligands/naming
You would name the ligands in alphabetical order, not including the prefixes, and then put the transition metal at the end, followed by whatever was not in the brackets.
- Sat Dec 05, 2020 7:11 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Final
- Replies: 21
- Views: 871
Re: Final
I believe they'll be very similar otherwise we would have been informed. I would suspect it would once again be on a lockdown browser with a second device on a zoom call.
- Sat Dec 05, 2020 7:07 pm
- Forum: Naming
- Topic: naming sphere of influence
- Replies: 5
- Views: 253
Re: naming sphere of influence
Hi! In this example, the second Cl is not directly bonded to the TM cation but instead bonded to the coordination compound that is formed. This would cause it to be outside the sphere of influence for the cation, and so its name wouldn't be changed in regards to being in the sphere of influence.
- Sat Dec 05, 2020 7:04 pm
- Forum: Lewis Structures
- Topic: Most Stable Structure
- Replies: 23
- Views: 3621
Re: Most Stable Structure
The most stable structure will have the lowest formal charge. If there must be a charge, it is most stable if the most electronegative atom holds the negative charge.
- Sat Dec 05, 2020 7:01 pm
- Forum: Lewis Acids & Bases
- Topic: Bronsted vs. Lewis bases
- Replies: 11
- Views: 424
Re: Bronsted vs. Lewis bases
From what Dr. Lavelle said during the lecture, a Bronsted base and a lewis base are the same, it is just the way you observe them that's different. In terms of a Bronsted base, you would observe it from the actions of the protons, as it will receive a proton, in comparison to Lewis bases which will ...
- Sat Dec 05, 2020 6:58 pm
- Forum: Naming
- Topic: Naming Order
- Replies: 16
- Views: 736
Re: Naming Order
From what I have seen, it appears that you would put the TM cation first and then put the ligands after it. I do not think the ligands need to be in alphabetical order but it couldn't hurt to follow that convention.
- Sat Nov 28, 2020 8:35 pm
- Forum: Sigma & Pi Bonds
- Topic: sapling #15
- Replies: 24
- Views: 1208
Re: sapling #15
You look at the number of bonds for the atom. If it's a single bond, it is just one sigma bond. Double bonds will contain one sigma bond and one pi bond and triple bonds will contain one sigma bond and two pi bonds. Basically, there is only ever one sigma bond, the rest of them have to be pi bonds.
- Sat Nov 28, 2020 8:31 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polarity
- Replies: 17
- Views: 727
Re: Polarity
Hi! If the structure is symmetric, with the same kinds of atoms evenly spaced out then the molecule will be nonpolar. However, if the structure isn't symmetric and there are different atoms on each side, then the structure will be polar. This includes lone pairs, as if the structure is symmetric wit...
- Tue Nov 24, 2020 12:17 am
- Forum: Hybridization
- Topic: e density
- Replies: 30
- Views: 1122
Re: e density
Yes! Every bond and lone pair is an area of electron density. However, double and triple bonds do not count as separate areas of electron density but instead are a single area of electron density.
- Tue Nov 24, 2020 12:12 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: isoelectronic
- Replies: 12
- Views: 1135
Re: isoelectronic
Hi! Isoelectronic means that the atoms have the same amount of electrons. For example, O2-, F1- and Ne are isoelectric as they all have 10 electrons. From my understanding, isoelectronic atoms share similar properties, so knowing that they are isoelectronic can help you in understanding the properti...
- Mon Nov 23, 2020 11:47 am
- Forum: Resonance Structures
- Topic: Resonance implying electron delocalization?
- Replies: 5
- Views: 490
Resonance implying electron delocalization?
In Dr. Lavelle's lecture today he mentioned that in the case of Benzene, the carbon will form three hybrid orbitals and keep one normal p orbital. He then said that the electron in the remaining p orbitals of each carbon will be delocalized and shared equally among the carbons. I was wondering if th...
- Mon Nov 23, 2020 11:42 am
- Forum: Hybridization
- Topic: Why are lone pairs hybridized?
- Replies: 4
- Views: 233
Re: Why are lone pairs hybridized?
Hi! From my understanding, I think that they contribute as they are a region of electron density around the central atom and contribute to the octet of the central atom, so they must be taken into account when forming hybrid orbitals as they impact the shape of the molecule.
- Sun Nov 22, 2020 12:14 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone Pair E-
- Replies: 47
- Views: 2093
Re: Lone Pair E-
Yes, they do! Lone pair electrons count as another region of electron density. In fact, they often have a larger electron density than a bond!
- Sun Nov 22, 2020 12:11 am
- Forum: Lewis Structures
- Topic: Sapling Hw #12
- Replies: 3
- Views: 203
Re: Sapling Hw #12
Yea! Just use the mass percentage to determine the empirical formula, and then divide by the molar mass to find the molecular formula. Then you can make a lewis structure of the molecular formula.
- Sat Nov 21, 2020 11:43 pm
- Forum: Ionic & Covalent Bonds
- Topic: Radicals
- Replies: 10
- Views: 456
Re: Radicals
Yes, the answer key is most probably wrong. C has 4 electrons and each H has 1 electron, which will result in 7 electrons, implying a radical.
- Sat Nov 21, 2020 11:38 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Linear shape
- Replies: 7
- Views: 386
Re: Linear shape
There's a lone pair in NO2- which changes its shape from linear to bent! The lone pair repels the bonds creating the lone pair shape.
- Sat Nov 21, 2020 11:33 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polar or Nonpolar
- Replies: 13
- Views: 1084
Re: Polar or Nonpolar
Hi! If the shape is symmetric with the same atoms on each side, it won't be polar. If the same is asymmetric at all or has different atoms at different points, the bond will be polar.
- Thu Nov 12, 2020 10:42 pm
- Forum: Lewis Structures
- Topic: Trouble with question 1 on sapling.
- Replies: 3
- Views: 197
Re: Trouble with question 1 on sapling.
That's right! The oxygen will have 2 lone pairs and will be double-bonded with C. The hydrogens will be single bonded with the C as well. Maybe double-check and see if the question asks for charges because that could be resulting in your error.
- Thu Nov 12, 2020 8:27 pm
- Forum: Bond Lengths & Energies
- Topic: Sapling HW Bond Length
- Replies: 7
- Views: 414
Re: Sapling HW Bond Length
Hi! S actually has a larger atomic radius as it has more electrons, which would make the bond length between Si-S longer than that of Si-O. Atomic radii increase down the period! And as S has a larger radius, it will have a longer bond length in comparison to O.
- Wed Nov 11, 2020 7:29 pm
- Forum: Ionic & Covalent Bonds
- Topic: Hydrogen Bond Homework Question
- Replies: 3
- Views: 125
Re: Hydrogen Bond Homework Question
That's right! Hydrogen bonds can only form when hydrogen is bonded to a highly electronegative ion, such as F. The difference in their electronegativities leads to the dipoles that are formed in the molecule which allows for the hydrogen bonds to occur. This is why hydrogen bonds only happen with N,...
- Wed Nov 11, 2020 7:26 pm
- Forum: Dipole Moments
- Topic: Dipole dipole vs LDF
- Replies: 10
- Views: 3455
Re: Dipole dipole vs LDF
Dipole-dipole and LDF forces are similar as they occur from the dipoles of molecules. However, dipole-dipole forces occur in polar atoms/molecules while LDF forces occur spontaneously in any atom/molecule as a result of a shift in its electron density.
- Wed Nov 11, 2020 7:24 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Audio-Visual Modules for MD 2 Material?
- Replies: 5
- Views: 345
Re: Audio-Visual Modules for MD 2 Material?
I don't think there are any more modules for the subjects we are covering and Dr. Lavelle said that he probably won't upload anymore.
- Sat Nov 07, 2020 12:03 am
- Forum: Resonance Structures
- Topic: Bond lengths
- Replies: 20
- Views: 763
Re: Bond lengths
Hi! I'm pretty sure that the length of the bonds in your Lewis Structures don't matter as long as you conceptually understand that double and triple bonds are shorter and the reasoning behind this.
- Sat Nov 07, 2020 12:01 am
- Forum: Electronegativity
- Topic: Noble Gases
- Replies: 40
- Views: 12791
Re: Noble Gases
Noble gases are usually left out of periodic table trends as they have a full octet and therefore do not want to gain any or lose any electrons. So, they are not used in periodic table trends such as electronegativity.
- Fri Nov 06, 2020 11:57 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Isoelectric atoms
- Replies: 9
- Views: 692
Re: Isoelectric atoms
Hi! Isoelectric atoms have the same number of electrons (ex. F- and Ne). However, as you can see they will have different charges and different properties overall.
- Fri Nov 06, 2020 11:45 pm
- Forum: Lewis Structures
- Topic: lewis structure
- Replies: 17
- Views: 633
Re: lewis structure
Hi! So the charge on the outside of the brackets represents the overall charge of the atom or molecule. Usually, you can figure out the charge of the molecule based on the properties of the atoms that make it up. As Dr.Lavelle said in the lecture, you would use the formula (FC = ( S/2 + LP)) to find...
- Tue Nov 03, 2020 11:13 pm
- Forum: Lewis Structures
- Topic: sides
- Replies: 12
- Views: 627
Re: sides
I don't think it matters at all! As long as your structure is accurate the way you put the atoms should not influence anything.
- Mon Nov 02, 2020 10:41 pm
- Forum: Trends in The Periodic Table
- Topic: # of electrons
- Replies: 23
- Views: 702
Re: # of electrons
Hi! I agree with the above statements. If you want to find the number of total electrons of the element, you look at the atomic number. And if you want to find the number of valence electrons, you would look at the number of electrons in the s and p orbitals for rows 1-3.
- Sat Oct 31, 2020 4:52 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Sapling Homework
- Replies: 8
- Views: 321
Re: Sapling Homework
That does look like the correct answer. I agree with what is said above about removing the commas! The only other thing I can think of is if you are using the carrots (^) to show the exponents instead of putting the actual exponents. Make sure to use the exponent feature on sapling to actually put e...
- Sat Oct 31, 2020 4:46 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: n and l numbers
- Replies: 5
- Views: 390
Re: n and l numbers
Hi! Generically, the corresponding orbitals do follow the pattern l = 0 is s, l = 1 is p, l = 2 is d, and l = 3 is f. So, for the 7p^5 example you mentioned, it would have quantum numbers of n = 7 and l = 1, as you are in the p-orbital.
- Sat Oct 31, 2020 4:40 pm
- Forum: Ionic & Covalent Bonds
- Topic: Is ionic or covalent stronger?
- Replies: 31
- Views: 16743
Re: Is ionic or covalent stronger?
I have always been told ionic bonds are the strongest, then covalent bonds, then London forces. I would assume that ionic would be the strongest because the atoms actually give up or gain electrons, they don't share them as is the case with covalent bonds.
- Sat Oct 31, 2020 4:38 pm
- Forum: Ionic & Covalent Bonds
- Topic: lone pairs
- Replies: 5
- Views: 371
Re: lone pairs
Yes! Lone pairs indicate a higher reactivity as the atom either wants to lose that electron or gain another one in order to have a full orbital or subshell.
- Sat Oct 31, 2020 4:34 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Sapling #21
- Replies: 3
- Views: 137
Re: Sapling #21
Hi! So what helps me in understanding orbitals is to think of them as addresses! You will need to memorize a few properties of the orbitals, for example, that p orbitals have 6 electrons, but when you think of them as addresses it becomes clearer. Think of the energy level, n, as a country. So, anyo...
- Mon Oct 26, 2020 11:08 pm
- Forum: DeBroglie Equation
- Topic: De Broglie wavelength
- Replies: 3
- Views: 135
Re: De Broglie wavelength
I believe that Dr. Lavelle has stated that objects with a wavelength of 10^-15 m or larger have wavelike properties, and objects with a smaller wavelength do not have discernable wavelike properties as their wavelength is so small it is imperceptible.
- Fri Oct 23, 2020 8:21 pm
- Forum: DeBroglie Equation
- Topic: Sapling #22
- Replies: 11
- Views: 326
Re: Sapling #22
De Broglie's formula is used to find the velocity of an electron. You cannot immediately use E = hv, as the kinetic energy is a portion of this energy, not all of it. Due to this, you would have to isolate the electron's velocity and then solve for the kinetic energy using the kinetic energy equatio...
- Fri Oct 23, 2020 8:18 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Orbitals
- Replies: 9
- Views: 333
Re: Orbitals
Hey! An electron in the 5s state is said to be at the 5th energy level in the s orbital. So, n= 5 and l = 0.
- Fri Oct 23, 2020 8:15 pm
- Forum: Properties of Light
- Topic: Units for wavelength/frequency
- Replies: 18
- Views: 1381
Re: Units for wavelength/frequency
Wavelength is measured in m, or some variety of meters, like nanometers, which will probably be given to us in the problem itself if we need to change the length to nm or do any other conversions. Frequency is measured in Hertz (Hz), which is 1/s. This too can be converted into MHz and similar value...
- Fri Oct 23, 2020 8:11 pm
- Forum: Student Social/Study Group
- Topic: How are you studying?
- Replies: 204
- Views: 21257
Re: How are you studying?
Hi! What I tend to do is attempt to practice problems so that I can understand the steps that should be taken to start each solution. By practicing lots of problems, I am able to grasp the overall flow of how to solve them quicker. For more conceptual topics, I take notes on them and then proceed to...
- Fri Oct 23, 2020 7:44 pm
- Forum: *Black Body Radiation
- Topic: Midterm 1
- Replies: 15
- Views: 947
Re: Midterm 1
He mentioned during lecture that black body radiation is not a concept we need to know!