Search found 107 matches
- Sun Mar 15, 2020 7:13 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Endgame Q.9
- Replies: 1
- Views: 127
Re: Endgame Q.9
basically; you have to remember that solid and liquids are not used in Q or K calculations, which is where they try to trick you!
- Sun Mar 15, 2020 7:11 am
- Forum: Phase Changes & Related Calculations
- Topic: Midterm Q4
- Replies: 7
- Views: 528
Re: Midterm Q4
the reason Br- doesn't need to be included is that it is a spectator ion. spectator ions are ions that do not participate in the reaction and are literally "spectators". if you notice in the question, you'll see that the change is changing on the NH3+ and NH2, and those are the only ions t...
- Sun Mar 15, 2020 7:01 am
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Flipping the anode
- Replies: 4
- Views: 353
Re: Flipping the anode
in terms of the equations representing galvanic cells, we'd flip the anode because all of the standard cell equations are in the form of reduction, which is the process that is occurring at the cathode. We'd flip the anode in a chemical equation because doing so, we'd represent the reaction occurrin...
- Sun Mar 15, 2020 6:58 am
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: final review slide 4
- Replies: 4
- Views: 401
Re: final review slide 4
he finds the net production of gas because there are 3 mols of gas on the right side (products), 2 mols of gas on the left (reactants). Because this is a standard 1.00 mole reaction of O2, meaning the equation presented is what is occurring, you find the total production with a 3-2=1 mole of gas. th...
- Sun Mar 15, 2020 6:47 am
- Forum: Administrative Questions and Class Announcements
- Topic: "Open Book" Final?
- Replies: 30
- Views: 1953
Re: "Open Book" Final?
thank you everyone! this helped much including lavelle's email. I think lecture notes, discussion notes, and textbook are the way to go.
- Fri Mar 13, 2020 10:23 am
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Endgame Q.2D
- Replies: 2
- Views: 244
Endgame Q.2D
Can anyone guide me through part D of question 2 on the 'endgame' review? I've correctly calculated part B (which is to find deltaGo, Eo, and K) I'm quite sure, but every time I go through part D I feel like I'm getting a crazy answer. The galvanic cell is at 25C: Fe(s) | Fe2+(aq) || Ce4+(aq), Ce3+(...
- Wed Mar 11, 2020 8:05 pm
- Forum: Administrative Questions and Class Announcements
- Topic: "Open Book" Final?
- Replies: 30
- Views: 1953
"Open Book" Final?
I'm not sure if this question has been answered yet on Chem Community, but what are the resources we'd use in this "open book" final scenario? Would it be our textbook and/or notes and/or chem community? That's what I've been assuming but is it stricter or looser than that?
- Mon Mar 09, 2020 12:01 am
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Ecell
- Replies: 5
- Views: 334
Re: Ecell
Ecell[o] is the standard cell potential; basically the calculated cell potential in standard conditions, which you find using standard reduction potentials. Ecell is the cell potential outside of these standard conditions, which you can use Ecell[o] to find this nonstandard potential.
- Sun Mar 08, 2020 11:57 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: n in NFE
- Replies: 64
- Views: 2956
Re: n in NFE
When you are solving for a redox reaction, and you split the original reaction into its respective half-reactions, you have to balance both the molecules involved and the electrons transferred. That final balanced value of electrons transferred is your n value. The top answer in this forum helps! ht...
- Sun Mar 08, 2020 11:43 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: G=-nFe
- Replies: 7
- Views: 784
Re: G=-nFe
n indicates the number of electrons that are involved in the transfer between the oxidizing agent and reducing agent. When you have your two half-reactions for OX and RED, you have to balance your electrons to make sure your electron transfer is balanced out. The balanced value of electrons is what ...
- Sun Mar 08, 2020 11:30 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: kinetics vs thermo
- Replies: 3
- Views: 393
Re: kinetics vs thermo
So in cases where kinetics dictate reaction rates, it is typically when there's a large energy barrier between the reactants and products & the reaction wouldn't happen in regular conditions & is typically irreversible. the example Lavelle gave was the reaction from Carbon (diamond) to Carbo...
- Sun Mar 08, 2020 11:14 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K notation
- Replies: 4
- Views: 296
Re: K notation
it probably won't count against you as long as you keep track of which K you're working with, e.t.c; I think in terms of concentration, I think Kc you can remember as c=concentration, Kp as p=pressure (equilibirum). it shouldn't be too big of an issue!
- Sun Mar 01, 2020 11:53 pm
- Forum: First Order Reactions
- Topic: First order plot
- Replies: 3
- Views: 258
Re: First order plot
the straight-line plot essentially means that as the reaction proceeds, the natural log of the reactant declines at the rate constant of k and is in first-order, and doesn't accelerate or decline across a particular time span.
- Sun Mar 01, 2020 11:39 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Voltage
- Replies: 6
- Views: 390
Re: Voltage
it's more to keep track of whether or not you definitively have a positive voltage value, but it's always a good idea to put + or - in front of your values because those voltage values (whether positive or negative) must be defined.
- Sun Mar 01, 2020 11:19 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 6M.1 reversed anode and cathode?
- Replies: 3
- Views: 224
Re: 6M.1 reversed anode and cathode?
so in general, I think it's a really good idea to always think of it in anode/cathode terms over left/right terms, just in case a question switches it on you. In this case, they actually do flip the cell diagram so you have to be a tad careful. so the standard reduction potential of Cu2+/Cu is +.34V...
- Sun Mar 01, 2020 10:15 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: n value
- Replies: 4
- Views: 369
Re: n value
the n values in a balanced set of half-reactions don't change, but if the set of reactions happened twice for example, then yes technically the number of electrons transferred would change (but not fundamentally within the half-reactions themselves). you're right though with cell potential being int...
- Sun Mar 01, 2020 9:55 pm
- Forum: First Order Reactions
- Topic: rate constants
- Replies: 30
- Views: 1373
Re: rate constants
the rate constant (which is k) should always be positive; you can think of a rate as always positive because k (a proportion between concentrations) is positive, and rate can be presented as K[R]^n, which must be positive as negative concentration or proportions cannot exist. on a graph of a first-o...
- Sun Feb 23, 2020 9:57 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Positive or Negative Sign
- Replies: 4
- Views: 277
Re: Positive or Negative Sign
you change the sign only on the anode because the anode is losing electrons (is the oxidation 1/2 reaction). every cell potential is given in reduction form, so you'll need to switch the sign to account for the oxidation 1/2 reaction.
- Sun Feb 23, 2020 9:55 pm
- Forum: Balancing Redox Reactions
- Topic: Test 2
- Replies: 9
- Views: 510
Re: Test 2
week 9, starts on Tuesday! that's what lavelle posted at the end of lecture :)
- Sun Feb 23, 2020 9:52 pm
- Forum: Balancing Redox Reactions
- Topic: Oxidation?
- Replies: 10
- Views: 663
Re: Oxidation?
oxidation is the process in which an atom loses an electron (LEO = Lose Electron Oxidation). an example of a redox reaction is Cu2+ + Zn -> Cu + Zn2+. A plus following an atom indicates that the respective atom has less negative charge (electrons) than it would in its standard form on the periodic t...
- Sun Feb 23, 2020 9:34 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell Potentials
- Replies: 2
- Views: 189
Re: Cell Potentials
the method to use without changing the signs is subtracting the anode cell potential from the cathode cell potential (subtract "Left" from "Right"). In the example of a Cu/Zn battery, the potential for the Copper reduction is .34V, and the Zinc reduction is -.76. You subtract -.7...
- Sun Feb 23, 2020 4:11 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Platinum Cell Diagram
- Replies: 2
- Views: 176
Re: Platinum Cell Diagram
platinum is used when there are no conducting solids, and Iodine in a solid form isn't a conductor; if you look on a periodic table, Iodine is one of the noble gases, which are all nonmetals (& on the nonmetal "side" of the table) and generally unreactive. they can't conduct electricit...
- Sun Feb 23, 2020 4:08 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: electrode
- Replies: 4
- Views: 378
Re: electrode
an electrode is an electrical conductor that carries a current to and from non-metallic materials (solids, liquids, gas, e.t.c). in the example of an electrochemical cell (the diagrams Lavelle shows in his lectures), the electrode is that conductor that is inside the ionized liquid/gas to transfer e...
- Mon Feb 17, 2020 10:41 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Van't Hoff
- Replies: 6
- Views: 283
Re: Van't Hoff
when you use Van't Hoff, it's assumed that you're using it with a system that's under constant pressure, because the equation is in part derived from the Gibbs-Helmholtz equation, where pressure is assumed to be constant.
- Mon Feb 17, 2020 10:28 pm
- Forum: Balancing Redox Reactions
- Topic: Oxidation numbers [ENDORSED]
- Replies: 4
- Views: 315
Re: Oxidation numbers [ENDORSED]
to figure out oxidation numbers, there are different rules that help you figure out oxidation numbers. for example, any substance that contains atoms of only one element all have an oxidation number of zero, and H in any compound with a nonmental has an oxidation number of 1+. this article https://c...
- Mon Feb 17, 2020 10:16 pm
- Forum: Balancing Redox Reactions
- Topic: Electron transfer and entropy
- Replies: 1
- Views: 170
Re: Electron transfer and entropy
entropy is tied to the 2nd law of thermodynamics (which is that the entropy in a closed system never decreases; either remains constant in equilibrium or increases), and as far as I've looked electrons are so small in conjunction with the 2nd law, as well as somewhat having 0 entropy because of thei...
- Mon Feb 17, 2020 12:13 am
- Forum: Balancing Redox Reactions
- Topic: Oxidation Number Rules
- Replies: 7
- Views: 466
Re: Oxidation Number Rules
I think it's always nice to remember those "essential" ones, like how free elements always have 0, oxygen is typically 2- in compounds, hydrogen is 1+, or ox number typically equals charge of a monoatomic ion. There's ~5 more I believe, so I think having the idea behind those wouldn't be b...
- Mon Feb 10, 2020 10:30 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Is heat capacity/specific heat capacity a state function?
- Replies: 2
- Views: 85
Re: Is heat capacity/specific heat capacity a state function?
heat capacity is a state function, because it doesn't matter how you added/lost heat or manipulated the temperature, it only matters what material the heat capacity reflects and the heat capacity in that particular moment, ignoring the pathways to get there.
- Mon Feb 10, 2020 10:25 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: q, qv, qp
- Replies: 1
- Views: 289
Re: q, qv, qp
you can use qv and qp to denote which constant the system is in, but they also serve an important purpose because depending on whether a system is in a constant volume or pressure state changes the capacity to do work regardless of having the same internal energy. For example, because deltaU = q+w, ...
- Mon Feb 10, 2020 9:59 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Extensive and State properties
- Replies: 3
- Views: 140
Re: Extensive and State properties
state functions can be considered both extensive and intensive; a good example are heat capacity values. regular heat capacity, for example, is an extensive property because it depends on the mass amount in that particular moment. specific heat capacity(and molar heat capacity), on the other hand, i...
- Sun Feb 09, 2020 5:49 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Notes from class
- Replies: 1
- Views: 116
Re: Notes from class
I can send you them if needed!
- Sun Feb 09, 2020 3:40 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: combustion rxn
- Replies: 2
- Views: 174
Re: combustion rxn
I don't remember having written down a specific equation, but combustion problems should probably ask for expansion/work of the gaseous products, and if you know the chemical equation as well as the starting number of moles for one of the reactants, you can. An example of this is the reaction C6H6(s...
- Sun Feb 02, 2020 11:10 pm
- Forum: Phase Changes & Related Calculations
- Topic: phase changes, temperature constant?
- Replies: 11
- Views: 577
Re: phase changes, temperature constant?
heat remains constant during a phase change because heat is being supplied to the phase change mechanism itself, not to the actual heating of the subject being heated. heat is being used in creating the phase change at the same rate that it's being applied to the actual material, so the heat remains...
- Sun Feb 02, 2020 11:07 pm
- Forum: Phase Changes & Related Calculations
- Topic: calorimeter vs bomb calorimeter
- Replies: 1
- Views: 107
Re: calorimeter vs bomb calorimeter
a regular calorimeter is insulated similarily to a bomb calorimeter, it's simply less sophisticated. a bomb calorimeter is completely isolated from the environment around it, while a regular calorimeter allows the contents to adjust to the external pressure, so it is not completely isolated to the e...
- Sun Feb 02, 2020 11:00 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: qp = ΔH?
- Replies: 5
- Views: 317
Re: qp = ΔH?
qp=enthalpy change when there is no change in pressure; for example if the reaction occurred in a system where pressure was constant(an open beaker).
- Sun Feb 02, 2020 10:57 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Heat capacity vs. specific heat capacity
- Replies: 3
- Views: 360
Re: Heat capacity vs. specific heat capacity
heat capacity is, by definition, the heat required to raise the temperature of an object by 1 degree C. heat capacity by itself is an extensive property, which essentially means that heat capacity depends on the mass amount. specific heat capacity is an intensive property, which doesn't depend on th...
- Sun Feb 02, 2020 10:51 pm
- Forum: Calculating Work of Expansion
- Topic: Integrals
- Replies: 4
- Views: 165
Re: Integrals
I think you primarily have to understand that integrals basically represent the change in value over time (ex. the change in volume used in the work equation, e.t.c), and because we calculate that, we're essentially using integrals. I don't think we'll have to use it/explain it in terms any more com...
- Sat Jan 25, 2020 4:43 pm
- Forum: Phase Changes & Related Calculations
- Topic: Bond Enthalpies
- Replies: 5
- Views: 99
Re: Bond Enthalpies
using bond enthalpies to find overall enthalpy gains/losses is considered the least accurate because save for diatomic molecules, all other compounds are from averages across different molecules
- Sat Jan 25, 2020 3:47 pm
- Forum: Phase Changes & Related Calculations
- Topic: State Functions - Heat vs. Temperature
- Replies: 2
- Views: 58
Re: State Functions - Heat vs. Temperature
heat is a property that is heavily influenced by that path taken to reach its final value, which is what a state function is not. because heat is typically defined as the energy transferred between a system and its surroundings, the amount of heat transferred depends on the process happening in that...
- Sat Jan 25, 2020 3:41 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: standard enthalpy
- Replies: 2
- Views: 41
Re: standard enthalpy
so conceptually, standard (reaction) enthalpy (which is what I think you're asking about) is the enthalpy when reactants are in their standard (most stable) state and the reactants are in their standard state as well. additionally, these standard enthalpies are all measured at 1atm, because at diffe...
- Sat Jan 25, 2020 3:28 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Chem Community Questions Due Date
- Replies: 2
- Views: 67
Re: Chem Community Questions Due Date
chem community questions are always due on sunday (11:59pm) I'm almost positive; that was the due date last quarter & I always posted before then and got full credit!
- Sat Jan 25, 2020 3:26 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: work
- Replies: 5
- Views: 279
Re: work
work is defined as achieving some sort of motion against an opposing force, and is characterized by the equation w= opposing force(on object/system) x distance moved. you can think of it as lifting an object up off the ground; you're opposing the force of gravity by lifting that object, and moving i...
- Sat Jan 25, 2020 3:06 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: state functions?
- Replies: 6
- Views: 729
Re: state functions?
state functions are only determined by final & initial values, much like how a state property is determined by its current state & not the path taken to obtain that state.
- Sat Jan 25, 2020 2:31 pm
- Forum: Phase Changes & Related Calculations
- Topic: Lecture Notes Last Friday 1/17/20
- Replies: 2
- Views: 89
Re: Lecture Notes Last Friday 1/17/20
the lecture last Friday was primarily focused on a lot of math concepts surrounding % pronation, pHs of salt solutions, buffers, and weak base/acid calculations. there were a lot of examples for calculations surrounding this, so I can send you an email with those examples!
- Mon Jan 20, 2020 3:16 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5I.25
- Replies: 2
- Views: 79
Re: 5I.25
so I did this problem & checked the solutions manual, and really the only way it works well to get the final concentrations is to use the quadratic formula. Because every compound has an initial value (& will, as a result, have an "x" value of product added/removed), your K= P/R ra...
- Mon Jan 20, 2020 3:07 pm
- Forum: *Making Buffers & Calculating Buffer pH (Henderson-Hasselbalch Equation)
- Topic: pH of a buffer solution calculation
- Replies: 4
- Views: 1483
Re: pH of a buffer solution calculation
you can use an ICE table for a buffer solution; we had the example of HNO2+H2O = H3O+ + NO2- in lecture to find the pH of that particular buffer solution; we can probably easily use the Henderson-Hasselbach equation too (as long as you don't get the acid/base & it's conjugate flipped around!)
- Mon Jan 20, 2020 3:05 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: ka/kb and pH/pOH relationship
- Replies: 1
- Views: 212
Re: ka/kb and pH/pOH relationship
if you're talking about the "conjugate seesaw" example in lecture, you're correct in that [H3O+] is related to Ka (because it's the K constant of the acid). Ka and Kb are related to pH and pOH, because taking the negative log of that particular K value value (where it's the Ka or Kb depend...
- Mon Jan 13, 2020 12:25 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: PV=nRT
- Replies: 9
- Views: 380
Re: PV=nRT
have we gone over this in class in an example equation? not really; lavelle primarily showed us pv=nrt and how we can get the calculation for concentration (concentration=p/rt) from the equation. there are a lot of practice problems in the textbook that are about going from partial pressure (p) and...
- Mon Jan 13, 2020 12:21 pm
- Forum: Properties of Electrons
- Topic: wave particle duality of electron
- Replies: 2
- Views: 201
Re: wave particle duality of electron
electrons have properties that can identify them as both particles and waves. a good example of electrons being presented as particles is the photoelectric effect, where one photon at a particular level of energy can eject one (and only one) electron from a metal surface. Because one photon removes ...
- Mon Jan 13, 2020 12:33 am
- Forum: Ideal Gases
- Topic: equilibrium constant purpose
- Replies: 7
- Views: 179
Re: equilibrium constant purpose
K is a summary of the composition of a reactant mixture at equilibrium essentially; it's a value that represents where reactants and products have no net change during the reaction, and this state is represented by K (which is essentially a ratio value between reactants and products).
- Mon Jan 13, 2020 12:27 am
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Q=K
- Replies: 14
- Views: 605
Re: Q=K
Q is representative of a chemical system's direction towards products/reactants at any given moment; so it can represent a system out of equilibrium or possibly a system in equilibrium at a very specific moment. Q can equal K in a given moment in time during a chemical reaction; it simply means that...
- Mon Jan 13, 2020 12:23 am
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Units for Q- HW 5I.11
- Replies: 3
- Views: 180
Re: Units for Q- HW 5I.11
K and Q values are found in mol/L most often, so you should convert those values from mmol to mol to get standard concentration values .
- Sun Dec 08, 2019 1:14 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Oxalate
- Replies: 2
- Views: 225
Re: Oxalate
oxalate is only a bidentate ligand because once two oxygens bind to a metal, their position is essentially fixed there. The two other oxygen atoms on the opposing side can't cross over to bind to the metal because it's impossible due to the existing bonds.
- Sun Dec 08, 2019 1:08 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Co3 2-
- Replies: 1
- Views: 279
Re: Co3 2-
it's not possible for CO3 2- to be bidentate to ONE metal (120 degree bond angle isn't big enough basically). However, if there's another metal present, another oxygen in CO3 2- can bind to that other metal, which will make carbonate bidentate.
- Sun Dec 08, 2019 1:04 am
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: 6B.5 help
- Replies: 1
- Views: 112
Re: 6B.5 help
first, you'll have to use stoich to get the 13.6 mg of NaOH to moles (Because NaOH dissolves at 100% disassociation, you don't have to worry about any partial dissolving etc). once you have converted your NaOH to moles, you divide that value of moles by the number of liters. there's a 1:1 ratio of O...
- Sun Dec 08, 2019 12:55 am
- Forum: Industrial Examples
- Topic: Cisplatin Vs. Transplatin
- Replies: 7
- Views: 1403
Re: Cisplatin Vs. Transplatin
it's because cisplatin is more effective in binding to guanine to prevent DNA replication as opposed to transplatin. cis- and trans- determine the configuration of ligands around the platinum metal; cis means that two of the same atoms/molecules are on the same side of a molecule as the other, trans...
- Sun Dec 08, 2019 12:52 am
- Forum: Air Pollution & Acid Rain
- Topic: Options to reduce acid rain
- Replies: 8
- Views: 552
Re: Options to reduce acid rain
in the textbook, there's a box in chapter 6 (6E.1) which does a really good job in explaining the different acids involved in acid rain. it proposes the automobile solution of reducing NO to harmless N2 to prevent it from forming nitric acid but doesn't go too into a deep explanation of chemical sol...
Re: Cyanido
in new naming conventions, both are cyanido. however, the old conventions (which I would use, personally) designate it as cyano (CN-, bonding on C) and isocyano (NC-, bonding on N)
- Sun Dec 08, 2019 12:37 am
- Forum: Polyprotic Acids & Bases
- Topic: HCLO4 vs. H3PO4
- Replies: 4
- Views: 459
Re: HCLO4 vs. H3PO4
HClO4 is the stronger acid. The comparison here is that you have to look at electronegativities, a quality that Cl is stronger in than P. Cl is more electronegative, which means it draws electrons closer to itself and delocalizes electrons. This pull pulls electrons from H, making it unfavorable for...
- Sun Dec 08, 2019 12:32 am
- Forum: Naming
- Topic: Ferrate and Cuprate? [ENDORSED]
- Replies: 5
- Views: 515
Re: Ferrate and Cuprate? [ENDORSED]
ferrate and cuprate are used when the coordination complex is negative overall. all of the metals can have -ate added to the end of their names, but iron and copper need to be in their latin terms (an easy way to remember is that iron = Fe & copper = Cu. FErrate and CUprate).
- Sun Dec 08, 2019 12:29 am
- Forum: Hybridization
- Topic: Lone Pair Hybridization
- Replies: 3
- Views: 239
Re: Lone Pair Hybridization
you only write out the coefficient (the 2 in 2sp3) when involved in a bond where the quantum number involved in the bond is needed. lone pairs don't need the coefficient because they aren't involved in a bond where the quantum number needs to be specified.
- Sun Dec 01, 2019 9:43 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Polydentate
- Replies: 5
- Views: 327
Re: Polydentate
polydentate ligands are ligands that bind to a central metal atom with more than one atom (more than 1 binding site, or more than 1 e- pair donated). EDTA is an example of this - a hexa(6)dentate ligand with six donor atoms, all with e- pairs that can bind to a central metal atom or ion.
- Sun Dec 01, 2019 9:36 pm
- Forum: Lewis Acids & Bases
- Topic: Protons in Acids
- Replies: 6
- Views: 277
Re: Protons in Acids
because strong acids almost completely disassociate (overall, a higher number of protons are produced because a higher proportion of acid molecules disassociate). weak acids incompletely ionize, with a lower proportion of the acid ionized, which results in a lower number of protons produced.
- Sun Dec 01, 2019 9:36 pm
- Forum: Lewis Acids & Bases
- Topic: Protons in Acids
- Replies: 6
- Views: 277
Re: Protons in Acids
because strong acids almost completely disassociate (overall, a higher number of protons are produced because a higher proportion of acid molecules disassociate). weak acids incompletely ionize, with a lower proportion of the acid ionized, which results in a lower number of protons produced.
- Sun Dec 01, 2019 9:27 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Calculating pH for acids and bases
- Replies: 1
- Views: 112
Re: Calculating pH for acids and bases
this is true; for weak acids/bases we'd need to use the equilibrium constant equation which Lavelle said we wouldn't be using until 14B
- Sun Dec 01, 2019 9:24 pm
- Forum: Lewis Acids & Bases
- Topic: Properties of Bases
- Replies: 3
- Views: 227
Re: Properties of Bases
it's because bases reacts with oils & fatty acids on your skin (basically dissolves them), which removes friction, leading to that soapy feeling.
- Sun Dec 01, 2019 9:20 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Why sulfuric acid is stronger than phosphoric acid
- Replies: 4
- Views: 3653
Re: Why sulfuric acid is stronger than phosphoric acid
it has to do with the formal charge of both; sulfur in H2SO4 has a charge of +2, while phosphorus has a +1 charge. Sulfur has a higher charge, so it'll withdraw e- density more from the surrounding oxygens than phosphorus. (e- density decreases so more H atoms in H2SO4 will disassociate). hope that ...
Re: Order
the TM cation comes after the ligand names, and if there are any anions with a hydrate, anions follow the TM cation.
- Sun Nov 24, 2019 3:47 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Focus 9C.1 and 9C.2
- Replies: 2
- Views: 131
Re: Focus 9C.1 and 9C.2
9C.1 is called coordination complexes, and 9C.2 is called the shapes of complexes, hope this helps!
- Sun Nov 24, 2019 3:12 pm
- Forum: Naming
- Topic: Naming & Dashes
- Replies: 1
- Views: 96
Re: Naming & Dashes
you're typically don't use dashes I believe - when you write out a coordination compound all of the naming components come one after another (ex. the example from class. - [CO(NH3)5Cl]Cl*2H2O = pentaaminechlorocolbalt(II) chloridedihydrate)
- Sun Nov 24, 2019 3:03 pm
- Forum: Naming
- Topic: Week 9 and Week 10 HW?
- Replies: 21
- Views: 958
Re: Week 9 and Week 10 HW?
that's what I'm planning to do, just putting a little header before week 9 hw and a different one before week 10. probably be easier for TAs too?
- Sun Nov 24, 2019 3:00 pm
- Forum: Hybridization
- Topic: Why do we use Hybridization?
- Replies: 2
- Views: 191
Re: Why do we use Hybridization?
hybridization is favored when we have bond formation because the overall energy of two combined orbitals from hybridization is lower than if there were two separate orbitals in bond formation. lower energy indicates more stability, so hybridization is more favored. hope this helps!
- Sat Nov 16, 2019 1:30 pm
- Forum: Sigma & Pi Bonds
- Topic: Sigma & Pi Bonds
- Replies: 4
- Views: 930
Re: Sigma & Pi Bonds
sigma and pi bonds are fairly easy to understand; the names are more used for identification more than anything else. sigma bonds are the first bonds that form between two atoms (that first line when you draw between two atoms in a diagram). pi bonds are any more bonds after that (double bond, tripl...
- Sat Nov 16, 2019 1:23 pm
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: Polar/non-polar
- Replies: 3
- Views: 114
Re: Polar/non-polar
a lot of how a molecule is polar or not can be determined by the symmetry of the molecule. if a dipole is present in an individual bond but has an identical counterpart opposite to that bond, the dipoles will cancel and the molecule will be nonpolar. if dipoles do not cancel due to symmetry, the mol...
- Sat Nov 16, 2019 12:40 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: T-shape
- Replies: 6
- Views: 466
Re: T-shape
He didn't talk about T-shaped structures, but the VSEPR equation for T-shaped structures is AX3E2; 5 areas of e-density total, 3 bonded regions, 2 lone pairs (around central atom). The 2 lone pairs are in opposition to each other and push the 3 bonded atoms into a T-shape I found a good slideshow th...
- Sat Nov 16, 2019 12:33 pm
- Forum: Dipole Moments
- Topic: Dipole-Dipole vs. Dipole-Induced Dipole
- Replies: 3
- Views: 135
Re: Dipole-Dipole vs. Dipole-Induced Dipole
dipole-dipole refers to the interaction between two molecules that both have dipole moments; that is, both molecules/bonds are polar. dipole-induced dipole is the weaker interaction between a polar molecule and a nonpolar one; the dipole in the polar disturbs the e- field of the nonpolar structure e...
- Sat Nov 16, 2019 12:20 pm
- Forum: Ionic & Covalent Bonds
- Topic: Polarity
- Replies: 6
- Views: 412
Re: Polarity
Polarity in individual bonds is most often determined by the difference in electronegativity between two atoms; typically a difference of 0.5-1.7 between two atoms determines a polar bond. this is the more quantitative way to determine polarity in one bond. you can also look at the periodic table an...
- Sun Nov 10, 2019 11:12 pm
- Forum: Resonance Structures
- Topic: Contribution of each structure?
- Replies: 4
- Views: 410
Re: Contribution of each structure?
formal charge indicates stability (0 is best unless there is a distinct negative/positive charge on the molecule) but I don't think there's a particular way we need to know to find the contribution of each resonance structure? just understand that all structures contribute to an overall average (whi...
- Sun Nov 10, 2019 11:05 pm
- Forum: Sigma & Pi Bonds
- Topic: Sigma & Pi Bonds
- Replies: 4
- Views: 246
Re: Sigma & Pi Bonds
possibly? the addition of pi bonds in a molecule does lead to increased electron density/orbital overlap, which impacts bond length and angles, which can impact geometry. mostly I think we'll have to see, but maybe know that bond number does impact strength and thus angle. hope this helps!
- Sun Nov 10, 2019 11:01 pm
- Forum: Lewis Structures
- Topic: CH2Cl2 structure
- Replies: 1
- Views: 206
Re: CH2Cl2 structure
when writing out the lewis structure, the order of molecules in this structure doesn't really matter (as long as carbon is central). The reason why the H's and Cl's are with their respective twin in a lot of diagrams rather than across has to do with dipoles and electric charge on each individual at...
- Sun Nov 10, 2019 10:54 pm
- Forum: Electronegativity
- Topic: Iodine
- Replies: 6
- Views: 616
Re: Iodine
Isn't there a greater shielding effect because iodine has a larger atomic radius than the other molecules? Im having trouble conceptualizing this becuase I would think F2 would have a stronger interaction because fluorine is the most electronegative atom and I thought they want the electrons the mo...
- Sun Nov 10, 2019 10:32 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Differentiation
- Replies: 1
- Views: 77
Re: Differentiation
typically the indication on a three-atom molecule is the electron pairs around a central atom. When you draw out the lewis structure and determine whether or not the central atom has lone pairs determines angularity. If there are no lone pairs on the central atom, this typically means the molecule h...
- Sun Nov 03, 2019 6:58 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Nodes
- Replies: 1
- Views: 123
Re: Nodes
nodes are where the probability to find an electron in that orbital are zero. the number of nodes increases with quantum orbital number. for example, in a 2s orbital, there's one radial node, in a 3s orbital, there are two radial nodes. there important in terms of drawing the orbitals, but it's prob...
- Sun Nov 03, 2019 6:54 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Formal Charge and Energy
- Replies: 4
- Views: 303
Re: Formal Charge and Energy
formal charge is basically a way to keep track of electrons, and determine which lewis structure you draw is more stable for that respective molecule (especially if there's resonance)
- Sun Nov 03, 2019 6:49 pm
- Forum: Sigma & Pi Bonds
- Topic: Sigma vs Pi Bonds
- Replies: 2
- Views: 188
Re: Sigma vs Pi Bonds
both sigma and pi bonds are from the overlap of orbitals - sigma is end-to-end (of two atoms), pi to orbital to orbital (of different atoms). a sigma bond is your first "basic" covalent bond - basically, the first line that you draw between two atoms is a sigma bond. Any more bonds added a...
- Sun Nov 03, 2019 6:43 pm
- Forum: Electronegativity
- Topic: Covalent Character and Polarizability
- Replies: 2
- Views: 292
Re: Covalent Character and Polarizability
the more polarizability a bond has, the covalent the bond (basically the less ionic) it is. a good example of this is H2O; water is a polar molecule because the tendency of the anion (Oxygen) to be polarized by the cation (Hydrogen) is high; Hydrogen is able to distort Oxygen's outer electron hold e...
- Sun Nov 03, 2019 6:30 pm
- Forum: Bond Lengths & Energies
- Topic: Focus 2.25
- Replies: 2
- Views: 145
Re: Focus 2.25
A relates to the inverse bond order-bond length, and B is related to the size of an atom and the how bond length increases/decreases as related, hope this helps!
- Fri Oct 25, 2019 2:38 pm
- Forum: Octet Exceptions
- Topic: Determining Exceptions
- Replies: 3
- Views: 242
Re: Determining Exceptions
since lavelle only introduced P, S, and Cl as the *current* exceptions we have to know, i'd say memorize those. But the general explanation for this is that Period 3(and greater) atoms have d-orbitals in their valence shells, which means that they can accommodate more electrons. (ex., Sulfer has the...
- Fri Oct 25, 2019 2:33 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ionization Energy
- Replies: 4
- Views: 246
Re: Ionization Energy
Why is there more energy the farther an atom is from a nucleus? I'm going to assume you mean electron, but as an electron is further away from the nucleus, it's n value (representing energy and size of the shell) increases. additionally, an electron farther away from the nucleus is said to have hig...
- Fri Oct 25, 2019 2:27 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: 1D.19
- Replies: 1
- Views: 76
Re: 1D.19
if you're asking about the value of L, L really only gives the shape of a subshell (s, p,d...). It's a label of the different subshells to distinguish them but doesn't explicitly tell you how many orbitals in the whole atom. electrons are more clear because there can only be a particular amount of e...
- Fri Oct 25, 2019 2:15 pm
- Forum: Ionic & Covalent Bonds
- Topic: Bond length
- Replies: 11
- Views: 397
Re: Bond length
Will bond length be given to us on tests or are we supposed to know bond lengths/assume resonance? Do you just base your lewis structure on the lowest formal charge? we probably don't need to memorize bond lengths, but in terms of resonance, I think that's something that we should be able to show (...
- Fri Oct 25, 2019 2:10 pm
- Forum: Ionic & Covalent Bonds
- Topic: Resonance
- Replies: 7
- Views: 314
Re: Resonance
I didn’t understand why oxygen received a negative charge instead of silver. Can someone please explain this to me? This has to do with the formal charge, or gaining/losing electrons when forming bonds. this is found with the equation FC = V - (L+(S/2)). To find the formal charge of oxygen in this ...
- Sun Oct 20, 2019 6:21 pm
- Forum: Properties of Electrons
- Topic: Energy increasing
- Replies: 7
- Views: 461
Re: Energy increasing
for erica, think of electron energy being completely separate from the electrostatic attraction; this is primarily because the quantum levels for an electron solely depend on the electron itself, not the forces acting on it.
- Sun Oct 20, 2019 5:58 pm
- Forum: Properties of Light
- Topic: Unit for Wavelength
- Replies: 34
- Views: 2306
Re: Unit for Wavelength
wavelength, as everyone said above ^ is in meters, but probably know picometers (10^-12) and nanometers (10^-9) conversions, since those are the most asked/common ways its asked for wavelength!
- Sun Oct 20, 2019 5:51 pm
- Forum: Photoelectric Effect
- Topic: 1B.15
- Replies: 2
- Views: 140
Re: 1B.15
the unit keV is a kiloelectron volt, where an electronvolt is the KE gained/lost by a single electron (which would correlate with the photons in the question). the electronvolt is the standard unit, so a kiloelectronvolt is equal to 1000 electronvolts. **an electron has energy equal to 1.6022x10^-19...
- Sun Oct 20, 2019 5:39 pm
- Forum: Einstein Equation
- Topic: When do we use the Einstein Equation?
- Replies: 14
- Views: 752
Re: When do we use the Einstein Equation?
Like Taryn said, we use it to find energy/photon, substitute it in the rydberg equation (the equation used to find frequency, energy,et.c. of light when electrons go up/down quantum levels) & c=v(wavelength. it's used a lot; besides c=v(wavelength) I think it's probably one of the most commonly ...
- Sun Oct 20, 2019 5:35 pm
- Forum: Properties of Light
- Topic: Light as a wave
- Replies: 4
- Views: 181
Re: Light as a wave
Where the light strikes doesn't really matter, primarily because we're focusing on the energy of the photon itself. Intensity doesn't impact energy/photon, just number of photons. However, if the number of photons was needed to be found in a certain amount of energy, you can find that with the energ...
- Sat Oct 12, 2019 9:48 pm
- Forum: Properties of Light
- Topic: Quantum Levels
- Replies: 9
- Views: 386
Re: Quantum Levels
there's really no limit on the levels, but we give electrons quantum levels to serve as a quantifiable measure. additionally, the quantum levels correlate with the type of electromagnetic radiation (visible, ultraviolet) that is present at those energy levels (Lavelle had a slide demonstrating this ...
- Sat Oct 12, 2019 9:32 pm
- Forum: DeBroglie Equation
- Topic: wave like properties
- Replies: 2
- Views: 97
Re: wave like properties
not completely sure what you're asking, but in terms of value, typically anything smaller than a 10^-15 m wavelength has no detectable wave-like properties. the key here is detectable because it's assumed that every object with momentum has wavelike properties (like a car). however, a car is so larg...
- Sat Oct 12, 2019 9:19 pm
- Forum: Properties of Light
- Topic: 1A.3
- Replies: 4
- Views: 208
Re: 1A.3
(a) from v(wave)=c, it must be true that the speed of light (electromagnetic radiation) is constant. thus, it's impossible for speed to decline (b) this is also false because of v(wave)=c. Because c is a constant, frequency and wavelength must have an inverse relationship to maintain this constant. ...