What does this formula represent/what is it used for?
Pn ∝ e(-En/kbT)
Search found 100 matches
- Sat Mar 13, 2021 5:16 pm
- Forum: General Science Questions
- Topic: Pn ∝ e(-En/kBT)
- Replies: 3
- Views: 3045
- Sat Mar 13, 2021 5:03 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing Reactions with elements besides O and H
- Replies: 2
- Views: 300
Re: Balancing Reactions with elements besides O and H
Because HNO 3 dissociates completely in solution, they can be written as aqueous ions in the chemical formula. In balancing the oxidation half-reaction, it becomes clear that NO 3 - is not one of the products of the reaction- the question is somewhat misleading when it suggests that Cu(NO 3 ) is bei...
- Sat Mar 13, 2021 4:44 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Changing k
- Replies: 3
- Views: 306
Changing k
Besides changing the temperature or introducing a catalyst, are there any ways to change the rate constant of a reaction?
- Sat Mar 13, 2021 11:39 am
- Forum: First Order Reactions
- Topic: Half-life independent from initial concentration
- Replies: 8
- Views: 1673
Half-life independent from initial concentration
I understand how the half-life equation is derived from the integrated rate law, but I was curious if there was a conceptual basis for the half-life being independent of initial concentration. I don't understand why the half-life of a first-order reaction wouldn't be dependent on initial concentrati...
- Sat Mar 13, 2021 11:34 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell potential equals 0
- Replies: 1
- Views: 147
Cell potential equals 0
Why does the cell potential of a galvanic cell decrease as the reaction proceeds? And at what point does the cell potential of a galvanic cell equal 0, assuming that the initial potential was some positive value?
- Fri Mar 12, 2021 11:00 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Sapling #13
- Replies: 3
- Views: 311
Sapling #13
Problem #13 on Sapling asks to find the overall rate law for a reaction given its elementary steps. I was wondering why OH-, which seems to be an intermediate, is in the overall rate law.
- Fri Mar 12, 2021 4:29 pm
- Forum: Balancing Redox Reactions
- Topic: determing n (moles of e)
- Replies: 12
- Views: 641
Re: determing n (moles of e)
I had trouble with this one too! Because the equation is balanced for us, the change in charge in one species will give us the overall number of electrons that moved. In this case, 2 Ce 4+ has a net charge of +8, and 2 Ce 3+ have a net charge of +6. Therefore, 2 electrons must have been transferred ...
- Fri Mar 12, 2021 4:26 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: n in ΔG = -nFE
- Replies: 6
- Views: 660
Re: n in ΔG = -nFE
Does this mean that you must balance the half-reactions before you can calculate the n for the overall reaction?
- Fri Mar 12, 2021 4:24 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Identifying reducing and oxidizing agents
- Replies: 8
- Views: 427
Identifying reducing and oxidizing agents
Textbook problem 6L.9 asks "Write balanced half-reactions for the redox reaction of an acidified solution of potassium permanganate and iron(II) chloride." The correct answer is that MnO 4 - is reduced to Mn 2+ and Fe 2+ is oxidized to Fe 3+ . How do you identify which species are being ox...
- Fri Mar 12, 2021 4:20 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Textbook 6L.7a
- Replies: 2
- Views: 204
Re: Textbook 6L.7a
How did you know to make Ag+(aq) --> Ag(s) when Ag(s) doesnt appear in the chemical formula?
- Fri Mar 12, 2021 3:35 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Textbook 6L.7a
- Replies: 2
- Views: 204
Textbook 6L.7a
Textbook problem 6L.6a is "Write the half-reactions and devise a galvanic cell (write a cell diagram) to study each of the following reactions: AgBr(s) ⇌ Ag + (aq) + Br - (aq), a solubility equilibrium. I'm confused by what "solubility equilibrium" means in this context, and how one c...
- Fri Mar 12, 2021 2:25 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: n in ΔG = -nFE
- Replies: 6
- Views: 660
n in ΔG = -nFE
What does n in ΔG = -nFE represent, and how do you find it?
- Fri Mar 12, 2021 2:09 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Anode and Cathode
- Replies: 25
- Views: 1436
Re: Anode and Cathode
Yes. By definition, oxidation always occurs at the anode and reduction at the cathode. Therefore, electrons flow from the anode to the cathode.
- Fri Mar 12, 2021 1:19 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Galvanic/ Concentration Cells
- Replies: 4
- Views: 965
Re: Galvanic/ Concentration Cells
A galvanic cell is a chemical system where an electric current is generated through a spontaneous redox reaction. A concentration cell is a type of galvanic cell where the reduction and oxidation half-reactions involve the same species. Different concentrations of the species in the anode and cathod...
- Fri Mar 12, 2021 1:11 pm
- Forum: Environment, Ozone, CFCs
- Topic: catalysis vs intermediate
- Replies: 25
- Views: 2105
Re: catalysis vs intermediate
For a visual example: A + B --> C + D D + E --> B + F B would be the catalyst C would be the intermediate is B the catalyst in both? I think that this is showing the two elementary steps of the overall reaction A + E (+B) --> C + F (+B). In this case, B is a catalyst in the overall reaction because...
- Fri Mar 12, 2021 1:02 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: When to split molecules into their ions for Kc
- Replies: 1
- Views: 254
Re: When to split molecules into their ions for Kc
If an ion is in an aqueous phase, the equilibrium expression should use the concentration of the ion's constituent cation and anion. The KNO 3 in your example doesn't appear in the equilibrium expression because both K + and NO 3 - are spectator ions and arent involved in the reaction. The reaction ...
- Fri Mar 12, 2021 12:30 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Temperature change in isobaric compression
- Replies: 1
- Views: 287
Temperature change in isobaric compression
If an isobaric compression is performed on an ideal gas, would the temperature of the gas decrease (assuming the moles of gas remained constant)? The ideal gas law holds that V ∝ T, so it seems like the temperature of the system would decrease, but I'm not sure.
- Fri Mar 12, 2021 12:24 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Pre-Exponential Factor
- Replies: 3
- Views: 417
Re: Pre-Exponential Factor
You are correct! Catalysts (most often enzymes) can increase A by aligning the reactants in the proper orientation for a successful collision.
- Fri Mar 12, 2021 12:19 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Entropy of vaporization
- Replies: 4
- Views: 488
Re: Entropy of vaporization
Is this formula given on the formula sheet? Or are we just expected to memorize it?
- Fri Mar 12, 2021 12:18 pm
- Forum: Balancing Redox Reactions
- Topic: Textbook 6K.5a
- Replies: 6
- Views: 493
Textbook 6K.5a
How do you divide the reaction given in 6K.5a (O3 + Br- -> O2 + BrO3-) into reduction and oxidation half-reactions? I understand that the Br is oxidized and the O is reduced, but I don't get how these two processes can be divided as they occur in the same molecule.
- Thu Mar 11, 2021 9:46 pm
- Forum: General Science Questions
- Topic: Water in combustion
- Replies: 3
- Views: 557
Water in combustion
Is the water that is produced in combustion generally in the liquid or gaseous phase? Does the Δn of gaseous molecules in a combustion reaction = (mol H2O + CO2) - (moles of gaseous reactants)?
- Wed Mar 10, 2021 8:54 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Entropy of vaporization
- Replies: 4
- Views: 488
Entropy of vaporization
How is the entropy of vaporization of a liquid calculated? In Michael's workshop worksheet #6, he states that one can calculate the entropy of vaporization for water at room temp. I was curious how this is computed.
- Wed Mar 10, 2021 7:28 pm
- Forum: General Rate Laws
- Topic: rate constant of reverse reaction
- Replies: 3
- Views: 275
Re: rate constant of reverse reaction
Thanks so much!
- Wed Mar 10, 2021 3:38 pm
- Forum: General Rate Laws
- Topic: rate constant of reverse reaction
- Replies: 3
- Views: 275
rate constant of reverse reaction
What is the relationship between the rate constant of the forward and reverse reaction? Is the rate constant of the reverse reaction the inverse of the forward reaction?
- Tue Mar 09, 2021 9:50 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Writing cell diagrams
- Replies: 5
- Views: 280
Re: Writing cell diagrams
I was really confused about these too. I find it helpful to draw a picture of the reaction before I try to write the cell diagram notation because it helps me orient what is reacting with what.
- Tue Mar 09, 2021 9:48 am
- Forum: Balancing Redox Reactions
- Topic: Balancing Redox/Oxd Equations
- Replies: 3
- Views: 225
Re: Balancing Redox/Oxd Equations
I would definitely recommend the guides on how to balance the reactions in acidic and basic conditions.
- Tue Mar 09, 2021 9:39 am
- Forum: General Science Questions
- Topic: 14C chemistry community
- Replies: 5
- Views: 701
Re: 14C chemistry community
Im pretty sure that only Lavelle's current students can post on chemistry community. I don't think we will be able to post after this quarter.
- Tue Mar 09, 2021 9:37 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Deprotonated bases
- Replies: 2
- Views: 308
Deprotonated bases
I am confused by this statement:
"When pOH is less than pKb, the acid is deprotonated."
What does it mean for a base to be deprotonated?
"When pOH is less than pKb, the acid is deprotonated."
What does it mean for a base to be deprotonated?
- Tue Mar 09, 2021 9:33 am
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: What was your favorite chem topic?
- Replies: 137
- Views: 13283
Re: What was your favorite chem topic?
I really enjoyed chemical equilibrium because I thought it was very intuitive.
- Thu Feb 25, 2021 12:23 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: ideal gas U
- Replies: 5
- Views: 555
Re: ideal gas U
The change in internal energy of an ideal gas is dependent on the temperature, pressure, and volume. If one of these is constant, the change in internal energy will be different than if a different aspect was held constant.
- Thu Feb 25, 2021 12:20 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Textbook 4C.5
- Replies: 2
- Views: 224
Re: Textbook 4C.5
I must have misread the assigned problems. Thanks for the response.
- Thu Feb 25, 2021 12:19 pm
- Forum: Van't Hoff Equation
- Topic: Delta H naught VS delta H
- Replies: 28
- Views: 2593
Re: Delta H naught VS delta H
Thank you for all the responses!
- Thu Feb 18, 2021 2:00 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Spontaneity using delta S total
- Replies: 1
- Views: 152
Re: Spontaneity using delta S total
Delta S total represents the entropy of the system and the surroundings. According to the 2nd law of thermodynamics, spontaneous processes always increase the total entropy of the system and its surroundings, even if the entropy of the system decreases.
- Thu Feb 18, 2021 1:56 pm
- Forum: Van't Hoff Equation
- Topic: Delta H naught VS delta H
- Replies: 28
- Views: 2593
Re: Delta H naught VS delta H
Thanks! All your responses were very helpful.
- Thu Feb 18, 2021 1:55 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Different entropy measures 4.37
- Replies: 4
- Views: 365
Re: Different entropy measures 4.37
Thanks! That was very helpful.
- Thu Feb 18, 2021 10:47 am
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Different entropy measures 4.37
- Replies: 4
- Views: 365
Different entropy measures 4.37
What is the difference between ΔS and ΔStotal? And why is ΔStotal always greater than 0 in a spontaneous process if ΔS is necessarily positive in a spontaneous reaction?
- Wed Feb 17, 2021 7:59 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Textbook 4C.5
- Replies: 2
- Views: 224
Textbook 4C.5
4C.5: Predict the contribution of each type of molecular motion to the heat capacity and their total for each of the following atoms and molecules: (a) HCN; (b) C 2 H 6 ; (c) Ar; (d) HBr. Ignore vibrations. I don't remember the types of molecular motion and was wondering if anyone knew which lecture...
- Tue Feb 16, 2021 10:34 pm
- Forum: Van't Hoff Equation
- Topic: Delta H naught VS delta H
- Replies: 28
- Views: 2593
Delta H naught VS delta H
What is the difference between ΔH and ΔH°?
- Thu Feb 11, 2021 10:12 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Entropy and volume in irreversible expansion
- Replies: 2
- Views: 198
Entropy and volume in irreversible expansion
Does the formula ∆S = nRln(V1/V2) only work for reversible expansion? If so, is there a formula that relates the change in volume in an irreversible expansion to ∆S?
- Mon Feb 08, 2021 2:23 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Textbook 4.15
- Replies: 2
- Views: 134
Re: Textbook 4.15
The equation for the ΔH of the reaction is :
ΔH = (ΔHH2 + ΔHZn2+ + 2*ΔHCl-) - (2*ΔHHCl)
(2*-167.16) appears twice in the ΔH equation because the ΔH of formation for Cl- is the same as ΔH of formation for HCl. (ΔH of Cl- = -167.16, and ΔH of HCl(aq) = -167.16).
Hope this helps!
ΔH = (ΔHH2 + ΔHZn2+ + 2*ΔHCl-) - (2*ΔHHCl)
(2*-167.16) appears twice in the ΔH equation because the ΔH of formation for Cl- is the same as ΔH of formation for HCl. (ΔH of Cl- = -167.16, and ΔH of HCl(aq) = -167.16).
Hope this helps!
- Mon Feb 08, 2021 2:06 pm
- Forum: Student Social/Study Group
- Topic: Spring 2021
- Replies: 106
- Views: 21005
Re: Spring 2021
I wonder if the lab skills that would normally be taught in person for 14bl are important for 14cl. If so, it might be a good idea to wait to take 14bl in person fall 2021
- Fri Feb 05, 2021 6:33 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Combustion = Exothermic
- Replies: 23
- Views: 948
Re: Combustion = Exothermic
You are right that breaking to bonds of the reactants is an endothermic process. But combustion is always exothermic because the formation of O-H bonds in H 2 O and C=O bonds in CO 2 always releases more energy than required to break the O=O bonds in O 2 and the C-C/C-H bonds in the material being c...
- Fri Feb 05, 2021 6:27 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Textbook problem 6.61
- Replies: 7
- Views: 313
Re: Textbook problem 6.61
If the glucose solution was sufficiently concentrated, adding water would cause the equilibrium to shift right, as it would decrease the concentration of glucose (a product). However, in this reaction, the glucose solution is so dilute that changing the volume of solvent would not appreciably change...
- Fri Feb 05, 2021 6:15 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: How to identify Thermodynamic
- Replies: 5
- Views: 394
Re: How to identify Thermodynamic
Reversible reactions are almost always isothermal and systems that expand without increasing T are normally the product of a reversible process. Systems that change volume as the result of temperature change are generally irreversible. Also, if the problem states that the pressure of the system is d...
- Fri Feb 05, 2021 6:04 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Molar Heat Capacity of Lead vs Diamond
- Replies: 1
- Views: 527
Re: Molar Heat Capacity of Lead vs Diamond
You are right! Diamond has a relatively low specific heat capacity because of its molecular structure. The carbon molecules in the crystal lattice of a diamond are strongly coupled, so motion in one molecule transmits the kinetic energy to surrounding molecules very efficiently. This decreases the t...
- Tue Feb 02, 2021 12:51 pm
- Forum: Calculating Work of Expansion
- Topic: Equilibrium expansion / reversible expansion
- Replies: 2
- Views: 105
Equilibrium expansion / reversible expansion
What is the difference between equilibrium expansion and reversible expansion?
- Fri Jan 29, 2021 2:07 pm
- Forum: Student Social/Study Group
- Topic: Spring 2021
- Replies: 106
- Views: 21005
Re: Spring 2021
Are we allowed to take 14C before we take 14BL? If so, do you think it would be worth it to take 14C in the spring and then take 14BL fall of 2021?
- Sun Jan 10, 2021 9:09 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Concentration vs Pressure
- Replies: 9
- Views: 602
Re: Concentration vs Pressure
Concentration is moles of solute per volume, represented mathematically as n/V. Pressure is related to concentration but also factors in the temperature of the system. This relationship is seen in the ideal gas law, where P ∝ T*(n/V).
- Sun Jan 10, 2021 9:09 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Concentration vs Pressure
- Replies: 9
- Views: 602
Re: Concentration vs Pressure
Concentration is moles of solute per volume, represented mathematically as n/V. Pressure is related to concentration but also factors in the temperature of the system. This relationship is seen in the ideal gas law, where P ∝ T*(n/V).
- Sat Dec 12, 2020 10:57 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Coordination Compounds and Ionic Bonds
- Replies: 2
- Views: 411
Re: Coordination Compounds and Ionic Bonds
The bond between a ligand and a TM in a coordination compound is a coordinate covalent bond. Coordinate covalent bonds form when a lewis base donates a pair of electrons to a lewis acid. Unlike an ionic bond, the electrons are shared between the two atoms and the bond is often very polar. Remember t...
- Sat Dec 12, 2020 3:48 pm
- Forum: Trends in The Periodic Table
- Topic: Ionization period trend
- Replies: 3
- Views: 380
Re: Ionization period trend
You are right that ionization energy generally increases from left to right. However, there are two inconsistencies in the ionization energy of period 2 elements: boron and oxygen. Boron has a lower ionization energy than beryllium because boron has one unpaired electron in the 2p subshell, which is...
- Sat Dec 12, 2020 3:29 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Oxoacids
- Replies: 3
- Views: 360
Re: Oxoacids
The hydrogen is bonded to the oxygen in each oxoacid, so atomic radius is not really considered when comparing the strengths of these acids (the O-H distance is similar in each acid). Like you said, chlorine has the highest electronegativity (and therefore the strongest electron-withdrawing effect) ...
- Sat Dec 12, 2020 12:49 pm
- Forum: Air Pollution & Acid Rain
- Topic: pH of hard water
- Replies: 4
- Views: 409
Re: pH of hard water
Thanks for all the responses! I checked with a TA who confirmed that hard water is alkaline.
- Fri Dec 11, 2020 3:52 pm
- Forum: Air Pollution & Acid Rain
- Topic: pH of hard water
- Replies: 4
- Views: 409
pH of hard water
Is hard water acidic or alkaline? I think Lavelle said that hard water is acidic, but a UA and a few other online resources state that it is generally alkaline. It seems like it would make more sense if hard water is alkaline because it contains CO 3 2- ions which would deprotonate H 2 O, but I'm no...
- Thu Dec 10, 2020 11:48 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: pKa and pH
- Replies: 1
- Views: 108
Re: pKa and pH
K a is the dissociation constant of an acid (a measure of how strong an acid is). As its name implies, K a is an intrinsic property of an acid. pK a is just the -log of K a . pH is a measure of the H 3 O + concentration in a solution. If you add an acid to a solution with a pH that is greater than t...
- Thu Dec 10, 2020 10:24 pm
- Forum: Naming
- Topic: elements with 1 charge state (cations)
- Replies: 1
- Views: 236
Re: elements with 1 charge state (cations)
Here is a list of common ions: https://wps.prenhall.com/wps/media/objects/3079/3153869/tools/common.gif In addition to group one elements, there are three examples of +1 cations: NH 4 +, Cu+, and Ag+ You could figure out that NH 4 is a +1 cation based on the formal charges of the possible lewis stru...
- Thu Dec 10, 2020 10:08 pm
- Forum: Properties & Structures of Inorganic & Organic Bases
- Topic: Strong Base Question
- Replies: 1
- Views: 297
Re: Strong Base Question
Because all strong bases completely ionize in solution, it only makes sense to compare the strength of weak bases. This is what I was able to find on how to determine the comparative strength of weak bases: Weak bases do not provide OH- ions by dissociation. Instead, they react with water to generat...
- Thu Dec 10, 2020 9:51 pm
- Forum: Hybridization
- Topic: Non-rotating pi bonds
- Replies: 2
- Views: 359
Re: Non-rotating pi bonds
The fact that pi bonds cant rotate affects the shape, and therefore reactivity, of some molecules. It is particularly important in the shape of organic molecules. This website has a pretty good description : https://chem.libretexts.org/Courses/Sacramento_City_College/SCC%3A_Chem_420_-_Organic_Chemis...
- Tue Dec 08, 2020 3:35 pm
- Forum: Ionic & Covalent Bonds
- Topic: Comparative strength of sigma bonds
- Replies: 2
- Views: 279
Re: Comparative strength of sigma bonds
Is it possible to determine the comparative length of bonds? Did you have to look up the bond lengths for C-N and C-O, or is there some way you can tell which is shorter using trends in the periodic table?
- Tue Dec 08, 2020 3:27 pm
- Forum: Ionic & Covalent Bonds
- Topic: Comparative strength of sigma bonds
- Replies: 2
- Views: 279
Comparative strength of sigma bonds
How can you determine the comparative strength of single bonds? For example, how would you determine if a single bond between a carbon and nitrogen is stronger than a single bond between a carbon and oxygen? Does it have something to do with the difference in electronegativity?
- Sun Nov 29, 2020 11:11 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Delocalized pi bond?
- Replies: 4
- Views: 281
Re: Delocalized pi bond?
I find it helpful to use examples to understand delocalized pi bonding. Let's use ozone (O 3 ). The lewis structures for ozone are O=O-O and O-O=O. We know that the real structure of ozone is a combination of the two resonance structures - the oxygens are bound by two bonds of equal length that are ...
- Sun Nov 29, 2020 10:57 pm
- Forum: Hybridization
- Topic: Contributions to Hybridization for different bonds
- Replies: 1
- Views: 152
Re: Contributions to Hybridization for different bonds
Hybridization accounts for equal orbitals in the same plane. Single bonds occur when one of these planar (and hybridized) orbitals sigma-bonds with an orbital on a nearby atom. Double bonds occur when a sigma bond forms (like a single bond), but also requires that one orthogonal orbital bond to an o...
- Sun Nov 29, 2020 8:09 pm
- Forum: Hybridization
- Topic: Counting for Hybridization
- Replies: 2
- Views: 108
Re: Counting for Hybridization
Hybridization accounts for equal orbitals in the same plane. Single bonds occur when one of these planar (and hybridized) orbitals sigma-bonds with an orbital on a nearby atom. Double bonds occur when a sigma bond forms (like a single bond), but also requires that one orthogonal orbital bond to an o...
- Sun Nov 29, 2020 7:58 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond angles
- Replies: 7
- Views: 311
Re: Bond angles
Bond angles are experimentally determined, but generally follow the rules we learned in lecture (trigonal planar molecules have bond angles of 120, tetrahedral have 109.5, etc.) Factors that affect bond angles are lone pairs, which we discussed in class, and the relative size of the peripheral atoms...
- Sun Nov 29, 2020 7:31 pm
- Forum: Hybridization
- Topic: hybridization model in textbook
- Replies: 2
- Views: 180
Re: hybridization model in textbook
I believe the equations are showing that each hybrid sp 3 orbital is the sum of the wave functions of the component orbitals. Adding together wave functions is essentially measuring wave interference. The signs assigned to each orbital on the right side of the equation represent whether the interfer...
- Sun Nov 29, 2020 7:19 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Coordination compound and ions
- Replies: 4
- Views: 370
Re: Coordination compound and ions
Thanks for the response! I'm pretty sure ligands can be molecules or atoms as long as they have a lone pair that can be donated to the central transition metal. I was wondering why transition metals sometimes form ionic compounds, as is the case with FeCl 3 , and why they sometimes form coordinate c...
- Sat Nov 28, 2020 11:23 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Coordination compound and ions
- Replies: 4
- Views: 370
Coordination compound and ions
When do transition metals form coordinate compounds and when do they form traditional ions? For example, is NiCl2 an ionic compound or a coordination compound, and why?
- Sat Nov 28, 2020 10:10 pm
- Forum: Sigma & Pi Bonds
- Topic: Pi bonds and hybridization
- Replies: 2
- Views: 211
Re: Pi bonds and hybridization
Thanks, your response was very helpful!
- Fri Nov 27, 2020 9:59 pm
- Forum: Sigma & Pi Bonds
- Topic: Pi bonds and hybridization
- Replies: 2
- Views: 211
Pi bonds and hybridization
How does pi bonding occur if the orbitals of bound atoms hybridize to form orbitals based on areas of electron density? For example, it is my understanding that a double bond would result when a p-orbital electron and s-orbital electron from one atom match with a p-orbital electron and an s-orbital ...
- Wed Nov 25, 2020 2:13 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Fixed geometry of cis-dichloroethene
- Replies: 1
- Views: 79
Fixed geometry of cis-dichloroethene
In lecture #22, Dr. Lavelle explains that the geometry of cis-dichloroethene is fixed because the pi-bond between the carbons prevents them from rotating. I understand why the carbons can't rotate, but I was wondering why the chlorine and hydrogen cant rotate around the fixed carbon. The chlorine an...
- Tue Nov 24, 2020 4:49 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 2E.13 Solution Manual Part A
- Replies: 3
- Views: 226
Re: 2E.13 Solution Manual Part A
VSEPR notation always includes A to represent the central atom, so I think this is a mistake. Hope this helps
- Sun Nov 15, 2020 11:44 pm
- Forum: Coordinate Covalent Bonds
- Topic: Lone Pairs and Lewis Bases
- Replies: 4
- Views: 296
Lone Pairs and Lewis Bases
Do all lewis bases have lone pairs on the central atom? Are all molecules with lone pairs on the central atom considered lewis bases?
- Sun Nov 15, 2020 11:34 pm
- Forum: Ionic & Covalent Bonds
- Topic: Polymer Chain Hydrogen Bonding (Sapling)
- Replies: 1
- Views: 409
Re: Polymer Chain Hydrogen Bonding (Sapling)
The difference in electronegativity between carbon and hydrogen is so small that a H-C bond is nearly nonpolar. It definitely isn't as polar as a H-N bond, which is so polar it exhibits hydrogen bonding. Hope this helps!
- Sun Nov 15, 2020 11:30 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Sapling Cl Oxidation Number
- Replies: 2
- Views: 227
Re: Sapling Cl Oxidation Number
Oxygen almost always has an oxidation number of -2. Because the net charge of the ion equals -1, the sum of the oxidation numbers must equal -1. Therefore, the oxidation number for Cl can be solved algebraically: 4(-2)+x=-1, where x = oxidation number of Cl. In this case, chlorine's oxidation number...
- Wed Nov 11, 2020 10:37 pm
- Forum: Octet Exceptions
- Topic: 2C. 3 part b
- Replies: 2
- Views: 87
Re: 2C. 3 part b
While you could technically have double bonds between the oxygens and phosphorus, it is far less energetically favorable. Because oxygen is more electronegative than phosphorus the negative formal charges should be placed on the oxygen atoms. In general, when a molecule must have negative formal cha...
- Wed Nov 11, 2020 10:15 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: Ion-dipole interactions with symmetrical molecules
- Replies: 1
- Views: 168
Ion-dipole interactions with symmetrical molecules
Would ion-dipole attraction occur between an ion and a symmetrical molecule that has bond dipoles? For example, would Na+ ions be attracted to the Cl atoms in CCl₄ ? CCl₄ is a nonpolar molecule, but I believe the Cl atoms still have a ẟ- charge.
- Wed Nov 11, 2020 6:03 pm
- Forum: Ionic & Covalent Bonds
- Topic: Hydrogen Bond Homework Question
- Replies: 3
- Views: 136
Re: Hydrogen Bond Homework Question
You're right! Hydrogen bonding occurs because the electrostatic attraction between two oppositely oriented dipole moments is very strong. These dipole-dipole interactions are so strong because the atomic radii of nitrogen, oxygen, and fluorine are very small. Electronegativity is related to atomic r...
- Wed Nov 11, 2020 5:53 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polarisability for Ionic bonds
- Replies: 3
- Views: 151
Re: Polarisability for Ionic bonds
I was curious about this too, and this is what I found online: - Percent ionic character/percent covalent character is most relevant in determining the bond character of ionic compounds. - In molecules, where the bonds between atoms are overwhelmingly covalent, % covalent character is less important...
- Wed Nov 11, 2020 5:42 pm
- Forum: Resonance Structures
- Topic: Sapling HW Bond length
- Replies: 3
- Views: 220
Re: Sapling HW Bond length
The way I solved that problem was by comparing the experimentally determined bond length to the expected bond length. If the experimental bond length was somewhere between the expected bond length for a double bond and a single bond, I figured the bond exhibited characteristics of both a single and ...
- Wed Nov 11, 2020 5:30 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ionic Character and Dipoles
- Replies: 2
- Views: 126
Ionic Character and Dipoles
What is the difference between the percent ionic character and the electric dipole moment of a bond? Does % ionic character only apply to ions?
- Mon Nov 02, 2020 4:33 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: 4s and 3d orbitals in period 4 transition metals
- Replies: 2
- Views: 169
4s and 3d orbitals in period 4 transition metals
I was curious why the 4s subshell fills before the 3d subshell in ground-state period-4 transition metals. As the 4s subshell is listed after the 3d subshell in the electron configurations, I assumed that the 4s subshell is more energetic. Assuming this is correct, why would the electrons fill the 4...
- Sun Nov 01, 2020 11:33 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: N,L,mL
- Replies: 3
- Views: 182
Re: N,L,mL
The quantum number ml indicates which orbital the electron belongs to, and there can only be two electrons in the same orbital. Therefore, a maximum of two electrons can occupy the same energy level (n), subshell (l), orbital (ml).
- Sun Nov 01, 2020 11:23 pm
- Forum: Einstein Equation
- Topic: Focus 1 Exercise 3
- Replies: 2
- Views: 347
Re: Focus 1 Exercise 3
The way I solved it is : I calculated the energy per photon (3.13 * 10^-19 joules) and multiplied this value by the number of photons produced per second (2.4 * 10^21). This gave me the amount of energy in joules per second (751 J/sec). Because 1joule/sec = 1 watt, the answer is 751 watts. This is r...
- Mon Oct 26, 2020 8:20 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Orbitals Material
- Replies: 4
- Views: 186
Re: Orbitals Material
Yes. Dr. Lavelle said at the end of lecture #9 that all material on the midterm had been covered by that point.
- Sun Oct 25, 2020 11:59 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Electron Affinity
- Replies: 1
- Views: 117
Re: Electron Affinity
I was curious about this too. conceptually, I don't understand why would the work function be equivalent to the electron affinity conceptually.
- Sun Oct 25, 2020 11:55 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Orbitals Material
- Replies: 4
- Views: 186
Re: Orbitals Material
I believe Dr. Lavelle said that everything covered up to the end of lecture #9 will be covered on the midterm. Lecture #9 included information on orbitals in the context of Schrodinger equation, so I assume it will be on the midterm.
- Sun Oct 25, 2020 11:52 pm
- Forum: Properties of Electrons
- Topic: Sapling #20
- Replies: 1
- Views: 133
Re: Sapling #20
I believe nitrogen has a higher ionization energy than oxygen because it has a half-full P shell, which is more stable than a p-shell with 2 paired electrons as found in oxygen. Oxygen has a lower ie than fluorine because of the periodic trends in atomic radius.
- Sun Oct 25, 2020 11:46 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Uncertainty in velocity of proton in hydrogen atom
- Replies: 2
- Views: 142
Re: Uncertainty in velocity of proton in hydrogen atom
Thanks for the response. I also realized that the nucleus of a hydrogen atom is usually only one proton, so the measurement Dr. Lavelle used was the diameter of a proton. This might have contributed to the really high uncertainty.
- Sun Oct 25, 2020 11:41 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Atomic Specta Post-Module Assessment #41
- Replies: 3
- Views: 144
Re: Atomic Specta Post-Module Assessment #41
Because an electron is being emitted, the energy of the electron must be negative. The correct formula is -hv=(-hR/n^2)-(-hR/n^2). Note the negative in front of the first term hv, which denotes the negative energy. When you plug the values into this formula you get n=6. Hope this helps!
- Fri Oct 23, 2020 2:55 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Uncertainty in velocity of proton in hydrogen atom
- Replies: 2
- Views: 142
Uncertainty in velocity of proton in hydrogen atom
In lecture 9, Dr. Lavelle works an example which shows that the uncertainty in the velocity of an electron contained in the nucleus of an atom exceeds the speed of light. Using this reasoning, I attempted to calculate the uncertainty in the velocity of a proton, which we know is contained in the nuc...
- Sun Oct 18, 2020 11:52 pm
- Forum: Properties of Light
- Topic: Constructive and Destructive Interference
- Replies: 2
- Views: 117
Re: Constructive and Destructive Interference
Waves with different frequencies would still interfere with each other, but the resulting interference pattern would be far more complex. I think the interference pattern could be determined using the superposition principle.
- Sun Oct 18, 2020 11:41 pm
- Forum: Properties of Light
- Topic: How to quantify uncertainty
- Replies: 2
- Views: 147
How to quantify uncertainty
The Heisenberg uncertainty principle formula requires one to quantify the uncertainty of momentum and position. How do you find the uncertainty of an object? What units is it measured in?
- Sun Oct 18, 2020 11:32 pm
- Forum: Einstein Equation
- Topic: E=hv vs. Ephoton = Erequired + KEelectron
- Replies: 2
- Views: 233
Re: E=hv vs. Ephoton = Erequired + KEelectron
E=hv defines the energy of a photon (hv = Ephoton). Therefore you can replace Ephoton with hv in any formula, including the one used for the photoelectric effect.
- Sun Oct 18, 2020 11:21 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Atomic Specta Post-Module Assessment #41
- Replies: 3
- Views: 144
Re: Atomic Specta Post-Module Assessment #41
You begin with the formula v=R(\frac{1}{final level^2}-\frac{1}{initial level^2}) . The problem gives the frequency as 1.14*10^14Hz (v), and the final energy level as 4. Rydberg's constant is 3.29*10^15. You are trying to solve for the intitial level. When you plug those numbers in you will ...
- Sun Oct 18, 2020 11:06 pm
- Forum: Einstein Equation
- Topic: Particles with mass
- Replies: 5
- Views: 174
Re: Particles with mass
Photons do not have mass, but experiments confirm they have momentum. This is one of the failings of classical physics.
- Sun Oct 11, 2020 11:12 pm
- Forum: Properties of Light
- Topic: Light Intensity and Frequency
- Replies: 7
- Views: 308
Re: Light Intensity and Frequency
The energy of light is directly proportional to frequency as defined in E=h*nu, where h is the Planck constant. Increasing frequency will always result in higher energy light. However, the intensity of light is representative of its amplitude, which is completely independent of the light's energy.
- Sun Oct 11, 2020 10:57 pm
- Forum: Empirical & Molecular Formulas
- Topic: What is the actual yield in Sapling #10
- Replies: 2
- Views: 118
Re: What is the actual yield in Sapling #10
The .23 grams of 3-methyl-3-hexanol is the actual yield of the reaction. Percent yield = (actual yield)/(theoretical yield), so I believe you can derive the percent yield with the theoretical yield you calculated and the actual yield given in the problem.
- Sun Oct 11, 2020 10:33 pm
- Forum: Properties of Light
- Topic: Properties of Light Question wavelength/frequency
- Replies: 2
- Views: 79
Re: Properties of Light Question wavelength/frequency
Amplitude is completely independent of wavelength and frequency. Wavelength and frequency are inversely proportional because light moves at a constant velocity, but no such relationship exists between amplitude and wavelength in electromagnetic radiation.
- Sun Oct 11, 2020 10:27 pm
- Forum: Limiting Reactant Calculations
- Topic: General Limiting Question
- Replies: 9
- Views: 929
Re: General Limiting Question
In a chemical reaction, the amount of products created is always dependent on the amount of reactants consumed during the reaction. The moles of product calculated using the limiting reactant represents a theoretical maximum yield if the reaction goes to completion. It is impossible for more product...
- Sun Oct 04, 2020 11:03 pm
- Forum: Limiting Reactant Calculations
- Topic: Week 1 Sapling HW Chem 14A Problem 10
- Replies: 10
- Views: 415
Re: Week 1 Sapling HW Chem 14A Problem 10
I believe you can also determine the chemical formula, and therefore molar mass, of the reactants based on their given structures. The reactants and products are shown in bond line notation, which is similar to a Lewis structure. This website has a really brief explanation of bond line structures an...