Search found 102 matches

by 405268063
Sat Mar 14, 2020 11:42 am
Forum: Balancing Redox Reactions
Topic: Endgame 3B
Replies: 3
Views: 91

Re: Endgame 3B

The reduction reaction should be Br2 + 2e- --> 2Br-. You would multiply this whole thing by 5 to balance the electrons when trying to write the overall reaction.
by 405268063
Sat Mar 14, 2020 11:36 am
Forum: Administrative Questions and Class Announcements
Topic: online
Replies: 3
Views: 49

Re: online

I think that's unclear right now, but Dr. Lavelle should be sending out an email with all of that information probably later today.
by 405268063
Sat Mar 14, 2020 11:35 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: elementary rate law
Replies: 4
Views: 80

Re: elementary rate law

I believe that an elementary rate law corresponds to the rate law for one step of an equation for a multi-step reaction. The overall rate law refers to all the steps of a reaction, and that is determined by the slowest step.
by 405268063
Sat Mar 14, 2020 11:34 am
Forum: First Order Reactions
Topic: k versus k prime
Replies: 6
Views: 92

Re: k versus k prime

Yes, like the previous responders have said, k prime generally refers to the reverse reaction rate and k refers to the forward reaction rate.
by 405268063
Sat Mar 14, 2020 11:33 am
Forum: Zero Order Reactions
Topic: zero order reactions
Replies: 5
Views: 63

Re: zero order reactions

Zero order reaction rates are independent of [R]. This means that the rate law is just k which makes its units mol/(L x s).
by 405268063
Sun Mar 08, 2020 11:54 pm
Forum: Balancing Redox Reactions
Topic: Reversing the anode
Replies: 10
Views: 139

Re: Reversing the anode

The standard cell potentials are written so that each compound is gaining electrons (aka cathode reaction) so if we want the equation where electrons are actually being lost, you have to reverse that standard cell potential value.
by 405268063
Sun Mar 08, 2020 11:45 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: G=-nFe
Replies: 7
Views: 102

Re: G=-nFe

Yes, you basically just need to know that however many electrons you have in your overall balanced equation will be plugged into n.
by 405268063
Sun Mar 08, 2020 11:42 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Concentration Cell
Replies: 7
Views: 77

Re: Concentration Cell

Like everybody else is saying, a concentration cell just happens when both the anode and cathode have the same electrodes in it but with different concentrations. The most important thing to remember for concentration cells though is that E standard cell is equal to 0.
by 405268063
Sun Mar 08, 2020 4:00 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: kinetically stable?
Replies: 10
Views: 126

Re: kinetically stable?

I believe this means that the reaction's delta G is negative so it is technically spontaneous, but the reaction won't normally proceed because it has such a high activation energy.
by 405268063
Sun Mar 08, 2020 3:51 pm
Forum: General Rate Laws
Topic: slow step
Replies: 9
Views: 89

Re: slow step

I believe that the slowest step of a multi-step reaction is the rate-determining step.
by 405268063
Sun Mar 08, 2020 3:42 pm
Forum: Zero Order Reactions
Topic: Not used Half life
Replies: 8
Views: 428

Re: Not used Half life

Yes there is a half-life for zero order reactions and it is: [A initial] / 2k
by 405268063
Sun Mar 08, 2020 2:13 pm
Forum: General Science Questions
Topic: Review Packet
Replies: 14
Views: 277

Re: Review Packet

I think we will be getting a review packet that will be gone over in Lyndon's session... at least that's how it worked for Chem 14A. Dr. Lavelle would make an announcement tomorrow in class or sometime this week about that.
by 405268063
Sun Mar 08, 2020 2:10 pm
Forum: General Rate Laws
Topic: Product in Rate Law
Replies: 2
Views: 51

Re: Product in Rate Law

I think HI in this case is a solid, and we don't include solids or liquids in the rate law expressions. As far as I know, I believe that if a product is gaseous or aqueous, we would include those.
by 405268063
Sun Mar 08, 2020 2:04 pm
Forum: General Rate Laws
Topic: Graphs of rate laws
Replies: 8
Views: 70

Re: Graphs of rate laws

For zero order, the rate law makes a linear graph, which means that the rate just goes at constant k (slope). For first order reactions, the graph is also linear if you plot ln[A] versus time. For second order reactions, the graph is linear is you plot 1/[A] versus time.
by 405268063
Mon Mar 02, 2020 11:18 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Adding Pt?
Replies: 2
Views: 35

Adding Pt?

I was wondering when we add an inert electrode to a cell reaction. Is it when the states are aqueous? The solution manual just says "An inert electrode such as Pt is necessary when both oxidized and reduced species are in the same solution."
by 405268063
Tue Feb 25, 2020 1:07 am
Forum: Balancing Redox Reactions
Topic: Reducing Agent versus Reduced Species
Replies: 2
Views: 36

Re: Reducing Agent versus Reduced Species

Yes, there is a difference. The reducing agent is the one being oxidized and the reduced species is reduced in the reaction.
by 405268063
Tue Feb 25, 2020 12:51 am
Forum: Balancing Redox Reactions
Topic: Flipping Reactions
Replies: 4
Views: 49

Re: Flipping Reactions

Flip whichever one will best fit the equation given. I like to think of it as an addition problem.
by 405268063
Tue Feb 25, 2020 12:49 am
Forum: Van't Hoff Equation
Topic: Converting K back to Kc
Replies: 5
Views: 126

Re: Converting K back to Kc

I think Kc can signify K for all intents and purposes at least on the test. Kc is generally most used for the equilibrium constant for a rxn that is made up of aqueous solutions though, and Kp for for gases since Kc stands for concentration and Kp stands for pressure.
by 405268063
Tue Feb 25, 2020 12:46 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free energy units
Replies: 4
Views: 79

Re: Gibbs Free energy units

I believe that in class, we have been mostly using Gibbs free energy in kJ/mol but as Esha said, you can technically put it into whatever units you want it to be in.
by 405268063
Tue Feb 25, 2020 12:44 am
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: electrolytic cells
Replies: 3
Views: 37

Re: electrolytic cells

Also, I believe Dr. Lavelle said today that in an electrolytic cell, electrical energy is converted into chemical energy,
by 405268063
Mon Feb 24, 2020 10:05 am
Forum: Balancing Redox Reactions
Topic: Oxidation Number of O2 and O3
Replies: 3
Views: 57

Re: Oxidation Number of O2 and O3

In cases like this, I usually look at whether the other molecule involved the reaction is being oxidized or reduced, and then use process of elimination.
by 405268063
Mon Feb 24, 2020 10:00 am
Forum: Administrative Questions and Class Announcements
Topic: Thermo
Replies: 3
Views: 48

Re: Thermo

I think practice problems are the way to go for thermo. Personally, it is helpful to go through different types of problems and have set techniques for solving them.
by 405268063
Sun Feb 23, 2020 10:34 pm
Forum: Balancing Redox Reactions
Topic: Determining direction of flow
Replies: 15
Views: 175

Re: Determining direction of flow

Yes, I believe electrons always move from the anode to the cathode.
by 405268063
Sun Feb 23, 2020 9:43 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Difference
Replies: 5
Views: 53

Re: Difference

There's not really a huge difference. You can apply what we've learned about delta H and delta S to help you find delta G now.
by 405268063
Sun Feb 23, 2020 9:42 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: What to exclude in K
Replies: 9
Views: 85

Re: What to exclude in K

Yup, H2O as a gas is still included in K. Basic rule of thumb is just to exclude anything designated (s) or (l).
by 405268063
Sun Feb 23, 2020 9:40 pm
Forum: Balancing Redox Reactions
Topic: Hydroxide and H+
Replies: 6
Views: 60

Re: Hydroxide and H+

I believe you only use hydroxide and H+ to balance a solution only if you are told it is acidic or basic. I would agree with everyone else that you should probably use water to balance things out in a neutral solution.
by 405268063
Sun Feb 23, 2020 9:39 pm
Forum: Balancing Redox Reactions
Topic: Polyatomic Ions
Replies: 4
Views: 38

Re: Polyatomic Ions

I memorized all the basic ones and I find that it's really helped me in the homework. On tests, I think he usually gives you the charge but I have found that just knowing the charges and the atoms is way easier for his class.
by 405268063
Sun Feb 09, 2020 7:45 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Boltzmann Entropy Equation Clarificaiton
Replies: 3
Views: 22

Re: Boltzmann Entropy Equation Clarificaiton

Yes, if you have more possible states (aka higher W), there is more entropy in the system. Also, as the previous responder said, I would use the equation when we are given the number of particles/microstates in the question.
by 405268063
Sun Feb 09, 2020 7:40 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Second law equation
Replies: 3
Views: 29

Re: Second law equation

I don't think that this equation shows that entropy always increases in a system. I think during the review session today, we were told to use this only for phase changes.
by 405268063
Sun Feb 09, 2020 7:38 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Delta S Universe
Replies: 3
Views: 52

Re: Delta S Universe

In a reversible reaction, delta S of the system is equal to delta S of the surroundings because delta S of the universe is 0. But I'm pretty sure that the general equation you described in your question applies to all reactions.
by 405268063
Sun Feb 09, 2020 7:35 pm
Forum: Phase Changes & Related Calculations
Topic: Heat & Temperature of Phase Changes
Replies: 5
Views: 33

Re: Heat & Temperature of Phase Changes

If you look at the graph Dr. Lavelle drew of q versus T early on in thermochemistry, you can see that at the phase changes, the graph plateaus.
by 405268063
Sun Feb 09, 2020 7:33 pm
Forum: Ideal Gases
Topic: Change in pressure
Replies: 7
Views: 132

Re: Change in pressure

I like to think of it as a balancing act. If you decrease the volume on one side which increases the pressure, the reaction will favor the side with less molecules because the pressure needs to go somewhere else, if that makes sense.
by 405268063
Sun Feb 02, 2020 9:05 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: negative delta U value
Replies: 2
Views: 22

Re: negative delta U value

I believe that if the delta U value is negative, it just means that the temperature was decreased which caused the gas molecules to slow down.
by 405268063
Sun Feb 02, 2020 8:52 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Quadratic Equation
Replies: 5
Views: 122

Re: Quadratic Equation

I just wanted to add that you might be able to avoid doing the quadratic equation is the Ka value is less than 10^-3 or percent ionization is less than 5%.
by 405268063
Sun Feb 02, 2020 8:37 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Shifts
Replies: 6
Views: 128

Re: Shifts

For more clarification on your question, are you asking about how Le Chatelier's works?
by 405268063
Sun Feb 02, 2020 8:35 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Purpose
Replies: 2
Views: 34

Re: Purpose

Yup, I just wanted to add that bomb calorimeters are used to measure heat of combustion at constant volume and that a calorimeter is used at constant pressure.
by 405268063
Sun Feb 02, 2020 8:07 pm
Forum: Phase Changes & Related Calculations
Topic: Reversible and Irreversible
Replies: 5
Views: 64

Re: Reversible and Irreversible

In an irreversible reaction, reactants will create a product that cannot be then turned back into reactants.
by 405268063
Sun Jan 26, 2020 9:02 pm
Forum: Phase Changes & Related Calculations
Topic: enthalpy of phase changes
Replies: 8
Views: 67

Re: enthalpy of phase changes

I would think that since heat is required to make those phase changes, the reaction would be endothermic. Therefore, delta H would have to be positive.
by 405268063
Sun Jan 26, 2020 8:47 pm
Forum: Phase Changes & Related Calculations
Topic: Phase Changes
Replies: 7
Views: 88

Re: Phase Changes

Yes, as the previous response said, you must add the enthalpy of the phase change.
by 405268063
Sun Jan 26, 2020 8:08 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Method 2
Replies: 4
Views: 37

Re: Method 2

I think the method you are referring to is using bond enthalpies to calculate delta H. In class, Dr. Lavelle said that this was a less accurate way of finding delta H than using Hess' Law. I'm not quite sure if that means we would be tested on it, but it is possible he could give us bond enthalpies ...
by 405268063
Sun Jan 26, 2020 8:05 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Delta U
Replies: 2
Views: 21

Re: Delta U

From a mathematical standpoint, Delta H is the change in enthalpy and this is equal to change in U +P*delta V.
by 405268063
Sun Jan 26, 2020 2:42 pm
Forum: Phase Changes & Related Calculations
Topic: Combustion
Replies: 5
Views: 46

Re: Combustion

Not entirely... combustion does include these processes (for example, carbon and H2O molecules are oxidized in a combustion reaction, but all of these actions are not the same.
by 405268063
Sun Jan 19, 2020 12:48 am
Forum: Ideal Gases
Topic: Ideal gas law and [P]/[R]
Replies: 3
Views: 44

Re: Ideal gas law and [P]/[R]

I believe we are supposed to use the ideal gas equation only when we need to convert from Kp to Kc (from bars to moles).
by 405268063
Sun Jan 19, 2020 12:37 am
Forum: Ideal Gases
Topic: Topics on Test 1
Replies: 37
Views: 417

Re: Topics on Test 1

I believe that my TA told me the first test would cover both equilibria as well as what we learned up until Wednesday about Acids/Bases.
by 405268063
Sun Jan 19, 2020 12:34 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Identifying Acids, Bases, and Salts in a Rxn
Replies: 4
Views: 48

Re: Identifying Acids, Bases, and Salts in a Rxn

I would look at proton/electron transfers to identify acids and bases (depending on whether you are talking about Lewis/Bronsted). If something is donating a proton or accepting electrons, it is an acid. If something is accepting a proton or donating an electron, it is a base. Salts, as a previous p...
by 405268063
Sun Jan 19, 2020 12:28 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Buffers
Replies: 3
Views: 36

Re: Buffers

I believe that buffers are mixtures of weak acids and their conjugate bases, so whenever an acid or base is added, it can use either its products or reactants to neutralize the solution.
by 405268063
Sun Jan 19, 2020 12:24 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Decreasing pressure
Replies: 4
Views: 44

Re: Decreasing pressure

I personally like to think of the system trying to alleviate stress within itself. So if pressure is increased on one side, it wants the reaction to go the other way to relieve it.
by 405268063
Sun Jan 12, 2020 6:06 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: the "quick way"
Replies: 4
Views: 50

Re: the "quick way"

I like to think of the "quick way" Dr. Lavelle referred to in class as just a balancing act. If there's more pressure on one side, the reaction will want to go to the other, if that makes sense.
by 405268063
Sun Jan 12, 2020 6:04 pm
Forum: Ideal Gases
Topic: P=(n/v)RT
Replies: 12
Views: 117

Re: P=(n/v)RT

n/V is also a way of writing molarity since its units are mols/L. This is nice for understanding how you can use the ideal gas equation to determine Kc as well I believe.
by 405268063
Sun Jan 12, 2020 6:02 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Situations in which Q=K
Replies: 7
Views: 61

Re: Situations in which Q=K

If Q=K, as everybody has been saying, you know the equation has reached its equilibrium. However, K really is the right way to label the ratio of reactants to products at equilibrium.
by 405268063
Sun Jan 12, 2020 6:00 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Finding K: liquids and aqueous
Replies: 7
Views: 73

Re: Finding K: liquids and aqueous

Yes, this is the same case for solids. Their concentrations do not change.
by 405268063
Sun Jan 12, 2020 5:58 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q and K
Replies: 6
Views: 76

Re: Q and K

K never changes since the equilibrium will always have the same ratio of reactants to products. However, Q values can change depending on how far along into a reaction you are since they are not calculated at equilibrium. Depending on if the equation is shifted to the left or the right, there can be...
by 405268063
Sun Dec 08, 2019 8:33 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: polydentate
Replies: 4
Views: 158

Re: polydentate

Yes, the definition of a ligand is just that it is a Lewis base and can donate at least one pair of electrons.
by 405268063
Sun Dec 08, 2019 8:25 am
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Strong Acids
Replies: 2
Views: 44

Re: Strong Acids

Yes, I was also told by my TA that it would be easiest just to memorize the above list for strong acids.
by 405268063
Sun Dec 08, 2019 8:24 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Uncertainty
Replies: 1
Views: 122

Re: Uncertainty

I believe that all of the questions asked about Heinsenberg's have included values for delta x and/or delta p (or some portion of delta p like mass).
by 405268063
Sun Dec 08, 2019 8:16 am
Forum: Calculating the pH of Salt Solutions
Topic: kbr?
Replies: 1
Views: 74

Re: kbr?

If we look at each ion in KBr, we get K+ and Br-. K+ is a Group 1 metal, which means it has too small of a charge to affect the pH of the solution. If Br- accepts a hydrogen like it wants to (because it's an anion), it will form HBr, which is a strong acid and immediately completely dissociate into ...
by 405268063
Sun Dec 08, 2019 8:14 am
Forum: Naming
Topic: ion at end of name
Replies: 4
Views: 120

Re: ion at end of name

Yup, if there are no cations or anions attached to it, you also add "ion" at the end of the name.
by 405268063
Sun Dec 01, 2019 5:25 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: chelate complex
Replies: 1
Views: 27

Re: chelate complex

As far as I know, coordination compounds involving polydentate ligands are considered chelates.
by 405268063
Sun Dec 01, 2019 4:53 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Kb
Replies: 2
Views: 36

Re: Kb

Just like for Ka, Kb is calculated by this equation: [B+][OH-]/[BOH]. A lower Kb value indicates a stronger base.
by 405268063
Sun Dec 01, 2019 4:50 pm
Forum: Naming
Topic: Cis & Trans
Replies: 3
Views: 36

Re: Cis & Trans

I believe that the molecular name should stay the same. Cis and trans are used only to specify which isomer you are referring to.
by 405268063
Sun Dec 01, 2019 3:22 pm
Forum: Naming
Topic: Roman Numeral
Replies: 13
Views: 116

Re: Roman Numeral

I have personally not seen an instance where the transition metal has a negative anion charge if the charge is designated by a parentheses. If I see a roman numeral, I assume it's "plus whatever that charge is" and it works for me.
by 405268063
Sun Dec 01, 2019 3:21 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: pKa
Replies: 4
Views: 51

Re: pKa

As everyone above has said, the pKa constant can tell you the strength of an acid, but this number is generally used for weak acids.
by 405268063
Sun Nov 24, 2019 2:20 pm
Forum: Bronsted Acids & Bases
Topic: Naming Acids and Bases
Replies: 2
Views: 34

Re: Naming Acids and Bases

Yes, considering that the final will entail everything we have covered in lectures this quarter, I would assume naming will also be on the final.
by 405268063
Sun Nov 24, 2019 2:12 pm
Forum: Biological Examples
Topic: Cisplatin
Replies: 15
Views: 160

Re: Cisplatin

Cisplatin, unlike transplatin, can bond to the same piece of DNA with two bonds to block DNA replication. This lack of replication can kill cancerous cells. The structure of transplatin makes it so that it can only bond at one site on DNA, which is not strong enough to stop DNA replication.
by 405268063
Sun Nov 24, 2019 2:08 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: dipole-dipole in a solid phase vs gas phase
Replies: 15
Views: 237

Re: dipole-dipole in a solid phase vs gas phase

I'm pretty sure that in one of the UA sessions we were told to think of dipole-dipole in the gas phase as induced dipole-induced dipole, which is a very weak IMF.
by 405268063
Sun Nov 24, 2019 12:59 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Bronsted vs. Lewis Acids
Replies: 9
Views: 106

Re: Bronsted vs. Lewis Acids

Bronsted and Lewis acids essentially mean the same thing but there is a difference in what part of the atom you look at to determine if it's an acid or base. Bronsted acids are proton donors whereas Lewis acids are electron acceptors.
by 405268063
Sun Nov 24, 2019 12:06 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Identifying Polydentate Ligands
Replies: 5
Views: 47

Re: Identifying Polydentate Ligands

As far as I understand, if the ligand binds at more than one site (meaning it donates more than 1 electron pair), it can be considered polydentate.
by 405268063
Sun Nov 17, 2019 10:14 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Seesaw Shape
Replies: 3
Views: 35

Re: Seesaw Shape

When you pick a lone pair position, you want to look for the least amount of electron repulsions. If you pick one of the three equatorial atoms for the positioning of a lone pair, we only have two electron repulsions happening. If you pick one of the two axial atoms for this positioning though, we w...
by 405268063
Sun Nov 17, 2019 10:11 am
Forum: Bond Lengths & Energies
Topic: Dissociation Energy
Replies: 2
Views: 39

Re: Dissociation Energy

The dissociation energy is a measure of the strength of a bond. Stronger IMF's such as hydrogen bonding have a higher dissociation energy because it takes more energy to break a strong bond. Weaker IMF's like London forces have a lower dissociation energy.
by 405268063
Sun Nov 17, 2019 10:07 am
Forum: Dipole Moments
Topic: Dipole-Dipole Conti.
Replies: 2
Views: 27

Re: Dipole-Dipole Conti.

Yes, it is possible for a molecule to have dipole-dipole bonds and also be nonpolar. If the polarities occur on opposite sides of a molecule between the same atoms, the molecule becomes nonpolar.
by 405268063
Sun Nov 17, 2019 10:05 am
Forum: Determining Molecular Shape (VSEPR)
Topic: regions of electron density
Replies: 10
Views: 86

Re: regions of electron density

Yes, regions of electron density include both bonds and lone pairs.
by 405268063
Sun Nov 10, 2019 1:52 pm
Forum: Bond Lengths & Energies
Topic: Shape of Molecules and bond strength
Replies: 5
Views: 54

Re: Shape of Molecules and bond strength

I believe the example Professor Lavelle used in class was the two rod shaped molecules vs. two spherical shaped molecules. The bonds in the two rod shaped molecules were stronger than the ones in the spherically shaped molecules because they were physically closer together.
by 405268063
Sun Nov 10, 2019 1:44 pm
Forum: Dipole Moments
Topic: Boiling Point
Replies: 11
Views: 136

Re: Boiling Point

Boiling point is when a liquid goes to the gas phase, and this requires a release of energy, and this comes from the breaking of these intermolecular bonds. But, stronger bonds mean that they are harder to break. In this way, boiling point could be a useful tool for telling us how strong the IMFs are.
by 405268063
Sun Nov 10, 2019 1:41 pm
Forum: Coordinate Covalent Bonds
Topic: Coordinate Covalent Bond
Replies: 8
Views: 194

Re: Coordinate Covalent Bond

There is unequal sharing of electrons in coordinate covalent bonds. In a regular covalent bond, two atoms would be contributing one electron each, but in a coordinate covalent bond, one atom is contributing both electrons.
by 405268063
Sun Nov 10, 2019 12:22 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: What is hydrogen bonding?
Replies: 3
Views: 36

Re: What is hydrogen bonding?

Hydrogen bonds form between oxygen, nitrogen, and fluorine atoms and hydrogen atoms. Oxygen, nitrogen, and fluorine are the only ones that are electronegative enough for this type of bond. But, I would also remember that hydrogen bonds are fairly weak.
by 405268063
Sun Nov 03, 2019 10:45 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Loss from 4s over 3d?
Replies: 4
Views: 51

Re: Loss from 4s over 3d?

I think you remove electrons with the highest electron affinity first, which in this case would be from the 4s orbital.
by 405268063
Sun Nov 03, 2019 10:13 am
Forum: Coordinate Covalent Bonds
Topic: Coordinate covalent bond?
Replies: 12
Views: 705

Re: Coordinate covalent bond?

The acid would be the electron acceptor and the base is the electron donor.
by 405268063
Sun Nov 03, 2019 10:07 am
Forum: Formal Charge and Oxidation Numbers
Topic: When to calculate formal charge
Replies: 7
Views: 96

Re: When to calculate formal charge

Yes, you would want to get the FC as close to zero as possible to get the most stable Lewis structure.
by 405268063
Sun Nov 03, 2019 9:56 am
Forum: Resonance Structures
Topic: Defining Resonance Structures
Replies: 3
Views: 41

Re: Defining Resonance Structures

Resonance structures I believe only apply to when there are multiple ways of drawing the exact same structure. For example, moving the location of a double bond would make another resonance structure.
by 405268063
Sun Nov 03, 2019 9:49 am
Forum: Dipole Moments
Topic: Dipole Moments
Replies: 3
Views: 47

Re: Dipole Moments

As we discussed in class on Friday, increasing difference in electronegativity means increasing ionic character of a covalent bond, and that charge difference (electric dipole moment) can be measured.
by 405268063
Fri Oct 25, 2019 11:21 pm
Forum: Properties of Light
Topic: visible light
Replies: 2
Views: 43

Re: visible light

Personally, I would just know generally what categories the different wavelengths fall into. X-rays/gamma rays are less than 3 nm, UV rays are up to 350 nm, visible light is from 400-700 nm, infrared light is 1000 nm, and microwaves and radio waves are greater than 3x10^6 nm.
by 405268063
Fri Oct 25, 2019 11:17 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: 1D 15
Replies: 2
Views: 39

Re: 1D 15

Yup, I just wanted to elaborate on what the person before me said. The angular momentum (l) is based on the orbital you are talking about. So, it's 0 for the s-orbital, 1 for the p-orbital, 2 for the d-orbital, and 3 for the f-orbital.
by 405268063
Fri Oct 25, 2019 11:15 pm
Forum: Ionic & Covalent Bonds
Topic: Meaning of Brackets
Replies: 7
Views: 69

Re: Meaning of Brackets

The brackets denote a noble gas, and it's just used for efficiency purposes so you don't have to use a huge list to describe the ground state of an atom.
by 405268063
Fri Oct 25, 2019 11:12 pm
Forum: Lewis Structures
Topic: Double Bonds
Replies: 6
Views: 72

Re: Double Bonds

I agree with the person before me who suggested using double bonds first when you are trying to satisfy the octet rule after you have figured out how many total electrons belong in that molecule. After that, you can use double bonds to make the FC equal to 0 for resonance structures.
by 405268063
Fri Oct 25, 2019 3:26 pm
Forum: Ionic & Covalent Bonds
Topic: Bond length
Replies: 11
Views: 110

Re: Bond length

Yes, Prof Lavelle did mention that the bond lengths of these atoms are not actually shorter or longer in real life. This is contrary to what a lot of textbooks will tell you (at least in my experience), and I think it's important in understanding conceptually what resonance structures really are.
by 405268063
Thu Oct 17, 2019 2:42 pm
Forum: DeBroglie Equation
Topic: Constant Question
Replies: 7
Views: 127

Re: Constant Question

On tests, I personally would just use all of the figures in the constants the sheet gives you to get the most accurate number. Even in doing informal practice problems, I would use 6.626 because changing the number to 6.63 will give you a slightly different answer and sometimes you don't know if it'...
by 405268063
Thu Oct 17, 2019 2:30 pm
Forum: Properties of Electrons
Topic: 1B.15
Replies: 1
Views: 67

Re: 1B.15

According to the equations Professor Lavelle gave us in the presentation in class, E of the photon = E of energy required to remove the electron + kinetic energy According to the Photoelectric Experiment, it is the incoming photons that release the electrons from the metal surface. You can't really ...
by 405268063
Thu Oct 17, 2019 2:27 pm
Forum: Photoelectric Effect
Topic: Photoelectric Effect and Kinetic Energy
Replies: 2
Views: 67

Re: Photoelectric Effect and Kinetic Energy

Yes, you are correct. The electron would be released but it really wouldn't travel since KE = 0.
by 405268063
Thu Oct 17, 2019 12:56 pm
Forum: DeBroglie Equation
Topic: De Broglie's Equation
Replies: 17
Views: 260

Re: De Broglie's Equation

The first equation you've listed is the De Broglie equation and that's used for electrons or objects that have a mass. You cannot use light with the De Broglie equation. The second equation you CAN use for photons (light).
by 405268063
Thu Oct 17, 2019 12:27 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Advice for studying
Replies: 70
Views: 1772

Re: Advice for studying

My routine so far has been to go to lecture and then to come back to my room and then watch the video modules again so that I can try to recall the same information that he just went over. I try to spread out my homework problems over the week so that I'm forced to remember how to do certain things ...
by 405268063
Sat Oct 12, 2019 8:08 pm
Forum: Properties of Electrons
Topic: Wavelike vs Particle-like Behavior
Replies: 6
Views: 85

Re: Wavelike vs Particle-like Behavior

Dr. Lavelle made a point in class on Friday that kind of cleared things up for me. He said that if you imagine two holes, particles would just go through one but waves would hit both holes at the same time (or at least that's how I interpreted his analogy). Diffraction of light tells us that it has ...
by 405268063
Sat Oct 12, 2019 7:30 pm
Forum: Properties of Light
Topic: 1A #11
Replies: 3
Views: 40

Re: 1A #11

Wavelengths are grouped together in certain series so that the principal quantum number for their lower energy level is the same. For example, we know the Lyman series' lower energy level is n=1 and the Balmer series' is n=2.
by 405268063
Sat Oct 12, 2019 7:14 pm
Forum: Properties of Electrons
Topic: Derivation of De Broglie Equation
Replies: 4
Views: 45

Re: Derivation of De Broglie Equation

I think you may be referencing when Dr. Lavelle emphasized at the end of his lecture that the De Broglie equation cannot be applied to light because you need a measurement for the momentum of the object, for which you need also need a mass. Light does not have a mass. Hopefully, this made things a l...
by 405268063
Fri Oct 11, 2019 9:23 am
Forum: Photoelectric Effect
Topic: Wavelengths?
Replies: 8
Views: 158

Re: Wavelengths?

Could someone also explain if there is any correlation between amplitude and frequency?
by 405268063
Fri Oct 11, 2019 9:05 am
Forum: Molarity, Solutions, Dilutions
Topic: G27
Replies: 3
Views: 184

Re: G27

I'm sorry this is such a late response to your clarification question (I just checked back into this post right now), but I thought that I might answer anyway in case you want to come back to this problem for a midterm/final. I think what you are asking is why the 37.5 g of HCl is on the bottom of t...
by 405268063
Thu Oct 03, 2019 5:43 pm
Forum: Molarity, Solutions, Dilutions
Topic: G27
Replies: 3
Views: 184

Re: G27

G27) Yes, when you see a dilution problem the equation you want to use is: (M initial)(V initial) = (M final)(V final) The problem gives us the final values: (M final)(V final) = (0.7436 M)(10 L) = 7.436 mol HCl (formula mass = 36.46 g) We want the same amount of mols of HCl on the other side of the...
by 405268063
Thu Oct 03, 2019 5:33 pm
Forum: Significant Figures
Topic: Sig Figs in Mulitstep Problems
Replies: 10
Views: 118

Re: Sig Figs in Mulitstep Problems

Yes, that's what I would do. Keep more figures than you know you need for the sig figs at the end of the problem (you can figure this out by looking at the numbers given in the problem) and then round at the very end for your solution.
by 405268063
Thu Oct 03, 2019 5:31 pm
Forum: Properties of Light
Topic: What does μm mean?
Replies: 4
Views: 84

Re: What does μm mean?

That symbol designates micrometers, which is a common unit of measurement for wavelengths of infrared light and biological cells.

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