## Search found 60 matches

Sun Mar 17, 2019 3:41 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Drawing cells
Replies: 3
Views: 327

### Re: Drawing cells

You also do not want to forget about the porous disk for concentration cells
Sun Mar 17, 2019 3:40 pm
Forum: Van't Hoff Equation
Topic: Van't hoff
Replies: 2
Views: 919

### Van't hoff

How do you derive the equation for van't hoff using delta G?
Sun Mar 17, 2019 3:31 pm
Forum: Calculating Work of Expansion
Topic: Work in a System
Replies: 4
Views: 313

### Re: Work in a System

Work is equal to 0 when the conditions are isochoric (constant volume). An example of this is a bomb calorimeter.
Sun Mar 10, 2019 9:54 pm
Forum: First Order Reactions
Topic: half life
Replies: 2
Views: 144

### Re: half life

It really depends on what information the problem provides you with, but one example would be if it asked you to calculate how long it takes for the reactant concentration to decrease by half. Another one would be like if they gave you the order and the actual half life, and you have to calculate fo...
Sun Mar 10, 2019 9:50 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Log version vs ln Version
Replies: 7
Views: 296

### Re: Log version vs ln Version

I would recommend using the ln version more because that version is given in the formula sheet
Sun Mar 10, 2019 9:48 pm
Forum: First Order Reactions
Topic: Molar coefficients
Replies: 4
Views: 190

### Re: Molar coefficients

No, the coefficients have no effect on the order of the reactant.
Sun Mar 03, 2019 11:01 pm
Forum: Balancing Redox Reactions
Topic: Order in Cell diagrams
Replies: 3
Views: 187

### Re: Order in Cell diagrams

Cell diagrams are anode|| cathode. In the anode and the cathode, the metal conductor is the outermost, aqueous solutions are nearest to the salt bridge (denoted by ||) and if there is a change in phase for different compounds | is used. If they are in the same phase a comma is used instead.
Sun Mar 03, 2019 10:59 pm
Forum: Balancing Redox Reactions
Topic: Cell diagrams
Replies: 8
Views: 292

### Re: Cell diagrams

In order for a cell diagram to work, you need a metal conductor. If a metal conductor isn't found in the anode or cathode, Pt is added.
Sun Mar 03, 2019 10:55 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: TEST 2
Replies: 3
Views: 180

### Re: TEST 2

How do you find the pH from K?
Sat Feb 23, 2019 11:58 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: gibbs free units
Replies: 3
Views: 131

### Re: gibbs free units

I believe that in both cases, gibbs free energy is measured in kJ overall. The only time I think Gibbs free energy is measured in kJ/mol is when you have to use the delta G reaction formula that requires the delta G (products) - delta G (reactants). The individual compounds in the reaction will be m...
Sat Feb 23, 2019 11:53 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Calculating E naught of the cell
Replies: 3
Views: 172

### Re: Calculating E naught of the cell

I believe that Lavelle will ask for the half-reactions to be applied more for Test 2
Sat Feb 23, 2019 11:51 am
Forum: Van't Hoff Equation
Topic: Deriving Equations
Replies: 3
Views: 160

### Re: Deriving Equations

In my opinion, I believe that the quizzes are typically applying the knowledge you learned in class, so I do not think that there will be a question asking you to derive an equation, but then again there is always a possibility.
Sat Feb 23, 2019 11:49 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Test 2 Help
Replies: 7
Views: 325

### Re: Test 2 Help

According to his website, the nernst equation will not be covered in Test 2
Sat Feb 23, 2019 11:47 am
Forum: Balancing Redox Reactions
Topic: Test 2 Material
Replies: 11
Views: 315

### Re: Test 2 Material

Do you think he will also have enthalpy and entropy questions imbedded in Gibbs questions, since Gibbs free energy contains a formula that requires both delta H and delta S?
Mon Feb 18, 2019 3:07 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Replies: 35
Views: 1226

It might be during our discussion session or after the lecture.
Mon Feb 18, 2019 3:06 pm
Forum: Calculating Work of Expansion
Topic: Units for R
Replies: 10
Views: 629

### Re: Units for R

It depends on the information you are given, and ultimately what you are solving for.
Mon Feb 18, 2019 3:04 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Pressure Change
Replies: 4
Views: 158

### Pressure Change

How come in the delta S formula it is T2 over T1 and V2 or V1, but pressure is P1 over P2?
Mon Feb 11, 2019 1:25 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Midterm 2019
Replies: 9
Views: 303

### Re: Midterm 2019

If you are doing the hw questions on the 6th edition it will be all the homework problems he has written down up to 9.51
Mon Feb 11, 2019 1:23 am
Forum: Calculating Work of Expansion
Topic: Proving the work equation
Replies: 2
Views: 143

### Re: Proving the work equation

I believe that all the derivations of those formulas are fair game on the midterm since Professor Lavelle went over it in class.
Mon Feb 11, 2019 1:22 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Difference between delta U and delta H?
Replies: 3
Views: 195

### Re: Difference between delta U and delta H?

Delta H refers to the change in energy/heat at constant pressure, that is exchanged between the surroundings and system. This means that if you are adding 10 J to the system, you are taking away 10 J from the surroundings (-10 J).
Sun Feb 10, 2019 12:55 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Using Bond Enthalpies
Replies: 2
Views: 126

### Re: Using Bond Enthalpies

My TA said that Lavelle will most likely provide the average bond enthalpies for resonance structures, as in the average of the single, double, and triple bonds, so I do not think that we will have to worry about the individual bonds.
Sun Feb 03, 2019 11:39 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond Enthalpies
Replies: 4
Views: 152

### Bond Enthalpies

Is there an easier way to calculate bond enthalpies if you are only given the chemical formula without having to draw out the whole lewis structure?
Sun Feb 03, 2019 11:37 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Midterm [ENDORSED]
Replies: 49
Views: 2135

### Re: Midterm[ENDORSED]

Professor Lavelle provides many resources such as Step up, Workshop, and Drop in Sessions for students to use. If you are confused about the topics and feel like you need more practice, I would recommend going to a Step up or Workshop session, since they teach the basics and provide worksheets to he...
Sun Feb 03, 2019 11:32 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpies
Replies: 2
Views: 119

### Enthalpies

What is the difference between the different type of notations when it comes to enthalpy such as delta Hf, delta Hc, and delta H?
Sun Jan 27, 2019 3:20 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: What not to count
Replies: 9
Views: 385

### Re: What not to count

You should only include gases in ICE tables, so any liquids or solids should be omitted. However, be careful because sometimes H20 can be a vapor, and thus a gas, so if it is in gas form, it should be included in your ICE table.
Sun Jan 27, 2019 3:17 pm
Forum: Ideal Gases
Topic: Approximations for ICE
Replies: 20
Views: 572

### Approximations for ICE

When can we use approximations like making (x-0.89) become just x?
Sun Jan 27, 2019 3:14 pm
Forum: Phase Changes & Related Calculations
Topic: Why are phase changes endothermic?
Replies: 11
Views: 429

### Re: Why are phase changes endothermic?

Phase changes are endothermic because heat is required to break the bonds between the atoms in order for it to go from a solid to a liquid or a liquid to a gas. This is why during a phase change, the temperature does not change.
Sun Jan 20, 2019 8:04 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Water in ICE tables
Replies: 10
Views: 700

### Water in ICE tables

Why do we omit water in the ICE tables?
Sun Jan 20, 2019 8:03 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: ICE Table Calculations
Replies: 4
Views: 203

### Re: ICE Table Calculations

Yes you will be required to I think. There have been some homework problems that had more than 3 species already, so I would prepare for more on the test this week.
Fri Jan 18, 2019 2:09 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kp or Kc
Replies: 3
Views: 115

### Kp or Kc

How do you know when to use Kp or Kc? If the question does not specify, can you use either?
Mon Jan 14, 2019 3:13 pm
Forum: Ideal Gases
Topic: Using Kc or Kp
Replies: 13
Views: 437

### Using Kc or Kp

How do we know when to use Kp or Kc? Sometimes it seems like you can use both?
Mon Jan 14, 2019 3:11 pm
Forum: Ideal Gases
Topic: R [ENDORSED]
Replies: 5
Views: 322

### Re: R[ENDORSED]

I also asked my TA about this question, and he said that R is a constant, so we should not have to worry about remembering it like how we are given constants on the constant wkst.
Mon Jan 14, 2019 3:10 pm
Forum: Ideal Gases
Topic: R in PV=nRT
Replies: 34
Views: 736

### Re: R in PV=nRT

R is gas constant, but the units can be different like atm, torr, or bar.
Sun Dec 02, 2018 5:30 pm
Forum: Administrative Questions and Class Announcements
Topic: Charge on ligands
Replies: 2
Views: 136

### Charge on ligands

Are we required to memorize the charges on the different ligand compounds or will the test give us the charge?
Sun Dec 02, 2018 5:29 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: LDF
Replies: 7
Views: 1076

### LDF

Is the intermolecular force, LDF, found in all molecules?
Sun Dec 02, 2018 5:27 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Polydentate Ligands
Replies: 1
Views: 54

### Polydentate Ligands

On question 17.33, it asks whether the compounds are polydentate ligands, and if they are, to give the max number of places the ligand can bind to the metal atom. How do you determine the max number of places a ligand can bind to the metal atoms?
Tue Nov 20, 2018 3:13 pm
Forum: Lewis Structures
Topic: Midterm question
Replies: 8
Views: 318

### Midterm question

On the midterm, there was a question that asked for the bond lengths of NO2-. I got the structure correct, but can someone tell me how to find the bond lengths?
Tue Nov 20, 2018 3:10 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR Notation
Replies: 2
Views: 146

### VSEPR Notation

In class, we were taught the VSEPR notation to determine the molecular shape, however are we required to learn the VSEPR notation or if we were taught a different way can we use that method? Will VSPER notation be on the test?
Tue Nov 20, 2018 3:07 pm
Forum: Lewis Structures
Topic: Lewis Structure for NO3-
Replies: 3
Views: 1008

### Re: Lewis Structure for NO3-

NO3- has resonance, which allows all the bond angles to be the same between the different resonance structures since resonance doesn't move the actual formation of the atoms, but only rearranges the double bonds. Since NO3- has resonance, there are three different "most stable" structures,...
Sun Nov 18, 2018 8:15 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shape vs. Electron Geometry
Replies: 4
Views: 204

### Molecular Shape vs. Electron Geometry

What's the difference between electron geometry and molecular shape?
Sun Nov 18, 2018 8:10 pm
Forum: Lewis Acids & Bases
Topic: Bronsted Acids & Bases vs. Lewis Acid & Bases
Replies: 3
Views: 110

### Bronsted Acids & Bases vs. Lewis Acid & Bases

What's the different between Bronsted and Lewis acids and bases? I know that acids are electron acceptors, while bases are electron donors, however I don't know the different between the two labels of acids and bases.
Sun Nov 18, 2018 8:06 pm
Forum: Administrative Questions and Class Announcements
Topic: Thanksgiving Wednesday Class
Replies: 19
Views: 628

### Re: Thanksgiving Wednesday Class

What about those that have discussion on Mondays or Tuesdays? Do we have discussion too?
Sun Nov 11, 2018 8:32 pm
Forum: Electronegativity
Replies: 13
Views: 787

Electronegativity is the attractive force between the protons and the electrons. As the atomic radius increases, the protons in the nucleus have a less attractive force to the electrons which is why the electrons are further from the nucleus, expanding the atom, and thus electronegativity decreases....
Sun Nov 11, 2018 8:24 pm
Forum: Resonance Structures
Topic: Resonance structures
Replies: 7
Views: 494

### Re: Resonance structures

Resonance structures refer to different ways that we can arrange the double bonds in a Lewis structure, so this is where the double sided arrow between the different structures come in. One important thing to keep in mind is that the formation of the atoms must be the same in order for it to be a re...
Sun Nov 11, 2018 8:19 pm
Forum: Lewis Structures
Topic: Lewis Structure
Replies: 10
Views: 396

### Re: Lewis Structure

I've been to a couple of different Workshops, and some UAs have a different method of deciding which element goes in the center. Some say that you want the structure to be as symmetrical as possible, so you should be placing the atom that least occurs in the middle, whereas some say that it should b...
Sun Nov 04, 2018 9:07 pm
Forum: Octet Exceptions
Topic: Octet Exceptions
Replies: 3
Views: 172

### Octet Exceptions

I know that H, He, and B are exceptions to the octet rule, but I don't understand why they are exceptions.
Sun Nov 04, 2018 9:04 pm
Forum: Electronegativity
Replies: 3
Views: 213

10d) Rank the following in order of increasing ionization energies: C N O F Why is the order C<O<N<F? If the period trend for ionization energy is decreasing as we go down the periods on the periodic table, and increasing as the we go from left to right on the period, shouldn't it be C<N<O<F?
Sun Nov 04, 2018 9:00 pm
Forum: Lewis Structures
Replies: 2
Views: 100

12b) Draw the lowest energy Lewis structure for ClO4- Why is the lowest energy Lewis structure have one of the three Oxygen atoms with 6 lone pairs instead of doing a double bond with Cl and 4 lone pairs like the rest of the oxygen atoms? The formal charges are the same, either Cl has -1 or the O ha...
Sun Oct 28, 2018 12:05 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Configurations Full or Abbreviated
Replies: 2
Views: 115

### Electron Configurations Full or Abbreviated

Should we be writing out the full electron configuration starting from 1s^2 or can we abbreviate it using noble gas configuration? Do you know if there will be a preference toward one or the other when we take the midterm or it doesn't really matter?
Sun Oct 28, 2018 12:00 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Valence shell and other electrons
Replies: 4
Views: 205

### Re: Valence shell and other electrons

It also affects ionization energy. Since ionization energy is the energy needed to remove electrons from the atom, if they are in the same period (meaning they have the same # of electron shells) then those elements that have more protons will make it harder for the electron to be removed since the ...
Sun Oct 28, 2018 11:53 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Copper exception
Replies: 4
Views: 216

### Copper exception

So I understand that the 4s^2 has a higher energy level than 3d^10 which is why it comes after 3d^10 say in element Bromine, however for Copper's electron configuration its exception makes it 3d^10 and 4s^1, but the 4s^1 is still after 3d^10, even though 4s^1 has a lower energy level than 3d^10, why...
Sun Oct 21, 2018 4:13 pm
Forum: Quantum Numbers and The H-Atom
Topic: 6th Edition HW 2.29
Replies: 2
Views: 81

### Re: 6th Edition HW 2.29

in a) n=2, l=1, that means that ml=-1,0,1, but there are also different spins in electrons, so since -1,0,1 (3 options), and there's a possibility of either electron being 1/2 or -1/2 (2 options), 3*2=6. So there are 6 different electrons that can have the following quantum numbers. b) n=4, l=2, ml=...
Sun Oct 21, 2018 4:04 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Test 2
Replies: 1
Views: 93

### Re: Test 2

Test 2 will cover everything from what we learned up to last Friday's lecture. That includes Photoelectric Effect, Atomic Spectra, Wave Properties of Electrons, Quantum Mechanics (which incorporate all the important fundamental equations), and atomic orbitals. I would recommend knowing the electroma...
Sun Oct 21, 2018 3:58 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Heisenberg Equation Confusion
Replies: 4
Views: 181

### Heisenberg Equation Confusion

In the Heisenberg equation, why is Planck's constant over 4pi?
Sun Oct 14, 2018 10:14 pm
Forum: SI Units, Unit Conversions
Topic: Homework for Week 2
Replies: 16
Views: 532

### Re: Homework for Week 2

It really depends on your TA, but it is recommended that you do the homework that corresponds to the topic that we are studying that week. That way you are more prepared to learn new concepts that may build on previous lessons.
Sun Oct 14, 2018 10:07 pm
Forum: Administrative Questions and Class Announcements
Replies: 1
Views: 113

There was an email that was sent out last week that said it was required to have the textbook, so is it okay if you still use the pdf version or do you have to buy the textbook?
Sun Oct 14, 2018 9:59 pm
Forum: Properties of Light
Topic: C=Wavelength*Frequency
Replies: 11
Views: 737

### Re: C=Wavelength*Frequency

C is the constant for the speed of light. It is 3.00x10^8m/s. Since it is a constant, it will be given during tests, so there's no pressure to remember this value for tests.
Sat Oct 06, 2018 9:53 pm
Forum: Empirical & Molecular Formulas
Topic: F.13
Replies: 1
Views: 109

### F.13

So in problem F.13 in the Chem textbook, it asked for the name of the compound PCl5. I was just wondering if we would be expected to know the names and the chemical formula of compounds (if only given the name) on the test this week?
Sat Oct 06, 2018 9:49 pm
Forum: Molarity, Solutions, Dilutions
Topic: G.13
Replies: 1
Views: 81

### G.13

Question: "To prepare a fertilizer solution, a florist dilutes 1.0 L of 0.20 m NH4NO3(aq) by adding 3.0 L of water. The florist then adds 100. mL of the diluted solution to each plant. How many moles of nitrogen atoms will each plant receive? Solve this exercise without using a calculator."...
Thu Oct 04, 2018 2:12 pm
Forum: Limiting Reactant Calculations
Topic: Question 34 on Module 3 [ENDORSED]
Replies: 1
Views: 125

### Question 34 on Module 3[ENDORSED]

For some reason, I keep getting .014 grams of HCl at the end instead of any of the options on the quiz. Please help :)