## Search found 61 matches

Thu Mar 14, 2019 11:42 am
Forum: First Order Reactions
Topic: Integrated Rate Laws
Replies: 1
Views: 101

### Integrated Rate Laws

Should we know how to integrate the differential rate laws for the final exam?
Thu Mar 14, 2019 11:27 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Determining Catalysts from Diagrams (7E.5)
Replies: 3
Views: 174

### Re: Determining Catalysts from Diagrams (7E.5)

A catalyst is a molecule that is used up in a reaction and then re-created. I usually use this fact to help differentiate the catalyst from the intermediate (which is created then consumed by the rxn).
Thu Mar 14, 2019 11:23 am
Forum: Administrative Questions and Class Announcements
Topic: lyndon's review?
Replies: 5
Views: 504

### Re: lyndon's review?

Yes, he is but it will probably not be posted before tonight or tomorrow as I am sure he has his own finals too.
Thu Mar 14, 2019 11:17 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium Partial pressure Units
Replies: 2
Views: 84

### Re: Equilibrium Partial pressure Units

Usually, it is bar or atm.
Thu Mar 07, 2019 9:49 am
Forum: Van't Hoff Equation
Topic: test 2
Replies: 7
Views: 562

### Re: test 2

Yes, the Van't Hoff equation would be needed in this case. Essentially you use this equation when you are given a K value for a specific temperature (K1 at T1) and use it to find the K value at another temperature (K2 at T2).
Thu Mar 07, 2019 9:44 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: the phases in a cell diagram
Replies: 4
Views: 161

### Re: the phases in a cell diagram

^ order for the aqueous ions does not matter as long as they are on the appropriate side (anode or cathode).
Thu Mar 07, 2019 9:30 am
Forum: Administrative Questions and Class Announcements
Topic: Homework for Week 9
Replies: 3
Views: 178

### Re: Homework for Week 9

I think anything from the second half of electrochem or kinetics is acceptable.
Sat Mar 02, 2019 9:43 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Calculations using the Van't Hoff Equation
Replies: 2
Views: 221

### Re: Calculations using the Van't Hoff Equation

This problem would not require the Van't Hoff equation. An instance where you would need to use the Van't Hoff equation would be if you were looking to find a K value at a given temperature T2 (you would have to be given K at another temperature as well to use as K1 and T1 in the equation).
Sat Mar 02, 2019 9:36 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagram
Replies: 4
Views: 282

### Re: Cell Diagram

For cell diagrams it usually doesn't matter which aqueous species comes first, however, you do want to make sure of a few things: --the electrodes are always on the ends --cathode is always on the right and and anode always on the left. --aqueous ions (H+ and OH- included) are always closest to salt...
Sat Mar 02, 2019 9:30 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Order of Cell Diagrams
Replies: 13
Views: 479

### Re: Order of Cell Diagrams

Builidng off of the above reponse, just make sure that all aqueous ions are closest to the salt bridge. Also note that if a particular half reaction inlcudes H+ or OH- in it when balanced, you must also include that in the cell diagram on the respective side (anode or cathode depending on which half...
Thu Feb 21, 2019 3:46 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Midterm #1 14B
Replies: 17
Views: 992

### Re: Midterm #1 14B

^Lyndon's for sure. Not sure I can recommend any of the others since I didn't go to them....
Thu Feb 21, 2019 3:39 pm
Forum: Balancing Redox Reactions
Topic: sections covered on test
Replies: 4
Views: 204

### Re: sections covered on test

I think it covers 4J + the end of chapter problems, 5G, and 5J for sure for the 7th edition. I am not entirely sure about which electrochemistry sections will be covered though.
Thu Feb 21, 2019 3:27 pm
Forum: Van't Hoff Equation
Topic: Van't Hoff use
Replies: 13
Views: 1033

### Re: Van't Hoff use

You would use this equation when you are trying to find out how a K value would change if you increased the temperature of a reaction (you would need to be given another K value at a lower or higher temp which is why there is K1/K2 and T1/T2).
Thu Feb 14, 2019 4:47 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: ΔU= 3/2nRT
Replies: 5
Views: 298

### Re: ΔU= 3/2nRT

We rarely need to use this equation but since professor Lavelle did mention it in class, it may be a good idea to know anyways.
Thu Feb 14, 2019 4:45 pm
Forum: Phase Changes & Related Calculations
Topic: Phase Change Diagram of Water
Replies: 6
Views: 260

### Phase Change Diagram of Water

Why does steam at 100oC burn more than water at 100oC?
Thu Feb 14, 2019 4:42 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: isothermal irreversible free expansion
Replies: 2
Views: 299

### isothermal irreversible free expansion

Why is the entropy of surroundings 0 for an isothermal irreversible free expansion? (From Figure 4I.6 in 7th edition textbook)
Thu Feb 07, 2019 9:32 pm
Forum: Phase Changes & Related Calculations
Topic: Units of enthalpy
Replies: 5
Views: 211

### Re: Units of enthalpy

In the textbook the most common unit used for enthalpy is kJ/mol.
Thu Feb 07, 2019 9:30 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Isolated System
Replies: 4
Views: 128

### Re: Isolated System

since the system is isolated, no matter or energy can be exchanged with the surroundings. Therefore, after 100 years the amount of energy in the system (the internal energy, U) will remain constant at 100kJ. Remember that DeltaU=0 for all isolated systems.
Thu Feb 07, 2019 9:27 pm
Forum: Phase Changes & Related Calculations
Topic: Work equation
Replies: 4
Views: 200

### Re: Work equation

101.325 J = 1 atm(L)
Thu Jan 31, 2019 1:21 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Homework
Replies: 9
Views: 324

### Re: Homework

If you read the section before you start answering the questions, you should be able to do most of the homework by following the format of the examples given. Dr. Lavelle is going a bit out of order for this unit so I would pick something we've already covered (like Hess's Law) and start with that.
Thu Jan 31, 2019 1:13 pm
Forum: Ideal Gases
Topic: breaking bond - heat released and gained
Replies: 5
Views: 433

### Re: breaking bond - heat released and gained

When a bond is broken it does release energy, but in order to break that bond, usually some amount of energy is needed. The amount released by breaking the bond tends to be more than what is needed to initiate the breaking of that bond.
Thu Jan 31, 2019 1:04 pm
Forum: Calculating Work of Expansion
Topic: Reversible Expansion
Replies: 3
Views: 126

### Re: Reversible Expansion

The equation we use is :
A reversible process is a process whose direction can be "reversed" by inducing infinitesimal changes to some property of the system via its surroundings.
Thu Jan 24, 2019 7:39 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: When to ignore change in Acid
Replies: 5
Views: 214

### Re: When to ignore change in Acid

However, always make sure to double check your approximation and ensure that change in x is less than 5% of the inital concentration!
Thu Jan 24, 2019 7:33 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Second deprotonation
Replies: 3
Views: 135

### Re: Second deprotonation

There really isn't much to it. Just know that the K values decrease significantly after each deprotonation so for most acids we only consider the 1st deprotonation (H 2 SO 4 is the only excpetion according to the textbook where the first and second deportonations must be considered and two ice table...
Thu Jan 24, 2019 7:20 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: predict solubility
Replies: 2
Views: 127

### Re: predict solubility

The higher the constant Ksp, the greater the solubility. Think about this conceptually. Something that has a high Ksp favors the products so it must be very soluble or dissolvable...
Tue Jan 15, 2019 1:01 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: When is X assumed to be negligible?
Replies: 1
Views: 95

### When is X assumed to be negligible?

When using an ICE table, the book stated that we can assume that a change in concentration, x, is negligible if it is less than 5% of the initial concentration of a particular substance. It also stated that one could tell by looking at how small the K value is, but it did not specifiy a particular v...
Tue Jan 15, 2019 12:44 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Simplifying Cubic Equations
Replies: 2
Views: 141

### Simplifying Cubic Equations

One of the bullets on Outline 1 states that we should be able to simplify cubic equations (for ICE tables). Do we need to know how to do this as none of the textbook or module questions required us to work with cubic functions and they were also not covered during lecture?
Tue Jan 15, 2019 12:24 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Test 1
Replies: 2
Views: 103

### Re: Test 1

Expect all of Equilibrium and Acids and Bases to be on it. Professor Lavelle will make an in-class announcement about what the test will cover, probably this Friday. He also posts his announcements on his website so keep watching that too for more info!
Fri Jan 11, 2019 12:35 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: HW questions for discussion
Replies: 2
Views: 62

### Re: HW questions for discussion

You can turn in any 7 of the homework questions that are listed in Lavelle's syllabus for credit every week.
Fri Jan 11, 2019 12:32 pm
Forum: General Science Questions
Topic: Transition from 20 Series to 14 Series
Replies: 2
Views: 435

### Re: Transition from 20 Series to 14 Series

My roomates were both in the 20 series and the material they covered seemed more or less the same as what I covered in the 14 series with Lavelle. However, they did go more in depth than we did. The one thing we did cover that they did not cover at all in the 20 series would be acids and bases (unde...
Fri Jan 11, 2019 12:27 pm
Forum: General Science Questions
Topic: Chem 20A to Chem 14B
Replies: 3
Views: 200

### Re: Chem 20A to Chem 14B

The 14 series is very similar to AP Chemistry so if you took that in high school you will be fine. The 20 series just tends to go more in-depth on certain topics but the material is more or less the same as the 14 series.
Thu Dec 06, 2018 10:51 pm
Forum: Lewis Acids & Bases
Topic: Electron Withdrawing Atoms?
Replies: 1
Views: 101

### Re: Electron Withdrawing Atoms?

Electron withdrawing ability is essentially referring to the ability of a bonded atom to pull the oxygen's electrons towards itself in order to minimize the likelihood that the conjugate base will just reform the acid (If oxygen's electrons are being pulled away and towards this other bonded atom th...
Thu Dec 06, 2018 10:44 pm
Forum: Amphoteric Compounds
Topic: Determining Amphoteric Compounds
Replies: 3
Views: 129

### Re: Determining Amphoteric Compounds

Also, remember that water is amphoteric as well!
Thu Dec 06, 2018 10:23 pm
Forum: Naming
Topic: Common Names
Replies: 1
Views: 60

### Re: Common Names

I am not sure. From what I know those are the only two exceptions to the rule so I would just remember them just in case.
Wed Nov 28, 2018 9:36 pm
Forum: Dipole Moments
Topic: Magnitude
Replies: 2
Views: 105

### Re: Magnitude

^ It is just another term for the strength of the dipole. A value can be assigned to magnitude using the formula Lavelle gave us during lecture, but we do not need to know how to calculate it. He just gave us that formula so we can gain a better understanding conceptually.
Wed Nov 28, 2018 9:31 pm
Forum: Administrative Questions and Class Announcements
Topic: Final
Replies: 11
Views: 540

### Re: Final

I think the final is on the entire course. Professor Lavelle said he will be telling us the details about the final during lecture on Friday (11/30/18).
Wed Nov 28, 2018 9:29 pm
Forum: Hybridization
Replies: 3
Views: 172

single electrons found as radicals occupy an unhybridized p-orbital. That said, the single electron is still counted as a region of electron density so I think it is still considered when determining hybridization.
Thu Nov 22, 2018 2:00 am
Forum: Bond Lengths & Energies
Topic: H bonding
Replies: 14
Views: 707

### Re: H bonding

Hydrogen bonding results in higher melting and boiling points since it is the strongest type of intermolecular force (other than ionic bonding).
Thu Nov 22, 2018 1:55 am
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Sigma and Pi Bonds
Replies: 3
Views: 137

### Re: Sigma and Pi Bonds

Try Khan Academy! That is my go-to for any confusing topics.
Wed Nov 21, 2018 11:02 pm
Forum: Electronegativity
Topic: electron density
Replies: 4
Views: 197

### Re: electron density

In addition to the above reply, remember that a single unpaired electron (found in radicals) counts as a single region of electron density (basically a single unpaired electron is treated as if it were a normal lone pair).
Thu Nov 15, 2018 3:50 pm
Forum: General Science Questions
Topic: Audio Visuals
Replies: 6
Views: 487

### Re: Audio Visuals

There will not be anymore audio visual modules for the rest of the quarter. There may be some for 14B next quarter though!
Thu Nov 15, 2018 3:47 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Double Bonds in VSEPR
Replies: 5
Views: 144

### Re: Double Bonds in VSEPR

Regardless of whether the bond is single, double, or triple, it is still one region of electron density. Therefore, there are no changes made to the VSEPR model.
Thu Nov 15, 2018 1:19 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Arrangement vs Shape
Replies: 3
Views: 196

### Re: Arrangement vs Shape

The arrangement is dependent only on the number of regions of electron density whereas the molecular geometry has to take into account the number of bonded electrons vs. the number of lone pairs and how they interact among each other (lone pairs force bonded atoms closer together and therefore creat...
Wed Nov 07, 2018 12:33 am
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizing Power vs Polarisabiltiy
Replies: 2
Views: 123

### Re: Polarizing Power vs Polarisabiltiy

The ability of a cation to distort an anion is known as its polarization power . Smaller, more positive cations pull electrons more strongly so these cations are said to have a strong polarization power. Polarizability is essentially the ability of the anion to pull in those electrons. Smaller negat...
Wed Nov 07, 2018 12:27 am
Forum: Lewis Structures
Topic: Central Atom
Replies: 3
Views: 151

### Re: Central Atom

It is best to choose the atom with the lowest ionization energy because as ionization energy decreases, you are more likely to find an atom that wants to share its electrons (get rid of them in a way) than hold on to them as lone pairs.
Wed Nov 07, 2018 12:24 am
Forum: Administrative Questions and Class Announcements
Topic: HW for this week
Replies: 2
Views: 175

### Re: HW for this week

I think anything that we have covered within the last week is acceptable.
Thu Nov 01, 2018 11:43 pm
Forum: Student Social/Study Group
Topic: Midterm
Replies: 15
Views: 760

### Re: Midterm

According to professor Lavelle it will be 8 questions with multiple subparts. It should be quite similar in difficulty to test 2 according to my TA. My TA also said that we should have plenty of time to complete it since it will be just a bit longer than test 2 even though we will have almost triple...
Thu Nov 01, 2018 11:40 pm
Forum: Trends in The Periodic Table
Replies: 3
Views: 81

I think they are using values the values shown in Figures 1F.4 and 1F.6 on pages 54-55. We would not need those values on a test. We are just required to know the basic trends of atomic radii.
Thu Nov 01, 2018 11:35 pm
Forum: Ionic & Covalent Bonds
Topic: Electron Configuration
Replies: 3
Views: 125

### Re: Electron Configuration

According to the textbook, [Ar] 4s23d104p5 is the correct way to write the electron configuration of Br.
Thu Oct 25, 2018 1:23 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Online Modules
Replies: 4
Views: 202

### Re: Online Modules

From what I know, Professor Lavelle only created the modules for specific topics that his students have struggled with in the past. I guess people seem to have a relatively good understanding of the topics covered after the quantum world unit.
Thu Oct 25, 2018 1:18 pm
Forum: Administrative Questions and Class Announcements
Topic: Midterm
Replies: 7
Views: 403

### Re: Midterm

Not 100% sure but I would think that is all we will have time for. I am sure professor Lavelle will be making an in-class announcement as well as online announcement very soon in regards to what will be covered on the midterm.
Tue Oct 23, 2018 11:03 am
Forum: Administrative Questions and Class Announcements
Topic: TEST 3 during Thanksgiving week?
Replies: 5
Views: 344

### Re: TEST 3 during Thanksgiving week?

According to the test schedule on Professor Lavelle's website, test 3 will be administered starting Tuesday November 27 in discussion section (the week after Thanksgiving).
Fri Oct 19, 2018 11:21 am
Forum: Photoelectric Effect
Topic: Post-Module Assessment Q15
Replies: 1
Views: 120

### Re: Post-Module Assessment Q15

There is no equation to solve this. During the video module, professor Lavelle states that one photon can only dislodge one electron (assuming it has a high enough energy to do so). Therefore, if 1 million photons hit a metal surface, the absolute maximum number of electrons that could be ejected wo...
Fri Oct 19, 2018 11:16 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Video Modules
Replies: 7
Views: 368

### Re: Video Modules

From what I have heard, there will not be any more Audio-Visual Modules this quarter. Professor Lavelle only created the modules for the topics he found his students to struggle with most (Quantum World) and high school review material.
Fri Oct 19, 2018 11:11 am
Forum: Administrative Questions and Class Announcements
Topic: Test #2
Replies: 3
Views: 161

### Re: Test #2

According to Professor Lavelle's in-class announcement on Friday 10/19, test #2 will cover everything on the outline except Section 1F (Periodic Trends) which we did not yet cover in class.
Wed Oct 10, 2018 9:20 pm
Forum: Einstein Equation
Topic: sig fig numbers
Replies: 4
Views: 142

### Re: sig fig numbers

It should be the lowest number of significant figures out of the values given to you in the problem. So for example, if I am given two values, one with 3 significant figures and one with 2 significant figures in the problem, my final answer should have 2 significant figures, regardless of any outsid...
Wed Oct 10, 2018 9:16 pm
Forum: Empirical & Molecular Formulas
Topic: Empirical & Molecular Formulas
Replies: 11
Views: 930

### Re: Empirical & Molecular Formulas

Yes, there are cases when the empirical and molecular formulas are the same. This happens when the molar mass of the calculated empirical formula matches the molar mass given to you for the molecular formula.
Tue Oct 09, 2018 1:37 pm
Forum: Administrative Questions and Class Announcements
Topic: Test 1 Study Plan
Replies: 6
Views: 328

### Re: Test 1 Study Plan

Hello, I am also taking the first test this Thursday. My plan is to study up for the test and worry about homework for chapter 1 later. The homework due this week can be from either outline one or outline two so personally I would prefer to hold off on working a new topic until I completely master t...
Fri Oct 05, 2018 11:40 am
Forum: General Science Questions
Topic: Nomenclature
Replies: 1
Views: 137

### Re: Nomenclature

I am not entirely sure myself. Given this is a college chemistry course, I would think professor Lavelle would like us to know all of the naming categories you mentioned. That said, I would think the test would focus on naming things like ionic compounds (ex: cobalt (II) chloride) and covalent compo...
Fri Oct 05, 2018 9:38 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: % Yield
Replies: 8
Views: 651

### Re: % Yield

There is no set cutoff. Multiple factors come into play when deciding whether a reaction is 'efficient' or not including the time needed for the reaction to occur, the cost of the materials involved, and the percent yield. Therefore, every reaction's efficiency will have to be gauged individually.
Fri Oct 05, 2018 9:20 am
Forum: General Science Questions
Topic: Common ions
Replies: 4
Views: 304

### Re: Common ions

When I had to essentially memorize them for AP Chem in high school, I paid close attention to the prefixes and suffixes because they usually have a pattern associated with them. For example, polyatomic ions ending with 'ate' have one more oxygen atom than polyatomic ions ending with the suffix 'ite'...