Search found 62 matches
- Sun Mar 18, 2018 11:53 pm
- Forum: General Science Questions
- Topic: Grade
- Replies: 8
- Views: 1523
Re: Grade
The class is graded for sure.
- Sun Mar 18, 2018 10:01 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3641617
- Sun Mar 18, 2018 10:00 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3641617
- Sun Mar 18, 2018 10:00 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3641617
- Sun Mar 18, 2018 9:54 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: mechanism differentiation
- Replies: 2
- Views: 577
Re: mechanism differentiation
You find the slowest step and you find the concentration of the fast step. If there is a catalyst or intermediate, you have to isolate that and put everything on the other side. Then, you can plug in those values into the rate law of your fast step.
- Sun Mar 18, 2018 9:50 pm
- Forum: *Alkanes and Substituted Alkanes (Staggered, Eclipsed, Gauche, Anti, Newman Projections)
- Topic: nucleophiles
- Replies: 3
- Views: 3944
Re: nucleophiles
I think of nucleophiles as something that is "positive" loving, so it wants to be paired up by something with a positive charge in order to make it more stable/have a 0 charge.
- Sun Mar 18, 2018 9:47 pm
- Forum: General Science Questions
- Topic: Grade
- Replies: 8
- Views: 1523
Re: Grade
I'd check the Bruinwalk reviews, but our class is kinda odd because we were doing well, from what I heard. I would expect a curve, but not by much.
- Sun Mar 18, 2018 9:42 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Saying Thank You to Dr. Lavelle
- Replies: 490
- Views: 566974
Re: Saying Thank You to Dr. Lavelle
Dr. Lavelle, I hated chemistry in high school and I honestly was dreadful in it. I had a good teacher, don't get me wrong. It just felt like chemistry and I had a terrible relationship. I decided to give chemistry one final go. Going into my fall quarter, I had resigned to myself that if I didn't li...
- Sun Mar 18, 2018 9:22 pm
- Forum: Administrative Questions and Class Announcements
- Topic: FINAL
- Replies: 9
- Views: 1434
Re: FINAL
Functional groups and possibly an SN2 reaction will be covered in the final.
- Sat Mar 17, 2018 10:52 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Arrhenius Graph
- Replies: 2
- Views: 1045
Arrhenius Graph
Are the axis always going to be 1/T for the x axis and ln(k) for the y axis? And why or why not?
- Sat Mar 17, 2018 10:46 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Final Winter 2013
- Replies: 3
- Views: 645
Re: Final Winter 2013
Can't you also tell because there is (OH)2 meaning that there will be 4e-'s due to the charge of O always being 2- and there's 2 of them?
- Thu Mar 15, 2018 4:21 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Lavelle: Professor by day, wizard by night
- Replies: 6
- Views: 1541
Re: Lavelle: Professor by day, wizard by night
Jade, you're the true MVP of our discussion.
I thoroughly enjoy watching these old extra credit videos. They're pretty helpful actually!
And somebody better give Dr. Lavelle an Oscar!
I thoroughly enjoy watching these old extra credit videos. They're pretty helpful actually!
And somebody better give Dr. Lavelle an Oscar!
- Sat Mar 10, 2018 2:30 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: HW 15.49
- Replies: 5
- Views: 1026
Re: HW 15.49
So, if it was the slow step, would we then disregard HOBr? And it's because the slow step determines the overall rate of the reaction right?
- Sun Mar 04, 2018 6:59 pm
- Forum: First Order Reactions
- Topic: Units in 15.29
- Replies: 2
- Views: 461
Units in 15.29
I thought that it was standard to change your units from whatever unit of time to seconds. Why did the book express the answers in terms of minutes? And how do we know when to switch up the units or to let them stay the same?
- Sat Mar 03, 2018 3:11 pm
- Forum: General Rate Laws
- Topic: 15.17
- Replies: 1
- Views: 358
15.17
For part C, why do we use the first experiment's values to find the reaction rate constant? Shouldn't we do them all and average them out? Or will it be the same regardless?
- Tue Feb 27, 2018 6:08 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Unique Average Rate vs. Average Rate
- Replies: 3
- Views: 591
Unique Average Rate vs. Average Rate
Is there a difference between these two terms or are they interchangeable?
- Tue Feb 27, 2018 6:07 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Hw 15.1 [ENDORSED]
- Replies: 7
- Views: 1108
Re: Hw 15.1 [ENDORSED]
Yes, because the rate of N2 is simply the rate of H2 x mols of N2/H2
- Sun Feb 25, 2018 11:36 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Problem 15.101 [ENDORSED]
- Replies: 1
- Views: 455
Problem 15.101 [ENDORSED]
How exactly does the rate law differ if the reactions were carried out in an organic solvent? I'm not really understanding this concept.
- Sun Feb 25, 2018 11:32 pm
- Forum: Environment, Ozone, CFCs
- Topic: Test 3 Kinetics and Environment
- Replies: 1
- Views: 1102
Test 3 Kinetics and Environment
Will we be tested on a kinetics and environment problem? If so, what will we have to know about the environment?
- Sun Feb 25, 2018 11:29 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3641617
- Sun Feb 18, 2018 9:32 pm
- Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
- Topic: Iron Reduction
- Replies: 1
- Views: 493
Iron Reduction
Why does iron have a tendency to reduce silver? Is it because of its standard potential?
- Sun Feb 18, 2018 9:20 pm
- Forum: Balancing Redox Reactions
- Topic: "Rules"
- Replies: 7
- Views: 863
Re: "Rules"
The book has these set of rules that I've abided by that I think is pretty helpful. It's under Section 14.2. Step 1. Identify the species being oxidized and the species being reduced by looking at the change of oxidation numbers. Step 2. Write two skeletal equations (unbalanced) for oxidation and re...
- Sun Feb 18, 2018 9:11 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: The Daniell Cell
- Replies: 4
- Views: 583
The Daniell Cell
Is the Daniell cell basically the only example of a galvanic cell that we need to know for this course? Or do we need to know more examples?
- Sun Feb 11, 2018 3:01 pm
- Forum: Biological Examples (*DNA Structural Transitions, etc.)
- Topic: Hemoglobin and Equilibrium
- Replies: 4
- Views: 2896
Hemoglobin and Equilibrium
How does the hemoglobin help your body to reach equilibrium or to achieve the process of homeostasis?
- Sun Feb 11, 2018 2:54 pm
- Forum: Balancing Redox Reactions
- Topic: nernst eq'n
- Replies: 2
- Views: 387
Re: nernst eq'n
I'm pretty sure that n is the number or moles of electrons transferred in the reaction when you balanced it.
- Sun Feb 11, 2018 2:46 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Total Entropy of the Freezing of Water
- Replies: 2
- Views: 1676
Re: Total Entropy of the Freezing of Water
Another thing to note is that, when there is an isothermal, reversible expansion of a gas, delta S tot = 0. When there is an isothermal, irreversible free expansion of a gas, the internal energy is 0, meaning work is equal to 0, so q is equal to 0. This means that delta S is equal to 0. This doesn't...
- Sun Feb 11, 2018 2:45 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Total Entropy of the Freezing of Water
- Replies: 2
- Views: 1676
Re: Total Entropy of the Freezing of Water
Generally when at equilibrium, delta S tot = 0. Keep in mind that the equation for total entropy is delta S tot = delta S surr + delta S sys . With water, you want to take into account that there is an unfavorable phase change, so you would have to take into account - delta S fus and you have to tak...
- Sun Feb 04, 2018 5:19 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm Content Question
- Replies: 4
- Views: 681
Re: Midterm Content Question
I would assume that we would cover electrochemistry. So I'd assume that the midterm will cover Chapter 8, 9, part of 11, and part of 14. We probably won't be asked to derive the equations, but we probably have to know how to apply them.
- Sun Feb 04, 2018 1:56 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Midterm
- Replies: 6
- Views: 837
Re: Midterm
It's also nice to just know the derivations. In case you are stuck on a question, I find that knowing the derivations and where exactly they come from helps to push me back on track.
- Sun Feb 04, 2018 1:54 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Delta G not
- Replies: 5
- Views: 792
Re: Delta G not
ΔG° is in standard condition, so you would have to calculate ΔH° and ΔS°, just like you would in the regular Gibbs Free Energy equation.
- Fri Jan 26, 2018 4:49 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Formation of Snow in Clouds [ENDORSED]
- Replies: 5
- Views: 7431
Formation of Snow in Clouds [ENDORSED]
Can someone explain to me why the formation of snow in the clouds is an exothermic reaction? I saw this on the Internet while studying for my test and now I am thoroughly confused.
- Fri Jan 26, 2018 9:42 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Iron Rusting: Exo or Endo? [ENDORSED]
- Replies: 4
- Views: 12913
Iron Rusting: Exo or Endo? [ENDORSED]
Can someone explain to me why iron rusting is an exothermic reaction?
- Wed Jan 24, 2018 10:39 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Formation of a Cation from an Atom
- Replies: 3
- Views: 1243
Formation of a Cation from an Atom
Can someone explain to me if the formation a cation from an atom in the gas phase is an endothermic or exothermic reaction? I saw this on the Internet while studying for my test and now I am thoroughly confused.
- Sun Jan 21, 2018 12:23 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 8.31
- Replies: 3
- Views: 287
Re: 8.31
The general equation that you're going to use is nC(delta)T or mC(delta)T. Now, C can either be C p , which is constant pressure or C v , which is constant volume. When you have C p , you would use 5/2 R. When you have C v , you would use 3/2 R. The R will be the gas constant, so you have to look at...
- Sun Jan 21, 2018 12:06 am
- Forum: Phase Changes & Related Calculations
- Topic: Question 8.87- Breaking phase changes up into steps [ENDORSED]
- Replies: 4
- Views: 1004
Re: Question 8.87- Breaking phase changes up into steps [ENDORSED]
For step 2, I realized that we had to use dHfus= 6.01 kJ.mol^-1. Do we always use this value whenever we are melting ice and only when we are melting ice at 0 degrees C?
- Sat Jan 20, 2018 4:38 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Test 1
- Replies: 3
- Views: 549
Re: Test 1
On the class site, Dr. Lavelle said that "Concept questions involving work and internal energy will be on Test 1, but not calculating w and delta U" Conceptionally, we are supposed to understand work and internal energy. But we will not have to solve for questions that uses delta U = q + w...
- Sat Jan 13, 2018 4:11 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Enthalpy of physical change?
- Replies: 3
- Views: 1109
Re: Enthalpy of physical change?
I'd like to start off by saying: there is no such thing as a stupid question! Every question that you have is valid, including this one. Standard enthalpies will be given to you; no worries. Table 8.3 lists some of the enthalpies for common substances, including water. All of the values given to you...
- Sat Jan 13, 2018 4:02 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Work vs. Heat
- Replies: 6
- Views: 720
Re: Work vs. Heat
I'd like to think that heat is basically the energy expended molecularly while work is more on a macro basis. Work is basically like you pushing a box; you know that energy is being used there and you can see it and feel it. Now, if you were to boil water, energy is expended molecularly because the ...
- Tue Jan 09, 2018 7:59 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Paths and Changes of State
- Replies: 3
- Views: 527
Paths and Changes of State
In this course, do we have to draw out the path of the state of change from one substance to another? And do we also have to describe, from the path that we drew, whether the process was reversible, irreversible, adiabatic, isobaric, isothermal..etc.? To clarify, I have an example of a path down att...
- Sat Dec 09, 2017 2:55 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polarity
- Replies: 2
- Views: 308
Re: Polarity
Basically, you want to look and see if the dipole moments cancel out. You can definitely look at the charges, which means you are looking to see whether there are lone pairs on the central atoms or there exists a lack or abundance of lone pairs from the outer atoms that make the outer atoms have a p...
- Sat Dec 09, 2017 2:42 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Non polar vs. Polar molecule Video example
- Replies: 2
- Views: 1312
Re: Non polar vs. Polar molecule Video example
First of all, nice video!
So, basically, anything with lone pairs is polar? If you were giving AXmEn, with m and n being whatever number you choose, you would think immediately, "Aha! This is a polar molecule!"?
So, basically, anything with lone pairs is polar? If you were giving AXmEn, with m and n being whatever number you choose, you would think immediately, "Aha! This is a polar molecule!"?
- Fri Dec 08, 2017 1:15 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 2013 Final Q5C
- Replies: 1
- Views: 325
2013 Final Q5C
Consider the follow reaction: Ni(CO) 4 (g) <--> Ni(s) + 4 CO(g) If the initial concentration of Ni(CO) 4 (g) is 1.0 M, and "x" is the equilirium concentration of CO(g), write a general expression for the equilibrium constant K c in terms of x. For this problem, I used an ICE Table to get m...
- Wed Dec 06, 2017 8:42 am
- Forum: Administrative Questions and Class Announcements
- Topic: Classes Today? [ENDORSED]
- Replies: 2
- Views: 421
Classes Today? [ENDORSED]
Will there be classes and review sessions today? There is a fire near UCLA right now and I was wondering if classes and review sessions are still in effect.
- Sun Dec 03, 2017 10:13 pm
- Forum: Naming
- Topic: Iron v ferrate in coordination compound naming
- Replies: 8
- Views: 5325
Re: Iron v ferrate in coordination compound naming
alyssawhite1L wrote:are there any other elements where the latin name is different from the name we know, other than iron?
Other than iron, I would say these following metals are different from the name that we know.
Copper = Cuprate
Lead = Plumbate
Silver = Argenate
Gold = Aurate
Tin = Stannate
- Sat Dec 02, 2017 9:56 pm
- Forum: Bronsted Acids & Bases
- Topic: Question J.5 [ENDORSED]
- Replies: 2
- Views: 568
Question J.5 [ENDORSED]
Complete the overall equation, and write the complete ionic equation and the net ionic equation for each of the following acid–base reactions. If the substance is a weak acid or base, leave it in its molecular form in the equations. (b) (CH 3 ) 3 N(aq) + HNO 3 (aq) --> For B, why does it become (CH...
- Sat Dec 02, 2017 9:41 pm
- Forum: Administrative Questions and Class Announcements
- Topic: 14B Syllabus
- Replies: 1
- Views: 389
Re: 14B Syllabus
I assume that the syllabus will not be posted until the end of Chem 14A. But, for the Winter Quarter 2017, the dates were: Quiz 1: Starting Tuesday Jan. 31 in discussion section. Midterm: exam Wednesday Feb. 15 from 6 to 8pm. Quiz 2: Starting Tuesday Feb. 21 in discussion section. Quiz 3: Starting T...
- Sun Nov 26, 2017 12:55 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Q.11.37
- Replies: 1
- Views: 294
Q.11.37
For the reaction N 2 (g) + 3 H 2 (g) Δ 2 NH 3 (g) at 400. K, K = 41. Find the value of K for each of the following reactions at the same temperature: (a) 2 NH 3 (g) --> <-- N 2 (g) + 3 H 2 (g) (b) (1/2) N 2 (g) + (3/2) H 2 (g) --> <-- NH 3 (g) (c) 2 N 2 (g) + 6 H 2 (g) --> <-- 4 NH 3 (g) Am I suppos...
- Sat Nov 25, 2017 11:16 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Molecules in Subscript
- Replies: 3
- Views: 562
Molecules in Subscript
Do you only have your molecules in subscript (i.e. PH2O) when you have just K? I noticed that, when the question asks for Kc, you don't need to write out P(molecule) to find your equilibrium constant.
- Sun Nov 19, 2017 9:42 pm
- Forum: Biological Examples
- Topic: Other Biological Examples
- Replies: 5
- Views: 998
Re: Other Biological Examples
Chromium has a very interesting biological function. It assists insulin by helping it control blood sugar, I believe.
- Sun Nov 19, 2017 9:37 pm
- Forum: Hybridization
- Topic: General Hybridization
- Replies: 3
- Views: 703
- Thu Nov 09, 2017 2:53 pm
- Forum: Ionic & Covalent Bonds
- Topic: Electron Configuration and d-block (3.11)
- Replies: 2
- Views: 411
Re: Electron Configuration and d-block (3.11)
The 5th period is where things get a little funky, so I don't think you have to worry about those elements too much. The short answer is that it's more stable when it has that configuration you are talking about, instead of what we expected to get. When you're dealing with 4d, the more stable config...
- Fri Nov 03, 2017 4:18 pm
- Forum: Hybridization
- Topic: Writing out the Hybridization [ENDORSED]
- Replies: 4
- Views: 708
Writing out the Hybridization [ENDORSED]
Is this where you would utilize px, py, and pz? And is there a common trend to remember hybridization that one can follow?
- Fri Nov 03, 2017 4:14 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: Sigma and Pi Bonds
- Replies: 3
- Views: 641
Sigma and Pi Bonds
Do sigma bonds simply that there is a sharing of two electrons between one elect to another? If so, can we also say that pi bonds are the double bonds? I'm a little bit confused on how these bonds can correlate to the material we have previously learned.
- Sat Oct 28, 2017 1:43 pm
- Forum: Trends in The Periodic Table
- Topic: Carbon Electron Affinity [ENDORSED]
- Replies: 3
- Views: 473
Carbon Electron Affinity [ENDORSED]
I asked this question in a previous forum but it didn't get answered. Why is it that carbon has a higher affinity than nitrogen when nitrogen is at the right of the carbon? I thought that as you go more right, there is a higher electron affinity. What is the exception with carbon that makes it have ...
- Thu Oct 26, 2017 12:19 pm
- Forum: SI Units, Unit Conversions
- Topic: Quantum Mechanics
- Replies: 4
- Views: 797
Re: Quantum Mechanics
Why is it that carbon has a higher affinity than nitrogen when nitrogen is at the right of the carbon? I thought that as you go more right, there is a higher electron affinity. What is the exception with carbon that makes it have a higher electron affinity?
- Mon Oct 23, 2017 10:15 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Test 3
- Replies: 2
- Views: 339
Test 3
Will Test 3 include parts of Chapter 3 or will we stop with just parts of Chapter 1 and 2?
- Sat Oct 21, 2017 11:08 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Quantum Number l exception [ENDORSED]
- Replies: 4
- Views: 722
Quantum Number l exception [ENDORSED]
We presume that, to find l, it is literally (n-1), correct? Now, would the only exception be when n is at an s-orbital, like 2s, 3s, or 4s? For instance, at 2s, isn't l = 0 because there's not really an orbital angular momentum until we reach 2p?
- Thu Oct 19, 2017 2:23 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Ground state vs excited state
- Replies: 3
- Views: 750
Re: Ground state vs excited state
The Rydberg Formula is basically used to find or predict the wavelength of the light from an electron as the electron moves from one energy level to another. If you remember Rydberg's formula, there was an n 1 and an n 2 energy level. Those are the principle quantum numbers that tells you the energy...
- Tue Oct 10, 2017 11:50 am
- Forum: Properties of Light
- Topic: Amplitude
- Replies: 6
- Views: 934
Re: Amplitude
Amplitude is related to the energy of the wave. If the wave has a low energy, then there will be a short amplitude. If the energy of a wave is high, then there will be a long amplitude.
- Tue Oct 10, 2017 11:42 am
- Forum: Properties of Light
- Topic: Chapter 1, problem 3 [ENDORSED]
- Replies: 10
- Views: 1484
Re: Chapter 1, problem 3 [ENDORSED]
For this question, my reasoning was that the answer would be A) the speed of the radiation decreases as frequency of electromagnetic radiation decreases, because a higher frequency means that more waves are traveling per second or more cycles per second. The solutions manual, however, states that A...
- Tue Oct 03, 2017 10:46 am
- Forum: Empirical & Molecular Formulas
- Topic: F.23 Question [ENDORSED]
- Replies: 5
- Views: 1166
F.23 Question [ENDORSED]
The CO 2 produced by the combustion of hydrocarbons contributes to global warming. Rank the following fuels according to increasing mass percentage of carbon: (a) ethene, C 2 H 2 ; (b) propanol, C 2 H 2 OH; (c) heptane, C 2 H 16 . Do you simply take the amount of carbon from each hydrocarbon and div...
- Mon Oct 02, 2017 1:14 pm
- Forum: Limiting Reactant Calculations
- Topic: Question M.1 [ENDORSED]
- Replies: 5
- Views: 2360
Question M.1 [ENDORSED]
Hydrazine, N2H4, is an oily liquid used as a rocket fuel. It can be prepared in water by oxidizing ammonia with hypochlorite ions: 2 NH31g2 ClO1aq2 S N2H41aq2 Cl1aq2 H2O1l2. When 35.0 g of ammonia reacted with an excess of hypochlorite ion, 25.2 g of hydrazine was produced. What is the perce...