Search found 111 matches
- Mon Mar 16, 2020 2:54 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Final Grades
- Replies: 6
- Views: 639
Re: Final Grades
I am really nervous and want to find out soon too, but in the email Dr. Lavelle sent earlier today, he said that he was updating Chem community scores on Thursday, so I imagine he will update all scores at the same time (final too)...but IDK...but soon hopefully...
- Mon Mar 16, 2020 2:53 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ATP QUESTION ON FINAL
- Replies: 9
- Views: 932
Re: ATP QUESTION ON FINAL
Sine it says pi comes from ATP, the two concentrations cancels and K depends on [ADP] only. Maybe I am wrong about how I interpreted this problem, but I assumed that since all the Pi came from ATP, I assumed it meant that it only came from ATP that was broken into ADP...so Pi = ADP concentration......
- Mon Mar 16, 2020 12:37 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Final Exam #15
- Replies: 3
- Views: 548
Re: Final Exam #15
I tend to forget stressful scenarios, so I don't remember what was on the final lol, but I believe I used the Van't Hoff equation. The equation relates delta H, two equilibrium and two different temperatures together. I used information given in the previous equation for the K values and T values. U...
- Thu Mar 12, 2020 6:56 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: What was your favorite chem topic?
- Replies: 137
- Views: 13322
Re: What was your favorite chem topic?
Shanzey wrote:I liked drawing Lewis structures!
Same!
- Thu Mar 12, 2020 6:53 pm
- Forum: Second Order Reactions
- Topic: 7B.17
- Replies: 2
- Views: 266
7B.17
Hi Everyone, I am super stuck on this problem. I would appreciate it if someone could please give me a detailed explanation about how to solve this problem. Calculate the time required for each of the following second-order reactions to take place: (a) 2A --> B + C, for the concentration of A to dec...
- Wed Mar 11, 2020 4:52 pm
- Forum: First Order Reactions
- Topic: Half Life Equations
- Replies: 10
- Views: 625
Re: Half Life Equations
It's an open book final...
- Tue Mar 10, 2020 9:33 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Email Announcement
- Replies: 8
- Views: 727
Re: Email Announcement
I would assume that we still have normal class because there hasn't been any emails from him yet I'm pretty sure there will be bad consequences for a professors that hold normal, in-person classes. My friend's RA sent a text with information on reporting professors that are holding in person classe...
- Tue Mar 10, 2020 4:43 pm
- Forum: Administrative Questions and Class Announcements
- Topic: ENDGAME Review Session
- Replies: 71
- Views: 5823
Re: ENDGAME Review Session
Thank you so much Lyndon! I appreciate all the time you have put into us even though you had a really busy schedule with upperdivs and other commitments.
- Tue Mar 10, 2020 4:42 pm
- Forum: Administrative Questions and Class Announcements
- Topic: final
- Replies: 6
- Views: 612
Re: final
alex_4l wrote:Does anyone have an idea if it will be proctored?
I read that for the online versions of the finals teachers can enforce students to turn on their webcam and audio.
- Tue Mar 10, 2020 4:13 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 6D.15 part b
- Replies: 2
- Views: 293
Re: 6D.15 part b
What edition textbook are you using? Part b on 6D.15 for me is asking about AlCl3...
- Tue Mar 10, 2020 4:09 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Final exam content
- Replies: 15
- Views: 1238
Re: Final exam content
If you genuinely understand how to do all the homework problems along with the small detials he mentions in lecture, you should be fine for the final. Emphasize the "small details in lecture" I would also go through the outlines...sometimes there are things that aren't tested/asked for on...
- Tue Mar 10, 2020 4:06 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Chemistry 14B Final
- Replies: 9
- Views: 748
Re: Chemistry 14B Final
Adding on, can we take the final from home or do we need to be on UCLA wifi?
- Tue Mar 03, 2020 8:39 pm
- Forum: Administrative Questions and Class Announcements
- Topic: HW Sections
- Replies: 2
- Views: 254
Re: HW Sections
All the Chapter 5 concepts/problems
- Tue Mar 03, 2020 8:39 pm
- Forum: General Science Questions
- Topic: Test 2
- Replies: 12
- Views: 993
Re: Test 2
VioletKo3F wrote:Would there be any conceptual ideas that we should know before the test?
I would go through his outlines. For 14A test2, there were definitely a lot of "conceptual" questions in addition to the "math-heavy" questions.
- Tue Mar 03, 2020 8:30 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 6M.1
- Replies: 5
- Views: 438
Re: 6M.1
Isn't Cu2+ being reduced to Cu? So shouldn't the textbook Standard Cell Potential be +0.34 as the textbook says? Isn't the left side of the cell diagram always the cathode (reduction half-reaction)?
I'm really confused now...
Thank you?
I'm really confused now...
Thank you?
- Sun Mar 01, 2020 10:31 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: salt bridge
- Replies: 9
- Views: 657
Re: salt bridge
nshahwan 1L wrote:Should there be any specific examples of salts that are in salt bridges that we should be aware of?
NaCl is an easy one to remember...the salts are there to balance out the charge and they don't react with the reactants or products.
- Sun Mar 01, 2020 10:27 pm
- Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
- Topic: Identifying cathode & anode in electrolytic cells
- Replies: 4
- Views: 385
Re: Identifying cathode & anode in electrolytic cells
Vinita Saxena 2I wrote:Yup, cathode is reduced and anode is oxidized!
My TA taught us an easy way to remember this: "an ox" for anode is oxidized and a "red cat" for reduction happens at the cathode.
- Sun Mar 01, 2020 10:25 pm
- Forum: Balancing Redox Reactions
- Topic: 6K 3 part a)
- Replies: 4
- Views: 394
Re: 6K 3 part a)
Here is a prior post I found on Chem Community that goes into every single detail: https://lavelle.chem.ucla.edu/forum/viewtopic.php?t=11377 that solves this question step by step. But in short, you would 1) write out the Cl and the S2O3 half-reactions separately to first figure out the change in ch...
- Sun Mar 01, 2020 10:05 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Galvanic Cells
- Replies: 10
- Views: 603
Re: Galvanic Cells
Yes, when a battery is dead, the system has reached equilibrium -- though I'm wondering now if it's possible to 'revive' a battery or replace its galvanic cells concentration gradient? Isn't this done by recharging it by sending an electric current in the reverse direction...isn't that basically wh...
- Sun Mar 01, 2020 10:03 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: test 2 topics
- Replies: 11
- Views: 802
Re: test 2 topics
All of the electrochemistry and the chapter 5 units in the Thermodynamics outline.
- Sun Feb 23, 2020 6:06 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Negative E
- Replies: 3
- Views: 246
Re: Negative E
Yes, it means that the reverse process is spontaneous...
- Sun Feb 23, 2020 6:04 pm
- Forum: Balancing Redox Reactions
- Topic: Flow of electrons
- Replies: 11
- Views: 824
Re: Flow of electrons
Anode and cathode are defined that way...electrons go from anode to cathode...
- Sun Feb 23, 2020 6:01 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Standard Cell Potential
- Replies: 4
- Views: 344
Re: Standard Cell Potential
So you would just flip the signs because the reverse is occurring...
- Sun Feb 23, 2020 5:49 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Le Chatelier’s Principle
- Replies: 11
- Views: 732
Re: Le Chatelier’s Principle
[/quote]
This would then affect Q in the Nernst equation right?[/quote]
Yup because Q is the concentration of reactants/products
This would then affect Q in the Nernst equation right?[/quote]
Yup because Q is the concentration of reactants/products
- Sun Feb 23, 2020 5:40 pm
- Forum: General Science Questions
- Topic: Organic Chemistry Tutor?
- Replies: 6
- Views: 2032
Re: Organic Chemistry Tutor?
Khan Academy is also really good.
- Sun Feb 16, 2020 11:35 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Signs for Gibbs Free Energy
- Replies: 11
- Views: 735
Re: Signs for Gibbs Free Energy
When the Gibbs Free Energy is negative it means that the forward reaction is spontaneous while if it is positive, it means that the reverse reaction is spontaneous.
- Sun Feb 16, 2020 11:34 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Midterm Curve
- Replies: 45
- Views: 2359
Re: Midterm Curve
Based on his syllabus and last quarter (14a), I don't think he curves to help a B+, A-, A student...I believe the "curve" he refers to on his syllabus is mostly for students in the C (getting a 50% to pass the class)...but I will say that the midterm was hard and I do hope things are diffe...
- Sun Feb 16, 2020 11:30 pm
- Forum: Balancing Redox Reactions
- Topic: oxidation number
- Replies: 10
- Views: 788
Re: oxidation number
Oxidation numbers are basically the charges on an atom/ion...do you have a specific question/reaction in mind? By the way, I found this really helpful article on Khan Academy https://www.khanacademy.org/science/chemistry/chemical-reactions-stoichiome/types-of-chemical-reactions/a/oxidation-number if...
- Sun Feb 16, 2020 11:21 pm
- Forum: Phase Changes & Related Calculations
- Topic: Fusion = Melting?
- Replies: 7
- Views: 1038
Re: Fusion = Melting?
Yes, fusion does mean melting and enthalpy is positive. For the other way, freezing, change in enthalpy is the same, but you change the sign and it becomes negative.
- Sun Feb 16, 2020 11:17 pm
- Forum: Balancing Redox Reactions
- Topic: 2-14-2020 lecture question
- Replies: 1
- Views: 130
Re: 2-14-2020 lecture question
Electrons are really important in electrochemistry and writing out the electrons helps you figure out what is being oxidized and reduced and really understand what is happening to the electrons in the reaction...It will make more sense when Dr. Lavelle goes into more details and we started doing mor...
- Tue Feb 11, 2020 8:16 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: HW 41.5
- Replies: 2
- Views: 248
Re: HW 41.5
Thank you!
- Tue Feb 11, 2020 8:10 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: HW 41.5
- Replies: 2
- Views: 248
HW 41.5
Hello, I am really stuck on this problem. I would super appreciate it if someone could please help me solve it. 4I.5 Suppose that 50.0 g of water at 20.0 8C is mixed with 65.0 g of water at 50.0 8C at constant atmospheric pressure in a thermally insulated vessel. Calculate ΔS and ΔS (total) for the ...
- Sun Feb 09, 2020 11:55 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: HW 4D7
- Replies: 4
- Views: 157
Re: HW 4D7
For gases, the change in enthalpy is defined by that equation. This is because when gas is produced work is done to clear the other gases so the enthalpy is lower than the internal energy. This is explained in detail on pg 274 in the textbook (4D.2)
- Sun Feb 09, 2020 11:47 pm
- Forum: Calculating Work of Expansion
- Topic: q=C delta T
- Replies: 5
- Views: 1422
Re: q=C delta T
Alexis Robles 2k wrote:when should we use the m/n in the equation?
Did mean to type: q=n*CdeltaT
If so, n refers to mols while m refers to grams...you would use whatever units the question asked for...
- Sun Feb 09, 2020 11:41 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Boltzmann equation
- Replies: 5
- Views: 226
Re: Boltzmann equation
The Boltzmann equation is giving the residual entropy of the system. Entropy is the amount of "disorder" and the Boltzmann equation is sort of giving a statistical answer of all the possible orientations and positions of all the molecules in the system.
- Sun Feb 09, 2020 11:36 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Question 4B.3
- Replies: 5
- Views: 346
Re: Question 4B.3
Thank you guys for your replies! I used the answer key at the back of the book (I don't have the solution manual) and it said 90 * 10^2 J...I think that the answer key in the book is wrong since the solution manual also says 490.
- Sun Feb 09, 2020 11:33 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Reversible Reactions vs. Irreversible Reactions
- Replies: 6
- Views: 296
Re: Reversible Reactions vs. Irreversible Reactions
I feel like it wouldn't hurt to know...there were a few graph questions on the 14A midterm and final last quarter...
- Fri Feb 07, 2020 9:08 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Question 4B.3
- Replies: 5
- Views: 346
Question 4B.3
Hello, I got the first part of this question right, but not the second, I was curious if someone could help me figure out what I'm missing. Thank you! The internal energy of a system increased by 982 J when it was supplied with 492 J of energy as heat. (a) Was work done by or on the system? (b) How ...
- Fri Feb 07, 2020 8:41 pm
- Forum: General Science Questions
- Topic: Midterm
- Replies: 17
- Views: 1032
Re: Midterm
Ben 1B wrote:Does anyone know if we will be able to take a practice midterm before the actual midterm?
The UAs made a practice midterm for us this quarter. Search up Pizza Rolls and you should find it.
- Sun Feb 02, 2020 8:06 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: U
- Replies: 4
- Views: 132
Re: U
You should watch this video for an introduction to internal energy and U
https://www.khanacademy.org/science/physics/thermodynamics/laws-of-thermodynamics/v/more-on-internal-energy
https://www.khanacademy.org/science/physics/thermodynamics/laws-of-thermodynamics/v/more-on-internal-energy
- Sun Feb 02, 2020 7:27 pm
- Forum: General Science Questions
- Topic: Midterm
- Replies: 17
- Views: 1032
Re: Midterm
Does anyone know if all the thermochemistry and thermodynamic equations will be supplied on the midterm? Dr. Lavelle is usually really nice about the equations and provides everything you would need. I'm pretty sure he uses the same equation sheet for all the tests so you can take a look at test 1....
- Sun Feb 02, 2020 7:19 pm
- Forum: General Science Questions
- Topic: Midterms
- Replies: 22
- Views: 1028
Re: Midterms
The outlines are a great resource to find practice problems and use as a study plan/guide. Additionally, attending all the (one per each topic) review sessions will also help you figure out what material will be covered and where you are. Sometimes the textbook can feel a bit too broad. I'm pretty s...
- Sun Feb 02, 2020 7:13 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Positive or negative work?
- Replies: 8
- Views: 316
Re: Positive or negative work?
I think about the same as I think about endothermic or exothermic reactions. If heat is being released by the system, enthalpy (delta H) is negative and like that, if the system is doing work, then the work is negative. If the system needs heat then the enthalpy (delta H) sign is positive, and if so...
- Sun Feb 02, 2020 7:02 pm
- Forum: General Science Questions
- Topic: Midterm
- Replies: 17
- Views: 1032
Re: Midterm
hopefully Lyndon, the UA will make us a practice midterm :/...
The one he made for 14A last quarter was really helpful and I really appreciated it :).
The one he made for 14A last quarter was really helpful and I really appreciated it :).
- Mon Jan 27, 2020 12:07 pm
- Forum: Student Social/Study Group
- Topic: Chemical Bonding Recording
- Replies: 1
- Views: 132
Chemical Bonding Recording
I found a really interesting article/video in my newsfeed. Recently, scientists published their experiment showing/recording of chemical bonds forming and breaking. Here is the link to the article if you all want to watch the too :) https://www.sciencenews.org/article/dance-two-atoms-reveals-chemica...
- Sun Jan 26, 2020 5:39 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: pH
- Replies: 7
- Views: 296
Re: pH
It really depends on what information you are given, I feel like for most problems this is how I've been dealing with it...
1) convert pKa to Ka
Ka = 10^(-pKa)
2) write Ka concentration out and figure out [H+]
3) plug into pH = -log [H+]
1) convert pKa to Ka
Ka = 10^(-pKa)
2) write Ka concentration out and figure out [H+]
3) plug into pH = -log [H+]
- Thu Jan 23, 2020 12:16 pm
- Forum: Calculating the pH of Salt Solutions
- Topic: Problem 6D.15
- Replies: 2
- Views: 290
Re: Problem 6D.15
Follow up question: I am still very stuck on this problem, can someone please post a step-by-step of the solution?
Thank you so much!
Thank you so much!
- Tue Jan 21, 2020 8:07 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Chemical Equilibrium Part 4 Question 13
- Replies: 3
- Views: 194
Re: Chemical Equilibrium Part 4 Question 13
I would assume that i is neither since the moles are equal on both sides. The pressure increases with the volume decreasing so the chemical reaction would favor the side with less moles but that is not an option. I didn't see this at first either, but the I2 in the products has an (s) next to it, s...
- Tue Jan 21, 2020 7:56 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Test #1
- Replies: 2
- Views: 203
Re: Test #1
Well, if Ka is less than 10^-3, then you are usually safe to approximate. In the end, though, you typically need to make sure that x is less than 5% of the initial concentration. If it is less than 5%, you are good, if it's not, you need to redo the problem. For the test specifically, I'm not sure i...
- Tue Jan 21, 2020 7:53 pm
- Forum: Calculating the pH of Salt Solutions
- Topic: Problem 6D.15
- Replies: 2
- Views: 290
Problem 6D.15
Hi Everyone, I am having a really hard time with this problem. I would appreciate if someone can please let me know what I'm doing wrong. 6D.15 Calculate the pH of (a) 0.19 m NH4Cl(aq); (b) 0.055 m AlCl3(aq). For part B) is the equation: AlCl3 <==> Al (OH-)3 + 3HCl. The 3HCl then dissociates complet...
- Sat Jan 18, 2020 9:57 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Equilibrium Constant Units
- Replies: 4
- Views: 512
Re: Equilibrium Constant Units
Dr. Lavelle, in the lecture, talked about how Kc should technically be measured by how much "activity" is occurring in the equation. So how much activity that is produced by the forward reaction and how much activity is produced by the reverse reaction. Since it is a bit hard to measure th...
- Sat Jan 18, 2020 9:51 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: 5 %
- Replies: 4
- Views: 259
Re: 5 %
I was doing a homework problem and I was using my calculator's quadratic function to solve the Kc equations. The funny part, I guess, is that my x value was so small that when I subtracted it from the initial value the first two digits/numbers were still the same. When you have two (or three) signif...
- Sat Jan 18, 2020 9:43 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: 5.39
- Replies: 1
- Views: 116
Re: 5.39
The volume was halved. So initially, you had 0.020 mols/Liter and now you have 0.020 mols/0.5Liters = 0.040 M. Equilibrium concentration, values when trying to find Kc, deal with values in mols/Liter or molarity.
- Thu Jan 16, 2020 10:16 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5l.29
- Replies: 5
- Views: 884
Re: 5l.29
I have a followup question: Why did you all decide to set x = to change in equilibrium for H2 or Cl2, and 2X = change in HCL instead of saying x = change in HCL and 0.5X = change in H2 and Cl2? I did it the second way and I got the wrong answer. I'm trying to understand conceptually why my way is wr...
- Wed Jan 15, 2020 10:41 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Writing K for heterozygous reactions
- Replies: 5
- Views: 191
Writing K for heterozygous reactions
Hello,
If there was an equation with liquids and gases in products and/or reactants side, how would you write Kc? Would you include both liquids and gases in it or only the gases or do you write two separate equations?
If there was an equation with liquids and gases in products and/or reactants side, how would you write Kc? Would you include both liquids and gases in it or only the gases or do you write two separate equations?
- Mon Jan 13, 2020 11:48 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Updating my account
- Replies: 2
- Views: 124
Re: Updating my account
Thank you!
- Mon Jan 13, 2020 11:42 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 6A.19
- Replies: 6
- Views: 207
Re: 6A.19
that's confusing...hmm...did it say millimolars? I'm interested in an answer too...
- Mon Jan 13, 2020 11:37 pm
- Forum: Ideal Gases
- Topic: When to use this equation
- Replies: 14
- Views: 503
Re: When to use this equation
This equation is super versatile. If you know a few variables and you are trying to figure out how to represent ideal gases differently, then, you can just rearrange the equation. For example, if you have the pressure of a gas, but want to know what the concentration of the gas is you just need to r...
- Mon Jan 13, 2020 11:34 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Updating my account
- Replies: 2
- Views: 124
Updating my account
Hello
I was in Dr. Lavelle's class (14A) last quarter, and I was curious if I had to do something to "update" my account to make sure I'm getting credit for participating in 14B class.
Thank you!
I was in Dr. Lavelle's class (14A) last quarter, and I was curious if I had to do something to "update" my account to make sure I'm getting credit for participating in 14B class.
Thank you!
- Mon Jan 13, 2020 11:29 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5J.5
- Replies: 4
- Views: 177
Re: 5J.5
I can answer why there is no change from the increase in pressure. Usually, in a Kp equation, the partial pressure is representative of the number of mole/concentrations of a substance at a certain temperature and volume. You can think of it as how much "stuff" is there increases with pres...
- Fri Jan 10, 2020 4:26 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Exercise 5G.1
- Replies: 4
- Views: 253
Re: Exercise 5G.1
c) if one starts with a higher pressure of reactant, the equilibrium constant will be larger This is false because the equilibrium constant will stay the same for reactions happening at the same temperature. Having a "greater pressure" of the reactant will affect or cause a shift to the le...
- Sat Dec 07, 2019 7:13 pm
- Forum: Naming
- Topic: -ate, -ide, -ite, -o
- Replies: 3
- Views: 312
Re: -ate, -ide, -ite, -o
According to the textbook, for any anion inside the [ ] (so any anion directly bonded to the central metal cation), the ending should be an -ato or an -ido or an -ito. For example, the Chloride anion is written as chlorido.
- Sat Dec 07, 2019 7:06 pm
- Forum: Conjugate Acids & Bases
- Topic: 6C.17
- Replies: 2
- Views: 226
Re: 6C.17
I believe its because there is a negative charge on the BrO- molecule.
- Sat Dec 07, 2019 6:51 pm
- Forum: Naming
- Topic: Latin Names
- Replies: 3
- Views: 169
Re: Latin Names
I'm pretty sure many of the elements have Latin names or come from Latin words. You just need to memorize that Iron is written as ferrate if a coordination molecule is negative.
- Sat Dec 07, 2019 9:55 am
- Forum: Photoelectric Effect
- Topic: Midterm Question 4
- Replies: 1
- Views: 428
Re: Midterm Question 4
Those are the same answers I got (and I got the answer correctly). En= Eupper - Elower, but En= - hR/n^2, so when you plug it in you would get: En = -Eupper - (-E lower) so En=-Eupper + Elower. Since as n increases, En get closer to 0, and as n gets smaller, En decreases (remember big negative numbe...
- Fri Dec 06, 2019 12:26 am
- Forum: Identifying Acidic & Basic Salts
- Topic: Electrons and pH
- Replies: 2
- Views: 233
Re: Electrons and pH
When the equation is NH4+ + H2O --> NH3 + H3O+
You notice how the NH4 is donating a Hydrogen. pH is the -log[H+] so as the concentration of H+ increases, then the pH decreases. NH4+ is a proton donator and therefore the concentration of H+ increases which then decreases the pH.
You notice how the NH4 is donating a Hydrogen. pH is the -log[H+] so as the concentration of H+ increases, then the pH decreases. NH4+ is a proton donator and therefore the concentration of H+ increases which then decreases the pH.
- Wed Dec 04, 2019 8:39 pm
- Forum: Identifying Acidic & Basic Salts
- Topic: Lecture
- Replies: 3
- Views: 148
Re: Lecture
Cl- does not affect the pH of a solution because Cl- is a really stable atom; it does not need to bind to a Hydrogen. While NH3- is a weak base so it's conjugate acid, NH4 will lose a few Hydrogens in the NH4 and act as an acid by donating its extra Hydrogen.
- Sat Nov 30, 2019 12:25 pm
- Forum: General Science Questions
- Topic: test taking nervousness
- Replies: 19
- Views: 1130
Re: test taking nervousness
I feel you! I do the easier problems first because it makes me feel better (psychologically) and then I try to the harder problems. Think about what you do know because chances are you do know a lot. Maybe, if you can, identify what chapter the question is from and write down all the equations you k...
- Sat Nov 30, 2019 11:59 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Explain VSEPR conceptually
- Replies: 12
- Views: 856
Re: Explain VSEPR conceptually
VSPER stands for Valence shell electron pair repulsion theory. While lewis structures are helpful to figure out single/double bonds and the number of lone pairs etc. VSPER takes electron pair repulsions into considerations and allows us to think about the 3D shape of the molecule.
- Sat Nov 30, 2019 11:55 am
- Forum: Bronsted Acids & Bases
- Topic: Net Ionic Equations
- Replies: 5
- Views: 307
Re: Net Ionic Equations
Do you have a specific example or a specific problem you are stuck on? I'm not quite sure how to answer your question broadly...
- Sat Nov 30, 2019 11:51 am
- Forum: Resonance Structures
- Topic: Molecules with resonance
- Replies: 4
- Views: 512
Re: Molecules with resonance
Those with resonance structures are weaker acids because it is harder for the hydrogen atoms to "break off" because the negative formal charge is distributed throughout so resonance structures are more stable.
- Sat Nov 30, 2019 11:49 am
- Forum: Amphoteric Compounds
- Topic: 6A.11
- Replies: 2
- Views: 164
Re: 6A.11
HPO4(2-) as an acid: PO4(3-) (conjugate base)
HPO4 (2-) as a base: H2PO4 (-1) (conjugate acid)...
HPO4 (2-) as a base: H2PO4 (-1) (conjugate acid)...
- Fri Nov 29, 2019 10:31 pm
- Forum: Dipole Moments
- Topic: Polar or nonpolar?
- Replies: 4
- Views: 9121
Re: Polar or nonpolar?
I know this video isn't really for the exact same molecule, but they are similar and you can use the same "technique" to analyze the polarity of CH2Br2
[youtube]https://www.youtube.com/watch?v=As-hcYY8Yaw[/youtube]
[youtube]https://www.youtube.com/watch?v=As-hcYY8Yaw[/youtube]
- Fri Nov 29, 2019 10:25 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Example 6A.2
- Replies: 1
- Views: 177
Example 6A.2
In example 6A.2 in the textbook, the question is: Barium hydroxide is a base that is sometimes used for titrating acids. When using it, you need to know the actual concentration of hydroxide ion in the solution. What are the molar concentrations of H3O1+ and OH2- in 0.0030 m Ba(OH)2(aq) at 25 C? In ...
- Sun Nov 17, 2019 5:58 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Dipole moment
- Replies: 5
- Views: 366
Re: Dipole moment
The dipole moment is basically when a partially negatively charged atom in a polar covalent bond is attracted to another positively charged thing (usually the positively charged atom of another polar covalent bond or a cation). This isn't like a bond, but there is a very weak, but still significant ...
- Sun Nov 17, 2019 5:44 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: bond order calculations
- Replies: 4
- Views: 981
Re: bond order calculations
I believe bond order just refers to the number of bonds between two atoms (single bonds, double bonds, triple bonds etc.) so I would just draw a lewis structure and count... https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Th...
- Sun Nov 17, 2019 5:41 pm
- Forum: Electronegativity
- Topic: Bond type for FeO2?
- Replies: 3
- Views: 889
Re: Bond type for FeO2?
I guess it officially described as being "polar covalent" but its super ionic in character.
- Sun Nov 17, 2019 5:38 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Grading
- Replies: 7
- Views: 475
Re: Grading
I would imagine so, but I would be interested in knowing how he curves the class considering the fact that the average score on the last midterm was like a high 70%...
- Sun Nov 17, 2019 5:37 pm
- Forum: Student Social/Study Group
- Topic: What will Test 2 be on?
- Replies: 8
- Views: 598
Re: What will Test 2 be on?
I understand, but what sort of specific questions might he ask? What textbook problems should I do? I feel like we did a lot of theory so I'm not sure what sort of questions I should be prepared for...
- Sun Nov 17, 2019 5:23 pm
- Forum: Student Social/Study Group
- Topic: What will Test 2 be on?
- Replies: 8
- Views: 598
What will Test 2 be on?
Can someone please direct me towards what lessons/pages I should read to prepare for Test 2?
- Wed Nov 13, 2019 9:45 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Test #2
- Replies: 22
- Views: 2960
Re: Test #2
Well my discussion is on Wednesday and I'm really nervous....can someone please post specific textbook sections we should study for the test?
Thank you!
Thank you!
- Tue Nov 05, 2019 7:27 pm
- Forum: Lewis Structures
- Topic: Homework Problem 2C. 3c
- Replies: 1
- Views: 111
Re: Homework Problem 2C. 3c
It looks like your Hydrogen is bonded directly to the Chlorine, but its almost always attached to an Oxygen with acids and (bases too I think)...
- Tue Nov 05, 2019 7:22 pm
- Forum: Octet Exceptions
- Topic: Did I summarize the octet rule exception correctly?
- Replies: 1
- Views: 186
Did I summarize the octet rule exception correctly?
So basically, when drawing Lewis Structures, the first goal should be to get the smallest formal charge for all the atoms. Does this mean that I should give double bonds to structures even if it means breaking the octet rule if it means that all the atoms in the molecule will have a formal charge of...
- Tue Nov 05, 2019 6:48 pm
- Forum: Octet Exceptions
- Topic: Naming molecules
- Replies: 2
- Views: 181
Naming molecules
For the midterm, do you think we need to know how ions are named? For example in HW problem 2C.3, they gave the name of the ion/molecule (instead of the molecular formula) and asked us to draw a Lewis structure. Do you think that's how the midterm is going to be or do you know if we will get a molec...
- Sun Nov 03, 2019 2:57 pm
- Forum: Dipole Moments
- Topic: Dipole Moment Significance
- Replies: 1
- Views: 103
Re: Dipole Moment Significance
Dipole moment exists for any covalently bonded molecules where the atoms have different electronegativities. This is because one atom will exert a stronger force on the electrons and "hog" the electrons from the less electronegative atom. Therefore, the dipole moment exists when there is a...
- Sun Nov 03, 2019 2:48 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: 1E.13
- Replies: 2
- Views: 226
Re: 1E.13
You should watch this video by Bozeman Science: https://www.youtube.com/watch?v=2AFPfg0Como. The first 7 minutes are an intro to what the different subshells and energy levels are, but he talks about writing electron configurations at the 7-minute mark.
- Sun Nov 03, 2019 2:40 pm
- Forum: Ionic & Covalent Bonds
- Topic: Ionic and Covalent Character
- Replies: 2
- Views: 127
Re: Ionic and Covalent Character
So there is a progressive scale of bonds that ranges from ionic to covalent. For example, if two atoms with really different electron affinities share "electrons" sometimes, electrons might hang out with the atom with more electron affinity (like the Oxygen side of H2O being a bit more neg...
- Sun Nov 03, 2019 10:11 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Quantum Numbers and subshells
- Replies: 2
- Views: 242
Quantum Numbers and subshells
Hello, I have a question about what subshells "l" numbers are. For example if n=3, then l = 0, 1, 2 or basically l = 0,1,2...n-1. Then if n = 5, then l = 0,1,2,3,4 right? So if an "l" value of 0 corresponds to the "s" subshell, 1 corresponds to the "p" subshel...
- Sun Nov 03, 2019 1:12 am
- Forum: Trends in The Periodic Table
- Topic: Units for energy
- Replies: 1
- Views: 103
Re: Units for energy
The standard unit used for kinetic energy is "Joules." For ionization energy, it is measured in Kilo Joules/mole or ElectroVolts. The units are all measuring the same thing, but the scale is different. For example, you can use inches, millimeters or even miles to measure different lengths,...
- Sun Oct 27, 2019 10:33 pm
- Forum: Resonance Structures
- Topic: Resonance
- Replies: 3
- Views: 184
Re: Resonance
I'm pretty sure you usually just have to draw like one of the structures (unless specifically asked to draw all).
- Sun Oct 27, 2019 10:31 pm
- Forum: Octet Exceptions
- Topic: Octet Guideline?
- Replies: 2
- Views: 121
Re: Octet Guideline?
I'm not sure what exactly you are asking clarification for, but the reason why we use the octet rule is that it usually works for the elements in the first two columns and the last six columns (well noble gases don't really react with anything because they have full octet) of the periodic table. Thr...
- Sun Oct 27, 2019 10:22 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: H atom
- Replies: 3
- Views: 154
Re: H atom
That's a really interesting question. I think it is because that Hydrogen is a really simple atom with one proton and one electron (which makes examples easier), but I'm curious to hear what other people have to say.
- Sun Oct 27, 2019 10:17 pm
- Forum: Ionic & Covalent Bonds
- Topic: electron configuration
- Replies: 5
- Views: 214
Re: electron configuration
For a list of atoms with different electron configurations check this website out: [url]https://www.scribd.com/doc/13771509/Electron-Configurations-of-Elements-Which-Are-Exceptions-to-the-Rule
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- Sun Oct 27, 2019 9:32 pm
- Forum: Ionic & Covalent Bonds
- Topic: What is the difference between an anion and cation?
- Replies: 7
- Views: 872
Re: What is the difference between an anion and cation?
anions are ions that are negatively charged (have more electrons than normal), and cations are those that are positively charged (have less electrons than normal).
- Sun Oct 27, 2019 7:11 pm
- Forum: *Shrodinger Equation
- Topic: schrodinger equation
- Replies: 2
- Views: 340
Re: schrodinger equation
Will do, Thank you!
- Sun Oct 27, 2019 6:38 pm
- Forum: *Shrodinger Equation
- Topic: schrodinger equation
- Replies: 2
- Views: 340
schrodinger equation
Hello, I am having trouble understanding the Schrodinger equation and lesson 1C in general, do you all have any videos or articles you recommend?
- Sun Oct 20, 2019 7:33 pm
- Forum: Properties of Electrons
- Topic: stern and Gerlach
- Replies: 1
- Views: 99
Re: stern and Gerlach
This video is really informative (and animations are cute). https://www.youtube.com/watch?v=cd2Ua9dKEl8, it goes over spin and the Stern and Gerlach experiment and why it is important.
- Sun Oct 20, 2019 7:27 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: spin magnetic quantum #
- Replies: 2
- Views: 122
Re: spin magnetic quantum #
The signs don't really matter, the -/+ or the "up" and "down" For the subshells, you can only have like a 1/2 or a -1/2 or up and down but you can't really have like two positive spins electrons in the same subshell or two negative spins electrons in the same subshell -- they nee...
- Sun Oct 20, 2019 7:22 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Yet Another Electron Spin Question
- Replies: 5
- Views: 270
Re: Yet Another Electron Spin Question
That a really good question and I'm looking forward to an answer too
- Sun Oct 20, 2019 7:00 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Advice for studying
- Replies: 92
- Views: 9147
Re: Advice for studying
I agree with everyone here. I am not a auditory learner, so I forget concepts when I just listen to someone explain it. I find it extremely helpful to read the textbook and do every single example problem . This is really helpful because when I'm doing HW problems, I like to classify the problem and...