Search found 197 matches
- Sat Mar 13, 2021 2:55 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Delta G naught
- Replies: 2
- Views: 312
Delta G naught
Is delta G naught zero if something is at its boiling point? Exercise 4I.3 in the textbook assumes delta g naught is zero even thought the system is never stated to be at equilibrium. Does anyone know why this is?
- Wed Mar 03, 2021 12:12 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Identifying which reactions have K>1
- Replies: 1
- Views: 178
Identifying which reactions have K>1
I am a bit confused as to how to determine whether products are favored or not based on Enaught values. I am also confused when we need to flip the half reactions when finding the Enaught. For example, question 6M.13 in the textbook asks us to identify if MnO4−(aq) + 8 H+(aq) + 5 Ce3+(aq)→5 Ce4+(aq)...
- Tue Mar 02, 2021 4:45 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell Diagram Question
- Replies: 3
- Views: 291
Cell Diagram Question
Do we need to find the volts for each half reaction when finding the reaction from a cell diagram? A TA told me that we need to find these values for each half reaction and make sure Enaught of the cell is positive. I don't remember lavelle talking about this- he told us the anode is on the left and...
- Tue Mar 02, 2021 11:49 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Textbook 6L.3
- Replies: 6
- Views: 496
Re: Textbook 6L.3
Hi Emily! So basically for the cell diagrams, the order of the species in the notation doesn't really have to do with the order of the species in the half reaction. Life you said, for the cathode in this problem would be Cl2 + 2e- —> 2Cl- But in the cell notion is it presented as Cl-|Cl2 The reason...
- Tue Mar 02, 2021 11:39 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Textbook 6L.3
- Replies: 6
- Views: 496
Re: Textbook 6L.3
Hi Emily! So basically for the cell diagrams, the order of the species in the notation doesn't really have to do with the order of the species in the half reaction. Life you said, for the cathode in this problem would be Cl2 + 2e- —> 2Cl- But in the cell notion is it presented as Cl-|Cl2 The reason...
- Tue Mar 02, 2021 11:27 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Textbook 6L.3
- Replies: 6
- Views: 496
Textbook 6L.3
6L.3 Write the half-reactions and the balanced equation for the cell reaction for each of the following galvanic cells: (b) C(gr)|H2(g)|H+(aq)∥Cl−(aq)|Cl2(g)|Pt(s) I am struggling to understand when we simply write out the half reactions in the order shown in the diagram (for ex H2 -> H+) and when w...
- Mon Mar 01, 2021 6:44 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Textbook problem 6L1
- Replies: 4
- Views: 374
Re: Textbook problem 6L1
For this one, you would have to write out the half reactions. oxidation: 3I- -> I3- + 2e- reduction: Ce4+ + 1e- -> Ce3+ You need a balanced number of electrons, so you would multiply the reduction half reaction by 2. So the moles of electrons transferred is 2. Hope this helps! Why do you keep the 3...
- Mon Mar 01, 2021 6:37 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Textbook problem 6L1
- Replies: 4
- Views: 374
Re: Textbook problem 6L1
For this one, you would have to write out the half reactions. oxidation: 3I- -> I3- + 2e- reduction: Ce4+ + 1e- -> Ce3+ You need a balanced number of electrons, so you would multiply the reduction half reaction by 2. So the moles of electrons transferred is 2. Hope this helps! Why do you keep the 3...
- Mon Mar 01, 2021 6:31 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Textbook problem 6L1
- Replies: 4
- Views: 374
Textbook problem 6L1
6L.1 Calculate the standard reaction Gibbs free energy for the following cell reactions: (a) 2 Ce4+(aq) + 3 I−(aq) →2 Ce3+(aq) + I3−(aq), Ecell°=+1.08V For the above problem, how would you determine how many moles of electrons are transferred? I am getting 1 but the book says 2. Can someone explain ...
- Sun Feb 28, 2021 5:53 pm
- Forum: Balancing Redox Reactions
- Topic: Determining Phases
- Replies: 28
- Views: 1225
Determining Phases
Can someone explain how you determine the phases everything is in after balancing a redox reaction in an acidic or basic solution?
- Sun Feb 28, 2021 4:49 pm
- Forum: Balancing Redox Reactions
- Topic: Sapling Question 5
- Replies: 3
- Views: 321
Sapling Question 5
Identify the oxidizing and reducing agents in the skeletal (unbalanced) reaction. Then, balance the reaction, including the phase (solid, liquid, etc.) of each species. The reaction takes place in basic aqueous solution. N2H4(g)+ClO−3(aq)⟶NO(g)+Cl−(aq) I've found the oxidizing and reducing agent, bu...
- Sun Feb 28, 2021 2:09 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 4039944
Re: Post All Chemistry Jokes Here
These jokes are so good, I'm diene of laughter
- Sun Feb 28, 2021 2:03 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Calculating equilibrium constant
- Replies: 11
- Views: 677
Calculating equilibrium constant
When calculating equilibrium constants from electrochemical data, why is it always necessary to flip one of the half reactions?
- Sun Feb 28, 2021 1:21 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Why is it called a cell?
- Replies: 3
- Views: 234
Why is it called a cell?
I apologize if this is a bad question- but why are galvanic and voltaic cells called "cells"? Do they relate to cells (defined in the way we have learned in previous bio classes) in any way?
- Sun Feb 28, 2021 1:13 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Meaning of K
- Replies: 55
- Views: 4492
Re: Meaning of K
Yes! Especially in this class, if we are finding K this is most always referring to the equilibrium constant. If we are meant to find temperature, we would likely be told to calculate temperature in K, rather than to calculate K.
- Sun Feb 28, 2021 1:11 pm
- Forum: Student Social/Study Group
- Topic: Points needed to pass?
- Replies: 76
- Views: 11992
Re: Points needed to pass?
I believe a 50% or higher is needed to pass the class.
- Fri Feb 19, 2021 8:47 am
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Textbook 4a13
- Replies: 4
- Views: 391
Re: Textbook 4a13
The first relationship you need to know for this problem is that q reaction = -q calorimeter , which means that if the reaction releases heat, then the calorimeter will gain that heat (and vice versa). Because q reaction = -3.5kJ, q cal will be +3.5kJ, and that is the value we use when calculating ...
- Thu Feb 18, 2021 6:14 pm
- Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
- Topic: Orientation Question
- Replies: 4
- Views: 498
Orientation Question
How do you determine the number of orientations a molecule will have when using the Boltzmann equation?
- Thu Feb 18, 2021 4:26 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Textbook 4F1
- Replies: 1
- Views: 141
Textbook 4F1
A human body generates heat at the rate of about 100.W. (a) At what rate does your body heat generate entropy in your surroundings, taken to be at 20.°C? The answer key writes deltaSsurr/time = -qrev/time, resulting in -100JS^-2/293K, but then the answer is positive. Why did they just lose the negat...
- Wed Feb 17, 2021 8:27 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Textbook Question 4C11
- Replies: 5
- Views: 502
Textbook Question 4C11
How much heat is needed to convert 80.0 g of ice at 0.0°C into liquid water at 20.0 °C (see Tables 4A.2 and 4C.1)?
The answer key shows that the equations for deltaH were used to solve this. Since the question is asking for heat, why do we not use the equation for q, and convert g to mol?
The answer key shows that the equations for deltaH were used to solve this. Since the question is asking for heat, why do we not use the equation for q, and convert g to mol?
- Wed Feb 17, 2021 6:47 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Q Question
- Replies: 7
- Views: 613
Q Question
Does q=CdeltaT whenever the reaction is closed while q=nCdeltaT when it is not closed? I am confused as to when we include n and when we don't based on the text book problems (for example, problem 4A13 doesn't consider n and I'm not sure why this is). How do we know which equation to use?
- Wed Feb 17, 2021 6:36 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Specific Heat
- Replies: 9
- Views: 734
Specific Heat
Can someone explain the difference between finding specific heat and heat capacity? Is specific heat kj/c^-1xmol^-1? How do we solve for heat capacity?
- Wed Feb 17, 2021 6:35 pm
- Forum: Calculating Work of Expansion
- Topic: Textbook Question 4A11
- Replies: 3
- Views: 262
Textbook Question 4A11
A calorimeter was calibrated with an electric heater, which supplied 22.5 kJ of energy as heat to the calorimeter and increased the temperature of the calorimeter and its water bath from 22.45 °C to 23.97°C. What is the heat capacity of the calorimeter? I am a bit confused on how the textbook solved...
- Wed Feb 17, 2021 6:33 pm
- Forum: Calculating Work of Expansion
- Topic: Textbook 4D.7
- Replies: 2
- Views: 285
Re: Textbook 4D.7
I believe this is because most reactions take place in 25 degrees celsius so we assume this condition if the temp is not given (learned in 14A). So I believe that's what it's doing - assuming 25 degrees celsius which would be 298K.
- Wed Feb 17, 2021 10:21 am
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Textbook 4C11
- Replies: 4
- Views: 344
Textbook 4C11
How much heat is needed to convert 80.0 g of ice at 0.0 °C into liquid water at 20.°C (see Tables 4A.2 and 4C.1)? For the above question, the textbook assumes the change in enthalpy is equal to q. Don't we need to know there is constant pressure to be able to assume this? What allows us to make this...
- Tue Feb 16, 2021 6:15 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Textbook 4a13
- Replies: 4
- Views: 391
Textbook 4a13
A constant-volume calorimeter was calibrated by carrying out a reaction known to release 3.50 kJ of heat in 0.200 L of solution in the calorimeter (q=−3.50kJ), resulting in a temperature rise of 7.32C. In a subsequent experiment, 100.0 mL of 0.200 M HBr(aq) and 100.0 mL of 0.200M KOH(aq) were mixed ...
- Tue Feb 16, 2021 3:27 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: When q=w
- Replies: 9
- Views: 494
When q=w
Can someone explain when exactly we would know that q=w?
- Sun Feb 14, 2021 5:32 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Sapling Question 6
- Replies: 5
- Views: 382
Sapling Question 6
A particular container holds 2.85 mol of neon gas. The volume of this container can be altered by sliding a piston in or out. The volume is changed from 7.80 L to 13.70 L while at the same time the temperature is changed from 255 K to 3.20×102 K. The molar heat capacity, CV,m, for neon is 12.47 J/(m...
- Sun Feb 14, 2021 9:15 am
- Forum: Student Social/Study Group
- Topic: Valentine's Day Long Weekend!
- Replies: 30
- Views: 2535
Re: Valentine's Day Long Weekend!
Happy Valentine's day everyone! I hope you all have a great weekend + week!
- Sun Feb 14, 2021 9:14 am
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Temperature Question
- Replies: 8
- Views: 538
Temperature Question
The textbook says the following:
the gas is heated from 20.°C to 100. °C (so ΔT=+80. K)
Why are 80 units in C equal to 80 units in K? Why don't we have to convert from C to K?
the gas is heated from 20.°C to 100. °C (so ΔT=+80. K)
Why are 80 units in C equal to 80 units in K? Why don't we have to convert from C to K?
- Sat Feb 13, 2021 3:44 pm
- Forum: Student Social/Study Group
- Topic: Chem 14C Question
- Replies: 8
- Views: 686
Chem 14C Question
I apologize if this has already been answered somewhere, but does anyone know if Chem 14C lectures will be asynchronous?
- Sat Feb 13, 2021 3:31 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: R Constant
- Replies: 91
- Views: 9041
Re: R Constant
I also look at the problem and choose the units that match the pressure units in the problem!
- Sat Feb 13, 2021 3:29 pm
- Forum: Student Social/Study Group
- Topic: Classes for next quarter?
- Replies: 165
- Views: 23285
Re: Classes for next quarter?
I (like many others) am debating whether or not I should take 14C with 14Bl! Does anyone have tips/ insight?
- Sat Feb 13, 2021 3:28 pm
- Forum: Student Social/Study Group
- Topic: Balance / Self Care Tips
- Replies: 62
- Views: 4488
Balance / Self Care Tips
How are you guys balancing studying with relax + self care time? I find it hard to do anything but study when a midterm is coming up, but there have been multiple times when I have burnt myself out right before an exam because of this. Does anyone have tips on how to allocate time to both studying a...
- Sat Feb 13, 2021 3:26 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Outline Progess
- Replies: 5
- Views: 357
Re: Outline Progess
How is everyone doing in regard to working through the outlines? I know everyone has different schedules/ works at different paces, but I am still taking notes on Outline 3 (I take really thorough notes that take me a long time) and I'm worried about getting/being behind.
- Sat Feb 13, 2021 3:24 pm
- Forum: Administrative Questions and Class Announcements
- Topic: tips if you're struggling!
- Replies: 77
- Views: 6609
Re: tips if you're struggling!
I can relate with a lot of the study methods in this post. I like to rewatch the lectures before midterms/ exams and it helps me catch the little things he mentions that I may have missed the first time. It's slow and I also take thorough notes, but I believe it works and it one of the main practice...
- Sat Feb 13, 2021 3:21 pm
- Forum: Student Social/Study Group
- Topic: Thoughts on Upcoming Midterm 2
- Replies: 41
- Views: 2130
Re: Thoughts on Upcoming Midterm 2
I also feel a bit worried. I have come to the conclusion that the exams for this class are rather hard to predict. Some midterms have been very easy, while I found others to be unfairly hard. I'm hoping that this midterm will not have any questions that are worded different than the textbook. Even t...
- Sat Feb 13, 2021 3:16 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Can We Review our Exams?
- Replies: 69
- Views: 4501
Re: Can We Review our Exams?
According to my TA, you can go to any TAs office hours to review your exam! Sometimes they make you wait until they've finished answering questions first since you have to go into a private breakout room.
- Sun Feb 07, 2021 11:06 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 4039944
Re: Post All Chemistry Jokes Here
The proton is not speaking to the other proton, he’s mad atom.
- Sun Feb 07, 2021 11:05 pm
- Forum: Student Social/Study Group
- Topic: Post Midterm 1...
- Replies: 39
- Views: 2244
Re: Post Midterm 1...
I think it would help if you could more closely identify the trends of mistakes you are making. Are they typically careless errors? Conceptual misunderstandings? Were you on the right track on most problems or were the solutions nothing you would have even guessed? I think identifying these factors ...
- Sun Feb 07, 2021 11:02 pm
- Forum: Student Social/Study Group
- Topic: Worried About MT 1 Grades
- Replies: 39
- Views: 2427
Re: Worried About MT 1 Grades
I do feel the midterms last quarter were not as challenging. Hopefully, since the average was down this time compared to last quarter, the next midterm will be a bit easier!
- Sun Feb 07, 2021 11:00 pm
- Forum: Student Social/Study Group
- Topic: Book Recommendations
- Replies: 135
- Views: 23144
Re: Book Recommendations
In regard to non-fiction books, I think the Sociology of Health and Illness by Peter Conrad is super interesting!
- Sun Feb 07, 2021 10:59 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Does phase matter in Hess's Law?
- Replies: 21
- Views: 2214
Re: Does phase matter in Hess's Law?
You can't cancel if the phases of the same compound are different. They have to be the exact same phase and compound in order to be able to cancel if they are on opposite sides of different equations. Do you know why this is? Is this because certain values change based on the phase? If so, what val...
- Sun Feb 07, 2021 9:26 pm
- Forum: Student Social/Study Group
- Topic: Midterm 2 study tips
- Replies: 26
- Views: 1616
Re: Midterm 2 study tips
If you have extra time after doing ALL textbook problems, I recommend rewatching some of the harder lectures. I've picked up on small things I missed the first time that were conceptually important on the midterm.
- Sun Feb 07, 2021 9:18 pm
- Forum: Student Social/Study Group
- Topic: Students Who Have a Job
- Replies: 103
- Views: 15497
Re: Students Who Have a Job
I don't have a full time or part time job but I just want to say how much I admire everyone who is balancing a job and schoolwork! I already feel so overwhelmed with classes and a couple extracurriculars, I can't imagine also having a job on top of everything :/ You guys are so amazing!
- Sun Feb 07, 2021 8:55 pm
- Forum: Calculating Work of Expansion
- Topic: Sapling Question 14
- Replies: 1
- Views: 105
Sapling Question 14
What value do we use for p when finding the number of moles for part a of question 14 on sapling? Do we use the difference for this part?
- Sun Jan 31, 2021 10:57 pm
- Forum: General Science Questions
- Topic: Midterm 1 Reactions
- Replies: 70
- Views: 6837
Re: Midterm 1 Reactions
I personally found the test to be a little more difficult than I had anticipated. I was able to do all the problems from workshops and the homework; however, the midterm's problems seemed a little harder. Maybe I was just nervous. Can anyone else relate? I really felt the "Maybe I was just ner...
- Sun Jan 31, 2021 10:53 pm
- Forum: Student Social/Study Group
- Topic: Favorite Music
- Replies: 113
- Views: 17699
Re: Favorite Music
I love classic rock :-) CSNY, The Beatles, Steely Dan, all great stuff
- Sun Jan 31, 2021 10:53 pm
- Forum: Student Social/Study Group
- Topic: Go treat yourself after MT1!
- Replies: 75
- Views: 7754
Re: Go treat yourself after MT1!
I love this post! It's so important for us to all stay positive! We're all so capable of achieving our future goals and one rough midterm certainly isn't going to stop us from achieving our dreams :-) I spend the weekend doing some thrift shopping and baking with my roomie!
- Wed Jan 27, 2021 9:31 pm
- Forum: Phase Changes & Related Calculations
- Topic: midterm 1
- Replies: 11
- Views: 769
Re: midterm 1
Week 1 - 3!! I'm scared! Is anyone else scared? I definitely feel nervous for the midterm but I would recommend going to UA sessions especially if you’ve finished all the textbook practice questions! I feel that the worksheets and practice problems they have are really helpful in prepping for exams...
- Wed Jan 27, 2021 9:29 pm
- Forum: General Science Questions
- Topic: Careless Mistakes
- Replies: 54
- Views: 4561
Re: Careless Mistakes
Additionally- I've started to write little reminders for things I typically make careless errors on. For example, I know I have written something like "5.6" instead of "5.6x10^-5" down from my calculator numerous times (not looking all the way to the end of the number) so I am no...
- Wed Jan 27, 2021 9:26 pm
- Forum: General Science Questions
- Topic: Careless Mistakes
- Replies: 54
- Views: 4561
Re: Careless Mistakes
I can totally relate to this! Sometimes it helps me to 'talk' through every step of the problem in my head so I am double checking that everything I'm writing down is making sense and in a way double checking that all my values are being written down correctly.
- Wed Jan 27, 2021 9:24 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K Values that aren't specified
- Replies: 2
- Views: 161
Re: K Values that aren't specified
I believe K unspecified is referring to Kc, so we would use units of molarity.
- Wed Jan 27, 2021 5:58 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Textbook Problem 6A.21
- Replies: 2
- Views: 193
Re: Textbook Problem 6A.21
Yasmina Zaarour 1G wrote:The Kw for water is 1.0x10^(-14) only when temperature is at 25C, but the question gives you a new value of Kw for water because it's asking about at 37C. Take the square root of the given value (2.1x10^(-14)).
ohh I missed that! Thank you!!
- Wed Jan 27, 2021 5:47 pm
- Forum: Phase Changes & Related Calculations
- Topic: Textbook problem 4D.17
- Replies: 3
- Views: 236
Textbook problem 4D.17
When solving this problem, why do we not have to do the same procedure as 15, where we needed to find the combustion reactions for each compound? Additionally, why is N2 not taken into account when finding the standard reaction enthalpy?
- Wed Jan 27, 2021 3:07 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Textbook Problem 6A.21
- Replies: 2
- Views: 193
Textbook Problem 6A.21
How would we come to the conclusion that the molar concentration of OH- in neutral water is 1.4 x 10^-7? What calculation would be done to come to this conclusion? I tried taking the square root of Kw=1*10^-14, since [OH-] would equal [H3O+], but I didn't end up with 1.4x10^-7
- Wed Jan 27, 2021 12:38 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Strong Acids/Bases
- Replies: 19
- Views: 1535
Re: Strong Acids/Bases
Vivian Chang 3L wrote:I think the only ones we need to know for this course are the strong acids H2SO4, HI, HBr, HNO3, HCl, HClO3, HClO4 and the strong bases are Group 1 & Group 2 metal oxides/hydroxides. Hope that helps!
Thank you!!
- Wed Jan 27, 2021 12:17 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: H2SO4 Dissociation
- Replies: 2
- Views: 250
H2SO4 Dissociation
When H2SO4 dissociates the first time, it produces H3O+ and HSO4. Wouldn't this make HSO4- it's conjugate base? In the second deprotonation, HSO4- is acting as a weak acid. Why is this?
- Wed Jan 27, 2021 11:58 am
- Forum: Identifying Acidic & Basic Salts
- Topic: Is AlCl3 acidic or basic?
- Replies: 3
- Views: 48357
Re: Is AlCl3 acidic or basic?
The Cl- anion is neutral, but the Al3+ is not. From the reaction AlCl3 + 3H2O <=> Al(OH)3 + 3HCl, HCl is a strong acid, so it will dissociate in water to form H+ and Cl-. As a result of this reaction, the solution will be acidic, with a pH < 7. so does this mean AlCl3 is a weak base since its conju...
- Wed Jan 27, 2021 11:42 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: determining strong acid
- Replies: 3
- Views: 204
determining strong acid
I am a bit confused as to how to determine if CH3NH3Cl is a strong acid or not. This is how I was thinking, I would appreciate if someone can let me know if this thought process is incorrect Since Cl- is a spectator ion, we disregard it and only look at CH3NH3+ which we can determine to be a strong ...
- Wed Jan 27, 2021 11:30 am
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Strong Acids/Bases
- Replies: 19
- Views: 1535
Strong Acids/Bases
Which chart should we be studying to memorize the strong acids+ bases? I believe chart 6C.3 has more strong acids and bases than the chart we had studied for 14A- is this the chart we should be referring to for 14b?
- Sun Jan 24, 2021 3:54 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Textbook Question 5I.15
- Replies: 2
- Views: 239
Textbook Question 5I.15
When solid NH4HS and 0.400 mol NH3(g)were placed in a vessel of volume 2.0 L at 24 °C, the equilibrium NH4HS(s)⇌NH3(g)+H2S(g), for which Kc=1.6×10−4, was reached.What are the equilibrium concentrations of NH3 and H2S? In regard to the above question, I am a bit confused why the fact that we are give...
- Sun Jan 24, 2021 3:40 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Textbook Problem 5I.13
- Replies: 1
- Views: 164
Textbook Problem 5I.13
In this textbook question, we are asked the following: In an experiment, 2.0 mmol Cl2(g) was sealed into a reaction vessel of volume 2.0 L and heated to 1000. K to study its dissociation into Cl atoms. Use the information in Table 5G.2 to calculate the equilibrium composition of the mixture. I thoug...
- Sat Jan 23, 2021 5:10 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Sapling Question 5
- Replies: 7
- Views: 266
Re: Sapling Question 5
The question is the same type as the one answered her https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=49&t=72607&sid=71ad910c0d27a25e2f6004ba1d1b9342 Thank you! Were you able to make the assumption that [OH-]=[NH4] simply because the molar ratio is 1:1? Does the pH not apply here when c...
- Sat Jan 23, 2021 5:07 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Sapling Question 5
- Replies: 7
- Views: 266
Re: Sapling Question 5
Since we know pH is a certain value, you just have to keep in mind that pH+pOH=14. So you would have to do 14-pH=pOH Using this pOH value, you can now solve for, first, [OH-], and then, using this concentration and the Kb value, the initial concentration. The % protonation would be the [OH]/[initia...
- Sat Jan 23, 2021 4:57 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Sapling Question 5
- Replies: 7
- Views: 266
Sapling Question 5
I believe in one of the UA sessions, we were solving an ICE table for a weak acid and we were told we couldn't assume that the concentration of H3O+ and the conjugate base were the same, even though they had the same molar ratios, because the solution had an acidic pH. Is it true that we need to tak...
- Sat Jan 23, 2021 3:26 pm
- Forum: Student Social/Study Group
- Topic: Lectures on Midterm
- Replies: 10
- Views: 631
Lectures on Midterm
Is the content from Friday's lecture the last lecture content that will be on the upcoming midterm?
- Sat Jan 23, 2021 3:23 pm
- Forum: Student Social/Study Group
- Topic: Study Guide - Midterm?
- Replies: 14
- Views: 948
Re: Study Guide - Midterm?
I don't know of any inclusive study guide that has been made, but in my experience taking 14A with lavelle, the outlines and 'learning objectives' on the outlines make a pretty good study guide. If you do all the textbook problems (and can do them correctly) and understand all the topics on the outl...
- Sat Jan 23, 2021 3:19 pm
- Forum: Student Social/Study Group
- Topic: Study Habits
- Replies: 96
- Views: 9249
Re: Study Habits
Start with the hard concepts! Don't put them off until the end. If you understand certain concepts, then you don't need to spend the same amount of time on them as topics you don't understand. This may seem obvious, but I know it's sometimes tempting to work on easier problems because it feels as th...
- Sat Jan 23, 2021 3:16 pm
- Forum: Phase Changes & Related Calculations
- Topic: State Property
- Replies: 71
- Views: 3730
Re: State Property
The 'mountain' example lavelle used in lecture really helped me understand this, showing that two people climbing a mountain could get to the same point with various paths, but in the case of state properties we don't care about those paths, just where the climbers started and ended. I recommend rew...
- Sat Jan 23, 2021 3:14 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: HClO3 Strong or Weak Acid
- Replies: 7
- Views: 483
Re: HClO3 Strong or Weak Acid
If I'm not mistaken, I thought he had classified it as an acid last quarter, but I agree with the above posts. It will probably be clearly indicated on the midterm if HCLO3 is used.
- Sat Jan 23, 2021 3:11 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Weak acids/ Weak Bases
- Replies: 3
- Views: 260
Weak acids/ Weak Bases
Can someone please tell me exactly what parts of the periodic table can be used to determine if a weak compound is an acid or base? I've heard people mention looking at the first two groups and something about the halogens, but I'm still unclear exactly how to determine this and I would really appre...
- Mon Jan 18, 2021 4:58 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Textbook Question Kw
- Replies: 5
- Views: 274
Textbook Question Kw
Referring to textbook question 6A.21 -
How do we know [H3O+]=[OH-]? Do we assume they are always the same if the problem just says "in water"?
How do we know [H3O+]=[OH-]? Do we assume they are always the same if the problem just says "in water"?
- Thu Jan 14, 2021 10:38 am
- Forum: Student Social/Study Group
- Topic: New Joke Chain
- Replies: 46
- Views: 3693
Re: New Joke Chain
Exothermic reactions? I studied them before they were cool.
- Thu Jan 14, 2021 10:27 am
- Forum: Student Social/Study Group
- Topic: Advice for study
- Replies: 31
- Views: 1767
Re: Advice for study
Study stuff you are struggling with first! Prioritize harder concepts. In order to truly check mastery, do tons of textbook problems. Once you can do a handful all right on your own, you can be pretty confident that you have the concept down.
- Wed Jan 13, 2021 8:07 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Salts
- Replies: 5
- Views: 315
Salts
I think I missed the discussion last quarter when Dr. Lavelle explained how we know something is a salt...can someone please explain? Is it anything with Na? Will Na always be acting as an acid when it dissociates from a compound?
- Wed Jan 13, 2021 8:05 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Lecture Question
- Replies: 9
- Views: 600
Lecture Question
In lecture today (1/13) what did Dr. lavelle mean when he said CH3COOH was acting as a base (22:36)? I thought anything with -COOH was a weak acid.
- Tue Jan 12, 2021 5:29 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K and Q question
- Replies: 4
- Views: 293
K and Q question
On sapling, there were a couple questions asking about the relationship between Q and K when temperature is increased for a reaction. For example, if the reaction was endothermic then (to my understanding) more reactants were made and K increased. According to sapling, K is now greater than Q. Why d...
- Tue Jan 12, 2021 5:20 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Chem Equilibria
- Replies: 6
- Views: 365
Chem Equilibria
The textbook states "at equilibrium, there is no tendency to form more reactants or more products". If this is true, then why do we say that "equilibria favors reactants/products"?
I am a bit confused and would really appreciate if anyone could clear this up!
I am a bit confused and would really appreciate if anyone could clear this up!
- Mon Jan 11, 2021 11:38 pm
- Forum: Ideal Gases
- Topic: Units of Temperature
- Replies: 82
- Views: 4839
Re: Units of Temperature
do we need to memorize how to convert between units of temperature?
- Mon Jan 11, 2021 11:36 pm
- Forum: Student Social/Study Group
- Topic: Study Habits
- Replies: 96
- Views: 9249
Re: Study Habits
Hi! I've found that my biggest problem with studying is I never spend enough time on the stuff I'm shaky on. I like going through concepts I know how to do, just to confirm I do, but it ends up taking way too much time. While it can be daunting to do practice problems on concepts you don't like/fin...
- Mon Jan 11, 2021 11:33 pm
- Forum: Student Social/Study Group
- Topic: Study Habits
- Replies: 96
- Views: 9249
Re: Study Habits
Focus studying on what really helps you, rather than just trying to get through all possible study materials! For me it helped to really focus in on doing textbook problems to study since the amount of potential study resources for this class can get overwhelming, and I found the textbook problems w...
- Mon Jan 11, 2021 11:31 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Participation
- Replies: 18
- Views: 1083
Re: Participation
I believe anything we post on here gets points! I'm not sure if they check how thoughtful the posts are, so I would try and have at least 5 considerably helpful posts each week :)
- Mon Jan 11, 2021 11:28 pm
- Forum: Student Social/Study Group
- Topic: Comfort Movies
- Replies: 168
- Views: 46722
Re: Comfort Movies
John Tucker Must Die is a really funny light chick flick as well!
- Mon Jan 11, 2021 11:25 pm
- Forum: Student Social/Study Group
- Topic: Comfort Movies
- Replies: 168
- Views: 46722
Re: Comfort Movies
The movie Little Miss Sunshine is so heartwarming and cute (even though some aspects of it are more serious). I also recommend Frozen or Tangled as some good Disney films :-)
- Mon Jan 11, 2021 11:23 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Exam Format
- Replies: 15
- Views: 1316
Re: Exam Format
If the exams are the same format as 14a, I recommend joining the zoom at least 5 minutes early! It gets a bit chaotic when everyone joins and the TA has to go around checking papers.
- Mon Jan 11, 2021 11:21 pm
- Forum: Student Social/Study Group
- Topic: Chemistry Community Posts
- Replies: 6
- Views: 332
Re: Chemistry Community Posts
I think this may vary based on your TA, so I recommend doing a little over 5 each week to be safe. We were also told last quarter that they have to be posted in the right place to count, so make sure you are doing this as well!
- Mon Jan 11, 2021 4:51 pm
- Forum: Student Social/Study Group
- Topic: Midterms?
- Replies: 14
- Views: 883
Re: Midterms?
Megan Sparrow 1A wrote:To clarify, these midterms are held in class this quarter. Last quarter they were held in discussion section times. They are still within the same time frame of 50 minutes for each midterm. You can also look at alternate times if you are an international student.
Thank you!
- Mon Jan 11, 2021 4:15 pm
- Forum: Student Social/Study Group
- Topic: Midterms?
- Replies: 14
- Views: 883
Midterms?
Does anyone know the date of our midterms? I can't find the Test and Exam Schedule (mentioned in the syllabus).
- Sun Jan 10, 2021 11:10 pm
- Forum: Ideal Gases
- Topic: value of R
- Replies: 24
- Views: 1193
Re: value of R
I believe he said we are mainly using atm in this class, so I would convert to this unit (using the R for atm) if you are unsure! Just make sure all units match.
- Sun Jan 10, 2021 11:09 pm
- Forum: Student Social/Study Group
- Topic: Study Tips
- Replies: 32
- Views: 1647
Re: Study Tips
Practice problems! These have really helped me work out points of confusion and accurately test myself for mastery of the course content. Once you can do a handful of problems from a certain concept and get them all correct, you can be pretty confident that you've mastered that concept!
- Sun Jan 10, 2021 11:05 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: States that effect equilibrium.
- Replies: 4
- Views: 339
Re: States that effect equilibrium.
Only pure solids and liquids do not effect equilibrium! The activity of these substances is 1 (if I interpreted this correctly from the textbook :))
- Sun Jan 10, 2021 11:04 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Clarification of terminology
- Replies: 15
- Views: 773
Re: Clarification of terminology
Additionally, he pointed out that equilibrium mixture, equilibrium concentration and equilibrium composition all mean the same thing, just in case anyone was getting confused with those terms as well!
- Sun Jan 10, 2021 11:02 pm
- Forum: Ideal Gases
- Topic: Kp to Kc
- Replies: 6
- Views: 307
Kp to Kc
In the textbook, a formula is given to directly convert Kp to Kc. Do we need to be able to use this formula, or can we make these conversions by using the pV=nRT equation?
- Sun Jan 10, 2021 11:00 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Outline 1
- Replies: 4
- Views: 328
Outline 1
In outline 1 when the textbook provides both thermodynamic and kinetic explanations, do we need to be focusing on the thermodynamic as well as the kinetic explanations? I know thermo will be covered later, but since we have not discussed it yet can we focus on the kinetic explanations?
- Sun Jan 10, 2021 10:56 pm
- Forum: Ideal Gases
- Topic: General Question
- Replies: 5
- Views: 292
General Question
Can someone describe exactly what an ideal gas is, as well as an inert gas?
- Fri Jan 08, 2021 11:34 am
- Forum: Student Social/Study Group
- Topic: Favorite TV shows
- Replies: 277
- Views: 59413
Re: Favorite TV shows
victoria_dao_3G wrote:Besides shows, what are some movies you guys are watching right now? I'm trying to get into the holiday spirit, so any Christmas movie recs?
some really good movies (not Christmas ones tho) I recommend are Knives Out, Paris Texas or the Farewell, depending on what your movie preference is!
- Fri Jan 08, 2021 11:32 am
- Forum: Student Social/Study Group
- Topic: Favorite TV shows
- Replies: 277
- Views: 59413
Re: Favorite TV shows
Nathan for you + the office >>>
- Fri Jan 08, 2021 11:05 am
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 4039944
Re: Post All Chemistry Jokes Here
I tell bad chemistry quotes because all the good ones Argon.
- Fri Jan 08, 2021 11:03 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Ionic Equations
- Replies: 2
- Views: 130
Ionic Equations
During Kate's UA session on Thursday, students were discussing additional steps necessary when finding equilibrium for ionic equations. Can someone explain how we would approach ionic equations/ finding K for these equations?