Search found 121 matches
- Thu Mar 11, 2021 8:17 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 6N homework problem
- Replies: 1
- Views: 139
6N homework problem
Hello, I was just wondering if anyone did this homework problem and understood the transfer of electrons in it. The solution manual states that there are 2 electrons transferred in the half-reaction of ln3+ going to form ln2+, I dont understand why there isn't one electron transferred. The appendix ...
- Thu Mar 11, 2021 5:09 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Sapling #20
- Replies: 5
- Views: 387
Re: Sapling #20
We can use the equation k = Ae^(-Ea/RT) to solve for this problem. Temperature values in Kelvin are given, so is activation energy E for the forward and reverse reactions. R is a constant 8.3145. (k catalized reaction)/(k uncatalized reaction) = (A*e^(-Ea1/RT))/(A*e^(-Ea2/RT)) goes to (e^(-Ea1/RT))/...
- Thu Mar 11, 2021 4:22 pm
- Forum: First Order Reactions
- Topic: Sapling 11 week 10
- Replies: 3
- Views: 175
Re: Sapling 11 week 10
Oh my gosh, that's so embarrassing hahah, thanks guys sometimes it just takes a fresh pair of eyes I guess.
- Thu Mar 11, 2021 3:56 pm
- Forum: First Order Reactions
- Topic: Sapling 11 week 10
- Replies: 3
- Views: 175
Sapling 11 week 10
Hi! I posted about this question a while ago but didn't get many responses, I've tried this question a million times the way people say to on chemistry community but I'm still somehow getting it wrong. The last part is the one I'm having issues with. I am using the equation ln[A]=ln[A]o-kt to solve ...
- Wed Mar 10, 2021 9:58 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Homework problem 6M.3
- Replies: 1
- Views: 179
Homework problem 6M.3
I am really confused about how to go about this problem, I tried doing it using the standard cell potential of the reactants but its not working. Will someone share how they did it?
- Tue Mar 09, 2021 10:39 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Calculating n
- Replies: 17
- Views: 921
Calculating n
Could someone explain how to calculate moles of gas exchanged for the equation delta g = -nFEcell when given a reaction because the book doesn't really explain and I'm very confused.
Thanks in advance!
Thanks in advance!
- Mon Mar 08, 2021 7:46 pm
- Forum: Balancing Redox Reactions
- Topic: Homework problem 6k3
- Replies: 2
- Views: 200
Homework problem 6k3
Balance each of the following skeletal equations by using oxidation and reduction half-reactions. All the reactions take place in acidic solution. Identify the oxidizing agent and reducing agent in each reaction. (a) Reaction of thiosulfate ion with chlorine gas: Cl2(g)+ S2O32−(aq)→Cl−(aq) + SO42−(a...
- Sun Mar 07, 2021 4:04 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: sapling #19
- Replies: 3
- Views: 193
Re: sapling #19
I agree it seems like numbers 13-20 on sapling we will learn how to do this week.
- Sun Mar 07, 2021 4:03 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Proposing Intermediate Species
- Replies: 2
- Views: 164
Re: Proposing Intermediate Species
I think it has to be proven experimentally in a lab using the proposed compounds, I beleive it's outside the scope of our class.
- Sun Mar 07, 2021 3:04 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Determining k when concentration is changed
- Replies: 3
- Views: 259
Re: Determining k when concentration is changed
You need to be given th erate law to determine this. The way I do it is by multiplying the change constant of each term For example if the rate law is k[A][B]^2-->P, then anything done to A is taken as that number itself. for example, if you double [A], you first have that the concentration of A inc...
- Sun Mar 07, 2021 2:57 pm
- Forum: General Rate Laws
- Topic: Units
- Replies: 10
- Views: 413
Re: Units
Units are different for different orders because of the differing rate laws. The units for zero order are M/s, the units for first order are 1/s, and the units for second order are 1/M*s. These can be calculated by looking at the different integrated rate laws, but in general, the units for these or...
- Sun Mar 07, 2021 2:54 pm
- Forum: First Order Reactions
- Topic: Sapling Homework 11
- Replies: 2
- Views: 156
Re: Sapling Homework 11
sabrina ghalambor 2J wrote:your set ups are correct so maybe just try it again in the calculator? also maybe theres an issue in how you entered it or because you moved the ln[A] to be before the -kt
I tried inputting just .045 and its correct. can anyone help with the third part?
- Sun Mar 07, 2021 2:44 pm
- Forum: First Order Reactions
- Topic: Sapling Homework 11
- Replies: 2
- Views: 156
Sapling Homework 11
Hi, does anyone mind sharing how they went about this question, i keep getting the second and third parts wrong. I am using the equation ln[A]=ln[A]o-kt to solve for [A] for part two and using the same equation to solve for t in pat 3. For part two, I solve the equation ln[A]=ln[.0611]-3*10^-5*(2.7*...
- Sun Feb 28, 2021 9:42 am
- Forum: Balancing Redox Reactions
- Topic: Sapling #5
- Replies: 6
- Views: 314
Re: Sapling #5
To begin, determine the oxidation numbers of each element in each half‑reaction. For the reduction step of the first reaction, the oxidation number of chlorine changes from +7 to+3. Cl2O7⟶ClO−2 Next, balance the atoms of each half‑reaction. Balance every element other than oxygen or hydrogen first....
- Sun Feb 28, 2021 9:40 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Sapling question 6 week 7/8
- Replies: 1
- Views: 101
Sapling question 6 week 7/8
Could someone explain why teh box "cations from the salt bridge flow tpward it" is under the Y electrode if the question states that the X electrode more readily reacts to form a cation than Y does? Wouldnt this mean that the box should go under the X electrode?
- Sun Feb 28, 2021 9:21 am
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Sapling question 17
- Replies: 2
- Views: 198
Sapling question 17
Does anyone understand the reasoning behind why we solve this problem the way we do? I figured out the answer from other chem community posts by doing at 25 c, and assuming Enot to be equal to 0. So 0-(.0592/1)*log(3.7/(.24^2). I just don't understand why we do it like this, could anyone understand?
- Sun Feb 28, 2021 9:14 am
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Concentration Cell cell potential
- Replies: 2
- Views: 186
Concentration Cell cell potential
Why is E usually equal to 0 in concentration cells? I did not understand this at all during the lecture, if anyone knows that'd be helpful!!
Thanks in advance!
Thanks in advance!
- Sun Feb 28, 2021 8:54 am
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: sapling 17
- Replies: 3
- Views: 134
Re: sapling 17
Sunny Wu 3A wrote:Can you tell me what the answer you got was? Your procedure seems to be correct (using n=2). With the values in your problem, I got -0.0535
I wasn't inputting the value as negative, thank you!
- Sat Feb 27, 2021 12:19 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: sapling 17
- Replies: 3
- Views: 134
sapling 17
I keep calculating this question wrong. I am using the short cut since the rxn is at 25 c, and assuming Enot to be equal to 0. So 0-(.0592/1)*log(3.7/(.24^2) This is how all the sapling posts previous have said to solve it but my answer is still wrong. I tried it using the value of n as 2 as well an...
- Sat Feb 27, 2021 8:05 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: anode / Cathode
- Replies: 9
- Views: 570
anode / Cathode
Is the anode or the cathode negatively charged? I know in Lavelle's lectures some of the cell diagrams have the anode labeled as (-), but when I look it up online it says that the anode is positively charged. Does anyone know?
- Sat Feb 27, 2021 7:19 am
- Forum: Balancing Redox Reactions
- Topic: Sapling #5
- Replies: 6
- Views: 314
Sapling #5
I have been doing this problem for two hours now and cannot get the correct balanced equation. If anyone else had this problem and could share how they did it or give me insight into what I'm doing wrong that would be very helpful, thank you!
- Mon Feb 22, 2021 1:16 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Conceptual understandings
- Replies: 7
- Views: 447
Re: Conceptual understandings
Electrochemistry has definitely felt more confusing than thermodynamics for me too. I think the Organic Chemistry Tutor on YouTube has really helped me though! This video goes through balancing redox half reactions in acidic or basic solutions, and it really helped me with some of the textbook prob...
- Mon Feb 22, 2021 11:58 am
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Conceptual understandings
- Replies: 7
- Views: 447
Conceptual understandings
For some reason this topic is just not landing with me when I watch the lectures, I don't know if its because I'm trying to write down all the concepts as Lavelle talks about them so I'm not actually internalizing the information or if it's just a hard topic, but I feel like I leave lecture not real...
- Sun Feb 21, 2021 9:50 pm
- Forum: Balancing Redox Reactions
- Topic: Sapling question 3
- Replies: 2
- Views: 256
Sapling question 3
For some reason, I've been struggling with this problem. I cannot get the balanced equation, I've been balancing the half equations and adding water. So far my half equations look like this SO32- + H2O--> SO42- + H2 + 2e- 2Ag+ + 2e- --> 2Ag I'm not sure where I'm going wrong here, if someone could s...
- Sun Feb 21, 2021 9:30 pm
- Forum: Balancing Redox Reactions
- Topic: Sapling question 2
- Replies: 3
- Views: 157
Re: Sapling question 2
RylanPurificacion 3J wrote:Are you capitalizing the letters? Sapling can get pretty specific with that, and I noticed that I had to capitalize each element or else nothing would show up.
Thank you! I wasn't capitalizing them
- Sun Feb 21, 2021 9:01 pm
- Forum: Balancing Redox Reactions
- Topic: Sapling question 2
- Replies: 3
- Views: 157
Sapling question 2
I'm having a hard time formatting this answer.. I try to type in the reaction but it won't let me type actual letters. I'm probably just being stupid but what should the format of the actual answer to this look like?
- Sun Feb 21, 2021 8:46 pm
- Forum: Administrative Questions and Class Announcements
- Topic: struggling
- Replies: 73
- Views: 3500
Re: struggling
I also recommend reading the textbook, it helps me because it concentrated on minute details and gives lots of examples on how to work through problems, and I find that it often includes things that Lavelle sometimes leaves out of his lectures.
- Sun Feb 21, 2021 8:42 pm
- Forum: Balancing Redox Reactions
- Topic: cool acronym
- Replies: 25
- Views: 1430
Re: cool acronym
Very helpful thank you for this!
- Sun Feb 21, 2021 8:39 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Porous vs Salt
- Replies: 2
- Views: 200
Re: Porous vs Salt
I think for the purposes of this class they are essentially the same thing and they serve the same purpose
- Sun Feb 21, 2021 8:37 pm
- Forum: Balancing Redox Reactions
- Topic: Oxidation numbers
- Replies: 4
- Views: 250
Oxidation numbers
Is there any easy way to remember how to find oxidation numbers of compounds or should we memorize them?
- Thu Feb 18, 2021 4:55 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Monatomic and Linear Gases
- Replies: 4
- Views: 348
Monatomic and Linear Gases
Should we be able to identify whether a gas is monatomic or linear for Midterm 2? / can anyone give me some examples of these?
- Sun Feb 14, 2021 7:50 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: Sapling question 7
- Replies: 8
- Views: 387
Sapling question 7
Does anyone understand why the higher entropy values were the ones associated with being the most ordered in this problem? I was under the impression that a higher entropy value would mean more disorder. C2H5OH has a delta S of 121.75, C6H6 has a delta s of 33.77 and C4H10 has a delta s of 21.6.
- Sun Feb 14, 2021 6:35 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Sapling question 18
- Replies: 4
- Views: 215
Sapling question 18
For this problem, the way I am going about it is by first subtracting deltaG (products) - deltag(reactants). I then use the equation deltag = -RTln(k) to solve for k, making sure to convert joules of the ideal gas constant to kj, and I keep getting it wrong. Does anyone know what I'm doing wrong or ...
- Sun Feb 14, 2021 6:29 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Sapling 18
- Replies: 3
- Views: 163
Re: Sapling 18
Hey! So for problem 18 its asking you to find K values for certain reactions given the reactants and products ΔG of formation values. In order to find this you multiply the ΔG of formation of each product and reactant by their stoichiometric coefficients, then add the ΔG of the products and subtrac...
- Sun Feb 14, 2021 6:25 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Sapling Week 5/6 #5
- Replies: 7
- Views: 360
Re: Sapling Week 5/6 #5
You are not solving for mols correctly, I also did this incorrectly to start and found .4068 to be the molar heat capacity. To solve for molar heat capacity using PV=nRT, you need to use 298.25 K as the temperature since we're solving for initial mols. using this to solve for n (.0986*18=n*.0826*29...
- Sat Feb 13, 2021 6:19 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Sapling question 5
- Replies: 2
- Views: 158
Sapling question 5
How are people finding the equation delta s= cv*ln(t2/t1) because I don't have it in my notes from the lecture, was it in the textbook?
- Sat Feb 13, 2021 6:12 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Sapling Week 5/6 #5
- Replies: 7
- Views: 360
Re: Sapling Week 5/6 #5
You are not solving for mols correctly, I also did this incorrectly to start and found .4068 to be the molar heat capacity. To solve for molar heat capacity using PV=nRT, you need to use 298.25 K as the temperature since we're solving for initial mols. using this to solve for n (.0986*18=n*.0826*298...
- Sat Feb 13, 2021 5:44 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Sapling question 4
- Replies: 9
- Views: 411
Sapling question 4
Does anyone understand how to do this question because I'm very lost as to where we start. Any help would be appreciated, thanks!
- Sun Feb 07, 2021 7:02 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Sapling #18
- Replies: 4
- Views: 217
Re: Sapling #18
This is my work from this problem with my given values if it helps, sometimes it helps me to actually see it written out
- Sun Feb 07, 2021 6:44 pm
- Forum: Calculating Work of Expansion
- Topic: Sapling #14 for Wk 3 and 4
- Replies: 12
- Views: 531
Re: Sapling #14 for Wk 3 and 4
I think we use two different values for R because the first value of .0826 has units of L atm K−1 mol−1, which are the units we need because we are dealing with temperature, atm, and mols and we want to be left with units respective to L since in the next part we are dealing with calculations relati...
- Sun Feb 07, 2021 6:22 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Question 19 sapling
- Replies: 3
- Views: 124
Question 19 sapling
Why do we ignore the masses given in this problem? I noticed the only thing you need to do to solve this is divide the q given by the origional change in temperature to obtain the heat capacity of the calorimeter and then multiply this value by the second change in t to obtain the new delta U, but i...
- Sun Feb 07, 2021 4:10 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Cp and Cv
- Replies: 7
- Views: 386
Cp and Cv
How does Cv relate to the constant‑pressure molar specific heat, Cp?
- Sun Feb 07, 2021 3:37 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: sapling question 14 week 5
- Replies: 3
- Views: 203
sapling question 14 week 5
Can anyone explain how they found the answer to part a of this question? Somehow I've found path b but keep getting a wrong
- Sun Jan 31, 2021 4:52 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Calculating heat of combustion
- Replies: 1
- Views: 93
Calculating heat of combustion
for the question: Suppose a 3.813 g sample of a second compound, compound B, is combusted in the same calorimeter, and the temperature rises from 24.45 ∘C to 28.32 ∘C. What is the heat of combustion per gram of compound B? Why do we multiply c* delta t and then divide by mass of compound b if the eq...
- Sun Jan 31, 2021 4:37 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: When to convert mass of a substance given to moles
- Replies: 5
- Views: 233
When to convert mass of a substance given to moles
I notice in question 10 on sapling week 3 and 4 homework, we convert the mass of ice given to moles in order to multiply by specific heat capacity, but in question 11 we don't convert the mass of aluminum given to moles. How do we know when to do this conversion and when not to?
- Sun Jan 31, 2021 2:56 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: How to calculate change in temperature
- Replies: 3
- Views: 242
How to calculate change in temperature
This might be a silly question, but for number 9 on the sapling homework for weeks 3 and 4, i'm confused on if we've learned how to do this yet: If you combine 320.0 mL of water at 25.00 ∘C and 120.0 mL of water at 95.00 ∘C, what is the final temperature of the mixture? Use 1.00 g/mL as the density ...
- Wed Jan 27, 2021 3:52 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Textbook problem 5I.13
- Replies: 1
- Views: 81
Textbook problem 5I.13
For some reason I keep getting this problem wrong, I am finding the equillibrium concentration of Cl for thefirs part by using the equation they give us in the table. I first convert 2 mmol to .002 mol, set up my ice table and use the k value to solve for the [cl] concentration at equillibrium but I...
- Mon Jan 25, 2021 3:08 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Monday's lecture clarification
- Replies: 3
- Views: 141
Monday's lecture clarification
In the last half of the lecture today when he was calculating the last example, did anyone understand the process he went through to obtain the value -2.9 kj? At one point I think he said it was actually 2900, and if so why did he find it to be 2.9? If anyone understood that example let me know
- Sun Jan 24, 2021 10:42 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Fridays Lecture Clarification
- Replies: 3
- Views: 220
Fridays Lecture Clarification
Did anyone understand the context of what Dr. Lavelle was explaining when he was listing the standard states for gasses, solutions, pure liquids and solids etc? I did not understand in what context this information would be useful
- Sun Jan 24, 2021 10:39 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: How to find equations
- Replies: 4
- Views: 216
Re: How to find equations
I mean like the balanced chemical equations you need to solve the problem
- Sun Jan 24, 2021 10:37 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Pka, Ph, charged and neutral species
- Replies: 7
- Views: 369
Pka, Ph, charged and neutral species
Are these statements correct:
For an acid, when pH>pKa, the charged species is dominant
For an acid, when pH<pKa, the neutral species is dominant
For a base, when pH>pKa, the neutral species is dominant
For a base, when pH<pKa, the charged species is dominant
For an acid, when pH>pKa, the charged species is dominant
For an acid, when pH<pKa, the neutral species is dominant
For a base, when pH>pKa, the neutral species is dominant
For a base, when pH<pKa, the charged species is dominant
- Sun Jan 24, 2021 10:35 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: How to find equations
- Replies: 4
- Views: 216
How to find equations
How do you find the chemical equations for problems like this: HClO is a weak acid ( ka=4.0×10−8 ) and so the salt NaClO acts as a weak base. What is the pH of a solution that is 0.018 M in NaClO at 25 °C?
- Sun Jan 24, 2021 10:18 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sapling Homework 2 #5
- Replies: 2
- Views: 57
Re: Sapling Homework 2 #5
Thank you so much, I was dividing the concentration of B by OH, not the other way around. I really appreciate it!
- Sun Jan 24, 2021 10:06 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sapling Homework 2 #5
- Replies: 2
- Views: 57
Sapling Homework 2 #5
The Kb for an amine is 1.250×10−5. What percentage of the amine is protonated if the pH of a solution of the amine is 9.387 ? Assume that all OH− came from the reaction of B with H2O. I think I'm setting up my ice table wrong for this problem. From the pH, I calculate pOH, and from there I calculate...
- Sun Jan 24, 2021 9:18 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sapling #2 week 2
- Replies: 5
- Views: 126
Re: Sapling #2 week 2
Thanks so much, I was dividing by .0024 instead of .128
- Sun Jan 24, 2021 9:08 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sapling #2 week 2
- Replies: 5
- Views: 126
Sapling #2 week 2
Im not sure why I'm getting this problem wrong, the question is: The ka of a monoprotic weak acid is 0.00247. What is the percent ionization of a 0.128 M solution of this acid? I first set up the ice table for the week acid, so HA +H2O --> A- + H I .128 - 0 0 C -x - +x +x E .128-x - x x Then, I solv...
- Sat Jan 16, 2021 6:41 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Temperature
- Replies: 12
- Views: 520
Re: Temperature
Yes I believe you would have to write two different equations, if there was a certain temperature required for equilibrium and the temperature suddenly changed, you would have to calculate the k and q values for temperature change.
- Sat Jan 16, 2021 6:35 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Week 1 Sapling #5
- Replies: 2
- Views: 106
Re: Week 1 Sapling #5
I think that we are able to manipulate equilibrium constants like this because regardless of concentration, equilibrium constants for a particular equation will always be constant. So if we are able to manipulate equations to eventually end up with the same products and reactants, we know that their...
- Sat Jan 16, 2021 6:32 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kw constant
- Replies: 25
- Views: 733
Re: Kw constant
Since water is in large excess, we assume its concentration to be relatively unchanged. That is, we aren't able to detect the change in water since it's probably something in the decimal units so it is essentially undetectable.
- Sat Jan 16, 2021 6:31 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE table and Molarity units
- Replies: 18
- Views: 719
Re: ICE table and Molarity units
I think that if it asks for the final concentration then it is assuming your final answer must be in mol/L, but if it asks for the final molar concentration I think keeping it in moles is fine. I usually always convert thought if it gives me a measurement for volume
- Thu Jan 14, 2021 7:30 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Sapling question 9
- Replies: 5
- Views: 262
Sapling question 9
Can anyone help me with question 9 on sapling? I keep getting a concentration of a negative value for x and I'm not sure what I'm doing wrong. If someone can share how they did this problem thatd be great thx!
- Sun Jan 10, 2021 11:50 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Module 2
- Replies: 2
- Views: 190
Module 2
Can anyone explain how to do this question?
- Sun Jan 10, 2021 10:56 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Video Module question 19
- Replies: 3
- Views: 67
Video Module question 19
19. Calculate the reaction quotient, QC, from the following equilibrium data collected in a 3.00 L sealed reaction vessel for the reaction: AsH3 (g) ⇌ As (s) + H2 (g) AsH3 = 5.55 x 10^-4 mol, As = 3.31 x 10^-3 mol, H2 = 1.23 x 10^-3 mol. I keep getting .006 for this question, I'm dividng (1.23 x 10^...
- Sun Jan 10, 2021 8:08 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: identifying solids and non homogeneous reactant/product
- Replies: 4
- Views: 253
Re: identifying solids and non homogeneous reactant/product
I think most of the time its labeled in the equation after the element (co2 will be listed as CO2 (g) in an equation) as (aq), (l), (s), or (g). I dont beleive were expected to know.
- Sun Jan 10, 2021 8:05 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: aqueous solutions
- Replies: 9
- Views: 348
aqueous solutions
cam elements in an equation labeled (aq) also not be included in the equilibrium constant equation?
- Sun Jan 10, 2021 8:03 pm
- Forum: Student Social/Study Group
- Topic: Group Me
- Replies: 6
- Views: 305
Group Me
Is there a group me for this class
- Sun Dec 13, 2020 9:13 am
- Forum: Trends in The Periodic Table
- Topic: When to use size and when to use electronegativity in respect to determining acidity
- Replies: 1
- Views: 161
When to use size and when to use electronegativity in respect to determining acidity
Does anyone know when we should use the size of an atom to determine acidity and when to use its electronegativity? I know that as ions get bigger, their bond to hydrogen becomes weaker since its a longer bond which makes this compound more acidic. Also, when Hydrogen is bound to two atoms, the more...
- Sun Dec 13, 2020 9:09 am
- Forum: *Shrodinger Equation
- Topic: Wave properties of electron diffraction
- Replies: 6
- Views: 369
Re: Wave properties of electron diffraction
One of the UA's in her review session posted this which I thought was helpful in understanding the concept
- Sun Dec 13, 2020 9:05 am
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Determining Which is More Acidic Between 2 Weak Acids
- Replies: 3
- Views: 173
Re: Determining Which is More Acidic Between 2 Weak Acids
I think you should always start by drawing out the lewis structures and seeing which molecules the partial charge lies on and keep in mind the electronegativity of the molecules(electron pulling ability)
- Sun Dec 13, 2020 9:03 am
- Forum: Calculating the pH of Salt Solutions
- Topic: Solving PH/PoH
- Replies: 11
- Views: 1073
Re: Solving PH/PoH
It helps me to remember these rules
pH: -log of (H+ concentration)
pH: 14-pOH
pOH:14-pH
pOH: -log of (OH- concentration)
H+: 10^-pH
OH-: 10^-pOH
pH: -log of (H+ concentration)
pH: 14-pOH
pOH:14-pH
pOH: -log of (OH- concentration)
H+: 10^-pH
OH-: 10^-pOH
- Sun Dec 13, 2020 8:59 am
- Forum: Identifying Acidic & Basic Salts
- Topic: Question 7 sapling
- Replies: 5
- Views: 219
Question 7 sapling
IS there an easier way to distinguish these salts acidic or basic? The solution for this question is sort of confusing
- Sat Dec 05, 2020 7:58 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Final Exam Material [ENDORSED]
- Replies: 7
- Views: 446
Re: Final Exam Material [ENDORSED]
I don't think we will need to calculate it but my TA always says that anything Dr. Lavelle says in lecture is fair game on tests.
- Sat Dec 05, 2020 7:56 pm
- Forum: Lewis Acids & Bases
- Topic: How do you tell if something is a strong base?
- Replies: 3
- Views: 121
How do you tell if something is a strong base?
I know that group 1 metal hydroxides and group 1/2 metal oxides are strong bases, but does anyone know the chemical properties that make them such?
- Sat Dec 05, 2020 7:51 pm
- Forum: Bronsted Acids & Bases
- Topic: Do acids always list hydrogens as the first element in a molecule?
- Replies: 3
- Views: 145
Do acids always list hydrogens as the first element in a molecule?
In the textbook it says that acids contain hydrogen atoms and always list them as the first element, but are there cases where this is not true?
- Sat Dec 05, 2020 7:25 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Pka and Ka
- Replies: 6
- Views: 336
Pka and Ka
Can anyone explain the difference between Pka and Ka values.
- Sat Dec 05, 2020 7:25 pm
- Forum: Bronsted Acids & Bases
- Topic: Relative strength of acids and bases
- Replies: 2
- Views: 130
Relative strength of acids and bases
Hi, Can anyone explain the equation Dr. Lavelle went over in lecture to calculate weak acids/bases, I understand that if Ka is a large value this means that the acid is strong but I'm a little unsure of what the variables are and what values you need to calculate this? ka = [A-][H+]/[AH].
- Sat Nov 28, 2020 6:13 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: sapling question 18
- Replies: 2
- Views: 132
sapling question 18
does anyone understand why in this question where H2C(Cx)CH2, x= a whole number, why when x is even the Hydrogen atoms are coplanar but when x is odd, the hydrogen atoms lie on perpendicular planes? I'm not sure what this means or why only two of the hydrogen strcutures are oriented this way. If som...
- Sat Nov 28, 2020 5:26 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Delocalized Pi Bond
- Replies: 5
- Views: 155
Re: Delocalized Pi Bond
Sorry disregard the above answer, I think it just has to do with resonance structures and whether or not double/triple bonds can be moved around.
- Sat Nov 28, 2020 5:04 pm
- Forum: Hybridization
- Topic: Question 11 sapling
- Replies: 5
- Views: 216
Re: Question 11 sapling
Okay thanks everyone that makes sense, I did'nt realize it was only wanting us to look at phosphorus.
- Sat Nov 28, 2020 5:02 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Delocalized Pi Bond
- Replies: 5
- Views: 155
Re: Delocalized Pi Bond
I think this has to do with when atoms have unhybridized p orbitals, like in the example he did in class for Benzene (C6H6). In this molecule, each carbon atom has a unhybridized p orbital, so each carbon contributes one electron to this ring of carbons. The unhybridized p orbitals make the C-C bond...
- Sat Nov 28, 2020 4:57 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: pi and sigma bonds
- Replies: 17
- Views: 1940
Re: pi and sigma bonds
Usually how I determine it is using the fact that a sigma bond is a single bond, and a double bond has one pi bond and one sigma bond. So if a molecule has 3 single bonds and one double bond, it would have 4 sigma bonds and 1 pi bond. Hope that helps.
- Sat Nov 28, 2020 4:55 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Sapling Weeks 7-8 #7
- Replies: 3
- Views: 137
Re: Sapling Weeks 7-8 #7
I beleive that since the Cl molecules have a -1 charge because of their 3 lone pair electrons, the shape of the molecule is asymmetrical which means that the dipole moments do not cancel. It might also have something to dow with the fact that the electronegativity difference between Cl and C is high...
- Sat Nov 28, 2020 4:51 pm
- Forum: Dipole Moments
- Topic: dipole moments
- Replies: 4
- Views: 225
dipole moments
How do you determine whether or not an atom has a high dipole moment
- Sat Nov 28, 2020 4:45 pm
- Forum: Hybridization
- Topic: hybridization
- Replies: 5
- Views: 292
Re: hybridization
During one of his lectures he did have a slide which described that if you have a trigonal bipyramidal atom (5 regions of electron density), you need to invoke 5dsp3 hybridization(1 s orbital, 3 p orbitals and 1 d orbital). And if you have an octahedral atom(6 regions of electron density), you need ...
- Sat Nov 28, 2020 4:37 pm
- Forum: Hybridization
- Topic: Question 11 sapling
- Replies: 5
- Views: 216
Question 11 sapling
Could someone explain why the hybridization if p4o6 is sp3? I understand all the rest of the atoms in this question except for this one. Thanks in adance
- Sun Nov 22, 2020 4:29 pm
- Forum: Student Social/Study Group
- Topic: CHEM 14B Time Conflict
- Replies: 13
- Views: 622
Re: CHEM 14B Time Conflict
I beleive on My UCLA it says that the lectures are recorded again, obviously not the lab but there are so many lab's hopefully you can find a time that works.
- Sun Nov 22, 2020 4:28 pm
- Forum: Student Social/Study Group
- Topic: grade worries
- Replies: 119
- Views: 14698
Re: grade worries
I am also worried, will probably end up taking the class for P/NP instead of a letter grade
- Sun Nov 22, 2020 4:25 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Week 7 Sapling
- Replies: 12
- Views: 682
Re: Week 7 Sapling
I beleive that they're both due next Sunday.
- Sun Nov 22, 2020 4:24 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm 2 Scores
- Replies: 28
- Views: 1297
Re: Midterm 2 Scores
I think within this week, although it could be later due to the holiday.
- Sun Nov 22, 2020 4:23 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Thanksgiving week lectures
- Replies: 5
- Views: 323
Thanksgiving week lectures
Does anyone know if we will be having lectures/discussions on Wednesday and Friday of thanksgiving week?
- Thu Nov 12, 2020 2:55 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Finding Oxidation number
- Replies: 1
- Views: 71
Finding Oxidation number
Have we learned how to find the oxidation number of an element yet? There's a question that asks us to on sapling and I don't remember Dr. Lavelle going over this is lecture
- Thu Nov 12, 2020 2:54 pm
- Forum: Ionic & Covalent Bonds
- Topic: Dipole-Dipole and Ion-Dipole
- Replies: 1
- Views: 64
Dipole-Dipole and Ion-Dipole
How should I go about telling the difference between Dipole-Dipole and Ion-Dipole interactions?
- Thu Nov 12, 2020 2:49 pm
- Forum: Ionic & Covalent Bonds
- Topic: Hydrogen Bond Homework Question
- Replies: 3
- Views: 101
Re: Hydrogen Bond Homework Question
Hydrogen bonds can only occur with a N,O, or F atom which must have a hydrogen atom covalently bonded to the electronegative atom. This atom must also have another electronegative atom bound to hydrogen close by with an available lone pair. It helps me to draw the molecules out and see what can bond...
- Thu Nov 12, 2020 2:44 pm
- Forum: Ionic & Covalent Bonds
- Topic: sapling homework question 12
- Replies: 4
- Views: 125
Re: sapling homework question 12
Thanks everyone that makes sense!
- Thu Nov 12, 2020 2:40 pm
- Forum: Octet Exceptions
- Topic: Octet Rule Exceptions
- Replies: 20
- Views: 1297
Octet Rule Exceptions
I know in class we were taught that H,He, Li, and Be are exceptions to the octet rule as well as group 13 elements, but are there any otheres? in the sapling homework I learned that phosphate is also an exception because it can have 10 (5 shared) if it makes the formal charge lesser. I'm curious to ...
- Wed Nov 11, 2020 8:19 pm
- Forum: Ionic & Covalent Bonds
- Topic: sapling homework question 12
- Replies: 4
- Views: 125
sapling homework question 12
I understand why the fourth option is a hydrogen bond, but I don't understand why the first or second option isn't, can anyone explain?
- Sun Nov 08, 2020 7:52 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm 2 Question Count
- Replies: 17
- Views: 591
Re: Midterm 2 Question Count
I've heard it will be more questions that are shorter
- Sun Nov 08, 2020 7:52 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm 2 Format
- Replies: 7
- Views: 261
Re: Midterm 2 Format
I've heard it will be the same format but it will be more questions that are shorter.
- Sun Nov 08, 2020 7:50 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm Scores
- Replies: 28
- Views: 1127
Re: Midterm Scores
You can't review your actual midterm but if you ask your TA to go over concepts that you got wrong mine helped me with that.
- Sun Nov 08, 2020 7:49 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm Solutions
- Replies: 4
- Views: 195
Re: Midterm Solutions
You can ask your TA to go over specific concepts that you missed! But they will not show you specific questions