Search found 106 matches
- Tue Mar 16, 2021 8:53 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Sapling Week 9/10 #13
- Replies: 12
- Views: 3730
Re: Sapling Week 9/10 #13
Hi! I can help with this one. so remember that the rate of the overall reaction is governed by the rate of the slowest step. so first you would need to identify the sow step with is step #2. then, write out the rate law for step #2: rate=k2[HClO][I^-] however, comparing step 1 and step 2 we know tha...
- Tue Mar 16, 2021 8:41 am
- Forum: Zero Order Reactions
- Topic: Sapling #6 (Week 9/10)
- Replies: 3
- Views: 405
Re: Sapling #6 (Week 9/10)
first of all, [X] vs t should be shown as a line with negative slope in both cases since reactants decrease in concentration; [Y] vs t should be shown as a line with a positive slope since products accumulate in the process. for first or second order reactions, rate=k[X] or rate=k[X]^2. which means ...
- Tue Mar 16, 2021 8:35 am
- Forum: Zero Order Reactions
- Topic: Sapling #4 (week 9/10) [ENDORSED]
- Replies: 4
- Views: 351
Re: Sapling #4 (week 9/10) [ENDORSED]
I also tried multiple times trying to figure out this one. I did not notice that M^2/s should stay in the answer box since it is neither one of them. Ultimately I figured out this question by writing out the formulas for each order reaction and then figure out the expression of k and thus the proper...
- Mon Mar 15, 2021 9:51 am
- Forum: Administrative Questions and Class Announcements
- Topic: THANK YOU DR LAVELLE!
- Replies: 47
- Views: 6281
Re: THANK YOU DR LAVELLE!
big THANKYOU to Dr. Lavelle. Had a great time learning Chem 14A & 14B with you. I love how you approached every concept in detail and explained everything so thoroughly! To be honest I didn't really need to read the textbook because you explained the concepts so well! I can only imagine how diff...
- Sat Mar 13, 2021 9:41 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: when to add Pt (s)
- Replies: 23
- Views: 927
Re: when to add Pt (s)
you would use an inert conductor such as Pt to transfer electrons if the half reaction has no conducting solid. for example, if both the reactant and products are in solution, then you would need pt.
- Sat Mar 13, 2021 9:39 am
- Forum: Balancing Redox Reactions
- Topic: Studying for finals?
- Replies: 47
- Views: 1994
Re: Studying for finals?
I would really suggest going over the textbook questions Dr. Lavelle assigned. Personally, I've found them very helpful in terms of preparing for exams.
- Sat Mar 13, 2021 9:37 am
- Forum: Zero Order Reactions
- Topic: When to use each order
- Replies: 19
- Views: 1066
Re: When to use each order
Dr. Lavelle talked about many aspects that you can use to tell whether a reaction is zero, first, second order. for one you can look at the graphs if given; you can also look at the values of half lives; you can also do a ratio of two rates of the same reaction, and see what the exponential is, whic...
- Sat Mar 13, 2021 9:35 am
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: EA
- Replies: 23
- Views: 1163
Re: EA
we generally use Ea for activation energy.
- Wed Mar 10, 2021 4:50 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: electrode
- Replies: 3
- Views: 247
electrode
Hey I was just wondering why electrodes are usually represented as only on one side of the cell diagram? For example, Cu(s) | Cu 2+ (aq) || Fe 3+(aq), Fe 2+(aq) | Pt(s). I thought Pt is in contact with both sides of the cell? Thank you!
- Sun Mar 07, 2021 8:29 pm
- Forum: Biological Examples (*DNA Structural Transitions, etc.)
- Topic: Application in Biology
- Replies: 4
- Views: 752
Re: Application in Biology
you know how LS 7A provides you with a weekly study guide, you can check Dr. Lavelle's website for something similar to that which helps you check your understanding of the big concepts and ideas. Other than that, I would really suggest go over the textbook questions Dr. Lavelle has listed out on th...
- Sun Mar 07, 2021 8:26 pm
- Forum: Van't Hoff Equation
- Topic: Celcius vs Kelvin for T1 and T2
- Replies: 84
- Views: 6442
Re: Celcius vs Kelvin for T1 and T2
i think kelvin is a safer choice, since all the formulas were created using kelvin basically. using celsius would cause an issue with the units not matching up, and you would have to switch all other components that are related to temperature from kelvin to celsius. that sounds like a lot of extra w...
- Sun Mar 07, 2021 8:23 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Delta H and Delta S both positive
- Replies: 31
- Views: 8065
Re: Delta H and Delta S both positive
from the equation that connects delta G, delta H and delta S, in case of when delta H and delta S are both positive, it really comes down to the temperature to determine whether the reaction is spontaneous or not.
- Sun Mar 07, 2021 8:21 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: State functions
- Replies: 18
- Views: 791
Re: State functions
Yes these are state functions. Remember the diagram Dr. Lavelle drew in class-- if it doesn't matter how you reached from A to B, then this would be a state function.
- Sun Mar 07, 2021 8:19 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Spontaneity of a System
- Replies: 38
- Views: 2710
Re: Spontaneity of a System
the determinant really is delta G. if Delta G is negative, then the reaction is spontaneous. But you would also need to consider factors that influence the delay G, ie delta H, temperature, and delta S. remember the formula that puts these three together: delta G=delta H -T delta S
- Sun Feb 28, 2021 10:41 pm
- Forum: Calculating Work of Expansion
- Topic: Reversible vs Irreversible
- Replies: 9
- Views: 630
Re: Reversible vs Irreversible
I had the same issue understanding the concept. I think for irreversible reactions, the process happens rapidly and the change is significant and relatively larger. But for reversible processes, the changes took multiple steps to happen and each step is not as significant and thus reversible. This i...
- Sun Feb 28, 2021 10:38 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE Tables
- Replies: 36
- Views: 1592
Re: ICE Tables
In order to get the correct ICE table, both factors would matter since the coefficient of reactants and products determines the coefficient of x, and whether it’s used up or being produced determines the sign in front of x
- Sun Feb 28, 2021 10:35 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Strong vs Weak acid/Bases
- Replies: 10
- Views: 505
Re: Strong vs Weak acid/Bases
We would use the ice table cuz weak acid / bases don’t ionize completely, whereas compared with strong acid / base. The C in ice allows us to consider the change in concentration.
- Sun Feb 28, 2021 10:34 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Factors that affect the equilibrium constant
- Replies: 31
- Views: 3974
Re: Factors that affect the equilibrium constant
I believe based on what we’ve learned so far, temperature is the only factor that affects the Equilibrium constant. Pressure and Volume doesn’t affect it at all.
- Sun Feb 28, 2021 10:32 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Telling Apart Weak Bases vs Weak Acids by their Formula
- Replies: 11
- Views: 790
Re: Telling Apart Weak Bases vs Weak Acids by their Formula
I think the best solution to that is by being clear of the list of strong acid/ bases. You can find the list in sapling solutions and also in the textbook. Basically everything beside those would be considered a weak acid / base.
- Sun Feb 28, 2021 10:28 pm
- Forum: Calculating Work of Expansion
- Topic: R constant of an Ideal Gas
- Replies: 16
- Views: 724
Re: R constant of an Ideal Gas
Basically what matters is the unit of R. So you would want to take a look at the units you have got and the unit you want to end up with. Usually R could fix the difference between the units and you would just select the R value with the proper units.
- Sun Feb 28, 2021 10:26 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: confusion on using Cp and Cv
- Replies: 24
- Views: 1023
Re: confusion on using Cp and Cv
Cp=Cv + R. Cp refers to the conditions under constant pressure, Cv refers to constant volume. If you take a look at the textbook problems you’ll find abundant examples
- Sun Feb 28, 2021 10:23 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: closed system energy change
- Replies: 16
- Views: 737
Re: closed system energy change
In a closed system, you would need to consider both work and heat as the two aspects are different in nature. The total amount of energy change doesn’t really tell you much, since you would also want to consider the nuance changes going on inside the closed system.
- Fri Feb 19, 2021 5:51 am
- Forum: Calculating Work of Expansion
- Topic: unit of w
- Replies: 17
- Views: 1131
unit of w
hey guys, i was wondering how does the units match up for the formula w= -P delta V? cuz P is usually in atm or barr, and V is usually in mL or L. how does multiplying these two together get the unit for work which should be J or KJ? don't we always have to multiply the result by R to convert it to ...
- Thu Feb 18, 2021 10:26 am
- Forum: Calculating Work of Expansion
- Topic: reversiible expansion
- Replies: 2
- Views: 152
reversiible expansion
Dr. lavelle said in class about reversible expansion in isothermal conditions. I was wondering what does it mean by expansion is reversible? I think Dr. Lavelle said since the change is very small each time, it is reversible. just checking my understanding.
- Sun Feb 14, 2021 8:52 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: difference in ΔG and ΔG⁰
- Replies: 15
- Views: 652
Re: difference in ΔG and ΔG⁰
it's pretty much similar to ΔH and ΔH⁰, ΔS and ΔS⁰. the ⁰ simply means the calculations are done under standard state
- Sun Feb 14, 2021 8:50 pm
- Forum: Ideal Gases
- Topic: Sapling week 3/4 #15
- Replies: 7
- Views: 488
Re: Sapling week 3/4 #15
you can use the moles of NaN3 to calculate the moles of N2 since according to the chemical reaction their mole ratio is 2:3. you can find the moles of NaN3 by dividing its mass by its molar mass
- Sun Feb 14, 2021 8:47 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: kJ/K*mol vs J/K*mol
- Replies: 7
- Views: 290
Re: kJ/K*mol vs J/K*mol
that's what i did for my sapling questions, and the final answer seems to be the same. As long as you make sure the units cancel out, I don't think there would be any problems.
- Sun Feb 14, 2021 8:46 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Sapling Week 5/6 #15
- Replies: 5
- Views: 266
Re: Sapling Week 5/6 #15
i think both ways would work and would give you the same results. because delta G, delta H and delta S are all state functions and so it shouldn't matter how you got your results. for this specific question, I simply added the delta G together since it was provided. so you would reverse the second e...
- Sun Feb 07, 2021 4:31 pm
- Forum: Phase Changes & Related Calculations
- Topic: Endo vs. exo & bond strenghts
- Replies: 8
- Views: 357
Re: Endo vs. exo & bond strenghts
just to add on to what's being said above,
bond enthalpies can reflect bond strength: the higher the bond enthalpy, the more energy is needed to break the bond and thus the stronger the bond
bond enthalpies can reflect bond strength: the higher the bond enthalpy, the more energy is needed to break the bond and thus the stronger the bond
- Sun Jan 31, 2021 8:21 pm
- Forum: Phase Changes & Related Calculations
- Topic: Enthalpy Reactions
- Replies: 13
- Views: 396
Re: Enthalpy Reactions
I think we would need to consider the phase changes especially if the reactants / products aren't in their most stable form there was a sapling question that required similar calculations. There was also an example given in the lecture where Dr. Lavelle mentioned if the product water isn't in liquid...
- Thu Jan 28, 2021 9:21 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Problem 12.69
- Replies: 8
- Views: 2875
Re: Problem 12.69
to be exact, NH3 and NH4+ are a conjugate acid and base pair, but you can use Kb of NH3 to calculate Ka of NH4Cl because Cl- would mainly be inert in water.
- Thu Jan 28, 2021 9:12 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: textbook 6D #15
- Replies: 3
- Views: 208
Re: textbook 6D #15
Chem_Mod wrote:NH3 and NH4+ are indeed a conjugate acid-base pair. NH4Cl is simply a salt of NH4+, the Cl- will be completely inert in water. You can use Ka x Kb= Kw to find Ka of NH4+ from Kb of NH3
okay got it! thanks so much :-)))
- Thu Jan 28, 2021 9:07 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: textbook 6D #15
- Replies: 3
- Views: 208
textbook 6D #15
for question a, how did you guys find the Ka for NH4Cl since it wasn't given in the charts provided. I'm confused about whether we can use the Kb for NH3 to calculate the Ka for NH4Cl, since the two aren't exactly conjugate acid and base pairs are they?
- Thu Jan 28, 2021 9:29 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: textbook 6A. 23
- Replies: 3
- Views: 170
Re: textbook 6A. 23
ellenulitsky Dis 1I wrote:Since you need to know the concentration which is mol/liters, it will be .0025mol/.1L which is 0.025M. as the concentration of [Ba(OH2)] and [Ba+], the concentration of [OH-] is 2*.025M since there are two [OH-]. Hope this helps!
ooops thank you I didn't read the whole question lmao!!
- Thu Jan 28, 2021 7:34 am
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Concentration via pH (Q11.35)
- Replies: 4
- Views: 5863
Re: Concentration via pH (Q11.35)
just to add on to the discussion above, when I was solving this question myself, I think it's helpful to note that concentration x volume = moles. Also, it's helpful to keep in mind of what stays the same and what changes throughout the questions. For example, the concentration of the 5ml extracted ...
- Thu Jan 28, 2021 4:44 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: textbook 6A. 23
- Replies: 3
- Views: 170
textbook 6A. 23
can anyone explain how they got their answers for 6A.23 textbook question? Somehow my answer is off by 10^-1. I know that since Ba(OH)2 is a strong base we don't need to do the ICE table. so I thought [Ba(OH)2] = [Ba2+] = 0.43g x 1 / 171.34(molar mass of Ba(OH)2) = 2.509 x 10^-3? the textbook answer...
- Wed Jan 27, 2021 10:30 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: textbook 4D.15
- Replies: 2
- Views: 108
textbook 4D.15
can anyone explain why the answer for this question is -312 instead of 312 kj / mol? I got 312 by doing H of products minus H of reactants.
- Sun Jan 24, 2021 8:39 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sapling Week 2 #7
- Replies: 8
- Views: 293
Re: Sapling Week 2 #7
I also faced some difficulties while answering this question. What should we consider as included in the solution in NaClO? I'm confused by the wording of this question.
- Sun Jan 24, 2021 8:36 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: X Approximations
- Replies: 23
- Views: 779
Re: X Approximations
if you don't want to do the 5% test, you can check if Ka or Kb given is less than 10-4. usually we can use approximations if they are less than 10-4.
- Sun Jan 24, 2021 8:33 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Approximately x
- Replies: 18
- Views: 614
Re: Approximately x
After reading this thread I am a little confused. What does it mean to approximate x as 0? Could you do this on any of the homework problems? I solved all of them with the quadratic equation. How would you do it the other way? when you list out the ICE table, you can assume that the reactant change...
- Sun Jan 24, 2021 8:29 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sapling Question 3
- Replies: 8
- Views: 553
Re: Sapling Question 3
just to add on to the discussion, when i did my calculations, i remember double checking to see if we can use approximation. but since Ka of this acid is 8.40×10−4, I remember I had to solve the quadratic equation to get the accurate answer. This might be the reason you didn't get the right answer. ...
- Sun Jan 24, 2021 8:13 pm
- Forum: Ideal Gases
- Topic: Q and K relationship
- Replies: 22
- Views: 773
Re: Q and K relationship
Hello! to simplify things I usually just remember them as one since basically the calculations are the same. but the only difference to remember is that K is for when the reaction is at equilibrium and Q is anything beside that.
- Sun Jan 24, 2021 12:36 am
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 2993433
Re: Post All Chemistry Jokes Here
saw this on instagram lmao
- Sun Jan 17, 2021 1:53 am
- Forum: Ideal Gases
- Topic: Sampling hw #4
- Replies: 16
- Views: 1723
Re: Sampling hw #4
just to add on to the discussion, you can refer to the professor's lecture 2 for guidance. he gave a very similar example during class i remember.
- Sat Jan 16, 2021 8:25 am
- Forum: Ideal Gases
- Topic: pure substance
- Replies: 4
- Views: 300
pure substance
can anyone recall why isn't gas considered a pure substance but solid and liquid are? I think Dr. lavelle mentioned in lecture but I can't quite recall. Thank you!
- Sat Jan 16, 2021 8:21 am
- Forum: Ideal Gases
- Topic: n/V = concentration
- Replies: 19
- Views: 2155
Re: n/V = concentration
besides the discussion above, you can also think of it similar to the density formula: density = mass / volume. In this case, mass would be similar to n and concentration would be like density, if that helps understand the equation better.
- Sat Jan 16, 2021 8:16 am
- Forum: Ideal Gases
- Topic: Kc vs Kp
- Replies: 109
- Views: 4369
Re: Kc vs Kp
just to add on to the discussion above,
it also depends on what is given to you. if the question gave you conditions in barr or atm, then go for Kp. if the question gave you concentration, then go for Kc.
it also depends on what is given to you. if the question gave you conditions in barr or atm, then go for Kp. if the question gave you concentration, then go for Kc.
- Sun Jan 10, 2021 7:25 pm
- Forum: Ideal Gases
- Topic: PV=nRT
- Replies: 74
- Views: 4211
Re: PV=nRT
P = Pressure (in atm)
V = Volume (in L)
n = # of moles
R = gas constant
T = Temperature (in K)
remember to use SI units!
V = Volume (in L)
n = # of moles
R = gas constant
T = Temperature (in K)
remember to use SI units!
- Sun Jan 10, 2021 7:23 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Units
- Replies: 27
- Views: 867
Re: Units
i don't think there is a preference as long as your value is correct. but usually we use atm or bars out of convenience.
- Sun Jan 10, 2021 7:21 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: How do you write the K for an equation with heterogeneous equilibria?
- Replies: 10
- Views: 724
Re: How do you write the K for an equation with heterogeneous equilibria?
you would only need to consider the aq formed components. gases and solids would not be considered!
- Sun Jan 10, 2021 7:18 pm
- Forum: Ideal Gases
- Topic: partial pressures
- Replies: 14
- Views: 357
Re: partial pressures
partial pressure is the gas pressure when this gas alone occupies the container at the same temperature. if it helps the total pressure of an ideal gas is the sum of all partial pressure of the gasses included.
- Wed Dec 16, 2020 6:02 am
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: [OH-] and pOH difference
- Replies: 9
- Views: 1760
Re: [OH-] and pOH difference
[OH-] is the concentration of OH- ions in the solution. pOH represents how alkaline a solution is. Mathematically, we can get pOH by calculating -log [OH-].
- Sun Dec 13, 2020 5:32 am
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: bond type for Resonance structure
- Replies: 1
- Views: 158
bond type for Resonance structure
I'm confused about how to characterize the bond types and count the # of bonds for a resonance structure. for example, how many pai bonds does the resonance for SO2 have? This resonance contains two possibilities and each has 1 pai bond. how do we characterize the bonds in the resonance as a whole i...
- Sun Dec 13, 2020 4:55 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: textbook problem 2E 25
- Replies: 2
- Views: 225
textbook problem 2E 25
in textbook problem 2E 25, the answer said that SF4 is a non polar molecule. however when I drew out the VSEPR, the molecule has a lone pair on S atom and shouldn't it be polar? thanks!
- Sat Dec 12, 2020 11:55 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Seesaw vs. trigonal pyramidal
- Replies: 22
- Views: 2250
Re: Seesaw vs. trigonal pyramidal
seesaw has 1 lone pair and 4 bonding pairs, that's a total of 5 areas of electron density.
trigonal pyramidal has 1 lone pair and 3 bonding pairs, that's a total of 6 electron density. hope that helps!
trigonal pyramidal has 1 lone pair and 3 bonding pairs, that's a total of 6 electron density. hope that helps!
- Fri Dec 11, 2020 12:32 am
- Forum: Biological Examples
- Topic: question about cisplatin
- Replies: 2
- Views: 198
question about cisplatin
In class, Dr. Lavelle gave an example of cisplatin. I was just wondering why does Guanine replaces the Cl on cisplatin and not the NH3?
- Thu Dec 10, 2020 11:23 pm
- Forum: Administrative Questions and Class Announcements
- Topic: lockdown browser for final
- Replies: 1
- Views: 125
lockdown browser for final
quick question, do we need to use respondus lockdown browser for the final? because I didn't see the link where you could check if your respondus is all set up under the FINAL tab on CCLE.
- Thu Dec 10, 2020 2:27 am
- Forum: Hybridization
- Topic: hybridization orbitals
- Replies: 1
- Views: 111
hybridization orbitals
Dr. Lavelle in class said whenever we have a hybridized orbital it is always going to be 90 degrees to the unhybridized orbital. I'm confused as to why it that? can someone please explain. thank you!!
- Wed Dec 09, 2020 11:53 pm
- Forum: Hybridization
- Topic: hybridization
- Replies: 1
- Views: 69
hybridization
I understand how hybridization works, but I'm confused about what's the driving factor for hybridization to occur. for example, Dr. Lavelle gave an example of CH4 in class and said Carbon atom would be hybridized to sp3. So what's driving this hybridization process? how did the electrons just move t...
- Wed Dec 09, 2020 12:56 am
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 2993433
Re: Post All Chemistry Jokes Here
Looking back at my screenshots from Dr. Lavelle's class, I found THIS!! this must be the cutest H2O I've ever seen lmaooooo!! looks just like Mickey Mouse :))))))
- Tue Dec 08, 2020 9:18 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: bond angle
- Replies: 3
- Views: 197
bond angle
quick question, does it mean that the chemical bonds are more stable if the bond angle is larger?
- Sun Dec 06, 2020 10:10 am
- Forum: Lewis Acids & Bases
- Topic: Lewis Acids & Bases
- Replies: 12
- Views: 1068
Re: Lewis Acids & Bases
Just to add to the discussion above: I usually think that Lewis acid and base as a bigger, more general group and it includes the traditional acid and base concept we’ve been taught in high school. Some of the compounds might not be traditionally considered as an acid but it may be considered as a L...
- Sun Dec 06, 2020 10:07 am
- Forum: Polyprotic Acids & Bases
- Topic: Strength of Acids
- Replies: 3
- Views: 227
Re: Strength of Acids
Just to add on to the discussion above:
I find this on google and I think it explained the concept well: https://www.shmoop.com/study-guides/che ... d-strength
Hope this helps!!!
I find this on google and I think it explained the concept well: https://www.shmoop.com/study-guides/che ... d-strength
Hope this helps!!!
- Sun Dec 06, 2020 10:00 am
- Forum: Conjugate Acids & Bases
- Topic: Conjugate acids vs conjugate base
- Replies: 12
- Views: 803
Re: Conjugate acids vs conjugate base
To find the conjugate base, you remove a proton, which would give you SO4-. To find the conjugate acid, you add a proton, which would give you H2SO4. Hope that helps!
- Sun Dec 06, 2020 9:56 am
- Forum: Lewis Acids & Bases
- Topic: Lewis Acid
- Replies: 4
- Views: 334
Re: Lewis Acid
Yes you are definitely right that Lewis acid is an electron acceptor. I think for the second part about proton production, you are right as well. Dr. Lavelle gave an example about HCl in class. He said that HCl only exhibits Lewis acid characteristics in aqueous form. So i guess this also depends on...
- Sun Nov 29, 2020 8:52 am
- Forum: Formal Charge and Oxidation Numbers
- Topic: Formal Charge and Ions
- Replies: 7
- Views: 671
Re: Formal Charge and Ions
if you are talking about a covalent compound, then the last part is correct because it would provide a more stable structure. As for ionic compounds, I don't think the formal charges apply to that, or is it just we haven't covered yet. I think what we discussed in class about formal charge only appl...
- Sun Nov 29, 2020 8:50 am
- Forum: Electronegativity
- Topic: General Explanation
- Replies: 9
- Views: 455
Re: General Explanation
from my understanding, yes higher electronegativity generally means the element is more reactive. Take F for example, the element with the highest electronegativity, it has 7 valence electrons and only need 1 more to achieve an Octet, and thus it is very reactive.
- Sun Nov 29, 2020 7:47 am
- Forum: Resonance Structures
- Topic: Valence Electrons [ENDORSED]
- Replies: 46
- Views: 3676
Re: Valence Electrons [ENDORSED]
excluding the d block, you can just look what column is the element in. elements in the first column has 1 valence electron and etc. for the d block, you can write out its electron configuration and see how many valence electrons it have.
- Sun Nov 29, 2020 7:44 am
- Forum: Lewis Structures
- Topic: Lewis Structure XeF_2
- Replies: 4
- Views: 2122
Re: Lewis Structure XeF_2
I think you can still draw the structure horizontally it doesn't really matter. as long as you represent the bond angle is roughly 180 degree I think it works either way you draw it.
- Sun Nov 29, 2020 7:40 am
- Forum: DeBroglie Equation
- Topic: Purpose of DeBroglie Equation
- Replies: 11
- Views: 549
Re: Purpose of DeBroglie Equation
the equation is meant to describe the wave properties of matter. It is also used to describe the mathematical relationship between the velocity, wavelength and momentum of a particle. this equations applies to both electrons and photons and contributes to the discussion of the dual property of both.
- Wed Nov 18, 2020 4:24 am
- Forum: Lewis Structures
- Topic: radicals
- Replies: 4
- Views: 206
radicals
for question 2c1 on the textbook. the answer said that only a and b are radicals. but what about c? OH has 7 electrons in total, doesn't that make it a radical, with an unpaired electron on O?
- Sun Nov 15, 2020 10:23 pm
- Forum: Bond Lengths & Energies
- Topic: sapling #4
- Replies: 3
- Views: 169
sapling #4
hi! for this question, I understand the part about carbon nitrogen bond, since the bond length is closer in value to the carbon-nitrogen double bond. But for carbon oxygen bond, the value is approximately the average of carbon oxygen double and single bond. So what kind of ample bond character does ...
- Sun Nov 15, 2020 10:17 pm
- Forum: Resonance Structures
- Topic: Resonance
- Replies: 11
- Views: 336
Re: Resonance
besides what listed above, it's also favorable to have negative formal charges on more electronegative atoms.
- Sat Nov 14, 2020 7:24 pm
- Forum: Octet Exceptions
- Topic: Expanded Octets
- Replies: 5
- Views: 813
Re: Expanded Octets
Just to add on to the discussion above, I think it's atoms in period 3 or higher have d-orbitals in their valence shells, so they can accommodate additional electrons.
- Sat Nov 14, 2020 6:27 am
- Forum: Octet Exceptions
- Topic: How to tell
- Replies: 6
- Views: 486
Re: How to tell
Just to add on to the discussion above: I found this on a chem learning website that says there are three general exceptions to the Octet rule: 1. Molecules, such as NO, with an odd number of electrons; 2. Molecules in which one or more atoms possess more than eight electrons, such as SF6; and 3. Mo...
- Sat Nov 14, 2020 6:20 am
- Forum: Ionic & Covalent Bonds
- Topic: London Dispersion Forces
- Replies: 11
- Views: 1514
Re: London Dispersion Forces
Hi! just to add on to the discussion above. I think what separates LDF from other intermolecular forces is that it exists in all kinds of molecules, no matter what other intermolecular bonds are there. while they are the weakest, some molecules are held together only/mainly by LDF, such as the halog...
- Sat Nov 14, 2020 6:15 am
- Forum: Resonance Structures
- Topic: delocalized electrons
- Replies: 4
- Views: 233
delocalized electrons
Hello! I've been a little troubled by the term "delocalized" when describing electrons in resonance structures. I understand how resonance structures are formed, but I don't see in what sense are these electrons delocalized? can someone please explain! thank you!
- Sun Nov 08, 2020 7:09 pm
- Forum: Limiting Reactant Calculations
- Topic: Excess reactant affecting limiting reactant
- Replies: 7
- Views: 450
Re: Excess reactant affecting limiting reactant
Just to add on to the discussion above, I think there always is a limiting reactant. so if O2 is the excess reactant, you'll have to calculate which is the limiting reactant since it's not always the case where you only have two reactants. But I agree that there is always a limiting reactant in ques...
- Sun Nov 08, 2020 8:29 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: The word "energy" used in different scenarios
- Replies: 3
- Views: 211
Re: The word "energy" used in different scenarios
yeah I agree that it should be referring to electrons, especially in this scenario you are describing. And from what we've learned in class, I think most of the times when we say "energy" we would be referring to electrons, since they are the ones moving around and generally exhibiting ene...
- Sun Nov 08, 2020 8:24 am
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: delta V. in. Heisenberg questions
- Replies: 6
- Views: 516
Re: delta V. in. Heisenberg questions
yeah it's 10 not 5. I googled this question and found a 2017 post on chemistry community where Chem_Adm confirmed this. There's also a section on Dr.Lavelle's website that includes all the textbook corrections. You can also refer to that! Hope this helps!
- Sun Nov 08, 2020 8:08 am
- Forum: Einstein Equation
- Topic: E=pc vs E=hv
- Replies: 15
- Views: 733
Re: E=pc vs E=hv
I think both can be used to calculate the energy of an electron, it just depends on the information you're giving in the question. From my experience, I think the equation we need to be careful with is E=mc squared.
- Sun Nov 08, 2020 8:03 am
- Forum: Properties of Electrons
- Topic: Electron Spin
- Replies: 7
- Views: 259
Re: Electron Spin
we usually consider the first electron to spin up (+1/2) and the second electron to spin down (-1/2). but I think Dr. Lavelle mentioned in class that these are just math models that scientists employed to represent the opposite spin of electrons in the same sub shell and they don't really exist.
- Thu Nov 05, 2020 5:40 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Fall 2020 Midterm 1 Instructions
- Replies: 20
- Views: 1854
Re: Fall 2020 Midterm 1 Instructions
Is there a way to see what question we missed on midterm 1? Thank you!
- Mon Nov 02, 2020 5:08 am
- Forum: Quantum Numbers and The H-Atom
- Topic: quantum number-s- vs p- orbitals
- Replies: 3
- Views: 218
quantum number-s- vs p- orbitals
I know Dr.Lavelle went through this in lectures, but I don't think I really understand it: so for electrons in the same shell, why does s- electrons have a lower energy than p-electrons in the same shell? if the outer electrons feel a reduced electrostatic attraction, then why is the order of energy...
- Sun Nov 01, 2020 6:07 pm
- Forum: Properties of Electrons
- Topic: question about diffraction
- Replies: 4
- Views: 235
question about diffraction
Hi guys, I have a question regarding diffraction. I understand that as Dr. Lavelle puts it, if light acts as particles, there would be two patterns shown at the spot of the openings, but instead we get this diffraction pattern. I just don't understand why this diffraction pattern shown in the diagra...
- Sun Nov 01, 2020 5:58 pm
- Forum: DeBroglie Equation
- Topic: Diffraction Pattern
- Replies: 9
- Views: 381
Re: Diffraction Pattern
just to add on to the discussion above, I find the textbook's summary of this very helpful: the textbook mentioned the wave-particle duality of electromagnetic radiation, and said the photoelectric effect means that electromagnetic radiation has particle like properties, and that diffraction means e...
- Sun Nov 01, 2020 5:50 pm
- Forum: DeBroglie Equation
- Topic: Finding the mass of a molecule
- Replies: 6
- Views: 231
Re: Finding the mass of a molecule
by diatomic structure, this question is referring to H2. so in order to find the mass of one H2 molecule, you just take the molar mass of H2, which is 2.014, and divide that by Na (Avagadro's constant), because this constant is referring to the number of molecules in one mole of substance. divide th...
- Wed Oct 28, 2020 8:11 am
- Forum: Empirical & Molecular Formulas
- Topic: textbook F13
- Replies: 2
- Views: 235
textbook F13
In an experiment, 4.14 g of phosphorus combined with chlorine to produce 27.8 g of a white solid compound. (a) What is the empirical formula of the compound? (b) Assuming that the empirical and molecular formulas of the compound are the same, what is its name? I had trouble getting the right answer ...
- Wed Oct 28, 2020 1:02 am
- Forum: Properties of Electrons
- Topic: Wavelength of radiation
- Replies: 12
- Views: 9273
Re: Wavelength of radiation
Just want to share: for part c, I was really confused whether you could use the 2.50 x 10^6 hz from part b because that was not given in the main question. but it turned out that the problem can't be solved just using what's given in the main question. Also, when I plugged in 9.11 x 10^-31 for mass ...
- Wed Oct 28, 2020 12:53 am
- Forum: Properties of Electrons
- Topic: Wavelength of radiation
- Replies: 12
- Views: 9273
Re: Wavelength of radiation
In the initial question, wouldn't you need to convert the velocity of the electron 3.6x10^3km.s^-1 into m.s^-1 so it would be 3.6m.s^-1 to be in SI units or am I mistaken? for part a of this question, yes you would need to convert that to SI units, but it's 3.6x10^6 m/s. the value should be getting...
- Sat Oct 24, 2020 8:55 pm
- Forum: Limiting Reactant Calculations
- Topic: Actual yield
- Replies: 20
- Views: 743
Re: Actual yield
for most of the questions I've seen, they usually give you the actual yield, mass/molar mass, and some clues to find the actual chemical equations. with these, you could calculate the theoretical yield and there you get your yield percentage.
- Sat Oct 24, 2020 8:47 pm
- Forum: Limiting Reactant Calculations
- Topic: Double Check my Understanding
- Replies: 11
- Views: 1387
Re: Double Check my Understanding
Hello, I also would like to pose a question in terms of understanding with limiting reactant questions; if we ignore the stoich coefficients, we would be focusing on just the mass, correct? So while the moles of a compound do indicate the amount of an element in terms of mass, we still need to keep...
- Sat Oct 24, 2020 8:39 pm
- Forum: Balancing Chemical Reactions
- Topic: States of matter in chem equations
- Replies: 13
- Views: 922
Re: States of matter in chem equations
I think we do need to include the state of matter at the bottom right of each substance. Most of the questions would give you the state of matter, if not I think we can rely on past experience.
- Sat Oct 24, 2020 8:35 pm
- Forum: Limiting Reactant Calculations
- Topic: Theoretical Yield
- Replies: 12
- Views: 581
Re: Theoretical Yield
the definition for theoretical yield says "amount", so I think we should automatically assume the answer should be in grams if the question didn't say otherwise. Prof.Lavelle also said in class that the unit should be grams I remember.
- Fri Oct 23, 2020 12:18 am
- Forum: Properties of Electrons
- Topic: question about circular wave model
- Replies: 2
- Views: 133
question about circular wave model
attached is a screenshot from lecture 8 when discussing the circular standing wave model. I understand that waves at the same phase could be connected and can become a stable model. But I don't understand how the circular lightwaves are formed here. there was a motion picture showing the circular wa...
- Sat Oct 17, 2020 7:20 am
- Forum: Electronegativity
- Topic: Determining Polarity
- Replies: 4
- Views: 2207
Re: Determining Polarity
this molecular is nonpolar. because C H I have similar electronegativity and the structure of the molecule is tetrahedral. tetrahedral molecules can "cancel out" the bonds because of it being symmetrical.
- Sat Oct 17, 2020 7:16 am
- Forum: Electronegativity
- Topic: Hydrogen
- Replies: 6
- Views: 637
Re: Hydrogen
I think it's because H only has 2 protons. and also, Hydrogen is not a very typical atom. although it's placed in the upper right corner on the periodic table, it doesn't follow some of the trends that apply to most other atoms.
- Sat Oct 17, 2020 7:13 am
- Forum: Electronegativity
- Topic: periodic table
- Replies: 16
- Views: 713
periodic table
can someone summarize the major trends that can be found in the periodic table? Thank you!
- Sat Oct 17, 2020 7:05 am
- Forum: Resonance Structures
- Topic: Resonance
- Replies: 2
- Views: 835
Re: Resonance
to check whether a molecule has a resonance or not, draw the lewis structure and see if you can find multiple possibilities that satisfy the requirement. N2H2 doesn't have a resonance structure because there's only one way to meet all the requirements.
- Sat Oct 17, 2020 7:02 am
- Forum: Ionic & Covalent Bonds
- Topic: Boiling point
- Replies: 4
- Views: 420
Re: Boiling point
NH3 can be considered as a special case because it has hydrogen bond which is relatively strong. NH3 and PH3 have similar molar mass.