Search found 103 matches
- Sun Mar 14, 2021 11:19 am
- Forum: Student Social/Study Group
- Topic: 14C
- Replies: 1
- Views: 172
14C
Hi! I tried to get into chem 14C for the spring but it was all filled up and I didn't see a waitlist. Is there a chance I could still get in? Bc I don't want to wait till next spring to take the third series.
- Sun Mar 14, 2021 11:17 am
- Forum: Student Social/Study Group
- Topic: Planning on dorming in the Fall?
- Replies: 61
- Views: 5514
Re: Planning on dorming in the Fall?
If classes are in person I'll be there but I doubt my parents would pay for an apartment for online school when I could just do it from home.
- Sun Mar 14, 2021 11:16 am
- Forum: Student Social/Study Group
- Topic: Final
- Replies: 63
- Views: 5579
Re: Final
textbook problems are the most helpful, don't waste time on fundamentals videos because you'll review them as you do the problems
- Sun Mar 14, 2021 11:15 am
- Forum: Student Social/Study Group
- Topic: Fave food
- Replies: 266
- Views: 62548
Re: Fave food
Grilled salmon, sushi or any seafood!
- Sun Mar 14, 2021 11:14 am
- Forum: Student Social/Study Group
- Topic: Final question
- Replies: 6
- Views: 756
Re: Final question
Just 14B!
- Sun Mar 07, 2021 11:01 pm
- Forum: Student Social/Study Group
- Topic: Fave food
- Replies: 266
- Views: 62548
Re: Fave food
I love seafood, any fish, crab, shrimp, sushi, etc. Some seafood freaks me out but I'm trying to get out of my comfort zone lol.
- Sun Mar 07, 2021 11:00 pm
- Forum: Student Social/Study Group
- Topic: Chem 14C
- Replies: 17
- Views: 1204
Re: Chem 14C
I tried to sign up for 14C in my second pass and it was full. Any advice on how to possibly get in?
- Sun Mar 07, 2021 10:59 pm
- Forum: Student Social/Study Group
- Topic: summer sessions costs?
- Replies: 8
- Views: 585
Re: summer sessions costs?
A lot of times it's cheaper to take classes at a community college nearby. You just have to make sure those units will be counted for UCLA but I'm definitely considering it. If anyone else knows about the process pls lmk.
- Sun Mar 07, 2021 10:57 pm
- Forum: Student Social/Study Group
- Topic: Chem 14B Final
- Replies: 86
- Views: 9107
Re: Chem 14B Final
Most of his questions of similar to that of the textbook, primarily the textbook examples he gives on his website. Sapling is good too but don't waste too much time on there, focus on textbook samples where they put sapling concepts into practice.
- Sun Mar 07, 2021 10:56 pm
- Forum: Student Social/Study Group
- Topic: What do you miss / What are you looking forward to?
- Replies: 92
- Views: 19689
Re: What do you miss / What are you looking forward to?
I'm a freshman and honestly experiencing something outside of my hometown is something I'm looking forward to. I want to meet new friends, socialize, and discover new things. I'm also looking forward to living apart from my family lol.
- Sun Feb 28, 2021 7:13 pm
- Forum: Balancing Redox Reactions
- Topic: sapling #19
- Replies: 6
- Views: 462
Re: sapling #19
I got the same thing but add in the phases and I didn't use parentheses in the product side, IDK if I was supposed to but it said it was right: 4Fe(s)+3O2(g)+6H2O(l)⟶2Fe2O3∙3H2O(s)
- Sun Feb 28, 2021 7:12 pm
- Forum: Student Social/Study Group
- Topic: Sapling Weeks 7-8 Homework Question
- Replies: 2
- Views: 190
Re: Sapling Weeks 7-8 Homework Question
Shorthand notation should be: Pb (s), PbCl2 (s), Cl- (aq), Cl-(aq), AgCl(s), Ag(s)
- Sun Feb 28, 2021 7:07 pm
- Forum: Balancing Redox Reactions
- Topic: Sapling Week 7/8 Question 3
- Replies: 5
- Views: 327
Re: Sapling Week 7/8 Question 3
Make sure you put phases in and the correct arrow (irreversible I think)
- Sun Feb 28, 2021 5:44 pm
- Forum: Balancing Redox Reactions
- Topic: reversible redox reaction
- Replies: 3
- Views: 278
reversible redox reaction
Can a redox reaction be reversible? How do we know if it is?
- Sun Feb 28, 2021 5:43 pm
- Forum: Balancing Redox Reactions
- Topic: states of matter
- Replies: 58
- Views: 3429
states of matter
Hi for Sapling Problems in week 7 and 8 I keep getting the balancing redox reaction problems wrong but feel like I'm doing it right. Can states of matter cause an equation on Sapling to be wrong?
- Sun Feb 21, 2021 6:35 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Boiling point
- Replies: 9
- Views: 786
Boiling point
Is boiling point always found at equilibrium (deltaG=0)? If so, why?
- Sun Feb 21, 2021 6:32 pm
- Forum: Calculating Work of Expansion
- Topic: adiabatic processes
- Replies: 18
- Views: 1141
adiabatic processes
In adiabatic processes is w=0?
- Sun Feb 21, 2021 6:30 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: calculating H through bond enthalpies
- Replies: 4
- Views: 391
calculating H through bond enthalpies
Why is there an added negative sign on the side of the products when using bond enthalpies to calculate total reaction enthalpy?
- Sun Feb 21, 2021 6:27 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Hfus
- Replies: 9
- Views: 1223
Hfus
How do we know when to use Hfusion?
- Sun Feb 21, 2021 6:21 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: state functions
- Replies: 6
- Views: 521
state functions
Why are heat and work not state functions? I'm having a little trouble understanding the definition of state functions.
- Sun Feb 14, 2021 9:44 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: thermodynamic reaction quotient
- Replies: 4
- Views: 234
thermodynamic reaction quotient
When calculating Q,, I know its (partial pressure of products/ partial pressure of reactants) and to use molar coefficients as exponents but do you multiply or add the partial pressures of individual molecules in the numerator (or denominator)? Like if there's multiple reactants or products.
- Sun Feb 14, 2021 9:41 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: values
- Replies: 3
- Views: 284
values
Will entropy, enthalpy, and deltaGf values of specific molecules from the sapling charts be given on tests?
- Sun Feb 14, 2021 9:39 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: units
- Replies: 5
- Views: 293
units
Are the standard units for thermodynamics questions always volume (L), temperature (K), energy (KJ)? Am I missing one?
- Sun Feb 14, 2021 5:24 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: qrev vs q
- Replies: 21
- Views: 2169
qrev vs q
What is the difference between qrev vs just regular q? When do we use each?
- Sun Feb 14, 2021 5:24 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: qrev vs q
- Replies: 8
- Views: 560
qrev vs q
What is the difference between qrev vs just regular q? When do we use each?
- Sat Feb 13, 2021 4:56 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: avogadro's number in Boltzmann Equation
- Replies: 4
- Views: 484
avogadro's number in Boltzmann Equation
When do we incorporate Avogadro's number in Boltzmann Equation?
- Sun Feb 07, 2021 11:57 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: sapling 20
- Replies: 3
- Views: 247
sapling 20
Hi does anyone know how to do this one? A 0.825 mol sample of CO2(g) initially at 298 K and 1.00 atm is held at constant volume while enough heat is applied to raise the temperature of the gas by 18.7 K. Assuming ideal gas behavior, calculate the amount of heat (q) in joules required to affect this ...
- Sun Feb 07, 2021 11:56 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: sapling 18
- Replies: 1
- Views: 141
sapling 18
Hi for 18 I was able to get deltaU which was 112.4 but couldn't find q. A 0.825 mol sample of Xe(g), initially at 298 K and 1.00 atm, is held at constant pressure while enough heat is applied to raise the temperature of the gas by 10.9 K. Calculate the amount of heat q required to bring about this t...
- Sun Feb 07, 2021 11:46 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: sapling 19
- Replies: 1
- Views: 169
sapling 19
Hi can anyone help on this one? A constant‑volume calorimeter was calibrated by carrying out a reaction known to release 1.05 kJ of heat in 0.700 L of solution in the calorimeter (q=−1.05 kJ) , resulting in a temperature rise of 2.19 ∘C . In a subsequent experiment, 350.0 mL of 0.30 M HClO2(aq) and ...
- Sun Feb 07, 2021 10:26 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Sapling 10 week 4
- Replies: 3
- Views: 173
Sapling 10 week 4
An ice cube with a mass of 46.8 g at 0.0 ∘C is added to a glass containing 401 g of water at 45.0 ∘C . Determine the final temperature of the system at equilibrium. The specific heat capacity of water, Cs , is 4.184 J/g⋅∘C , and the standard enthalpy of fusion, ΔH∘fus , of water is 6.01×103 J/mol . ...
- Sun Feb 07, 2021 9:58 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: -qlost=qabsorbed
- Replies: 4
- Views: 402
-qlost=qabsorbed
Hi, for saplng 9 week 4, we put a (-) in front of the side that lost heat. However, in sapling 10, no negative is inserted for the water that got cooled from the ice cube. Can anyone explain why?
- Thu Jan 28, 2021 9:50 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: lecture method 3 equation
- Replies: 3
- Views: 229
lecture method 3 equation
Hi, why did Dr. Lavelle leave out 2 H2O (l) from the method 3 class example but not 2 O2 (g) on the reactants side? Aren't they both at standard states? Also, when do we have to take into account the change in enthalpy of vaporization or any of phase change? The professor said that if H2O were to ha...
- Thu Jan 28, 2021 9:37 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Sapling week 3 #6
- Replies: 12
- Views: 528
Sapling week 3 #6
C(g)+4H(g)⟶CH4(g)
enthalpy of formation of CH4(g)
4×bond energy of C−H
enthalpy of combustion of C
−4×bond energy of C−H
Why is the answer -4 x bond energy rather than 4 x bond energy?
enthalpy of formation of CH4(g)
4×bond energy of C−H
enthalpy of combustion of C
−4×bond energy of C−H
Why is the answer -4 x bond energy rather than 4 x bond energy?
- Thu Jan 28, 2021 8:14 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Enthalpies
- Replies: 2
- Views: 146
Enthalpies
Will the enthalpies be given on the test for molecules? Bc in the lecture he says to look them up but obviously on the tests we can't do that. (this is in regards to the enthalpies used in methods 2 and 3)
- Mon Jan 25, 2021 4:36 pm
- Forum: Phase Changes & Related Calculations
- Topic: midterm 1
- Replies: 11
- Views: 834
midterm 1
Hi, does someone know if the cutoff for the midterm material on sapling question 10 from week 3/4? B/c the exam is only on week 1-3 right?
- Mon Jan 25, 2021 4:33 pm
- Forum: Phase Changes & Related Calculations
- Topic: heating curve
- Replies: 8
- Views: 365
heating curve
Hi, can someone explain the heating curve and how that applies to why steam causes severe burns? Dr. Lavelle explained in one of his lectures but I'm still a little confused.
- Sun Jan 24, 2021 8:49 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: pKa
- Replies: 14
- Views: 644
Re: pKa
p before a constant or value usually means taking the log or -log of it. In this cause pKa IS -log(Ka) which is your equilibrium constant of the dissociation recation of an acid.
- Sun Jan 24, 2021 8:47 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: X Approximations
- Replies: 23
- Views: 1089
Re: X Approximations
Usually if K is smaller than 10^-4, you can approximate and take it out of denominator so that you don't have to use the quadratic formula.
- Sun Jan 24, 2021 8:29 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Sapling Week 2 #7
- Replies: 8
- Views: 400
Sapling Week 2 #7
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 0.024 M in NaClO at 25 °C?
Why does the ICE table only include ClO- and HClO and OH-. What happened to the NaClO?
Why does the ICE table only include ClO- and HClO and OH-. What happened to the NaClO?
- Sun Jan 24, 2021 8:18 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: acids and bases
- Replies: 4
- Views: 307
acids and bases
Hi, I know this is primarily a 14A concept, but what are some tips that help you identify whether a substance is neutral, basic, or acidic?
- Sun Jan 24, 2021 7:15 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: approximating
- Replies: 10
- Views: 507
approximating
Hi, after creating the ICE table oftentimes we see that x will be too small to make a difference, therefore, we can approximate. However, why do we only take one x out from the denominator and not from the x^2 in the numerator?
- Sun Jan 17, 2021 5:55 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: endothermic vs exothermic
- Replies: 16
- Views: 965
endothermic vs exothermic
How can you tell if a reaction is endothermic or exothermic?
- Sun Jan 17, 2021 4:25 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Week 1 Sapling 5
- Replies: 4
- Views: 359
Week 1 Sapling 5
Consider the reaction of NH3 and I2 to give N2 and HI. 2NH3(g)+3I2(g)↽−−⇀N2(g)+6HI(g)K Using two or more of the given equations, determine the equilibrium constant, K , for the reaction of NH3 with I2. H2 (g) +I2 (g) >>> 2HI (g) Ka = 160 I2 (g) >>>2I (g) Kb = 2.1 * 10-3 N2 (g) + 3H2 (g) >>>2NH3 (g) ...
- Sun Jan 17, 2021 3:55 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Week 1 Sapling 3
- Replies: 11
- Views: 550
Week 1 Sapling 3
At a certain temperature, the equilibrium constant, Kc, for this reaction is 53.3. H2(g)+I2(g)↽−−⇀2HI(g)Kc=53.3 At this temperature, 0.700 mol H2 and 0.700 mol I2 were placed in a 1.00 L container to react. What concentration of HI is present at equilibrium? Would you use the quadratic formula for: ...
- Sun Jan 17, 2021 3:02 pm
- Forum: Ideal Gases
- Topic: R Value
- Replies: 17
- Views: 896
R Value
Hi, I've seen a lot of different posts about the R Value in the Ideal Gas Law. For tests, do we use 8.206 x 10^-2?
- Sun Jan 17, 2021 2:58 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: shifts left or right
- Replies: 23
- Views: 1381
shifts left or right
Hi, I know that when Q<K then its a forward reaction and it shift right. It shifts left when it is the opposite. But, what exactly does this shift indicate? I know it's important to know whether it is a forward or reverse reaction but what is the importance of identifying the shift?
- Sun Jan 10, 2021 7:57 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K vs P
- Replies: 6
- Views: 492
K vs P
When should you calculate P instead of K? I initially thought P was only for gases but then I think I saw K be calculated for a homogenous gas reaction.
- Sun Jan 10, 2021 7:55 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: reaction quotient
- Replies: 6
- Views: 360
reaction quotient
I know how to calculate reaction quotient but what does reaction quotient actually define?
- Sun Jan 10, 2021 7:54 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: adding heat
- Replies: 15
- Views: 675
adding heat
Why is heating endothermic reactions more favorable?
- Sat Jan 09, 2021 4:14 pm
- Forum: Ideal Gases
- Topic: gas law vs equlibrium constant vs quotient constant
- Replies: 3
- Views: 209
gas law vs equlibrium constant vs quotient constant
Hi! I understand how to use the ideal gas law, find equilibrium constant, and quotient constant but can someone summarize WHEN each should be used? I'm especially having trouble understanding when to apply the ideal gas law.
- Wed Jan 06, 2021 3:47 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: molar concentrations
- Replies: 5
- Views: 260
molar concentrations
Will the molar concentrations always be given in problems where we need to find Kc? If not, how do you calculate concentration?
- Wed Dec 16, 2020 5:27 pm
- Forum: Student Social/Study Group
- Topic: Final Exam
- Replies: 49
- Views: 3840
Re: Final Exam
Ya, I started on the problems I knew so that I would get points for those for sure. The others could've been wrong so if I ran out of time it probably would have the same effect on my grade. Wish there had been more time too!
- Wed Dec 16, 2020 5:26 pm
- Forum: Student Social/Study Group
- Topic: Plans for Relaxing After Finals
- Replies: 98
- Views: 32885
Re: Plans for Relaxing After Finals
I'm going to my cabin in the Sierra Nevadas for some isolation and relaxation. Hopefully there's snow this year!
- Wed Dec 16, 2020 5:25 pm
- Forum: Student Social/Study Group
- Topic: Course Evals
- Replies: 18
- Views: 1242
Re: Course Evals
I don't think they are mandatory or graded so don't stress. You don't have to do them but it helps teachers prep and make changes for next quarter/year.
- Wed Dec 16, 2020 5:23 pm
- Forum: Student Social/Study Group
- Topic: Words of encouragement
- Replies: 14
- Views: 961
Re: Words of encouragement
So proud of everyone! Don't be too hard on yourselves as we start getting final grades back. This semester was extra challenging and we should take that into account. Studying in a home environment, it's difficult to stay motivated. Pat yourself on the back for getting through it!
- Wed Dec 16, 2020 5:22 pm
- Forum: Administrative Questions and Class Announcements
- Topic: 14B Enrollment [ENDORSED]
- Replies: 67
- Views: 21514
Re: 14B Enrollment [ENDORSED]
Thank you Professor Lavelle for a great semester! See you in Chem 14B!
- Wed Dec 16, 2020 5:21 pm
- Forum: Student Social/Study Group
- Topic: Final Jitters
- Replies: 457
- Views: 555245
Re: Final Jitters
Congrats to everyone for completing this course! You should be very proud of yourselves given the circumstances! Don't be too hard on yourselves, it's immensely hard to learn from home so cut yourself some slack & give yourself some credit!
- Wed Dec 16, 2020 5:19 pm
- Forum: Student Social/Study Group
- Topic: grade calculation
- Replies: 12
- Views: 950
grade calculation
Is there any grade calculator available for this course?
- Sun Dec 06, 2020 9:56 pm
- Forum: Student Social/Study Group
- Topic: finals
- Replies: 4
- Views: 383
finals
How are you guys studying for finals? Do you start by reviewing old material or the new material? Also how do you simultaneously learn this week's topics and also review for finals without getting overwhelmed?
- Sun Dec 06, 2020 9:51 pm
- Forum: Bronsted Acids & Bases
- Topic: H2PO4- amphoteric
- Replies: 2
- Views: 195
H2PO4- amphoteric
How is H2PO4- amphoteric? Amphoteric means that is can be both an acid or a base right? Therefore, this molecule should be able to accept protons and donate?
- Sun Dec 06, 2020 9:49 pm
- Forum: Conjugate Acids & Bases
- Topic: NH3
- Replies: 4
- Views: 253
NH3
How is NH3 a base? Aren't acids the compounds containing H? and bases contain OH?
- Sun Dec 06, 2020 9:48 pm
- Forum: Conjugate Acids & Bases
- Topic: HSO4- conjugate base
- Replies: 4
- Views: 508
HSO4- conjugate base
How does the conjugate base of HSO4 end up being SO42-. B/c wouldn't that be taking an H+ away? I thought a base was a proton acceptor.
- Sun Dec 06, 2020 9:45 pm
- Forum: Lewis Acids & Bases
- Topic: lewis vs bronsted
- Replies: 10
- Views: 500
lewis vs bronsted
What is the difference between a lewis acid/base and a bronsted acid/base?
- Sun Nov 29, 2020 9:57 pm
- Forum: Electronegativity
- Topic: Be vs Cl
- Replies: 49
- Views: 3470
Re: Be vs Cl
Be is higher in electronegativity because the periodic trend for increasing electronegativity is going right and up.
- Sun Nov 29, 2020 9:48 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: AsO43-
- Replies: 9
- Views: 564
AsO43-
How is AsO43- a nonpolar molecule if it has a charge?
- Sun Nov 29, 2020 9:46 pm
- Forum: Hybridization
- Topic: PBr5
- Replies: 6
- Views: 708
PBr5
Why would the hybridization of PBr5 be sp3d?
- Sun Nov 29, 2020 9:29 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: trigonal bipyramidal
- Replies: 5
- Views: 294
trigonal bipyramidal
How do you know when the bond angle is 120 versus 90 for trigonal bipyramidal?
- Sun Nov 29, 2020 8:14 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: ions
- Replies: 8
- Views: 467
ions
If atoms in a molecule have a negative or positive charge, how would that affect the VSEPR theory?
- Fri Nov 20, 2020 3:03 pm
- Forum: Dipole Moments
- Topic: higher dipole moment sapling #10
- Replies: 5
- Views: 1369
higher dipole moment sapling #10
Sapling #10 Which molecule should have higher dipole moment, and why? a. COF2 because it contains more F atoms. b. COFH because the polar bonds in COF 2 nearly cancel each other out. c. COF2 because it contains more lone pairs. I'm confused as to why the answer is B. You'd think that COF2 has a high...
- Fri Nov 20, 2020 2:58 pm
- Forum: Dipole Moments
- Topic: Polarity
- Replies: 30
- Views: 1819
Polarity
How can a molecule be made up of polar bonds but not be polar as whole molecule?
- Fri Nov 20, 2020 2:57 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: determining molecular shape
- Replies: 10
- Views: 660
determining molecular shape
How is Co2 not polar but So2 is? Since they both have similar structures.
- Fri Nov 20, 2020 2:55 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Linear shape
- Replies: 7
- Views: 418
Linear shape
How is NO2- not a linear molecular shape?
- Fri Nov 20, 2020 2:54 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: axial and equatorial atoms
- Replies: 2
- Views: 283
axial and equatorial atoms
I'm having some trouble identifying axial and equatorial atoms. What's the difference? Because I feel like if I rotate the molecule, the perspective changes.
- Sun Nov 15, 2020 8:37 pm
- Forum: Resonance Structures
- Topic: resonance structures
- Replies: 10
- Views: 596
resonance structures
How do you know which resonance structure contributes most heavily to the true structure of the molecule?
- Sun Nov 15, 2020 8:01 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Sapling #20
- Replies: 12
- Views: 767
Re: Sapling #20
Sukhkiran_Kaur_3F wrote:Hydrogen bonds are not present in CH3CHO because none of the hydrogens are bonded to the oxygen.
How do you know the H isn't bonded to the electronegative O, thus creating a hydrogen bond? Would you have to draw the lewis structre out?
- Sun Nov 15, 2020 7:45 pm
- Forum: Electronegativity
- Topic: polar vs nonpolar
- Replies: 26
- Views: 1576
polar vs nonpolar
What does the minimum numerical difference in electronegativity have to be for a molecule to be considered polar?
- Sun Nov 15, 2020 6:39 pm
- Forum: Ionic & Covalent Bonds
- Topic: bond lengths
- Replies: 9
- Views: 637
bond lengths
Why are double bonds shorter than single bonds?
- Sun Nov 15, 2020 6:10 pm
- Forum: Octet Exceptions
- Topic: octet rule
- Replies: 8
- Views: 685
octet rule
Why does Cl get 18 octet electrons?
- Sun Nov 08, 2020 4:41 pm
- Forum: Bond Lengths & Energies
- Topic: bond lengths
- Replies: 9
- Views: 564
bond lengths
How do you know which bond lengths are longer than others?
- Sun Nov 08, 2020 4:36 pm
- Forum: Lewis Structures
- Topic: octet rule
- Replies: 7
- Views: 308
octet rule
How do we know if the octet rule should be followed or not? When is it allowed to be broken?
- Sun Nov 08, 2020 4:18 pm
- Forum: Lewis Acids & Bases
- Topic: Acids and Bases
- Replies: 3
- Views: 113
Acids and Bases
Can a lewis acid only react with a Lewis base?
- Thu Nov 05, 2020 9:33 pm
- Forum: Electronegativity
- Topic: polyatomic ions
- Replies: 4
- Views: 269
polyatomic ions
How do you know which atom is negative or positive in a polyatomic ion? I was looking for an extra electron when I saw a resonance structure of carbamate and the oxygen was negative, but it had the correct number. It was double bonded to a positive nitrogen (with four bonds) so does that automatical...
- Thu Nov 05, 2020 9:27 pm
- Forum: Ionic & Covalent Bonds
- Topic: resonance structures
- Replies: 2
- Views: 132
resonance structures
Can quadruple bonds be formed in resonance structures?
- Sun Nov 01, 2020 5:39 pm
- Forum: Properties of Electrons
- Topic: ion radius size
- Replies: 3
- Views: 221
ion radius size
What is the trend for ion radius size?
- Sun Nov 01, 2020 5:36 pm
- Forum: Bond Lengths & Energies
- Topic: ionization energy
- Replies: 6
- Views: 313
ionization energy
Why does oxygen have a lower first ionization energy than both nitrogen and flourine?
This was one of the sapling questions, and I completed it, but I am still a little confused. Can anyone clear this up please?
This was one of the sapling questions, and I completed it, but I am still a little confused. Can anyone clear this up please?
- Wed Oct 28, 2020 2:42 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: ground state electron configuration
- Replies: 2
- Views: 132
ground state electron configuration
What is the difference between excited and ground state electron configuration?
- Wed Oct 28, 2020 12:54 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: How many electrons in an atom
- Replies: 1
- Views: 569
How many electrons in an atom
How many electrons in an atom could have these sets of quantum numbers?
n=2
n=4, l=3
n=7, l=2, ml= -1
Hi, could someone explain this problem please? I'm so confused. I know that L=0,1, 2, 3 is correspondant with s, p, d, and f. and that s has one orbital, p=3, d=5, and f= 7.
n=2
n=4, l=3
n=7, l=2, ml= -1
Hi, could someone explain this problem please? I'm so confused. I know that L=0,1, 2, 3 is correspondant with s, p, d, and f. and that s has one orbital, p=3, d=5, and f= 7.
- Wed Oct 28, 2020 12:17 am
- Forum: Properties of Light
- Topic: Sapling Week 3 Problem 8
- Replies: 3
- Views: 577
Re: Sapling Week 3 Problem 8
Yes for this problem the ending energy level would be n=2, in the Balmer series. What equation did you plug n and the wavelength into? If you're using Rydberg's equation, it is v = R (1/n1^2 - 1/n2^2), where n1 is the final energy level and n2 is the initial level. Convert wavelength to meters. You...
- Wed Oct 28, 2020 12:03 am
- Forum: SI Units, Unit Conversions
- Topic: Angstrom
- Replies: 6
- Views: 654
Angstrom
I'm a little confused on converting units still. I know 1 Angstrom is 10^-10m. But if I have 6.001x10^-7 and I multiply that by 10^-10 on my calculator, I get 6.001x10^-17 when the answer should be 6001 angstroms I think. Any ideas?
- Tue Oct 27, 2020 11:01 pm
- Forum: Properties of Light
- Topic: Sapling Week 3 Problem 8
- Replies: 3
- Views: 577
Sapling Week 3 Problem 8
A blue line is observed at 486.1 nm in the spectrum of atomic hydrogen. Determine the values of n for the beginning and ending energy levels of the electron during the emission of energy that leads to this spectral line. I've seen a lot of these but can't seem to really grasp the answer. Since it is...
- Tue Oct 27, 2020 10:54 pm
- Forum: Properties of Light
- Topic: rydberg's equation
- Replies: 2
- Views: 127
rydberg's equation
On the equation sheet, rydberg's equation is v= R(1/n1^2-1/n2^2) , but online, it's usually 1/wavelength= R(1/n1^2-1/n2^2). Which one is better to use and why do they differ?
- Tue Oct 27, 2020 10:53 pm
- Forum: Properties of Light
- Topic: rydberg's constant
- Replies: 11
- Views: 1082
rydberg's constant
On the equation sheet, rydberg's constant is 3.28984 x10^15 Hz, but online, it's usually 1.097x10^7 m. Which one is better to use and why do they differ?
- Sun Oct 18, 2020 8:14 pm
- Forum: Significant Figures
- Topic: rounding during equations
- Replies: 14
- Views: 738
Re: rounding during equations
I recommend rounding at the end to get the most accurate result and sig figs.
- Sun Oct 18, 2020 8:13 pm
- Forum: SI Units, Unit Conversions
- Topic: studying tactics
- Replies: 8
- Views: 276
studying tactics
Hey guys what are the most productive studying tactics to study for the midterm? Do you recommend mostly book problems and step up sessions?
- Sun Oct 18, 2020 8:05 pm
- Forum: Student Social/Study Group
- Topic: How are you studying?
- Replies: 204
- Views: 36334
Re: How are you studying?
Hey, I think a key step in memorizing information from lectures is to write a summary at the end and then try to recite it later that day so the information stays fresh. Do chem everyday even if it's just for 15-20 minutes. Textbook problems are good to get a feel for similar questions on the test a...
- Sun Oct 18, 2020 7:46 pm
- Forum: SI Units, Unit Conversions
- Topic: unit conversions
- Replies: 24
- Views: 1644
unit conversions
When converting units do you just multiply by 10^x given number or is there a different way? For example if I convert centi to giga, I multiply the number I'm converting by 10^9 and leave it in scientific notation?
- Sun Oct 18, 2020 7:42 pm
- Forum: Significant Figures
- Topic: sig fig
- Replies: 20
- Views: 1475
sig fig
Do you guys recommend changing to the correct numbers of sig figs in the middle of an equation or when you have the final result? Also, will we get marked down if sig fig numbers of final result don't match the amount given?
- Sun Oct 18, 2020 7:29 pm
- Forum: Significant Figures
- Topic: Sig Figs and Zeroes
- Replies: 5
- Views: 656
Re: Sig Figs and Zeroes
Hi! Basically the rules for significant figures are: 1) non-zero numbers are always significant 2) any zeros between non-zero numbers are significant 3) a final zero in the decimal portion of a number is significant (ex. 111.900) 6 sigfigs * zeros after a decimal but before a non-zero don't count th...
- Sun Oct 11, 2020 6:49 pm
- Forum: Significant Figures
- Topic: Sapling #4
- Replies: 10
- Views: 691
Re: Sapling #4
Hi Adam! Yes, I think any number after a decimal counts, even zeros!
- Sun Oct 11, 2020 6:43 pm
- Forum: Limiting Reactant Calculations
- Topic: Help finding limiting reactant
- Replies: 4
- Views: 381
Help finding limiting reactant
Balance the reaction for the combustion of aspartame, an artificial sweetener (294.30g/mol): C14H18N2O5(s) + O2(g) -> CO2(g) + H2O(l) + N2(g) If you were to react exactly 2.00g O2 with 2.00g aspartame, what is the limiting reactant and the theoretical yield of liquid water? If the true yield is 0.05...