Search found 101 matches
- Sat Mar 13, 2021 5:51 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Catalysts and intermediates
- Replies: 10
- Views: 691
Re: Catalysts and intermediates
Intermediates are produced in a chemical reaction, but they are also used up to make a different product. Therefore, they won't be in the final equation. Catalysts won't be used up. It's just added to decrease activation energy, so it will be on the product side at the end of the equation since it's...
- Sat Mar 13, 2021 5:47 am
- Forum: Zero Order Reactions
- Topic: When to use each order
- Replies: 19
- Views: 1222
Re: When to use each order
You can add the exponents in the rate law together, use the units of the rate constant, or use graphs.
- Sat Mar 13, 2021 5:42 am
- Forum: Zero Order Reactions
- Topic: kind of reaction
- Replies: 25
- Views: 1305
Re: kind of reaction
It doesn't depend on reactant concentration. The graph of concentration vs. time is a negative linear line.
- Sat Mar 13, 2021 5:40 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Anode and Cathode
- Replies: 25
- Views: 1515
Re: Anode and Cathode
Yes. The flow of electrons therefore goes from the anode to the cathode, so the anode is oxidized while the cathode is reduced. The anode should also be on the left.
- Sat Mar 13, 2021 5:37 am
- Forum: Student Social/Study Group
- Topic: Planning on dorming in the Fall?
- Replies: 61
- Views: 4609
Re: Planning on dorming in the Fall?
I'm planning to dorm if I'm vaccinated by then.
- Sun Mar 07, 2021 10:50 pm
- Forum: Student Social/Study Group
- Topic: What do you miss / What are you looking forward to?
- Replies: 92
- Views: 15046
Re: What do you miss / What are you looking forward to?
I'm excited to meet people irl.
- Sun Mar 07, 2021 5:29 pm
- Forum: Balancing Redox Reactions
- Topic: Oxidizing Reactant
- Replies: 9
- Views: 703
Re: Oxidizing Reactant
An oxidizing reactant oxidizes something, so it gains electrons by doing so. Therefore, it's oxidation number decreases. Gain electron(s) means decreased oxidation number means it's the oxidizing reactant.
- Sun Mar 07, 2021 5:25 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K
- Replies: 33
- Views: 1643
Re: K
Kc is the equilibrium constant for molar concentrations while K is the general equilibrium constant.
- Sun Mar 07, 2021 5:23 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: flipping sign of E˚
- Replies: 7
- Views: 438
Re: flipping sign of E˚
You would also change the sign.
- Sun Mar 07, 2021 5:22 pm
- Forum: Balancing Redox Reactions
- Topic: How to Determine if a Reaction is in Basic or Acidic Solution?
- Replies: 53
- Views: 3764
Re: How to Determine if a Reaction is in Basic or Acidic Solution?
I think the problem should tell us.
- Sun Mar 07, 2021 5:21 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Final
- Replies: 48
- Views: 3407
Re: Final
I would go do the textbook problems.
- Sun Feb 28, 2021 10:30 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Anode/Cathode
- Replies: 45
- Views: 1825
Re: Anode/Cathode
Anode is always on the left and cathode is always on the right.
- Sun Feb 28, 2021 10:25 pm
- Forum: Student Social/Study Group
- Topic: Points Required for Full Credit of Chem Community
- Replies: 11
- Views: 1165
Re: Points Required for Full Credit of Chem Community
I would do it just in case because I think the syllabus says it's 5 posts per week not necessarily 50 overall.
- Sun Feb 28, 2021 10:20 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Chemistry Community Points
- Replies: 24
- Views: 1326
Re: Chemistry Community Points
Yeah, you can post as much as you want.
- Sun Feb 28, 2021 10:19 pm
- Forum: Balancing Redox Reactions
- Topic: Determining which molecule is the oxidizing agent
- Replies: 49
- Views: 2213
Re: Determining which molecule is the oxidizing agent
Yes. The oxidizing agent makes other molecules lose electrons by gaining them, therefore it is reduced.
- Sun Feb 28, 2021 10:13 pm
- Forum: Student Social/Study Group
- Topic: Chem community posts
- Replies: 1
- Views: 181
Re: Chem community posts
We should have 40 posts by now since it's the end of week 8.
- Sun Feb 21, 2021 10:13 pm
- Forum: Balancing Redox Reactions
- Topic: Oxidizing vs Reducing
- Replies: 55
- Views: 3025
Re: Oxidizing vs Reducing
I like to remember OIL RIG(oxidize is loss, reducing is gain). Remember that oxidizing agent oxidizes, so it gains the electrons while the reducing agent reduces substances, so it loses electrons.
- Sun Feb 21, 2021 10:11 pm
- Forum: Student Social/Study Group
- Topic: How to Reduce Nervousness before getting results
- Replies: 63
- Views: 6743
Re: How to Reduce Nervousness before getting results
There's nothing that can really be done since the test is over, so I try and take my mind off it by playing games or watching shows. Try to relax and do something you like to get less stressed.
- Sun Feb 21, 2021 10:10 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Final
- Replies: 48
- Views: 3407
Re: Final
Textbook problems and attending UA sessions are probably the best way to review.
- Sun Feb 21, 2021 10:09 pm
- Forum: General Science Questions
- Topic: MT 2 grades
- Replies: 34
- Views: 2319
Re: MT 2 grades
It'll probably be up in a week or so like last time.
- Sun Feb 21, 2021 10:05 pm
- Forum: Student Social/Study Group
- Topic: Classes for next quarter?
- Replies: 165
- Views: 23023
Re: Classes for next quarter?
I'm taking chem14bl, math 3c, ls 7b, and cluster 20cw.
- Sun Feb 14, 2021 7:45 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Units
- Replies: 20
- Views: 839
Re: Units
I think either one should work as long as you're consistent in what you're using. Just make sure you convert to whichever unit is wanted too.
- Sun Feb 14, 2021 7:41 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Likeliness to form products/reactants
- Replies: 27
- Views: 1095
Re: Likeliness to form products/reactants
delta G < 0 aka negative means it's spontaneous, favoring the forward reaction (products)
delta G > 0 aka positive means not spontaneous, favoring the reverse reaction.
delta G > 0 aka positive means not spontaneous, favoring the reverse reaction.
- Sun Feb 14, 2021 7:39 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Enthalpy vs Entropy
- Replies: 39
- Views: 3403
Re: Enthalpy vs Entropy
Entropy is disorder while enthalpy is heat. Enthalpy is the heat absorbed/released in a system while entropy is the measure of disorder.
- Sun Feb 14, 2021 7:34 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: temperature
- Replies: 32
- Views: 1540
Re: temperature
If it's abt temp change then you don't really need to convert. Just pay attention to the units needed/what the question is asking for. Make sure you use the same temperature unit in calculations.
- Sun Feb 14, 2021 7:31 pm
- Forum: Student Social/Study Group
- Topic: Finals
- Replies: 46
- Views: 4149
Re: Finals
I found the final to be harder than the midterms.
- Sun Feb 07, 2021 7:39 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Combustion = Exothermic
- Replies: 23
- Views: 993
Re: Combustion = Exothermic
It's exothermic because there are still bonds being formed that release more energy than the energy needed to break bonds.
- Sun Feb 07, 2021 7:36 pm
- Forum: Phase Changes & Related Calculations
- Topic: Vapor vs gas
- Replies: 121
- Views: 17162
Re: Vapor vs gas
They're the same thing.
- Sun Feb 07, 2021 7:35 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm 2
- Replies: 33
- Views: 2650
Re: Midterm 2
I don't think he's posted an outline yet.
- Sun Feb 07, 2021 7:34 pm
- Forum: Student Social/Study Group
- Topic: Spring 2021
- Replies: 106
- Views: 24810
Re: Spring 2021
I'm going to be taking it next quarter so I still remember material from 14B
- Sun Feb 07, 2021 7:33 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Can We Review our Exams?
- Replies: 69
- Views: 4462
Re: Can We Review our Exams?
go to TA hours!
- Sun Jan 31, 2021 3:26 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Pressure
- Replies: 7
- Views: 402
Re: Pressure
ΔPV doesn't mean ΔP x ΔV, it means the change in quantity of (pressure x volume). If pressure is constant, then your only change in the quantity (pressure x volume) is volume, so you can say ΔPV=PΔV Oh, that makes a lot of sense. So, basically if there is a change in the product of pressure times v...
- Sun Jan 31, 2021 3:24 pm
- Forum: Phase Changes & Related Calculations
- Topic: endothermic/exothermic
- Replies: 43
- Views: 5105
Re: endothermic/exothermic
Endothermic takes in heat while exothermic releases heat. Therefore, solid->liquid->gas would be endothermic since heat is required to break the bonds. Going reverse would be exothermic since forming bonds releases energy.
- Sun Jan 31, 2021 3:22 pm
- Forum: Phase Changes & Related Calculations
- Topic: Salt
- Replies: 19
- Views: 788
Re: Salt
Salts can be basic, acidic, or neutral depending on the anions/cations in the salt.
- Sun Jan 31, 2021 3:20 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Labs
- Replies: 10
- Views: 628
Re: Labs
I'm planning to take 14BL next quarter so I'll still remember what I learned in 14B :)
- Sun Jan 31, 2021 3:18 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Kelvin or Celsius?
- Replies: 86
- Views: 6808
Re: Kelvin or Celsius?
kelvin bc R is in kelvin
- Sun Jan 24, 2021 5:05 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm 1 Material?
- Replies: 8
- Views: 394
Re: Midterm 1 Material?
Weeks 1-3 lectures will be in the midterm. The week 3 topics are 4D.3, 4D.4, 4D.5, and 4E.3.
- Sun Jan 24, 2021 5:02 pm
- Forum: Calculating the pH of Salt Solutions
- Topic: pH sig figs
- Replies: 4
- Views: 403
Re: pH sig figs
It would have 4 SFs since we're following the same SF rules. One thing to remember though is that when taking the -log of a number, the total SFs of that number will be the number of SFs in the decimal place. In the case of pH = 7.834, for the -log(#), the # would have had 3 SFs that made 7.834 have...
- Sun Jan 24, 2021 4:58 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Question about 14B Exams
- Replies: 38
- Views: 1821
Re: Question about 14B Exams
Yes, they're during lecture time.
- Sun Jan 24, 2021 4:56 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Periodic Tables on Midterm
- Replies: 23
- Views: 1161
Re: Periodic Tables on Midterm
Yes, we're allowed to have print outs of the periodic table and formula sheet on his website.
- Sun Jan 24, 2021 4:56 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Increase in Pressure
- Replies: 31
- Views: 984
Re: Increase in Pressure
Changing pressure only affects gases, so you don't include aqueous.
- Sun Jan 17, 2021 5:24 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Q and K
- Replies: 46
- Views: 2148
Re: Q and K
I understand the relationship between Q and K, but can someone tell me why/when we would want to measure the Q/when it would be important? You could measure Q in order to figure out what direction the reaction is going towards. When Q<K, the reaction favors the forward reaction/products and if Q>K,...
- Sun Jan 17, 2021 5:20 pm
- Forum: Student Social/Study Group
- Topic: Comfort Movies
- Replies: 168
- Views: 45827
Re: Comfort Movies
I like Studio Ghibli movies and Spiderman: Into the Spiderverse!
- Sun Jan 17, 2021 5:19 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Q > K, Q< K
- Replies: 25
- Views: 929
Re: Q > K, Q< K
When Q < K, the reaction will favor the forward reaction, so there will be more products formed. When Q > K, the reverse reaction is favored with more reactants forming
- Sun Jan 17, 2021 5:13 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: shifts left or right
- Replies: 23
- Views: 1289
Re: shifts left or right
A shift to the left means that reactants are favored while a shift to the right favors products.
- Sun Jan 17, 2021 5:12 pm
- Forum: Ideal Gases
- Topic: Inverse Kc [ENDORSED]
- Replies: 41
- Views: 2729
Re: Inverse Kc [ENDORSED]
You want to use the inverse of Kc when solving for the Kc of the reverse reaction.
- Sun Jan 10, 2021 6:25 pm
- Forum: Ideal Gases
- Topic: Units of Temperature
- Replies: 82
- Views: 4807
Re: Units of Temperature
Kelvin. You can convert celsius to kelvin with K = C + 273.15.
- Sun Jan 10, 2021 6:19 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Counting Moles
- Replies: 11
- Views: 584
Re: Counting Moles
You only count gases since the question is asking abt pressure.
- Sun Jan 10, 2021 6:15 pm
- Forum: Student Social/Study Group
- Topic: Study Habits
- Replies: 96
- Views: 9121
Re: Study Habits
I found the assigned textbook problems on the syllabus to be really helpful in practicing my understanding. Also, try to space out your studying instead of a long intensive study session.
- Sun Jan 10, 2021 6:09 pm
- Forum: Student Social/Study Group
- Topic: Chemistry Community
- Replies: 29
- Views: 1673
Re: Chemistry Community
In an email, Professor Lavelle said 5 posts per week = 5 pts per week. I think the deadline is on sundays, but different TAs might have a different rules.
- Sun Jan 10, 2021 6:06 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Calculating Equilibrium Concentrations
- Replies: 10
- Views: 444
Re: Calculating Equilibrium Concentrations
yeah, solids and liquids aren't included because their change in concentration is very small.
- Tue Dec 15, 2020 3:54 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Square Planar vs. Tetrahedral [ENDORSED]
- Replies: 18
- Views: 1719
Re: Square Planar vs. Tetrahedral [ENDORSED]
Tetrahedral shapes are AX4, so there are only 4 bonded atoms while square planar is AX4E2, so it has 2 more lone pairs.
- Tue Dec 15, 2020 3:53 am
- Forum: Lewis Acids & Bases
- Topic: KA and pKA
- Replies: 19
- Views: 1027
Re: KA and pKA
Ka is the acidity constant and pKa is the -log of Ka. Ka = [H+][A-]/[HA]. Both can be used to find out how strong an acid is. A higher Ka means a lower pKa and stronger acid while a lower Ka means a higher pKa and weaker acid.
- Tue Dec 15, 2020 3:47 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: axial/equatorial
- Replies: 5
- Views: 421
Re: axial/equatorial
Equatorial are on the same horizontal plane as the central atom while axial are above/below that plane.
- Tue Dec 15, 2020 3:46 am
- Forum: Naming
- Topic: Ligand use -ate
- Replies: 18
- Views: 1173
Re: Ligand use -ate
You use ate when overall charge is negative.
- Tue Dec 15, 2020 3:45 am
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Balmer and Lyman Series
- Replies: 6
- Views: 537
Re: Balmer and Lyman Series
I remember that Lyman is around 100nm while Balmer is around 400-600nm, but knowing the energy levels is important for equations.
- Sun Dec 06, 2020 5:25 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Lectures not loading
- Replies: 13
- Views: 847
Re: Lectures not loading
I think lecture videos should be working now.
- Sun Dec 06, 2020 5:24 pm
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: Differences between intermolecular forces
- Replies: 3
- Views: 419
Re: Differences between intermolecular forces
There's ion-ion, ion-dipole, dipole-dipole, dipole-induced dipole, and induced dipole-induced dipole. Ion-ion is between 2 ions (Na+ and Cl-). Ion-dipole is between an ion and something that's not an ion but has ionic characteristic (Cl and H2O). Dipole-dipole is between two non ions but they still ...
- Sun Dec 06, 2020 5:14 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Memorization for final
- Replies: 9
- Views: 514
Re: Memorization for final
I think knowing the ligands might be something to memorize since I think we can only have the periodic table and formula sheet.
- Sun Dec 06, 2020 5:12 pm
- Forum: Administrative Questions and Class Announcements
- Topic: CCLE fixed?
- Replies: 19
- Views: 1105
Re: CCLE fixed?
My lecture videos are working right now, maybe try checking again or refreshing?
- Sun Dec 06, 2020 5:10 pm
- Forum: Calculating the pH of Salt Solutions
- Topic: pH formula?
- Replies: 69
- Views: 4715
Re: pH formula?
pH = -log[H+]. I don't think we need to how it was derived.
- Sun Nov 29, 2020 7:36 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Molecular Shape
- Replies: 12
- Views: 648
Re: Molecular Shape
Lone pairs affect molecular shape. They have more repulsion and change bond angles.
- Sun Nov 29, 2020 7:25 pm
- Forum: Student Social/Study Group
- Topic: Week 8/9 Thoughts/Worries
- Replies: 66
- Views: 5145
Re: Week 8/9 Thoughts/Worries
I also feel like it's going pretty well, but I'm learning new material now so I'm slightly nervous for that and for finals.
- Sun Nov 29, 2020 7:22 pm
- Forum: Student Social/Study Group
- Topic: Tips for Staying Focused
- Replies: 64
- Views: 5091
Re: Tips for Staying Focused
Don't forget to take breaks, so you don't get tired. Also, try not to be in a distracting environment (I avoid the living room bc the TV is on). I tend to study at night since that is when I feel the most focused personally. Taking notes and having a set goal for what I want to have studied also hel...
- Sun Nov 29, 2020 7:17 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent
- Replies: 9
- Views: 559
Re: Bent
yep
- Sun Nov 29, 2020 7:04 pm
- Forum: Student Social/Study Group
- Topic: Studying for Final Exam
- Replies: 57
- Views: 3515
Re: Studying for Final Exam
I'm going to solve the textbook problems assigned to us, and I'm probably going to attend some workshops as well throughout weeks 9 and 10 to avoid cramming.
- Sun Nov 22, 2020 3:28 pm
- Forum: Ionic & Covalent Bonds
- Topic: Covalent Character
- Replies: 33
- Views: 1843
Re: Covalent Character
Look at electronegativity. A smaller electronegativity difference means more covalent character.
- Sun Nov 22, 2020 3:27 pm
- Forum: General Science Questions
- Topic: # of chem posts
- Replies: 27
- Views: 2090
Re: # of chem posts
You need 5 posts per week, so 35 posts are needed.
- Sun Nov 22, 2020 3:23 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Week 7 Sapling
- Replies: 12
- Views: 854
Re: Week 7 Sapling
Week 7 and 8 are in the same sapling assignment, so it's due next sunday.
- Sun Nov 22, 2020 3:21 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm 2 Scores
- Replies: 28
- Views: 1758
Re: Midterm 2 Scores
I think we'll get them by this week since it took abt a week for midterm 1.
- Sun Nov 22, 2020 3:20 pm
- Forum: Sigma & Pi Bonds
- Topic: Sigma and Pi Bond Lecture
- Replies: 7
- Views: 333
Re: Sigma and Pi Bond Lecture
lecture 22!
- Sun Nov 15, 2020 5:25 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Sapling week 5 & 6 #5
- Replies: 20
- Views: 909
Re: Sapling week 5 & 6 #5
C should have a formal charge of -2. Valence - free - bonding/2 = 4 - 4 - 4/2 = -2.
- Sun Nov 15, 2020 5:23 pm
- Forum: Trends in The Periodic Table
- Topic: Electron Affinity
- Replies: 3
- Views: 274
Re: Electron Affinity
It's negative due to electron-electron repulsion. Adding the first electron makes group 16 elements an anion, so the second electron affinity is negative since the electron is trying to go into an already electron dense space, causing them to repel and need energy to add it.
- Sun Nov 15, 2020 5:12 pm
- Forum: Electronegativity
- Topic: Sapling Question 13
- Replies: 7
- Views: 327
Re: Sapling Question 13
The electronegative N and O and the slightly positive Hs can all hydrogen bond. N has 1 lone pair, so it can form 1 H bond (2 Ns = 2 H bonds) while O has 2 lone pairs, so it can form 2 H bonds. Each H (4 Hs in urea) can have one H bond, so the total becomes 8 bonds.
- Sun Nov 15, 2020 5:05 pm
- Forum: Administrative Questions and Class Announcements
- Topic: midterm 2 lecture content
- Replies: 4
- Views: 274
Re: midterm 2 lecture content
it's lectures 10-18.
- Sun Nov 15, 2020 5:02 pm
- Forum: Lewis Structures
- Topic: Sapling hw 3
- Replies: 11
- Views: 663
Re: Sapling hw 3
N can't have an expanded octet since it's in period 2.
- Sun Nov 08, 2020 4:23 pm
- Forum: Lewis Structures
- Topic: Lone Pairs Question
- Replies: 22
- Views: 1942
Re: Lone Pairs Question
Lone pairs are the electrons that aren't in a covalent bond, so they aren't shared between atoms.
- Sun Nov 08, 2020 4:20 pm
- Forum: Resonance Structures
- Topic: Valence Electrons [ENDORSED]
- Replies: 46
- Views: 4461
Re: Valence Electrons [ENDORSED]
You can find VE quickly by counting which group it's in. There are 8 groups from left to right when you don't include the d-block/transition metals, and the group it's in corresponds to the element's valence electrons.
- Sun Nov 08, 2020 4:14 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Taking Bio and Chem simultaneously
- Replies: 26
- Views: 2744
Re: Taking Bio and Chem simultaneously
I'm taking LS7A and Chem14A at the same time right now. I think LS7A has more work because of launchpad, but it's manageable as long as you don't procrastinate a lot.
- Sun Nov 08, 2020 4:11 pm
- Forum: Ionic & Covalent Bonds
- Topic: Size of Bonds
- Replies: 28
- Views: 996
Re: Size of Bonds
Double bonds have 2 shared pairs of electrons while single bonds only share 1 pair, so the greater number of electrons results in a stronger attraction to the nuclei, shomaking double bonds shorter.
- Sun Nov 08, 2020 4:06 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: What do we use formal charges for?
- Replies: 15
- Views: 473
Re: What do we use formal charges for?
When there are multiple resonance structures, formal charge can be used to find the most stable structure. The most stable have a formal charge that is or is closest to 0.
- Sun Nov 01, 2020 6:25 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Question 26 Sapling
- Replies: 5
- Views: 478
Re: Question 26 Sapling
You can use heisenberg's uncertainty principle where ΔxΔp >= h/4π. Δp = mΔv, so you can substitute that in and rearrange the equation for Δv which becomes Δv = h/(4πmΔx). Then, you can just plug in electron mass and Δx which is given to you.
- Sun Nov 01, 2020 6:19 pm
- Forum: Trends in The Periodic Table
- Topic: Ionization Energy
- Replies: 9
- Views: 438
Re: Ionization Energy
Ionization energy decreases from top to bottom since the valence electrons are in shells that are further away from the nucleus and held less tightly, making them easier to remove. Ionization energy increases from left to right since nuclear charge is also increasing, making it more difficult to rem...
- Sun Nov 01, 2020 6:11 pm
- Forum: Student Social/Study Group
- Topic: Sappling week 2-4 #22
- Replies: 6
- Views: 351
Re: Sappling week 2-4 #22
Kinetic energy is .5mv^2. You can use the constants sheet to get the mass of an electron, so you just need to find its velocity. You can use de Broglie's equation where λ = h / mv and rearrange it to get v = h / mλ and plug it into .5mv^2. Then, you just need to convert from Joules (since KE has uni...
- Sun Nov 01, 2020 6:05 pm
- Forum: DeBroglie Equation
- Topic: Avogadro's Number
- Replies: 21
- Views: 1789
Re: Avogadro's Number
Avogadro's number means that 1 mole (mol) is equal to 6.0221 * 10^23 particles. Particles can refer to molecules/atoms/formula units. You usually use it when you need to convert moles to atoms/molecules. For example, the mass on the periodic table is molar mass so you would divide by avogadro's numb...
- Sun Nov 01, 2020 6:02 pm
- Forum: DeBroglie Equation
- Topic: Sapling HW #17
- Replies: 6
- Views: 424
Re: Sapling HW #17
You can use the de Broglie equation, λ = h/p which becomes λ = h/mv. You already have velocity, and you can get fluorine's mass by converting its molar mass using avogadro's number to go from grams/mol to grams/molecule. Make sure you find molar mass of F2 when converting since it's a diatomic molec...
- Sun Oct 25, 2020 5:47 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Module #18
- Replies: 5
- Views: 199
Re: Module #18
I got D. I used ΔxΔp≥h/4Π which can also be written as Δxmv≥h/4Π (p = mv) and manipulated it to get v. V = (h/4Π) / (Δxm). We were given that position (x) was 1% of the radius, so I found x by calculating .01 * (.05 * 10^-9) <-since you need to convert to meters. Mass of an electron is a constant, a...
- Sun Oct 25, 2020 5:25 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: E.23 Part A and C
- Replies: 4
- Views: 370
Re: E.23 Part A and C
You don't need to find the mass percentage. You're right that you find the molar mass of the molecules, but afterwards just use molar ratios. Divide the given masses (make sure they're in grams) by molar mass to get the moles of the molecule, then use the molar ratio between the atom and the molecul...
- Sun Oct 25, 2020 5:21 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Rearranging uncertainty in velocity
- Replies: 5
- Views: 184
Re: Rearranging uncertainty in velocity
Since ΔP = M x ΔV, you can divide both sides by M to isolate ΔV, so ΔV= ΔP / M.
- Sun Oct 25, 2020 5:18 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Printouts for Midterm
- Replies: 8
- Views: 484
Re: Printouts for Midterm
We were sent an email with a periodic table sheet and constants/equations we can print out and use.
- Sun Oct 25, 2020 5:10 pm
- Forum: Einstein Equation
- Topic: Textbook Problem 1A.3
- Replies: 9
- Views: 545
Re: Textbook Problem 1A.3
Speed of light in a vacuum is constant where c = 3.00 * 10^8. c can also be found by c = λ * v, so frequency and wavelength are inversely related.
- Sun Oct 18, 2020 3:43 pm
- Forum: Student Social/Study Group
- Topic: Study Tips
- Replies: 8
- Views: 412
Re: Study Tips
I've been reading through the textbook sections listed on the syllabus and solving the problems as well.
- Sun Oct 18, 2020 3:39 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Will the midterm only consist of fundamental topics & 1A-1D?
- Replies: 1
- Views: 99
Re: Will the midterm only consist of fundamental topics & 1A-1D?
I think so. On his website, it said Midterm 1 is all the material through week 3 which is up to Q21 on Sapling and Topic 1D on the textbook.
- Sun Oct 18, 2020 3:34 pm
- Forum: Photoelectric Effect
- Topic: Sapling Week 2,3,4 #9
- Replies: 2
- Views: 125
Re: Sapling Week 2,3,4 #9
Since we're looking for the longest wavelength possible, this means that work function should be the same as the photon's energy (there won't be excess energy/kinetic energy from the electrons because that would mean that it wouldn't be the longest wavelength possible). We know the formula E = hv gi...
- Sun Oct 18, 2020 3:25 pm
- Forum: Properties of Electrons
- Topic: protons and electrons
- Replies: 33
- Views: 2868
Re: protons and electrons
An electron has a much smaller mass than protons and neutrons which are about the same. An electron's mass is basically negligible while the other 2 have masses of around 1 amu/dalton.
- Sun Oct 18, 2020 3:12 pm
- Forum: Student Social/Study Group
- Topic: How are you studying?
- Replies: 204
- Views: 28923
Re: How are you studying?
I'm using the fundamentals/problems posted on the syllabus as study materials. I take notes on the fundamentals, watch the audio-visual modules, and take notes on the lectures.
- Sun Oct 11, 2020 5:46 pm
- Forum: Limiting Reactant Calculations
- Topic: Sapling HW 10
- Replies: 9
- Views: 869
Re: Sapling HW 10
You can use the molecular formulas to find the molar mass, but I just searched it up and got molar mass of butanone on the internet. You would only need to know the formulas for the 2-butanone and 3-methyl-3-hexanol since the other product is in excess. To approach the problem, first use the density...
- Sun Oct 11, 2020 4:02 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: post video Q28
- Replies: 2
- Views: 88
Re: post video Q28
Wavelength is measured in meters so since you know how many wavelengths are in 1 meter from the problem, you can do wavelength = 1/1,650,763.73 and use that answer to find the region it falls under. Then for the photon question, you can use the formula E = hv.
- Sun Oct 11, 2020 3:28 pm
- Forum: Empirical & Molecular Formulas
- Topic: Molecular Formula
- Replies: 3
- Views: 244
Re: Molecular Formula
Once you find the empirical formula's molar mass, you can divide the mass of the molecular formula by the empirical formula to get the ratio. You can then use that number and multiply each element's subscript/number of atoms in the empirical formula by that number to get the molecular formula.
- Sun Oct 11, 2020 3:25 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Formulas involved in Determining Solution Concentration
- Replies: 8
- Views: 1105
Re: Formulas involved in Determining Solution Concentration
Try and note down what variables are being used in the problem. If there are 2 molarities or 2 volumes, you probably need to use M1V1 = M2V2. Another way to tell is that if a solution has been diluted/water was added, you probably need to use the same equation since number of moles (n) stays the sam...