Search found 100 matches
- Sat Mar 14, 2020 12:56 pm
- Forum: Zero Order Reactions
- Topic: Composition vs Decomposition
- Replies: 3
- Views: 338
Re: Composition vs Decomposition
Nope, it's the same rate equation.
- Sat Mar 14, 2020 12:53 pm
- Forum: Zero Order Reactions
- Topic: kind of reaction
- Replies: 25
- Views: 1091
Re: kind of reaction
It's a reaction that does not depend on the amount of the reactant. For example, a saturated catalyst reaction, where the rate is limited by the number of open catalysts, is a zero order reaction because increasing the reactant won't do anything.
- Sat Mar 14, 2020 12:52 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Delta S
- Replies: 8
- Views: 683
Re: Delta S
The delta S total is the delta S of the system plus surroundings.
- Sat Mar 14, 2020 12:50 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: E vs Eo
- Replies: 6
- Views: 498
Re: E vs Eo
In some cases, standard E will be zero, so this equation can be used to find Ecell in concentration cells.
- Fri Mar 13, 2020 4:18 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Why is Q the concentration of anode/cathode?
- Replies: 3
- Views: 10820
Re: Why is Q the concentration of anode/cathode?
I believe it's because the anode proceeds backwards from the standard form of half reactions (i.e. Fe2+ +2 e- -> Fe(s)).
- Fri Mar 13, 2020 4:03 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Saying Thank You to Dr. Lavelle
- Replies: 490
- Views: 513651
Re: Saying Thank You to Dr. Lavelle
THANK YOU DR. LAVELLE!!!
Dr. Lavelle is genuinely one of the most entertaining and funny professors I've had in a while. I really like how pleased he looks whenever he turns into DJ Lavelle and bops to the music.
Dr. Lavelle is genuinely one of the most entertaining and funny professors I've had in a while. I really like how pleased he looks whenever he turns into DJ Lavelle and bops to the music.
- Fri Mar 13, 2020 4:01 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Final
- Replies: 11
- Views: 702
Re: Final
It should be released by Sunday, and it's timed for the same 3 hours that we would've been given. I'm sure he'll release more details tomorrow regarding the specific details.
- Thu Mar 12, 2020 3:48 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Final Format
- Replies: 2
- Views: 296
Re: Final Format
I'm guessing it's still going to be 180 just because that would mess up his scaling if he made it worth that little points.
- Thu Mar 12, 2020 3:47 pm
- Forum: Balancing Redox Reactions
- Topic: Test 2 Return
- Replies: 20
- Views: 1148
Re: Test 2 Return
At least for Ben, he left his in his mailbox in Young Hall.
- Wed Mar 11, 2020 2:44 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: same equation?
- Replies: 5
- Views: 314
Re: same equation?
The one with ln has been rearranged so that you can create a graph of certain values that will result in a straight line, something that can't be done with the previous equation.
- Wed Mar 11, 2020 2:42 pm
- Forum: Balancing Redox Reactions
- Topic: Ecell values
- Replies: 12
- Views: 789
Re: Ecell values
You can use the appendix to look at the E values for the two half reactions. Since the equation for Ecell is E(c) = E(cath) - E(anode), then you can determine which reaction is cathode and which one is anode.
- Wed Mar 11, 2020 2:40 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: rate constant
- Replies: 5
- Views: 397
Re: rate constant
Catalysts lower the activation energy, meaning particles that are involved in collisions don't need as much energy to make the reaction go forward, increasing k.
- Wed Mar 11, 2020 2:39 pm
- Forum: Zero Order Reactions
- Topic: straight line to fit data
- Replies: 5
- Views: 416
Re: straight line to fit data
The slope will also give you a different constant value depending on the order of the reaction.
- Wed Mar 11, 2020 2:38 pm
- Forum: General Science Questions
- Topic: Chemistry Final
- Replies: 16
- Views: 1142
Re: Chemistry Final
I think it's safe to assume it might just be free response, just like normal.
- Wed Mar 11, 2020 2:37 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Final
- Replies: 5
- Views: 379
Re: Final
You can probably just scan it and send it to him, it sounds like this is all gonna be pretty informal.
- Tue Mar 10, 2020 12:54 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: Boltzmann Equation
- Replies: 2
- Views: 300
Re: Boltzmann Equation
R = Nk, where N is avogadro's constant and k is boltzmann's constant.
- Tue Mar 10, 2020 12:53 pm
- Forum: General Rate Laws
- Topic: pseudo rate laws
- Replies: 5
- Views: 310
Re: pseudo rate laws
I think it's just to note that it's not the original k that you're dealing with: it includes other constants.
- Tue Mar 10, 2020 12:51 pm
- Forum: Balancing Redox Reactions
- Topic: Half Reactions
- Replies: 15
- Views: 777
Re: Half Reactions
You first balance the oxygens by adding H2O on whatever side needs oxygen. Then you balance the extra hydrogens by adding H+ on the other side. If the reaction occurs in a basic solution, then you add to both sides the same amount of OH- as H+ you added.
- Sun Mar 08, 2020 8:55 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Exothermic vs. Endothermic
- Replies: 14
- Views: 921
Re: Exothermic vs. Endothermic
Generally, if the reactant energy is higher than the product energy, the reaction is exothermic, and vice versa for endothermic.
- Sun Mar 01, 2020 7:04 pm
- Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
- Topic: Dissolved Metal
- Replies: 3
- Views: 313
Re: Dissolved Metal
I believe that in the context of electrolytic reactions, the anode is always the one that corrodes.
- Sun Mar 01, 2020 5:44 pm
- Forum: Balancing Redox Reactions
- Topic: Anode and Cathode
- Replies: 9
- Views: 524
Re: Anode and Cathode
I believe it's based on the E value for the half reactions. The more negative half reaction is the anode and the more positive half reaction is the cathode.
- Sun Mar 01, 2020 5:42 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Salt Bridge
- Replies: 3
- Views: 229
Re: Salt Bridge
I think if there isn't a salt bridge, there needs to be a porous membrane for ions to diffuse through in order to maintain the charge balance.
- Sun Mar 01, 2020 5:41 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Free energy
- Replies: 3
- Views: 340
Re: Free energy
Probably negative free energy means positive E(cell) potential. There's also an equation I believe that you should know, it's on the equation sheet.
- Sun Mar 01, 2020 5:40 pm
- Forum: Balancing Redox Reactions
- Topic: anode/cathod reversible
- Replies: 4
- Views: 336
Re: anode/cathod reversible
I think because electrochemistry reactions generally only go forward, since they have a positive E(cell) value.
- Sun Mar 01, 2020 5:28 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Salt bridge
- Replies: 2
- Views: 213
Re: Salt bridge
It's to maintain the charge balance between the anode and the cathode. As electrons move, the ions in solution have to move the opposite direction to counterbalance the difference in charge.
- Sun Feb 09, 2020 11:44 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Q and K
- Replies: 3
- Views: 222
Re: Q and K
K is a constant for a reaction that tells you the concentrations of products and reactants needed for the reaction to be at equilibrium. Q is not a constant, and can be calculated (and is different) at any point in a reaction. The value of Q compared to K tells you which way the reaction is going at...
- Sun Feb 09, 2020 11:43 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: fractions
- Replies: 3
- Views: 179
Re: fractions
These are the fractions that you put in front of the ideal gas constant to get a Cp and Cv value, which are used for constant pressure and constant volume respectively. You can use this to calculate the heat put into a gas and its corresponding temperature change.
- Sun Feb 09, 2020 11:42 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: DeltaH
- Replies: 2
- Views: 116
Re: DeltaH
Delta H is enthalpy, which is the total heat change in a system. At constant pressures, it can be used interchangeably with q.
- Sun Feb 09, 2020 11:41 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: extensive vs intensive
- Replies: 4
- Views: 260
Re: extensive vs intensive
An extensive property depends on the amount (i.e. mass, volume). An intensive property is the same regardless how much you have (i.e. density, specific heat capacity).
- Sun Feb 09, 2020 11:40 pm
- Forum: Calculating Work of Expansion
- Topic: q=C delta T
- Replies: 5
- Views: 1295
Re: q=C delta T
The c in q = C * delta T is the heat capacity, measured in Joules per Kelvin. The C in q = m * c* delta T is specific heat capacity, which is measured in Joules per Kelvin gram. The difference is that the first c has different values depending on the amount of some material you have, while the secon...
- Sun Feb 02, 2020 11:16 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Second Law and Biological Examples
- Replies: 1
- Views: 49
Re: Second Law and Biological Examples
Essentially, the second law of thermodynamics says that the entropy of the universe always increases. Thus, in biology, when there's a reaction that lowers the entropy of the universe (like anabolic metabolism), it must be accompanied or powered by something that increases the entropy more than the ...
- Sun Feb 02, 2020 11:14 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Biological reactions
- Replies: 1
- Views: 62
Re: Biological reactions
Because humans are open systems, so air and other things can freely leave our bodies, making the pressure in our bodies equal to the pressure outside.
- Sun Feb 02, 2020 11:13 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: degeneracy
- Replies: 17
- Views: 592
Re: degeneracy
Degeneracy is used to help calculate the entropy of a system, which can be used to calculate the Gibbs free energy of a reaction or system.
- Sun Feb 02, 2020 11:12 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: Boltzmann Equation
- Replies: 3
- Views: 78
Re: Boltzmann Equation
It's basically a way to determine the positional entropy (disorder) of a system, which does not take into account the temperature.
- Sun Feb 02, 2020 11:11 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Combustion
- Replies: 5
- Views: 195
Re: Combustion
I believe the water that is produced is water vapor, since for combustion to occur the temperature would have to be most likely above 100 C.
- Sun Jan 26, 2020 11:26 pm
- Forum: Phase Changes & Related Calculations
- Topic: ∆H
- Replies: 17
- Views: 617
Re: ∆H
I'm not sure it's the only way, but it's probably the most reliable way.
- Sun Jan 26, 2020 11:25 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: autoprotolysis
- Replies: 7
- Views: 253
Re: autoprotolysis
Autoprotolysis is not just the transfer of a H+ ion between an acid and a base, it's the transfer of an H+ between two identical molecules, one that can act as an acid and a base (like H2O). If you then take the equilibrium constant of the equation 2 H2O -> OH- + H30+, you'll get Kw = [OH-][H30+].
- Sun Jan 26, 2020 11:24 pm
- Forum: Phase Changes & Related Calculations
- Topic: Temp. of sample
- Replies: 4
- Views: 97
Re: Temp. of sample
Yes, that is what he meant. If you heat an ice cube very slowly while taking its temperature, you'll notice that when the ice cube transitions to a liquid, the temperature of the sample is staying around 0 degrees, not increasing.
- Sun Jan 26, 2020 11:22 pm
- Forum: Phase Changes & Related Calculations
- Topic: Differentiating (q) and (w)
- Replies: 4
- Views: 170
Re: Differentiating (q) and (w)
Work is a way of transferring energy, while heat is a form of energy.
- Sun Jan 26, 2020 11:21 pm
- Forum: Calculating Work of Expansion
- Topic: equipartition theorem
- Replies: 2
- Views: 89
Re: equipartition theorem
Probably just wait and see if he talks about it.
- Sun Jan 19, 2020 9:35 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: 5% rule
- Replies: 4
- Views: 206
Re: 5% rule
This rule is also only applied if K is a small value (<10^-3).
- Sun Jan 19, 2020 9:34 pm
- Forum: Ideal Gases
- Topic: R Constant
- Replies: 18
- Views: 1038
Re: R Constant
The R constant is the universal gas constant, and the reason there are different values for it is because the units can vary, from atmospheres to barrs.
- Sun Jan 19, 2020 9:32 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Henderson Hasselbalch Equation
- Replies: 3
- Views: 221
Re: Henderson Hasselbalch Equation
The Henderson Hasselbalch Equation is an equation that uses the pKa and concentration of weak acid & conjugate base to quickly determine the pH, without having to go through the ICE table and quadratics.
- Sun Jan 19, 2020 9:29 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: temperature
- Replies: 10
- Views: 409
Re: temperature
Temperature changes the equilibrium constant, so make sure you have the right K constant if looking at a chart that gives you multiple.
- Sun Jan 19, 2020 9:29 pm
- Forum: Identifying Acidic & Basic Salts
- Topic: Strong Acids & Bases Ions
- Replies: 4
- Views: 189
Re: Strong Acids & Bases Ions
Strong acids and bases are just things you're going to have to memorize. Generally, strong bases are group 1 and group 2 metals with an OH group, meaning their conjugate ions are the metals. Strong acids are HBr, HCl, HI, HNO3, HClO4, HSO4, and their conjugate ions would just be those without the H.
- Sun Jan 12, 2020 9:09 pm
- Forum: Ideal Gases
- Topic: The Laws
- Replies: 7
- Views: 192
Re: The Laws
We get to gases later on so you don't really need to worry about it right now.
- Sun Jan 12, 2020 9:08 pm
- Forum: Ideal Gases
- Topic: P=(n/v)RT
- Replies: 12
- Views: 944
Re: P=(n/v)RT
Ruby Richter 2L wrote:So basically you're just multiplying the molarity times RT which gives you P?
Yea that's all you're doing.
- Sun Jan 12, 2020 9:07 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Reaction Direction
- Replies: 19
- Views: 957
Re: Reaction Direction
You determine it by comparing the equilibrium constant (K) with the reaction quotient (Q). If Q is less than K, then there are less products so the reaction is going to the right. If Q is greater than K, then there are more products so the reaction is going to the left. In this case, it doesn't matt...
- Sun Jan 12, 2020 9:05 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Calculating Q
- Replies: 16
- Views: 709
Re: Calculating Q
Calculating Q is the same as calculating for K, which means you include all aqueous solutions and gases, and disregard liquids/solids.
- Wed Jan 08, 2020 11:47 am
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: N2O4 <--> 2NO2, color?
- Replies: 3
- Views: 324
Re: N2O4 <--> 2NO2, color?
Thank you! I was looking for this answer!
- Sat Dec 07, 2019 4:20 pm
- Forum: Polyprotic Acids & Bases
- Topic: Ions
- Replies: 3
- Views: 310
Re: Ions
The polyatomic ones.
- Sat Dec 07, 2019 4:19 pm
- Forum: Identifying Acidic & Basic Salts
- Topic: Spectator Ions?
- Replies: 2
- Views: 266
Re: Spectator Ions?
Spectator ions are generally just group 1 cations or halogens. Since they are stable, they don't want to react.
- Sat Dec 07, 2019 4:18 pm
- Forum: Identifying Acidic & Basic Salts
- Topic: weak bases produce acidic solutions?
- Replies: 3
- Views: 309
Re: weak bases produce acidic solutions?
Salts of weak bases and STRONG acids produce acidic solutions because the conjugate base of the acid is a very weak base while the conjugate acid of the weak base is relatively stronger, so it makes the solution its in acidic.
- Sat Dec 07, 2019 4:16 pm
- Forum: Air Pollution & Acid Rain
- Topic: acid rain
- Replies: 13
- Views: 1167
Re: acid rain
It's just a real life example of an acidic reaction that he went over in class, and may show up on the test. He just went over the reactions involved.
- Sat Dec 07, 2019 4:11 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: weak acids have higher pH values?
- Replies: 1
- Views: 63
Re: weak acids have higher pH values?
Yes, it's just because strong acids dissociate more, so there will be more H+ present in a strong acid solution than a weak acid one even if they have the same concentration.
- Sun Dec 01, 2019 6:44 pm
- Forum: Biological Examples
- Topic: Polydentate
- Replies: 4
- Views: 249
Re: Polydentate
Polydentate refers to ligands that have multiple donor atoms and therefore can bind to a metal at multiple sites. Its significance can be seen in its biological aspects such as heme complexes and other things like that.
- Sun Dec 01, 2019 6:17 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: drawing a chelate
- Replies: 2
- Views: 183
Re: drawing a chelate
I think if you are given a chemical formula, it will have the bracket notation, so you will know it's a chelate complex. As for drawing the right structure, I guess you just follow the lewis structure rules and hope you get it right.
- Sun Dec 01, 2019 6:14 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Difference between weak acids/bases and strong acids/bases
- Replies: 6
- Views: 387
Re: Difference between weak acids/bases and strong acids/bases
Weak acids and bases will not fully dissociate when in an aqueous solution, strong acids and bases will.
- Sun Dec 01, 2019 6:11 pm
- Forum: Student Social/Study Group
- Topic: Study Strategies
- Replies: 6
- Views: 440
Re: Study Strategies
Probably just go to review sessions because those usually have the same concepts as what appear on the exam.
- Sun Dec 01, 2019 6:10 pm
- Forum: Conjugate Acids & Bases
- Topic: Acids and Bases
- Replies: 3
- Views: 268
Re: Acids and Bases
They're basically all referring to the same thing, but just approach it differently. Lewis acids are molecules that accept an electron pair, while lewis bases donate an electron pair. Bronsted acids donate a proton, while Bronsted bases accept a proton. Conjugate acids and bases are a little differe...
Re: #9C3 d
I think it has to do with the fact water is less relevant than bisoxalato.
- Sun Nov 24, 2019 3:24 pm
- Forum: Sigma & Pi Bonds
- Topic: Sigma & Pi Bonds
- Replies: 9
- Views: 559
Re: Sigma & Pi Bonds
Sigma bonds have better overlap because their tips touch. Pi bonds are side to side interactions so there is less overlap.
- Sun Nov 24, 2019 3:16 pm
- Forum: Hybridization
- Topic: Single Electron Orbitals
- Replies: 2
- Views: 210
Re: Single Electron Orbitals
Hybridization occurs to stabilize the energy of bonding orbitals. Single electrons can still form a bond, so they don't need to be hybridized.
- Sun Nov 24, 2019 3:14 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Tetrahedral and Square Planar
- Replies: 3
- Views: 246
Re: Tetrahedral and Square Planar
Cisplatin, the drug used to stop DNA replication, is a square planar.
- Sun Nov 24, 2019 3:06 pm
- Forum: Lewis Acids & Bases
- Topic: Strong Acids
- Replies: 8
- Views: 565
Re: Strong Acids
No, you need to know all of them I'm pretty sure.
- Sun Nov 17, 2019 5:44 pm
- Forum: Student Social/Study Group
- Topic: test 2
- Replies: 8
- Views: 350
Re: test 2
Probably roughly the same amount as test 1.
- Sun Nov 17, 2019 5:43 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Test 2
- Replies: 19
- Views: 818
Re: Test 2
He said that we will never be graded on drawing Lewis structures according to VSEPR model. All you have to do is write out the bond angle and shape and stuff.
- Sun Nov 17, 2019 5:37 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polar molecules
- Replies: 2
- Views: 183
Re: Polar molecules
Electrostatic potential is just a fancy way of saying an electric field. Polar molecules are one's that have a more negative end and positive end. So polar molecules, with their negative and positive ends, "interact" with an electric field. That is to say that the presence of an electric f...
- Sun Nov 17, 2019 5:35 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: 3F.3
- Replies: 1
- Views: 95
Re: 3F.3
For this problem, you basically have to determine which molecules are polar and which aren't. So looking at the four molecules, the molecules that aren't symmetric are going to be the polar molecules, and thus have "important" dipole-dipole interactions. In this case, it would be (b) and (...
- Sun Nov 17, 2019 5:30 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: 2E.15B
- Replies: 1
- Views: 130
Re: 2E.15B
We know that the bond angles are going to be distorted to slightly less than 120 and 90 degrees, but since we can't actually know how much, we usually say that there the bond angles are 90 and 120. In my discussion session, my TA said there would then be a followup question that asks if there is ang...
- Mon Nov 11, 2019 4:39 pm
- Forum: Dipole Moments
- Topic: Textbook question 3F.19 part b
- Replies: 2
- Views: 71
Re: Textbook question 3F.19 part b
Vapor pressure is lower with molecules with strong intermolecular forces. Since H2O has hydrogen bonding, it will have a lower vapor pressure than the other molecule.
- Mon Nov 11, 2019 4:35 pm
- Forum: Dipole Moments
- Topic: Textbook question 3F.1
- Replies: 5
- Views: 284
Re: Textbook question 3F.1
I'm not too sure but I think you just look at whether the molecule is polar (aka does it have dipoles that are not cancelled), whether the molecule can form hydrogen bonds, and other type of interactions that he went over in class.
- Mon Nov 11, 2019 4:32 pm
- Forum: Administrative Questions and Class Announcements
- Topic: 14BL
- Replies: 5
- Views: 252
Re: 14BL
Yea I think for the most part people take it in separate quarters just because it's easier that way.
- Mon Nov 11, 2019 4:29 pm
- Forum: Dipole Moments
- Topic: Textbook question 3F.19 part c
- Replies: 1
- Views: 79
Re: Textbook question 3F.19 part c
These two molecules are actually ones that he went over in class the other day. Because CH3(CH2)3CH3 is going to be more rectangular/spread out than the spherical shape of C(CH3)4, the dipole moments for the first molecule will be stronger because separate molecules will be able to get closer to eac...
- Mon Nov 11, 2019 4:08 pm
- Forum: Trends in The Periodic Table
- Topic: Ionization energy
- Replies: 6
- Views: 366
Re: Ionization energy
Because nitrogen has 3 parallel spin electrons in separate orbitals in the 2p subshell, while Oxygen has 3 parallel spin electrons and one antiparallel electron in the same orbital. Because of electron-electron repulsion and the fact that having a half-full 2p subshell is more stable, it is easier (...
- Sat Nov 02, 2019 5:31 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Ionic Character in Covalent Molecules and Vice-Versa
- Replies: 2
- Views: 247
Re: Ionic Character in Covalent Molecules and Vice-Versa
It becomes less confusing if you think of bonds as being on a spectrum rather than just either ionic or covalent. Bonds that are considered "covalent" still have ionic characteristics, which is why we talk about how electrons are not equally shared in covalent bonds. Bonds that are conside...
- Sat Nov 02, 2019 5:27 pm
- Forum: Octet Exceptions
- Topic: Covalent Bond
- Replies: 4
- Views: 216
Re: Covalent Bond
It's a covalent bond where one atom brings both electrons and one atom accepts both.
- Sat Nov 02, 2019 5:26 pm
- Forum: Properties of Electrons
- Topic: Lewis acids and bases
- Replies: 3
- Views: 252
Re: Lewis acids and bases
Coordinate covalent bonds are covalent bonds where one atom brings both electrons and one accepts electrons. Lewis acids (H+) accept two electrons to form a bond, while lewis bases donates both.
- Sat Nov 02, 2019 5:21 pm
- Forum: Electronegativity
- Topic: Definition
- Replies: 2
- Views: 101
Re: Definition
Electronegativity is a measure of the tendency of an atom to attract electrons. It has the same trend on the periodic table as atomic radius.
- Sat Nov 02, 2019 5:20 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: 2A.1
- Replies: 1
- Views: 134
Re: 2A.1
a) 5, b) 4 c) 7 d) 3
- Sun Oct 27, 2019 11:05 pm
- Forum: Ionic & Covalent Bonds
- Topic: using the octet rule
- Replies: 2
- Views: 89
Re: using the octet rule
Assume that you always apply the octet for any bond except for the exceptions (P, S, Cl)
- Sun Oct 27, 2019 10:12 pm
- Forum: Ionic & Covalent Bonds
- Topic: electron configuration order
- Replies: 6
- Views: 388
Re: electron configuration order
So just like the d-orbital and s-orbital, the 5s comes first, but after 2 electrons are in the 5s the 4f is actually placed before when you're writing out the electron configuration. You don't really need to worry about it because he said we wouldn't be tested on it.
- Sun Oct 27, 2019 10:09 pm
- Forum: Ionic & Covalent Bonds
- Topic: electron configuration
- Replies: 5
- Views: 193
Re: electron configuration
It's because having 10 electrons in the d orbital and 1 in the s orbital is actually more stable than 9 electrons in the d orbital and 2 in the s orbital. This also applies for 5 electrons in the d orbital.
- Sun Oct 27, 2019 9:40 pm
- Forum: Octet Exceptions
- Topic: octet exceptions
- Replies: 5
- Views: 271
Re: octet exceptions
You can also use formal charge to see if the atom would be more stable with an expanded octet.
- Sun Oct 27, 2019 9:36 pm
- Forum: Resonance Structures
- Topic: Drawing Resonance Structures
- Replies: 3
- Views: 168
Re: Drawing Resonance Structures
It should be the arrows indicated between the various structures because we haven't really learned orgo yet.
- Mon Oct 21, 2019 10:52 am
- Forum: *Shrodinger Equation
- Topic: Hamiltonian
- Replies: 6
- Views: 340
Re: Hamiltonian
Yea, he specifically said in lecture that we will never be tested on this.
- Mon Oct 21, 2019 10:48 am
- Forum: Einstein Equation
- Topic: Alternative unit for J
- Replies: 4
- Views: 249
Re: Alternative unit for J
In what types of circumstances would it be necessary for us to convert J into these units? Can someone give a sample problem or example? I don't think there's any instance in chemistry where you would have to break down these units and use them, but in physics it can be useful to know these units t...
- Mon Oct 21, 2019 10:47 am
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: How to use it
- Replies: 5
- Views: 238
Re: How to use it
In addition to Brianna Becerra 1F, you would typically use this equation when being asked for the minimum uncertainty in speed/velocity when given the physical constraints or vice versa. Is minimum uncertainty something different or when we solve this equation we get minimum uncertainty? Minimum un...
- Mon Oct 21, 2019 10:45 am
- Forum: Quantum Numbers and The H-Atom
- Topic: Z
- Replies: 5
- Views: 291
Re: Quantum Number Z
We have not learned about a quantum number Z, but the letter Z can represent the nuclear charge of an atom.
- Mon Oct 21, 2019 10:43 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: S and P orbital
- Replies: 3
- Views: 181
Re: S and P orbital
Because in the case of the s and p orbitals, the difference between the energy of the orbitals are too great to make a difference when you have a full p orbital vs a full s orbital. In the 3d orbital vs the 4s orbital, the energies are very similar, so the fullness of the subshell makes a difference.
- Sun Oct 13, 2019 11:32 am
- Forum: Properties of Light
- Topic: Rydberg constant
- Replies: 7
- Views: 261
Re: Rydberg constant
The formula was derived empirically, meaning they looked at the data they collected from performing a spectroscopic experiment with hydrogen and developed a formula that fit the data they had. This means that it's only applicable to hydrogen.
- Sun Oct 13, 2019 11:30 am
- Forum: Empirical & Molecular Formulas
- Topic: Nomenclature
- Replies: 11
- Views: 2254
Re: Nomenclature
Pretty sure we have to know how to do it at some point, but we're not expected to do it right now.
- Sun Oct 13, 2019 11:29 am
- Forum: Balancing Chemical Reactions
- Topic: F.3
- Replies: 5
- Views: 349
Re: F.3
When I asked my TA they said that we are expected to memorize the names of cations and anions, but I'm not sure if we have to memorize the acids yet since that's something we will cover later.
- Sat Oct 12, 2019 7:02 pm
- Forum: SI Units, Unit Conversions
- Topic: Weekly Posts
- Replies: 7
- Views: 246
Re: Weekly Posts
Pretty sure it's before 11:59 pm on Sunday
- Sat Oct 12, 2019 7:01 pm
- Forum: Significant Figures
- Topic: Sig Figs in Answer
- Replies: 8
- Views: 422
Re: Sig Figs in Answer
Although it's usually good practice to go to 4 for mass percentage composition, it actually depends on how many sig figs you have for the mass of elements you use. For example, if you use 12.01 for Carbon, you have 4. But if you use 12.0107, you have 6.
- Thu Oct 03, 2019 11:46 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Molarity Equation
- Replies: 2
- Views: 142
Re: Molarity Equation
Molarity does not have the units of moles. It has the units mol/L, which is denoted as M in some cases.
- Wed Oct 02, 2019 12:08 pm
- Forum: Empirical & Molecular Formulas
- Topic: Empirical and Molecular Formula Masses
- Replies: 5
- Views: 248
Re: Empirical and Molecular Formula Masses
If the given mass of the molecular formula is the g/mol, yes the empirical formula is wrong.
- Tue Oct 01, 2019 3:58 pm
- Forum: Significant Figures
- Topic: Question about significant figures and rounding a number
- Replies: 4
- Views: 308
Re: Question about significant figures and rounding a number
In regards to rounding for significant figures, you count out how many figures your answer should have first. So if your sig figs were 1, and your answer was 5.454545, you would only take the 5 in the ones place. Next, you would look one number to the right. You then apply the golden rule of roundin...
- Tue Oct 01, 2019 3:51 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: G.25 Dilution
- Replies: 4
- Views: 195
Re: G.25 Dilution
So if the wording is "double the volume 90 times," that means you have to multiply 10 mL by 2 90 times. An easy way to do this is just 10 mL * 2^90, which effectively "doubles the volume 90 times" since you multiply by 2 90 times. Now you have a volume initial (10 mL), a molarity...
- Mon Sep 30, 2019 4:24 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Fundamental E Problem 1
- Replies: 3
- Views: 209
Re: Fundamental E Problem 1
It's not really a formula, but you would use Avogadro's number multiplied by the diameter of an Ag atom, since 1 mol of Ag is 6.022 x 10^23 atoms. This would give you the length of the fiber assuming that it is only one atom thick and all the atoms are lined up perfectly.