Search found 58 matches

Sat Mar 17, 2018 9:12 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 Distributions
Replies: 3
Views: 256

Re: Boltzmann Distributions

What is a Boltzmann Distribution exactly?
Sat Mar 17, 2018 9:07 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: What's up with Torrs
Replies: 2
Views: 284

Re: What's up with Torrs

i thought this was a set up to a joke lmao
Sat Mar 17, 2018 8:19 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Midterm question 6a
Replies: 5
Views: 497

Re: Midterm question 6a

I believe you can safely assume that the entropy difference from liquid to gas is going to more than the increase in entropy of a more complex molecule.
Wed Mar 14, 2018 1:38 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Can someone help me identify the oxidizing and reducing agents in this galvanic cell?
Replies: 1
Views: 217

Can someone help me identify the oxidizing and reducing agents in this galvanic cell?

O3/O2, OH- and O3, H+/O2
Sat Mar 10, 2018 10:20 pm
Forum: Second Order Reactions
Topic: the slope
Replies: 12
Views: 827

Re: the slope

Matthew 1C wrote:In regards to the graphs, how do you know what the y intercepts are?

i think for zero order its [A]0, for first order it's ln([A]0, and for second, its 1/[A]0
Sat Mar 10, 2018 10:17 pm
Forum: Zero Order Reactions
Topic: Half Lives? [ENDORSED]
Replies: 7
Views: 691

Re: Half Lives?[ENDORSED]

yes because 1/4th product is = the amount left after two half lives
Sat Mar 10, 2018 8:41 pm
Forum: Second Order Reactions
Topic: Units of k for orders above 2nd
Replies: 6
Views: 499

Re: Units of k for orders above 2nd

isnt there supposed to be an L,L2... at the top??
Sat Mar 10, 2018 8:39 pm
Forum: Second Order Reactions
Topic: the slope
Replies: 12
Views: 827

the slope

can someone tell me what the slope is for the three orders of the reactions. Is it not just k for all of them?
Sat Mar 10, 2018 8:36 pm
Forum: First Order Reactions
Topic: Reaction Order [ENDORSED]
Replies: 6
Views: 541

Re: Reaction Order[ENDORSED]

there is a difference between a chemical reaction and a reaction mechanism. a reaction mechanism tells us exactly what is happening, so we can say the order. but with a simple chemical reaction we don't know what exactly is happening so we can't say the order
Sat Mar 10, 2018 8:32 pm
Forum: First Order Reactions
Topic: Help on 15.3
Replies: 7
Views: 580

Re: Help on 15.3

i think this is just some ambiguity in the solutions manual. the units for k are always mol * L/ s, and they converted to that but just didn't show the work
Sat Mar 10, 2018 8:30 pm
Forum: First Order Reactions
Topic: Units of Reactions. [ENDORSED]
Replies: 5
Views: 611

Re: Units of Reactions.[ENDORSED]

Just subtract 1 from the total order of the reactants (x), and than put Lx / molx * s
Mon Mar 05, 2018 12:59 am
Forum: Second Order Reactions
Topic: Week 9 HW and test promblems
Replies: 5
Views: 482

Re: Week 9 HW and test promblems

Wait I am confused, someone said mechanisms shouldn't be on the test and then also the class website says "Test 3 covers Kinetics Chapter 15.1 to end of 15.6"... why is everything fair game? Catalysts and a lot of the other topics weren't really covered in class were they (yet)? Im sure w...
Mon Mar 05, 2018 12:56 am
Forum: First Order Reactions
Topic: half-lives
Replies: 4
Views: 271

Re: half-lives

i think we just decided to use half life as the norm to help have a common understanding.
Mon Mar 05, 2018 12:50 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Test 2 Q5
Replies: 7
Views: 687

Re: Test 2 Q5

Reducing power is the ability of a species to reduce something else. If it's reducing something else, it is being oxidized itself. Therefore, based on reduction potentials, the more negative a potential is, the more likely it will be oxidized (and therefore has a greater reducing power as it is don...
Sun Feb 25, 2018 5:00 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Finding n
Replies: 15
Views: 1035

Re: Finding n

Justin Folk 3I wrote:How do we know it's a mole of reaction?

What do you mean?? It's the moles of electrons in the balanced reaction.
Thu Feb 22, 2018 2:19 am
Forum: Balancing Redox Reactions
Topic: 14.1 (b)
Replies: 2
Views: 204

14.1 (b)

pretty basic question but can someone help me understand how to find the oxidation numbers of the atoms in the C2H5OH and C2H4O?
Thu Feb 22, 2018 2:08 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Galvanic Cell model [ENDORSED]
Replies: 3
Views: 217

Re: Galvanic Cell model[ENDORSED]

We read cell diagrams from left to right and the anodic compartment is on the left and the cathodic on the right. In this particular example, you can imagine a strip of solid zinc metal submerged in an aqueous solution of Zn 2+ ions (there will also be counter-ions to maintain charge neutrality but...
Wed Feb 21, 2018 12:55 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Standard Potential of a couple
Replies: 3
Views: 177

Re: Standard Potential of a couple

"more negative" is just kind of a weird concept to understand. It just means it has more of a negative "push" on the electrons, giving the stronger reduction
Wed Feb 21, 2018 12:53 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: platinum in cell diagram
Replies: 3
Views: 133

Re: platinum in cell diagram

platinum acts as an innate (neutral) conducting metal in the galvanic cell when the chemical reaction you are observing doesn't have one.
Wed Feb 21, 2018 12:52 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Porous wall and salt bridge
Replies: 1
Views: 108

Porous wall and salt bridge

Can someone help me expand on what these are, if they're different or not, their function and just general information. Thanks
Wed Feb 21, 2018 12:50 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Galvanic Cell model [ENDORSED]
Replies: 3
Views: 217

Galvanic Cell model[ENDORSED]

Can someone help me understand the flow of the galvanic cell. For example, in ZN(s)|Zn2+||Cu2+(aq)|Cu(s), what is the metal component and what is the solution in each side. Also what is flowing through the porous wall.
Sun Feb 11, 2018 8:50 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Number of Bonds and Entropy
Replies: 3
Views: 214

Re: Number of Bonds and Entropy

I think that would work because you increase the vibrational entropy when you increase the number of bonds.
Sun Feb 11, 2018 8:47 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: When does C = 5/2 R or 6/2 R?
Replies: 2
Views: 203

When does C = 5/2 R or 6/2 R?

When should we use these values in the equations?
Sun Feb 11, 2018 8:44 pm
Forum: Van't Hoff Equation
Topic: Constants and formulas
Replies: 7
Views: 508

Re: Constants and formulas

Its not on the sheet he gave us online, but I think it's easy to derive. he gave us the two equations needed to derive it on the sheet, so you can just work from there.
Sun Feb 04, 2018 8:48 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: Reversible and Irreversible Pathways
Replies: 4
Views: 251

Re: Reversible and Irreversible Pathways

Basically, a reversible pathway is one that is in equilibrium. The external and internal pressures are equal, so work is only done if the external pressure decreases slightly, causing the gas to expand to decrease the internal pressure, allowing the system to come back to equilibrium. That is why f...
Sun Feb 04, 2018 8:43 pm
Forum: Van't Hoff Equation
Topic: Constants
Replies: 4
Views: 432

Re: Constants

im pretty sure since they are state functions, they can be considered constant
Fri Feb 02, 2018 1:11 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Replies: 3
Views: 181

I also don't get this. I know that for pressure it's Cp, and for volume it's Cv, but I don't exactly understand what that means.
Sun Jan 28, 2018 11:18 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Definition of Entropy
Replies: 10
Views: 591

Re: Definition of Entropy

entropy can be thought of as the number of possible states that a system can occupy. this idea is pretty synonymous with disorder because the more disorder, the more places things can be.
Sun Jan 28, 2018 11:16 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Test question [ENDORSED]
Replies: 16
Views: 911

Re: Test question[ENDORSED]

I said that energy cannot be created or destroyed, so i think if you said something along those lines you'll be fine. I also put the equation deltaU = q + w
Sun Jan 28, 2018 11:12 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Can a system exchange matter but not energy?
Replies: 4
Views: 226

Can a system exchange matter but not energy?

If it could, what would that classify as??
Fri Jan 19, 2018 1:15 pm
Forum: Student Social/Study Group
Topic: Discussion 1K (Friday 12-12:50) GroupMe link
Replies: 1
Views: 372

Discussion 1K (Friday 12-12:50) GroupMe link

https://app.groupme.com/join_group/37575346/tzZA0A

i think u have to open it on your phone. this is mainly for disc 1k but anybody can join if you're gonna be helpful and productive
Fri Jan 19, 2018 2:13 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpy at constant pressure and volume [ENDORSED]
Replies: 3
Views: 159

Re: Enthalpy at constant pressure and volume[ENDORSED]

I'm also wondering if the whole R concept is going to be tested on considering he didn't discuss it in class.
Fri Jan 19, 2018 2:12 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calorimeter
Replies: 5
Views: 330

Re: Calorimeter

you may have it confused like i did. The calorimeter basically provides the ideal environment so that you can observe certain aspects of a reaction. Sometimes it says it calibrates the calorimeter. That just means they're finding the heat capacity for that specific calorimeter so that they can see h...
Fri Jan 19, 2018 2:07 am
Forum: Calculating Work of Expansion
Topic: Work
Replies: 2
Views: 179

Work

Is an equation done in a piston that moves considered constant pressure? To explain more, if a chemical reaction expands, it causes a pressure increase, but since the piston is moving, the pressure decreases. In the end, it the net pressure 0?
Sun Jan 14, 2018 10:17 pm
Forum: Phase Changes & Related Calculations
Topic: Steam burning more than water question
Replies: 4
Views: 216

Steam burning more than water question

I need some help on clarification on why steam burns more than boiling water. So even though the temperature is the same, the steam burns more and this is because it has more energy? What does energy have to do with the amount of pain you feel? Doesn't only depend on the temperature of the substance...
Sun Jan 14, 2018 10:13 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Molar Heat Capacity
Replies: 4
Views: 118

Re: Molar Heat Capacity

I may have it confused but isn't molar heat capacity per mole?? So isn't it referring to a relationship/ratio so it wouldn't matter how much you had. Correct me if i have it confused.
Sun Jan 14, 2018 10:10 pm
Forum: Phase Changes & Related Calculations
Topic: Open/Closed/Isolated
Replies: 11
Views: 605

Re: Open/Closed/Isolated

I think it would be considered an open system because matter and energy can be transferred in and out of the system. I guess it depends on the experiment being performed in the fish tank or what aspect you're looking at.
Mon Dec 11, 2017 2:31 am
Forum: Administrative Questions and Class Announcements
Topic: Practice Test Fall 2017 [ENDORSED]
Replies: 19
Views: 2620

Re: Practice Test Fall 2017[ENDORSED]

Michelle Pham_3H wrote:The moles of iodine is in a solid state, so it wouldn't be included when determining which side has more moles of gas.
thanks!
Sun Dec 10, 2017 3:08 am
Forum: Administrative Questions and Class Announcements
Topic: Practice Test Fall 2017 [ENDORSED]
Replies: 19
Views: 2620

Re: Practice Test Fall 2017[ENDORSED]

Timothy Kim 1F wrote:for Week 9, problem 6c, why does expansion favor products?

I also have this question. It seems like there are two moles on each side of the reaction.
Tue Nov 28, 2017 10:22 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 11.49 question
Replies: 1
Views: 117

11.49 question

IN the change section of the ICE box for this problem, how do we know that were supposed to do +x, rather than -x?
Mon Nov 27, 2017 2:08 am
Forum: Shape, Structure, Coordination Number, Ligands
Replies: 5
Views: 335

thank you guys^^
Sun Nov 26, 2017 4:22 pm
Forum: Shape, Structure, Coordination Number, Ligands
Replies: 5
Views: 335

Can someone help me understand just what a ligand is?
Is it used when referring to the bonds, or the whole substance?
if its referring to the bond, how is it any different than any other bond?
basically i'm just asking you to tell me all you know about ligands hahaha,
Sun Nov 26, 2017 4:18 pm
Forum: Hybridization
Topic: Filling the hybrid orbitals?
Replies: 12
Views: 941

Re: Filling the hybrid orbitals?

Electrons fill atomic orbitals of the lowest available energy levels before occupying higher levels, so you would complete the orbital until moving on to the next. Yes, so spin-pair in the s-orbital and then parallel spins in the p-orbital before spin-pairing in the p orbital. (Right?) this only ap...
Mon Nov 13, 2017 2:08 am
Forum: Ionic & Covalent Bonds
Topic: different types of bonds
Replies: 6
Views: 457

Re: different types of bonds

I dont know about the polar and non polar, however if the difference between the electronegativities of two bonded atom is greater than two, than the bond is considered ionic. im pretty sure polar and non polar comes down to drawing the molecule and dipole moments, but someone correct me if I'm wrong.
Mon Nov 13, 2017 1:55 am
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Highly Polarizable
Replies: 4
Views: 439

Re: Highly Polarizable

also remember that cations are typically smaller, and anions are typically larger.
Mon Nov 13, 2017 1:53 am
Forum: Electronegativity
Topic: ELECTRON AFFINITY
Replies: 7
Views: 808

Re: ELECTRON AFFINITY

In response to Shannon's question, I think that in general, the noble gases should have an electron affinity of basically 0 because they already have a full valence shell and thus would not tend to try to gain or lose electrons. Halogens would have a high electron affinity because they really want ...
Mon Nov 13, 2017 1:51 am
Forum: Octet Exceptions
Topic: Expanded Octet
Replies: 6
Views: 1194

Re: Expanded Octet

just remember quantum numbers. The l value is the allowed orbitals for each atom.
Mon Nov 13, 2017 1:49 am
Forum: Formal Charge and Oxidation Numbers
Topic: A tip for calculating formal charge [ENDORSED]
Replies: 2
Views: 3084

A tip for calculating formal charge[ENDORSED]

Instead of counting each dot and dividing bonds by two, a tip I learned was just to count each component. one dot/ one line= one component. then subtract that from the valence electrons.
Tue Oct 31, 2017 6:57 pm
Forum: Trends in The Periodic Table
Topic: Negative Electron Affinity
Replies: 2
Views: 329

Re: Negative Electron Affinity

Atoms to the left of the noble gases are almost complete and readily accept electrons and therefore have highly positive electron affinity values. So you can think of negative values of the opposite. Atoms w negative values don't want electrons.
Tue Oct 31, 2017 6:54 pm
Forum: Trends in The Periodic Table
Topic: Effective Nuclear Charge [ENDORSED]
Replies: 4
Views: 705

Re: Effective Nuclear Charge[ENDORSED]

Can you help explain why it would decrease down a group?
Sun Oct 22, 2017 10:36 pm
Forum: Quantum Numbers and The H-Atom
Topic: quantum numbers [ENDORSED]
Replies: 5
Views: 506

Re: quantum numbers[ENDORSED]

what helped me understand was looking at this periodic table with all the electron configurations and testing myself
https://sciencenotes.org/color-periodic ... ions-2015/
the text is pretty small but you can zoom in
Sun Oct 22, 2017 6:59 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Quantum Numbers [ENDORSED]
Replies: 2
Views: 182

Re: Quantum Numbers[ENDORSED]

also the value of l is 0 to (n-1), so the n must be given if the l isn't
Mon Oct 16, 2017 2:00 am
Forum: Properties of Light
Topic: Light travels as a "wave"
Replies: 5
Views: 387

Re: Light travels as a "wave"

Using the idea of a wave is a easy way to understand of light works. When relating it to ocean waves we can see how it works. Just like the waves can vary in size and how often waves are coming in, the same variations work for light. Different light has different wave lengths and frequencies to use...
Sun Oct 15, 2017 11:18 pm
Forum: Einstein Equation
Topic: Lyman and Blamer series [ENDORSED]
Replies: 7
Views: 842

Re: Lyman and Blamer series[ENDORSED]

A weird way i use to remember which is which is to count the vowels. Lyman has one vowel (y doesnt count haha), so n=1, and balmer has two, so n=2
Sun Oct 15, 2017 11:15 pm
Forum: Properties of Electrons
Topic: Energy Level Change
Replies: 5
Views: 462

Re: Energy Level Change

is there any specific reason an electron wouldn't automatically just jump back to level one?
is it random?
Sun Oct 15, 2017 11:12 pm
Forum: Properties of Light
Topic: Light travels as a "wave"
Replies: 5
Views: 387

Light travels as a "wave"

Can someone clarify what that specifically means? What direction is that wave going? What is up and what is down to light? Are all of the waves traveling in the same orientation?
Thu Oct 05, 2017 10:47 pm
Forum: Significant Figures
Topic: Clarification
Replies: 4
Views: 375

Re: Clarification

Also, remember that constants don't count for sig figs in your calculations. So if you divide a number by 2, you don't have to round to one sig fig, because 2 is a constant and it is EXACTLY 2. You should only round to sig figs when the numbers you are using were calculated or found scientifically/e...
Thu Oct 05, 2017 10:38 pm
Forum: Empirical & Molecular Formulas
Topic: Question M19 (Molecular Formula)
Replies: 5
Views: 373

Re: Question M19 (Molecular Formula)

Also, its important to remember that oxygen is typically a reactant in combustion reactions. Remember to include this in your equation.