I don't have a list but I have two assumptions :
1. When a rxn is isothermal/reversible delta S Universe = 0
2. When a rxn is irreversible delta S Surroundings = 0
Search found 61 matches
- Tue Feb 12, 2019 5:58 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Reasonable Assumptions
- Replies: 2
- Views: 18
- Tue Feb 12, 2019 5:56 pm
- Forum: Student Social/Study Group
- Topic: Equations Sheet
- Replies: 1
- Views: 14
- Tue Feb 12, 2019 5:55 pm
- Forum: Calculating Work of Expansion
- Topic: moles and entropy
- Replies: 3
- Views: 19
Re: moles and entropy
I guess what it comes down to is if you have enough information to calculate moles using pv=nrt, so if you're given all the information then you'd solve for n.
- Sun Feb 10, 2019 6:18 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Midterm #1 14B
- Replies: 12
- Views: 113
Re: Midterm #1 14B
Ronald Thompson 1F wrote:Is there a solutions guide as well?
On the post Lyndon said that we shouldn't expect a solutions guide, so I'm assuming the only way to get answers is to go to the review session or get them from a buddy
- Thu Feb 07, 2019 12:40 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Textbook Question
- Replies: 1
- Views: 19
Re: Textbook Question
So for this problem you're gonna wanna use the ideal gas equations, Cp (constant pressure) is 5/2 of the gas constant (which is 8.314) and Cv (constant volume) 3/2 of the same gas constant. One you calculate the C for each scenario you'll plug it into equation nCdeltaT to solve for q which is the he...
- Thu Feb 07, 2019 12:34 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: delta u
- Replies: 2
- Views: 15
Re: delta u
I don't think so just because delta U is made up by the sum of heat and work done and work can still be done even if there's constant temperature.
- Thu Feb 07, 2019 12:32 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm
- Replies: 8
- Views: 77
Re: Midterm
I think Lavelle said something about what we learn up to Entropy will be the only thing we're tested on from Unit 4
- Thu Jan 31, 2019 8:08 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Reaction Enthalpy
- Replies: 3
- Views: 16
Re: Reaction Enthalpy
LedaKnowles2E wrote:What's delta U?
Delta U is the change in internal energy
- Thu Jan 31, 2019 8:06 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Enthalpy
- Replies: 6
- Views: 24
Re: Enthalpy
They're just given as positive values, but if you're forming the bond then you would write them as negative because it is an exothermic process
- Wed Jan 30, 2019 6:31 pm
- Forum: Phase Changes & Related Calculations
- Topic: Week 4 Homework
- Replies: 12
- Views: 95
Re: Week 4 Homework
Megan_Ervin_1F wrote:Why does this section talk about delta U? I don't recall learning about delta U in lecture...
I think we haven't learned about it yet. Lavelle in class today mentioned how he is teaching the material in a different order than the textbook goes.
- Thu Jan 24, 2019 10:34 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Polyprotic acid question
- Replies: 1
- Views: 22
Re: Polyprotic acid question
It mentioned in the textbook that if the second protonation is less than 1/1000 of the original one you can just solve for the first one and use that value of H3O/OH to calculate pH/pOH. It's because the second protonation would be so small there it would make no difference. H2SO4 is the exception i...
- Wed Jan 23, 2019 6:01 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Strong vs. weak acids and bases?
- Replies: 5
- Views: 24
Re: Strong vs. weak acids and bases?
Here's a list of the strong acids and bases! You can assume everything else is weak. Hope this helps!
- Wed Jan 23, 2019 4:38 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Ka and pH
- Replies: 6
- Views: 40
Re: Ka and pH
I don't believe there's any equation that will relate the two. You would just have to use an ICE box, solve for the concentration of H3O/OH and then calculate pH/pOH
- Thu Jan 17, 2019 5:44 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Strong acids and bases
- Replies: 2
- Views: 16
Re: Strong acids and bases
Here's a picture of the strong acids and bases!
- Thu Jan 17, 2019 5:42 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE Tables [ENDORSED]
- Replies: 11
- Views: 49
Re: ICE Tables [ENDORSED]
When using ICE tables, how do you know when its better to use the quadratic formula to find X or the 5% rule? If you're given a weak acid or base with an equilibrium constant less than 10^-3 you can assume that the x in the (number-x) is negligible and you can just get rid of that x. If it's not a ...
- Wed Jan 16, 2019 6:17 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Approximation of x
- Replies: 3
- Views: 22
Re: Approximation of x
Yes! Professor Lavelle mentioned that anytime the K value is less than 10^-3, the approximation of x in the reactant-x is negligible.
- Wed Jan 09, 2019 5:20 pm
- Forum: Ideal Gases
- Topic: post assessment questions
- Replies: 2
- Views: 20
Re: post assessment questions
To find the equilibrium constant you'll just use the equation concentration of the products/concentrations of the reactants, not pv=nrt.
- Wed Jan 09, 2019 5:18 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Temperature and Equilibrium
- Replies: 3
- Views: 28
Re: Temperature and Equilibrium
Usually you can tell by looking at whether or not the reaction is overall endothermic or exothermic. Usually with problems like that they should give you a delta H or just tell you.
- Tue Jan 08, 2019 8:01 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: HW questions for discussion
- Replies: 2
- Views: 39
Re: HW questions for discussion
Yes, I believe so
Re: Grades
I don't think that's been announced because I believe that's still being decided by Lavelle.
Your best bet for getting a solid answer on this might be emailing Lavelle (also if he does tell you this info plz share with the rest of chemistry community)
Your best bet for getting a solid answer on this might be emailing Lavelle (also if he does tell you this info plz share with the rest of chemistry community)
- Fri Dec 07, 2018 1:38 pm
- Forum: Ionic & Covalent Bonds
- Topic: Inter and Intramolecular Forces
- Replies: 3
- Views: 29
Re: Inter and Intramolecular Forces
Intramolecular forces are those that bind elements together, so for example covalent and ionic bonds.
Intermolecular forces are those that bind molecules or whole compounds together, so LDFs or H-Bonds.
Intermolecular forces are those that bind molecules or whole compounds together, so LDFs or H-Bonds.
- Fri Dec 07, 2018 1:37 pm
- Forum: *Shrodinger Equation
- Topic: Shrodinger Equation meaning
- Replies: 1
- Views: 28
Re: Shrodinger Equation meaning
Yes! All you need to know regarding shrodinger's equation is that it was what was used to calculate the electron densities in a cell and allowed for the "creation" of the orbitals!
- Thu Nov 29, 2018 10:46 pm
- Forum: Dipole Moments
- Topic: Cis vs trans
- Replies: 2
- Views: 23
Re: Cis vs trans
Yes, polarity does depend on whether the molecule is cis or trans.
I don't believe we will ever be given a molecule that could be either and asked about it's polarity if it's not specifically told which way it should be drawn.
I don't believe we will ever be given a molecule that could be either and asked about it's polarity if it's not specifically told which way it should be drawn.
- Thu Nov 29, 2018 11:12 am
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: Melting Points
- Replies: 2
- Views: 41
Re: Melting Points
The first molecule possesses iodine atoms, which are substantially larger than the fluorine atoms found in the second molecule. With a larger atomic number, iodine has more electrons and a larger electron cloud. Iodine, therefore, has a larger polarizability value than fluorine and forces a group o...
- Thu Nov 29, 2018 12:02 am
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: Melting Points
- Replies: 2
- Views: 41
Melting Points
Can someone explain why CHI4 has a higher melting point than CHF4. Thanks!
- Tue Nov 20, 2018 11:17 am
- Forum: SI Units, Unit Conversions
- Topic: Significant 0’s
- Replies: 4
- Views: 80
Re: Significant 0’s
https://www.youtube.com/watch?v=ZnP5vavICZw
this is a different way to remember significant figures
it's helpful if you get confused between decimal present and no decimal
this is a different way to remember significant figures
it's helpful if you get confused between decimal present and no decimal
- Tue Nov 20, 2018 11:14 am
- Forum: Hybridization
- Topic: d Orbital
- Replies: 6
- Views: 36
Re: d Orbital
I don't think we'll need to know how to draw the d orbital because it's complex compared to s and p
- Tue Nov 20, 2018 11:13 am
- Forum: Hybridization
- Topic: Bond Angles
- Replies: 4
- Views: 30
Re: Bond Angles
I believe so! You can also just memorize that a certain shape will have particular angles.
- Thu Nov 15, 2018 11:40 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Do we not need to know oxidation numbers for this class?
- Replies: 2
- Views: 47
Re: Do we not need to know oxidation numbers for this class?
As of right now we haven't covered oxidation numbers! It may be in a different class of the chem series.
- Thu Nov 15, 2018 11:39 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Molecular Shapes
- Replies: 3
- Views: 35
Re: Molecular Shapes
I think this is a good tool for classifying molecular shapes
- Thu Nov 15, 2018 11:36 pm
- Forum: Ionic & Covalent Bonds
- Topic: Polar/non polar molecules
- Replies: 5
- Views: 58
Re: Polar/non polar molecules
another way of looking at this is by looking at the types of bonds.
a molecule is most likely polar is has polar bonds, as in an atom with high EN is bonded to something with low EN.
a nonpolar molecule will compose of nonpolar bonds is two atoms with similar EN
a molecule is most likely polar is has polar bonds, as in an atom with high EN is bonded to something with low EN.
a nonpolar molecule will compose of nonpolar bonds is two atoms with similar EN
- Thu Nov 08, 2018 12:35 pm
- Forum: Lewis Structures
- Topic: Exceptions to the octet rule
- Replies: 3
- Views: 49
Re: Exceptions to the octet rule
Group 13 elements are an exception to the octet rule because in order for them to get an octet they need to form 5 bonds which they're unable to do.
Then any element in the third row or lower is able to have an expanded octet because they have access to an empty d orbital
Then any element in the third row or lower is able to have an expanded octet because they have access to an empty d orbital
- Wed Nov 07, 2018 6:51 pm
- Forum: Ionic & Covalent Bonds
- Topic: Covalent Bond Exception?
- Replies: 2
- Views: 51
Re: Covalent Bond Exception?
I don't think so just because non-metals and metals are usually charged as cations/anions, so these charges would make them ionic bonds. But! there may be exceptions that I've just never heard about.
- Mon Nov 05, 2018 12:07 am
- Forum: Octet Exceptions
- Topic: EXPANDED OCTET
- Replies: 5
- Views: 86
Re: EXPANDED OCTET
In order for them to have a complete octet they would need to create 5 bonds and that doesn't happen
- Mon Nov 05, 2018 12:05 am
- Forum: Empirical & Molecular Formulas
- Topic: Energy Emission of Photons
- Replies: 1
- Views: 39
Re: Energy Emission of Photons
The change in energy may be negative but the Energy given off can never be negative!
- Fri Nov 02, 2018 4:02 pm
- Forum: Ionic & Covalent Bonds
- Topic: Electronegativity Difference
- Replies: 6
- Views: 39
Re: Electronegativity Difference
I believe Lavelle said that we would be unable to make a definitive answer if it lies in between. We would need more information/experimentation to be able to tell which type of bond it is
- Fri Nov 02, 2018 3:57 pm
- Forum: Photoelectric Effect
- Topic: Question on kinetic energy
- Replies: 5
- Views: 61
Re: Question on kinetic energy
That equation is just for the kinetic energy of the ejected electron
You can't use that equation for the energy of a photon because mass is required and a photon has no measurable mass
hope this helped:)
You can't use that equation for the energy of a photon because mass is required and a photon has no measurable mass
hope this helped:)
- Fri Nov 02, 2018 3:55 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Determining electrons
- Replies: 3
- Views: 45
Re: Determining electrons
There are 2 electrons (up/down spin) per magnetic quantum. So for example n=2 l=1 Ml = -1,0,1 so for each of these three there are 2 electrons. So in this case it's a total of 6 electrons. For n=4 ... ms=-1/2 It is only 1 electron because they gave you all four quantum numbers and no 2 electrons in ...
- Fri Nov 02, 2018 3:50 pm
- Forum: Properties of Electrons
- Topic: Test 2
- Replies: 1
- Views: 54
Re: Test 2
By just multiplying by avogadro's number, you'll get how many electrons are in those 5 moles.
You just need to go one step further and multiple that number (the amount of electron in 5 mols) by the mass of an electron, so 9.109x10^-31 kg.
Hope this helped :)
You just need to go one step further and multiple that number (the amount of electron in 5 mols) by the mass of an electron, so 9.109x10^-31 kg.
Hope this helped :)
- Thu Nov 01, 2018 4:08 pm
- Forum: Properties of Electrons
- Topic: Electron Gaining/Losing energy
- Replies: 1
- Views: 51
Re: Electron Gaining/Losing energy
When the atom is excited it is gaining energy, that is why it is able to jump to higher energy levels.
Hope this helped! :)
Hope this helped! :)
- Thu Nov 01, 2018 4:03 pm
- Forum: Student Social/Study Group
- Topic: Studying
- Replies: 7
- Views: 226
Re: Studying
I find doing the homework problems to be really helpful and then usually before the test I'll go over the homework again and redo the problem that I had initially struggled with. Also! sometime scrolling through chemistry community is really helpful just because reading how other people understand/e...
- Thu Nov 01, 2018 1:57 pm
- Forum: Trends in The Periodic Table
- Topic: Electron Affinity of Gallium and Indium
- Replies: 2
- Views: 138
Re: Electron Affinity of Gallium and Indium
Hi Julia!
There are some exceptions to the general trends in the periodic table; however, we aren't expected to know them unless they're explicitly stated.
Hope this helped :)
There are some exceptions to the general trends in the periodic table; however, we aren't expected to know them unless they're explicitly stated.
Hope this helped :)
- Thu Oct 25, 2018 6:41 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Ground state vs. excited state
- Replies: 5
- Views: 93
Re: Ground state vs. excited state
when an electron is said to be in its excited state it has been "energized" and gone up to a particular shell, higher than the one it was originally at. Something that is in its ground state then it has either gone back down from being excited or there wasn't any source of energy and this ...
- Thu Oct 25, 2018 6:39 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Quantum Numbers n, l, and m
- Replies: 5
- Views: 100
Re: Quantum Numbers n, l, and m
Yes, that's how they could be described! and the highest possible subshell of a particular shell would be n-1!
Hope this helped!
Hope this helped!
- Thu Oct 25, 2018 6:37 pm
- Forum: *Shrodinger Equation
- Topic: Help on how to find l, ml, and ms
- Replies: 6
- Views: 127
Re: Help on how to find l, ml, and ms
The maximum value of l is n-1.
Ml is -l to l
and Ms is either +1/2 or -1/2, that's not something we can figure out.
For example, if N=2 then..
l can be 1 or 0
Ml's -1,0,1
Hope this helped!
Ml is -l to l
and Ms is either +1/2 or -1/2, that's not something we can figure out.
For example, if N=2 then..
l can be 1 or 0
Ml's -1,0,1
Hope this helped!
- Sat Oct 20, 2018 6:07 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Confused on Problem 1.57 (regarding the Balmer Series)
- Replies: 8
- Views: 1332
Re: Confused on Problem 1.57 (regarding the Balmer Series)
okay so I dug around a little and found a post that does a good job of explaining it, I'll link it below just in case anyone else is still confused :)
viewtopic.php?t=31402
viewtopic.php?t=31402
- Sat Oct 20, 2018 5:56 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Confused on Problem 1.57 (regarding the Balmer Series)
- Replies: 8
- Views: 1332
Re: Confused on Problem 1.57 (regarding the Balmer Series)
Hello, I'm reviving an old post. However, I don't understand why you can figure out that n2=7 using the Balmer series. Can someone please explain? I'm also confused. I thought the balmer series started at 2, so wouldn't it be: 656.3 (n2), 486.1 (n3), 434.0 (n4), 410.2 (n5)... so wouldn't the next o...
- Wed Oct 17, 2018 8:20 pm
- Forum: SI Units, Unit Conversions
- Topic: How does grading for discussion posts work?
- Replies: 73
- Views: 1297
Re: How does grading for discussion posts work?
I'm having trouble even finding a way to post in this forum. Can someone tell me where/how I can post a question? I agree I am having trouble with that too but in the upper left side with the three lines next to "Quick Links" shows a tab that you can view "your posts" So you go ...
- Wed Oct 17, 2018 8:16 pm
- Forum: *Shrodinger Equation
- Topic: Application
- Replies: 1
- Views: 40
Re: Application
I believe Lavelle said in class that we will never need to calculate anything using this equation, but instead we learned it in order to give us background about how it was utilized when the different orbitals were discovered.
- Wed Oct 17, 2018 8:13 pm
- Forum: Photoelectric Effect
- Topic: Work Function: Increase in Energy
- Replies: 3
- Views: 39
Re: Work Function: Increase in Energy
This depends on whether or not one photon of light has enough energy to eject one electron. If this one photon has enough energy then by increasing the intensity of light you then increase the amount of photons, which then increases the amount of electrons that are ejected (1 photon per electron sor...
- Wed Oct 17, 2018 8:09 pm
- Forum: DeBroglie Equation
- Topic: Energy of ejected electron from energy of light
- Replies: 1
- Views: 23
Re: Energy of ejected electron from energy of light
When you're given the amount of energy of light used to eject an electron it's important to know if there's any excess energy in the form of kinetic energy given off. If there isn't any excess kinetic energy given off then we know the energy of the incoming light is equivalent to the energy of that ...
- Wed Oct 10, 2018 9:47 pm
- Forum: Properties of Light
- Topic: Telling color by wavelength
- Replies: 3
- Views: 25
Re: Telling color by wavelength
Yes, you can! Depending on the color it usually has a range of wavelength it falls under - I'll attach a photo I found online that shows the different colors and their corresponding wavelengths
I hope this helps!
I hope this helps!
- Wed Oct 10, 2018 9:43 pm
- Forum: SI Units, Unit Conversions
- Topic: Ways to remember prefixes
- Replies: 7
- Views: 191
Re: Ways to remember prefixes
Okay this is kinda dumb, but hey whatever works, right? My (Mega) . 10^6 Kitten (Kilo) 10^3 Ben (Base) Null Doesn't (Deci) 10^-1 Count (Centi) 10^-2 Much (Milli) 10^-3 Money, (Micro) - you just have to remember here micro comes after milli 10^-6 No (Nano) 10^-9 Problem! (Pico) 10^-12 basically I thi...
- Wed Oct 10, 2018 9:37 pm
- Forum: SI Units, Unit Conversions
- Topic: State of the molecules
- Replies: 4
- Views: 110
Re: State of the molecules
I've also heard that we aren't expected to be able to identify different states of matter in the equation (like whether or not it's aqueous using solubility rules) so I don't think it'll be required of us!
- Wed Oct 10, 2018 9:34 pm
- Forum: Properties of Electrons
- Topic: Problem 1.15 6th ed.
- Replies: 1
- Views: 34
Re: Problem 1.15 6th ed.
So first things first you're going to want to convert to frequency using the c=wavelength*frequency equation. Then we will put these values in the Rydberg equation and for "n" you would use 1! I've also found this question worked out numerically and I'll go ahead and link that below. https...
- Thu Oct 04, 2018 5:13 pm
- Forum: Limiting Reactant Calculations
- Topic: Competing Reactions
- Replies: 2
- Views: 46
Re: Competing Reactions
I don't think we're ever going to have to identify that a competing reaction is going on. The main reason they mentioned that was to show why the actual yield is less than the theoretical yield (because the reactants can be used for something other than the main reaction going on).
- Tue Oct 02, 2018 11:54 am
- Forum: Significant Figures
- Topic: Mass Percent Composition
- Replies: 4
- Views: 56
Mass Percent Composition
When it comes to finding the mass percent composition of a substance how many sig figs should we round to? Or is there a certain amount of decimal places we need to round to? Or does it not make a difference? I've noticed that in the textbook solution they'll usually do up to two decimal places, but...
- Tue Oct 02, 2018 11:24 am
- Forum: Balancing Chemical Reactions
- Topic: Net Number of Moles
- Replies: 3
- Views: 52
Re: Net Number of Moles
I believe you'd just write out the complete chemical equation and the do total number of moles final - total number of moles initial to find out the net number of moles.
Also, when writing out the combustion remember that the other reactant is oxygen and the products are CO2 and H20
Hope this helped!
Also, when writing out the combustion remember that the other reactant is oxygen and the products are CO2 and H20
Hope this helped!
- Tue Oct 02, 2018 10:48 am
- Forum: Molarity, Solutions, Dilutions
- Topic: Pre-Module Assessment Q23 and Q25
- Replies: 2
- Views: 30
Re: Pre-Module Assessment Q23 and Q25
Hello! Okay, to start off #23 is a dilution problem, so we know we want to get it into a M1V1=M2V2 equation. First we're going to solve for M1 andyou're going to want to convert the grams of KMnO4 into mols (so divide by the molar mass). 5.00 g KMnO4/58.04 g/mol = .0316 mol KMnO4 Then you're going t...
- Sun Sep 30, 2018 8:25 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Happy Lavelle [ENDORSED]
- Replies: 5
- Views: 566
Re: Happy Lavelle [ENDORSED]
Hello, I just made my account and I cannot find where to post my questions? Please help. Hi Sarah! So you go to the main page and scroll down until you see the section labeled "Chem 14a", then go ahead and click on the subject matter that pertains to your question. Then you'll get to a pa...
- Sun Sep 30, 2018 8:10 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Molar Mass of Sulfide
- Replies: 2
- Views: 88
Re: Molar Mass of Sulfide
I found the answer to this question on an earlier post and I believe they did a good job of explaining it! I'll go ahead and link it below :)
viewtopic.php?t=5565
viewtopic.php?t=5565