Search found 65 matches
- Sat Mar 16, 2019 4:24 pm
- Forum: Balancing Redox Reactions
- Topic: multiplying half reactions [ENDORSED]
- Replies: 4
- Views: 4408
Re: multiplying half reactions [ENDORSED]
you don't multiply cell potential, only the coefficients in the half reaction
- Thu Mar 14, 2019 12:41 pm
- Forum: Experimental Details
- Topic: Collision Theory
- Replies: 8
- Views: 1300
Collision Theory
What exactly do we have to know about collision theory for the final?
- Thu Mar 14, 2019 12:37 pm
- Forum: Second Order Reactions
- Topic: solving for time elapsed
- Replies: 1
- Views: 222
Re: solving for time elapsed
find k using the half life equation then use integrated rate law equation for a second life reaction. Ainitial should be 1 and Afinal should be 1/16
- Sun Mar 10, 2019 9:16 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Formulas
- Replies: 6
- Views: 652
Re: Formulas
usually look for the unknown the question is asking for and list out the values they give you to know which equation to use.
- Sun Mar 10, 2019 9:15 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: K Value
- Replies: 7
- Views: 764
Re: K Value
most problems don't assign points for sig figs because they're appointed for something else, but with as many points that are on the final, I wouldn't be surprised if they count for something.
- Sun Mar 10, 2019 9:10 pm
- Forum: First Order Reactions
- Topic: Half life of 1st-Order Reaction
- Replies: 2
- Views: 378
Re: Half life of 1st-Order Reaction
because half life of any quantity of a first order reaction is the same, it'll take the same time to halve no matter how much it started with
- Sun Mar 10, 2019 8:42 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: What does K say about stability?
- Replies: 5
- Views: 3576
Re: What does K say about stability?
The higher the K the lower the stability of the reactants and higher the stability of the products
- Sun Mar 10, 2019 8:37 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Catalysts
- Replies: 6
- Views: 772
Re: Catalysts
Catalysts don't actually make the reaction slower or faster, what it does is it offers an alternate pathway in which the activation energy is lower, thereby making the reaction proceed more completely with a given energy.
- Sun Mar 10, 2019 8:34 pm
- Forum: Balancing Redox Reactions
- Topic: Acidic Solutions
- Replies: 7
- Views: 867
Re: Acidic Solutions
what do we do when the reaction isn't acidic. add oh- instead?
- Sun Mar 10, 2019 8:29 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Final Material
- Replies: 4
- Views: 499
Re: Final Material
he has also put a homework question on every test i believe
- Sun Mar 10, 2019 8:28 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Test 2
- Replies: 12
- Views: 1127
Re: Test 2
a negative gibbs free energy means it is spontaneous, unlike a negative entropy which means its nonspontaneous
- Sun Mar 10, 2019 8:27 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell diagram
- Replies: 6
- Views: 619
Re: Cell diagram
there must be a solid in the reaction so if there isn't one we add Pt(s) in place
- Wed Feb 27, 2019 6:36 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 4.37 c
- Replies: 1
- Views: 218
4.37 c
Why is Q listed with both Pressures on top and both concentrations on the bottom on the solution manual? I thought Q was Products over reactants?
- Wed Feb 20, 2019 5:22 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Deprotonation
- Replies: 3
- Views: 330
Re: Deprotonation
this is because the ka of that reaction relates to h3po4 losing it's first electron and ka2 is h3po4 losing its second electron or h2po4- losing an electron
- Wed Feb 20, 2019 5:21 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Deprotonation
- Replies: 3
- Views: 330
Re: Deprotonation
deprotonation is losing an electron, so ka2 would be losing two electrons
- Wed Feb 20, 2019 4:25 pm
- Forum: General Science Questions
- Topic: Midterm
- Replies: 5
- Views: 865
Re: Midterm
it's the second deprotonation of h3po4
the first would include h2po4- in the product, the second will include hpo4^2- in the product
the first would include h2po4- in the product, the second will include hpo4^2- in the product
- Wed Feb 20, 2019 3:18 pm
- Forum: Administrative Questions and Class Announcements
- Topic: midterm
- Replies: 2
- Views: 374
midterm
does anyone know when we'll get our midterms back?
- Tue Feb 19, 2019 10:41 am
- Forum: Phase Changes & Related Calculations
- Topic: #10 on Hotdog
- Replies: 3
- Views: 663
Re: #10 on Hotdog
thank you!!
- Tue Feb 12, 2019 2:58 pm
- Forum: Phase Changes & Related Calculations
- Topic: #10 on Hotdog
- Replies: 3
- Views: 663
#10 on Hotdog
10. Michael asks me for water with no ice at a dining hall. Just to spite him, I measure 25.0 g of ice at 0.00 oC and drop it into 265 mL of water at 25.0 oC. What is the final temperature of the water? i know we set qice=-qwater and from that i got a T of 296.91K. Now to find the final answer do I ...
- Tue Feb 12, 2019 2:35 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Lyndon's HOTDOG MIDTERM REVIEW SESSION!! FINALLY!
- Replies: 49
- Views: 11726
Re: Lyndon's HOTDOG MIDTERM REVIEW SESSION!! FINALLY!
with a corresponding q=-11.45kj?
- Tue Feb 12, 2019 2:34 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Lyndon's HOTDOG MIDTERM REVIEW SESSION!! FINALLY!
- Replies: 49
- Views: 11726
Re: Lyndon's HOTDOG MIDTERM REVIEW SESSION!! FINALLY!
I also got that the other part of w=9.12 from w=-pdv. so i got a total of 11.45kj or 1.145x10^5j for w. is this correct?
- Tue Feb 12, 2019 2:32 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Lyndon's HOTDOG MIDTERM REVIEW SESSION!! FINALLY!
- Replies: 49
- Views: 11726
Re: Lyndon's HOTDOG MIDTERM REVIEW SESSION!! FINALLY!
what was the full answer for w on #6? I got that part of it is 2.33KJ from the w=-nrtln(v2/v1)
- Wed Jan 30, 2019 3:09 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Homework/reading
- Replies: 3
- Views: 2331
Re: Homework/reading
skipping around is kinda necessary for the homework
- Wed Jan 30, 2019 3:07 pm
- Forum: Phase Changes & Related Calculations
- Topic: Week 4 Homework
- Replies: 12
- Views: 1261
Re: Week 4 Homework
i would stick to outline 3, but the homework kinda requires you to read because we haven't gone over too much in lecture so far
- Wed Jan 30, 2019 3:06 pm
- Forum: Phase Changes & Related Calculations
- Topic: J vs. kJ
- Replies: 9
- Views: 1092
Re: J vs. kJ
J is the SI unit, but if the rest of the problem is worked out in kJ then probably use that. on tests they'll probably specify
- Wed Jan 30, 2019 3:05 pm
- Forum: Phase Changes & Related Calculations
- Topic: Test #1
- Replies: 11
- Views: 981
Re: Test #1
yes, we usually get our tests back exactly a week after we take them
- Wed Jan 30, 2019 3:03 pm
- Forum: Phase Changes & Related Calculations
- Topic: Water phase change graph
- Replies: 6
- Views: 1488
Re: Water phase change graph
the horizontal lines represent the phase change and the length of the line represents the energy added over time
- Wed Jan 30, 2019 3:02 pm
- Forum: Calculating Work of Expansion
- Topic: Units for Work
- Replies: 6
- Views: 713
Re: Units for Work
^^ but yes, we will mostly be using SI units which includes joules
- Wed Jan 23, 2019 8:20 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 6th edition, 12.69
- Replies: 3
- Views: 379
Re: 6th edition, 12.69
^^divide kw by the kb for nh3 and you'll get the ka for nh4+
- Wed Jan 23, 2019 1:22 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Exothermic and endothermic
- Replies: 3
- Views: 440
Re: Exothermic and endothermic
an exothermic reaction gives off energy as heat for ex. and has a low activation energy, an endothermic reaction requires more energy and will take it from the surroundings
- Wed Jan 23, 2019 9:57 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5% Rule
- Replies: 3
- Views: 231
Re: 5% Rule
you can know it's okay to use it if the K is below 10^-3!
- Wed Jan 23, 2019 9:55 am
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Inert Gas
- Replies: 2
- Views: 188
Re: Inert Gas
inert gases are just basically saying noble gasses
- Tue Jan 22, 2019 3:28 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Ka and Kb
- Replies: 3
- Views: 242
Re: Ka and Kb
the same goes for Kb and Bases!
- Tue Jan 22, 2019 3:28 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Ka and Kb
- Replies: 3
- Views: 242
Re: Ka and Kb
Ka reflects how much the acid will disassociate in reaction so a high Ka(higher than 1000) will indicate it being a strong acid and a low Ka(lower than .001) will indicate it being a weak acid.
- Tue Jan 22, 2019 3:25 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Homework for Week 3
- Replies: 5
- Views: 497
Re: Homework for Week 3
Acid's and bases will probably be preferable, but in preparation for the test I'm sure you can do a mixture without it being an issue
- Wed Dec 05, 2018 10:04 pm
- Forum: Naming
- Topic: Oxidation Numbers
- Replies: 3
- Views: 360
Re: Oxidation Numbers
yeah i think so because oxidation is a process that takes electrons away, leaving the elements with positive charges
- Wed Dec 05, 2018 9:59 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polar or nonpolar
- Replies: 4
- Views: 405
Re: Polar or nonpolar
it's a tetrahedral shape so i don't think the angles would allow for the dipole moments to cancel out
- Tue Dec 04, 2018 1:29 pm
- Forum: Administrative Questions and Class Announcements
- Topic: About the test
- Replies: 8
- Views: 1076
Re: About the test
becca_vandyke_4b wrote:Are we going to get the same equation sheet for the final thats been on the tests? Trying to figure out if I need to memorize any equations.
yeah we're probably gonna get the same equation sheet
- Tue Dec 04, 2018 11:47 am
- Forum: Lewis Acids & Bases
- Topic: KBr
- Replies: 5
- Views: 459
Re: KBr
"KBr dissociates into K+ and Br-. Br- reacts to make HBr, a strong acid. Since Br- is the conjugate base of HBr, it is weak. K+ is also weak so the two weak components sort of offset and have no real effect on the pH, making it neutral."
- Mon Dec 03, 2018 12:11 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Seesaw
- Replies: 13
- Views: 2094
Re: Seesaw
I think less than 180 is also acceptable if you're considering the angle created by the top, middle, and bottom atoms in this structure
- Mon Dec 03, 2018 12:09 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Final Grades
- Replies: 10
- Views: 1084
Re: Final Grades
The class isn't based on a curve of our own class, but all the classes before us. This means that he has taken the averages from previous classes and uses them as a guideline for how grades should be set
- Mon Dec 03, 2018 12:06 pm
- Forum: Naming
- Topic: Naming the Shape
- Replies: 6
- Views: 629
Re: Naming the Shape
using the lewis formula can be helpful!
- Mon Nov 26, 2018 1:26 pm
- Forum: Dipole Moments
- Topic: Dipole Moments
- Replies: 4
- Views: 355
Re: Dipole Moments
They tell us about the charge separation in a molecule, the larger the difference in electronegativities of bonded atoms, the larger the dipole moment.
- Wed Nov 14, 2018 6:55 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: bent structure? also, intermolecular interactions
- Replies: 3
- Views: 225
Re: bent structure? also, intermolecular interactions
The bent shape occurs when there are three total atoms with a lone pair or 2 on the central atom such as on H2O
- Wed Nov 14, 2018 6:53 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Angular Shape
- Replies: 4
- Views: 661
Re: Angular Shape
Yeah that's basically it. An example is H2O where there's two lone pairs on oxygen which pushes down the Hydrogen atoms to make room
- Wed Nov 14, 2018 2:24 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Octet Rule
- Replies: 6
- Views: 791
Re: Octet Rule
Sulfur, phosphorus, silicon, and chlorine are common examples of elements that form an expanded octet which means they can have more than the usual 8.
- Wed Nov 14, 2018 2:22 pm
- Forum: Student Social/Study Group
- Topic: Test 3
- Replies: 6
- Views: 963
Re: Test 3
this is what Dr. Lavelle posted:
"Test 3 covers: End of Bonding from 3.12 (6 Ed.) and from 2D (7 Ed.); and all of Molecular Shape and Structure (see Syllabus and Outlines for details)."
"Test 3 covers: End of Bonding from 3.12 (6 Ed.) and from 2D (7 Ed.); and all of Molecular Shape and Structure (see Syllabus and Outlines for details)."
- Wed Nov 14, 2018 2:20 pm
- Forum: Resonance Structures
- Topic: Formal Charge
- Replies: 13
- Views: 1423
Re: Formal Charge
It should also be noted that certain atoms like Carbon almost always need to have a formal charge of zero to maintain it's stability
- Tue Nov 13, 2018 7:01 pm
- Forum: Octet Exceptions
- Topic: octet exceptions
- Replies: 2
- Views: 362
Re: octet exceptions
some exceptions to the octet rule can be found in the 3rd period in the p block because they have an unoccupied d block that lets them expand past the octet rule
- Tue Nov 13, 2018 2:25 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Thanksgiving Wednesday
- Replies: 9
- Views: 884
Re: Thanksgiving Wednesday
Does anybody know how we will turn in homework for Week 8 if we have discussion on Thurs/Fri? Dr. Lavelle said "Hand in homework for Weeks 8 and 9 in Week 9. Therefore in Week 9 discussion section hand in 14 homework problems. These will be excellent preparation for Test 3 during Week 9. Test ...
- Tue Nov 13, 2018 2:20 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polar vs. NonPolar
- Replies: 5
- Views: 606
Re: Polar vs. NonPolar
It is also important to note that molecular structure plays an important role in polarity. For example, C02 would be expected to be a polar molecule, since the difference in electronegativity of C and O is large. However, the two O's are on either side of the C, giving it a linear shape. Due to thi...
- Tue Nov 13, 2018 2:18 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Formal Charge
- Replies: 4
- Views: 480
Re: Formal Charge
octet rule is the first thing we consider, so as long as you keep in mind exceptions to the octet rule, then you should do octet rule first and check formal charges after.
- Tue Nov 13, 2018 2:14 pm
- Forum: Octet Exceptions
- Topic: Exceptions
- Replies: 10
- Views: 1379
Re: Exceptions
some exceptions to the octet rule can be found in the 3rd period in the p block because they have an unoccupied d block
- Sun Nov 04, 2018 9:10 am
- Forum: Ionic & Covalent Bonds
- Topic: covalent bonds
- Replies: 2
- Views: 358
Re: covalent bonds
Nonmetals typically have much higher ionization energies which makes them less likely to lose electrons and become cations
- Sun Nov 04, 2018 9:07 am
- Forum: Lewis Structures
- Topic: Triangle Bond?
- Replies: 2
- Views: 439
Re: Triangle Bond?
The outside oxygen atoms both connect to the central oxygen with one double bond and one single bond, but they aren't connected to each other
- Sun Nov 04, 2018 9:06 am
- Forum: Lewis Structures
- Topic: Triangle Bond?
- Replies: 2
- Views: 439
Re: Triangle Bond?
The lewis structure for O3 bent, but not triangular
- Thu Oct 25, 2018 10:31 pm
- Forum: Properties of Electrons
- Topic: Electron Energy
- Replies: 3
- Views: 487
Re: Electron Energy
it is absorbing energy
- Thu Oct 25, 2018 10:29 pm
- Forum: Properties of Electrons
- Topic: Degeneracy
- Replies: 11
- Views: 1252
Re: Degeneracy
"electron orbitals that have the same energy levels are called degenerate orbitals. ... For example, p orbitals consist of three degenerate orbitals that all have exactly the same energy level."
- Thu Oct 25, 2018 10:25 pm
- Forum: Properties of Electrons
- Topic: Textbook reading Test 2
- Replies: 2
- Views: 197
Re: Textbook reading Test 2
No, not everything in chapter two will be tested on this one
- Wed Oct 17, 2018 9:15 pm
- Forum: Properties of Light
- Topic: Electromagnetic Radiation
- Replies: 3
- Views: 357
Re: Electromagnetic Radiation
the slope of the wave decreases which in turn decreases the extent of change in the electric field
- Wed Oct 17, 2018 9:13 pm
- Forum: Properties of Light
- Topic: Test 2 [ENDORSED]
- Replies: 15
- Views: 1267
Re: Test 2 [ENDORSED]
this is also what i heard
- Wed Oct 17, 2018 9:11 pm
- Forum: Properties of Light
- Topic: Wave/particles
- Replies: 5
- Views: 492
Re: Wave/particles
yeah they have both properties seemingly at the same time
- Wed Oct 10, 2018 8:42 pm
- Forum: Significant Figures
- Topic: Test 1
- Replies: 3
- Views: 513
Re: Test 1
I don't think things like M=moles/liters will be given though!
- Wed Oct 10, 2018 8:40 pm
- Forum: Administrative Questions and Class Announcements
- Topic: How to list Chem_Mod posts
- Replies: 25
- Views: 93634
Re: How to list Chem_Mod posts
Thank you!!
- Wed Oct 10, 2018 8:40 pm
- Forum: Limiting Reactant Calculations
- Topic: Question M11
- Replies: 2
- Views: 362
Re: Question M11
Yes! and in the reaction that creates p4o10 from p4o6 and o2, o2 will be the limiting reactant.