Search found 60 matches
- Wed Mar 06, 2019 5:29 pm
- Forum: General Rate Laws
- Topic: Rate Laws and Temperature
- Replies: 4
- Views: 439
Re: Rate Laws and Temperature
k once calculated is only for that temperature, which is why we have the Arrhenius equation to help calculate the new k when temperature changes
- Wed Mar 06, 2019 5:26 pm
- Forum: General Rate Laws
- Topic: does k change if rxn is multiplied?
- Replies: 6
- Views: 1523
Re: does k change if rxn is multiplied?
k is a constant for the equation so it should not change if the rxn is multiplied
- Wed Mar 06, 2019 5:24 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: zero and first
- Replies: 5
- Views: 565
Re: zero and first
zero order reactions do not depend on the initial concentrations while 1st order reactions are directly proportional to the concentrations
- Mon Mar 04, 2019 8:47 am
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: rate of change
- Replies: 4
- Views: 781
Re: rate of change
the coefficents of the balanced reaction relate the rates to each other
- Mon Mar 04, 2019 8:46 am
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Activation energy
- Replies: 8
- Views: 840
Re: Activation energy
Activation energy is the energy needed for a reaction to occur, so the lower the activation energy, the more thermodynamically favorable the process is
- Mon Mar 04, 2019 8:41 am
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: how is kinetics different?
- Replies: 17
- Views: 1653
Re: how is kinetics different?
Thermo talks about the amount of energy transferred while kinetics talks about the rate that energy is transferred
- Sat Feb 23, 2019 9:56 am
- Forum: Balancing Redox Reactions
- Topic: Redox Rxn
- Replies: 3
- Views: 422
Re: Redox Rxn
I think we just need to memorize the normal periodic trends that we used last quarter and then we will figure out the transition metal ones based on the rxn
- Sat Feb 23, 2019 9:54 am
- Forum: Balancing Redox Reactions
- Topic: Test 2 Material
- Replies: 11
- Views: 948
Re: Test 2 Material
This is what the class website says : "Test 2 covers all topics on Gibbs free energy and electrochemistry up to but not including the Nernst equation (which is all the new material covered in class Weeks 6 and 7)", so I think everything from after the midterm up to Monday
- Sat Feb 23, 2019 9:53 am
- Forum: Balancing Redox Reactions
- Topic: difference between oxidation and reduction
- Replies: 8
- Views: 968
Re: difference between oxidation and reduction
oxidation loses electrons so the charge becomes more positive, while reduction gains electrons so the charge becomes more negative
- Fri Feb 15, 2019 1:42 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Quick Conceptual question
- Replies: 7
- Views: 913
Re: Quick Conceptual question
Enthalpy is a measure of heat transfer while entropy is a measure of disorder in a system
- Fri Feb 15, 2019 1:41 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Isobaric
- Replies: 12
- Views: 1675
Re: Isobaric
isobaric means that the volume is still changing so you can still calculate work
- Fri Feb 15, 2019 1:40 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3457713
Re: Post All Chemistry Jokes Here
What was the chemists favorite drink?
ChemisTEA
ChemisTEA
- Fri Feb 08, 2019 12:52 am
- Forum: Phase Changes & Related Calculations
- Topic: Units of enthalpy
- Replies: 5
- Views: 533
Re: Units of enthalpy
kJ/mol
- Fri Feb 08, 2019 12:48 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Isolated System
- Replies: 5
- Views: 789
Re: Isolated System
An isolated system is useful to calculate changes that happen based solely on the reaction and not due to exchanges with the surrounding
- Fri Feb 08, 2019 12:46 am
- Forum: Calculating Work of Expansion
- Topic: Degeneracy
- Replies: 6
- Views: 828
Re: Degeneracy
Degeneracy is the number of possible states that atoms can exist in and it is related to entropy because the higher the degeneracy the more potential for disorder and higher entropy.
- Fri Feb 01, 2019 7:59 pm
- Forum: Calculating Work of Expansion
- Topic: negative vs. positive internal energy
- Replies: 2
- Views: 309
Re: negative vs. positive internal energy
When U is negative, that means the net energy is out of the system or the system is doing work on the surrounding. When U is positive, that means net energy is into the system or the surroundings are doing work on the system.
- Fri Feb 01, 2019 7:56 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Qsystem+Qsurr=0?
- Replies: 6
- Views: 1841
Re: Qsystem+Qsurr=0?
The system gains the heat of the surroundings in some reactions but the system loses the heat to the surroundings in other reactions so the net change in heat is 0 which is why Qsyst + Qsurr = 0.
- Fri Feb 01, 2019 7:52 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Thermo Test/Midterm
- Replies: 9
- Views: 751
Re: Thermo Test/Midterm
I think we will be expected to know the basic shape of the structures but they won't need to be detailed.
- Sat Jan 26, 2019 5:06 pm
- Forum: Phase Changes & Related Calculations
- Topic: Why steam causes severe burns
- Replies: 9
- Views: 1965
Re: Why steam causes severe burns
In order to get to the phase of steam, the water will have had to accumulate more heat than just boiling water thus having the capability to cause more severe burns.
- Sat Jan 26, 2019 5:03 pm
- Forum: Phase Changes & Related Calculations
- Topic: Enthalpy as a state property
- Replies: 2
- Views: 364
Re: Enthalpy as a state property
Enthalpy is heat under constant pressure, so while enthalpy can be described as a state function, heat cannot because in its general definition it can have changing pressures
- Sat Jan 26, 2019 5:01 pm
- Forum: Phase Changes & Related Calculations
- Topic: The qp symbol
- Replies: 3
- Views: 1492
Re: The qp symbol
The q refers to heat but qp is enthalpy because it describes heat under a constant pressure. Enthalpy can be endothermic or exothermic, meaning qp can be positive or negative as well
- Sun Jan 20, 2019 5:09 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Kw
- Replies: 6
- Views: 560
Re: Kw
they are equal in water because they are at equilibrium
- Sun Jan 20, 2019 5:08 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: K vs. Q
- Replies: 5
- Views: 3976
Re: K vs. Q
K is the equilibrium constant, the proportion of products to reactants when the reaction is at equilibrium. Q is the reaction quotient and it show the proportion of products to reactants when the reaction is not at equilibrium.
- Sun Jan 20, 2019 5:05 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Equilibrium Arrow
- Replies: 7
- Views: 1013
Re: Equilibrium Arrow
If a rxn completely dissociates, ie a strong acid or base, then an equilibrium arrow is not used
- Fri Jan 11, 2019 3:27 pm
- Forum: Ideal Gases
- Topic: Reaction Quotient
- Replies: 5
- Views: 510
Re: Reaction Quotient
You use Kp or Kc based on the other information they give you, but gases can be found using either method.
- Fri Jan 11, 2019 3:26 pm
- Forum: Student Social/Study Group
- Topic: New to Lavelle
- Replies: 32
- Views: 5256
Re: New to Lavelle
I find the UA sessions really helpful and when preparing for tests to do a lot of practice problems, especially the ones that are integrated into the readings
- Fri Jan 11, 2019 3:24 pm
- Forum: Ideal Gases
- Topic: Pressure of gasses
- Replies: 5
- Views: 747
Re: Pressure of gasses
I think stick to the formulas he has given us in lecture so far, bc this one hasn't been mentioned yet.
- Tue Jan 08, 2019 7:26 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Aqueous in K expression
- Replies: 4
- Views: 327
Re: Aqueous in K expression
Aqueous substances are included in finding the equilibrium constant
- Tue Jan 08, 2019 7:24 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: aqueous solutions
- Replies: 2
- Views: 318
Re: aqueous solutions
For the equilibrium constant, you only include the substances that are in the aqueous and gas phases so the inclusion of water will depend on the equation that you are looking at.
- Tue Jan 08, 2019 7:19 pm
- Forum: Ideal Gases
- Topic: Solid/Liquid in Reactions
- Replies: 4
- Views: 213
Re: Solid/Liquid in Reactions
Solids and liquid concentration can't change and so they don't have any effect on the equilibrium constant
- Sun Dec 02, 2018 6:56 pm
- Forum: Naming
- Topic: Metal Prefixes
- Replies: 2
- Views: 291
Re: Metal Prefixes
I think we're supposed to know the compounds in the table that Lavelle posted on the course website
- Sun Dec 02, 2018 6:47 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Coordination Compounds
- Replies: 2
- Views: 334
Re: Coordination Compounds
You can't determine between tetrahedral and square planar by looking at it, so if a compound has four ligands, you can label it as a tetrahedral complex or a square planar complex.
- Sun Dec 02, 2018 6:42 pm
- Forum: Amphoteric Compounds
- Topic: Examples
- Replies: 6
- Views: 590
Re: Examples
Some other examples from problems in the book are HCO3- and HPO4^(2-)
- Mon Nov 26, 2018 3:52 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: test #3
- Replies: 14
- Views: 1488
Re: test #3
So what exactly is paramagnetism and diamagnetism?
- Mon Nov 26, 2018 3:46 pm
- Forum: Hybridization
- Topic: Hybridization
- Replies: 2
- Views: 284
Re: Hybridization
Hybrid orbitals have lower energy than their unhybridized counterparts, so I think hybridization occurs to make the compounds more stable due to lower energy pockets.
- Mon Nov 26, 2018 3:42 pm
- Forum: Hybridization
- Topic: Just Kind of Confused
- Replies: 13
- Views: 1014
Re: Just Kind of Confused
So order only matters for electron configuration but not hybridization?
- Fri Nov 16, 2018 2:21 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Tetrahedral shape
- Replies: 5
- Views: 440
Re: Tetrahedral shape
A molecule could have a distorted tetrahedral shape due to lone pair repulsion that causes bond angles to be less than suggested by the VSEPR model
- Fri Nov 16, 2018 2:17 pm
- Forum: Dipole Moments
- Topic: Test
- Replies: 15
- Views: 1269
Re: Test
From the course website: "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"
- Fri Nov 16, 2018 1:02 pm
- Forum: Sigma & Pi Bonds
- Topic: Strength
- Replies: 1
- Views: 234
Strength
Do sigma and pi bonds have a different strength or is the main significant difference the way in which they overlap?
- Sat Nov 10, 2018 5:11 pm
- Forum: Resonance Structures
- Topic: Expanded Octet and Resonance
- Replies: 2
- Views: 387
Re: Expanded Octet and Resonance
No, because having more than 4 single bonds would consist of an expanded octet. To have more than 4 single bonds the atom would have to be in the 3p block or higher.
- Sat Nov 10, 2018 5:02 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Molecular Shapes
- Replies: 4
- Views: 399
Re: Molecular Shapes
It is determined by the locations of the bonding and lone pairs and the repulsion associated with those electrons
- Sat Nov 10, 2018 4:59 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Test
- Replies: 2
- Views: 147
Re: Test
The updated test and exam schedule on the course website has the next test listed for the week of November 27th so it shouldn't conflict with Thanksgiving break at all :)
- Sat Nov 03, 2018 10:06 pm
- Forum: Lewis Structures
- Topic: Formal Charges on Midterm
- Replies: 2
- Views: 360
Re: Formal Charges on Midterm
At a workshop I went to, a UA said it would be a good idea to write them out but it wasn't completely necessary unless stated explicitly in the problem
- Sat Nov 03, 2018 9:52 pm
- Forum: Lewis Structures
- Topic: lewis acid/base
- Replies: 3
- Views: 322
Re: lewis acid/base
A lewis acid is an electron acceptor while a lewis base is an electron donor
- Sat Nov 03, 2018 9:50 pm
- Forum: Octet Exceptions
- Topic: Radicals - On Which Element Does the Unpaired Electron Go?
- Replies: 2
- Views: 398
Re: Radicals - On Which Element Does the Unpaired Electron Go?
To determine which atom the unpaired electron goes on, you have to look at the formal charges and determine which atom it will make the formal charge be closest to 0
- Sun Oct 28, 2018 11:36 pm
- Forum: Lewis Structures
- Topic: Lines that Represent Bonds
- Replies: 7
- Views: 615
Re: Lines that Represent Bonds
Both mean the same thing, so using the 2 dots instead of the line would not be incorrect, but I think Dr. Lavelle uses the line because it is more convenient and clearer.
- Sun Oct 28, 2018 11:31 pm
- Forum: Trends in The Periodic Table
- Topic: Periodic Trend - Ionization energy
- Replies: 2
- Views: 188
Re: Periodic Trend - Ionization energy
Elements in the top right corner have the highest electron affinity but it is less periodic than atomic radius
- Sun Oct 28, 2018 11:23 pm
- Forum: Lewis Structures
- Topic: Lewis Structures
- Replies: 13
- Views: 1009
Re: Lewis Structures
The central atom is generally the atom with the lowest ionization energy, which is usually furthest away from row 17 (bc atoms in row 17 typically have the highest ionization energy)
- Mon Oct 22, 2018 8:23 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Pauli Exclusion Principle
- Replies: 3
- Views: 436
Re: Pauli Exclusion Principle
This answer above is a great explanation!
- Mon Oct 22, 2018 3:38 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: 2. 39 [ENDORSED]
- Replies: 5
- Views: 751
Re: 2. 39 [ENDORSED]
So lowest energy configuration means that an atom is in ground state and anything else is excited?
- Sun Oct 21, 2018 7:49 pm
- Forum: *Shrodinger Equation
- Topic: Test 2
- Replies: 5
- Views: 717
Re: Test 2
Test 2 covers quantum and bond/orbital materials up until the Friday lecture of week 3.
- Mon Oct 15, 2018 8:47 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Negative v. Positive when calculating energy
- Replies: 8
- Views: 2481
Re: Negative v. Positive when calculating energy
When energy is released, it is negative/exothermic and when energy is absorbed, the reaction is positive/endothermic
- Mon Oct 15, 2018 5:19 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Number of Orbitals
- Replies: 3
- Views: 394
Re: Number of Orbitals
This is very helpful, thank you for the insight!
- Mon Oct 15, 2018 5:16 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Heisenberg's Indeterminacy Equation
- Replies: 2
- Views: 164
Re: Heisenberg's Indeterminacy Equation
Dr. Lavelle said in lecture that the 4pi comes from the derivation of the equation and that it is not specifically important that we know how to find it/why it is there for this class.
- Mon Oct 08, 2018 11:19 pm
- Forum: Properties of Light
- Topic: Difference between "intensity of light" and "frequency of light"
- Replies: 3
- Views: 9254
Re: Difference between "intensity of light" and "frequency of light"
That's a really great way to explain it, thanks for that clarification.
- Mon Oct 08, 2018 11:18 pm
- Forum: Properties of Electrons
- Topic: Is this movement noticeable?
- Replies: 4
- Views: 568
Re: Is this movement noticeable?
With bigger objects, there position is almost always measurable so their uncertainty is negligible.
- Mon Oct 08, 2018 10:56 pm
- Forum: Administrative Questions and Class Announcements
- Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sundays 4-6pm (Karen) [ENDORSED]
- Replies: 135
- Views: 38870
Re: DOWNLOAD SESSION WORKSHEETS HERE - Sundays 4-6pm (Karen) [ENDORSED]
Thank you! This is really helpful for the first test!
- Wed Oct 03, 2018 4:48 pm
- Forum: Empirical & Molecular Formulas
- Topic: Online Resources
- Replies: 2
- Views: 422
Re: Online Resources
Bozeman Science has videos that are very similar to Crash Course that cover AP Chemistry topics.
- Wed Oct 03, 2018 4:46 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Advice from a Medical Student [ENDORSED]
- Replies: 297
- Views: 396541
Re: Advice from a Medical Student [ENDORSED]
Such useful advice to keep in mind! Thanks!
- Wed Oct 03, 2018 4:42 pm
- Forum: Balancing Chemical Reactions
- Topic: Combustion
- Replies: 6
- Views: 617
Re: Combustion
Combustion is just the combination of an organic molecule with O2 and it includes the products CO2 and H2O