Search found 60 matches
- Sat Mar 16, 2019 11:31 pm
- Forum: Second Order Reactions
- Topic: Half Life
- Replies: 7
- Views: 1264
Half Life
Will the half life equations be given to us or will we have to derive them?
- Sat Mar 16, 2019 11:28 pm
- Forum: General Rate Laws
- Topic: pseudo rate laws
- Replies: 4
- Views: 657
pseudo rate laws
What exactly is a pseudo rate law and when would we use it?
- Sat Mar 16, 2019 11:23 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: atm to torr
- Replies: 3
- Views: 651
Re: atm to torr
1 atm= 760 torr
- Sat Mar 16, 2019 11:05 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Nerst Equation
- Replies: 10
- Views: 1022
Nerst Equation
Do we need to know how to derive the Nerst Equation or will it be given to us?
- Sat Mar 16, 2019 11:02 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: cell potential
- Replies: 2
- Views: 514
Re: cell potential
You reverse the half reaction that will given help produce the desired overall reaction. If you are using the Ecathode-Eanode then you do not need to flip the sign of E. Ex our reaction is Fe3+ + Cu ---> Cu2+ + Fe2+ our half reactions are Fe3+ + e- ---> Fe2+ E= .77V Cu2+ + 2e- -----> Cu E= .34 V We ...
- Sat Mar 16, 2019 10:54 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Activated Complex
- Replies: 1
- Views: 498
Activated Complex
What exactly is an activated complex model and how does it account for temperature dependence of a reaction?
- Sat Mar 16, 2019 10:48 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: UNITS
- Replies: 2
- Views: 551
UNITS
What is the unit used for ∆S
- Sat Mar 16, 2019 10:39 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: adiabatic systems
- Replies: 10
- Views: 946
Re: adiabatic systems
Adiabatic means there is no heat flow, no heat is being transferred between the system and the surroundings
- Sat Mar 16, 2019 10:36 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: n value
- Replies: 3
- Views: 559
Re: n value
n stands for the number of electrons and it has no units.
- Sat Mar 16, 2019 10:31 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bond enthalpy
- Replies: 2
- Views: 453
Re: Bond enthalpy
You would use
∆Hrxn=∆H(bonds broken)-∆H(bonds formed)
∆Hrxn=∆H(bonds broken)-∆H(bonds formed)
- Sat Mar 16, 2019 10:28 pm
- Forum: First Order Reactions
- Topic: Rate Law
- Replies: 4
- Views: 634
Re: Rate Law
The outline says we should know how to derive the rate laws so it is possible it may appear.
- Sat Mar 16, 2019 10:25 pm
- Forum: First Order Reactions
- Topic: Rate Law
- Replies: 2
- Views: 490
Re: Rate Law
On the outline it says know how to derive the rate law so a question involving/requiring derivation can potentially appear on the final.
- Sat Mar 16, 2019 10:21 pm
- Forum: Balancing Redox Reactions
- Topic: Acidic conditions
- Replies: 3
- Views: 544
Re: Acidic conditions
Acidic: If you are balancing in an acidic solution you would use H2O to balance the O and balance H by using H+.
Basic: If you are balancing in a basic solution use H2O to balance the O, balance H by using H2O to side of reaction that needs H and Add OH- to other side
Basic: If you are balancing in a basic solution use H2O to balance the O, balance H by using H2O to side of reaction that needs H and Add OH- to other side
- Sat Mar 16, 2019 10:08 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Elementary steps
- Replies: 3
- Views: 652
Re: Elementary steps
For naming molecularity you only consider the reactants taking part in a reaction.
- Sat Mar 16, 2019 10:05 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: cell potential
- Replies: 3
- Views: 642
Re: cell potential
If you reverse a half reaction and you do not change sign of E° then we use that equation Ecathode-Eanode, you will always subtract . If you do flip the sign of the E° in the reaction you reversed then you would add the 2 cell potentials.
- Sat Mar 16, 2019 10:00 pm
- Forum: Zero Order Reactions
- Topic: overall rate
- Replies: 5
- Views: 849
Re: overall rate
You do not include a zeroth order in the overall rate because anything to the power of zero is one. [A]^0=1 so it does not need to be included
- Sat Mar 16, 2019 9:34 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cellm Potential
- Replies: 1
- Views: 234
Cellm Potential
For E° when is the case that we do not flip its sign even if we reversed the reaction?
- Sat Mar 16, 2019 9:32 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell Diagram
- Replies: 4
- Views: 393
Cell Diagram
Will we always use platinum as our inert conductor? If not which other conductor would we use?
- Sun Feb 24, 2019 11:54 pm
- Forum: Student Social/Study Group
- Topic: Test 2
- Replies: 3
- Views: 336
Re: Test 2
I don't think it will, it should only cover the information in the outlines that are in this category. It might require the knowledge of previous concepts.
- Sun Feb 24, 2019 11:33 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: Wmax=-nFE
- Replies: 1
- Views: 432
Wmax=-nFE
Does Wmax always equal G or is that only when temperature and pressure are constant?
- Sun Feb 24, 2019 11:08 pm
- Forum: Balancing Redox Reactions
- Topic: Test #2
- Replies: 9
- Views: 895
Re: Test #2
I don't think so, the outline has the information that we need to know.
- Sun Feb 10, 2019 6:24 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Standard Enthalpies of Formation
- Replies: 3
- Views: 330
Re: Standard Enthalpies of Formation
I'm pretty sure that any standard enthalpy of formation that we will need will be given.
- Sun Feb 10, 2019 6:22 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Enthalpy of Phase Changes
- Replies: 4
- Views: 396
Enthalpy of Phase Changes
Why does going from a liquid to a gas have a larger enthalpy than going from a solid to a liquid?
- Sun Feb 10, 2019 6:15 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: Lecture notes 2/8/19
- Replies: 3
- Views: 360
Re: Lecture notes 2/8/19
I have a picture of the slides
- Sun Feb 03, 2019 10:03 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Midterm
- Replies: 12
- Views: 2124
Re: Midterm
I think a good way to prepare for the midterm is by doing the homework questions. There are usually multiple review sessions held by the TA's which he will probably announce in class or on his website.
- Sun Feb 03, 2019 9:58 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Example in class
- Replies: 1
- Views: 209
Re: Example in class
He solved this example using the equation
Δu=ΔH-PΔV=ΔH-ΔnRT (assuming P=1 atm)
Δu=(-50kJ)- (8 mol)(8.3124)(298K)
Δu=-50kJ-(-20kJ)
Δu=-70kJ
Δu=ΔH-PΔV=ΔH-ΔnRT (assuming P=1 atm)
Δu=(-50kJ)- (8 mol)(8.3124)(298K)
Δu=-50kJ-(-20kJ)
Δu=-70kJ
- Sun Feb 03, 2019 9:47 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bond Enthalpies and Lewis Structures
- Replies: 2
- Views: 305
Re: Bond Enthalpies and Lewis Structures
It is best to draw out the structures so that you can see all the bonds in the reaction. This will help figure out which bonds have been broken and which have been formed.
- Sun Jan 20, 2019 9:52 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ice table mols/molarity
- Replies: 3
- Views: 199
Re: ice table mols/molarity
I believe it is best to calculate the molarities before, this will make it easier when trying to solve for your unknown value.
- Sun Jan 20, 2019 9:33 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Strong/Weak Acids and Bases
- Replies: 1
- Views: 229
Re: Strong/Weak Acids and Bases
On page 461 there is an acid chart and on page 462 there is a base chart. They don't specifically indicate which is strong or weak but it gives K. We know anything smaller than 10^-3 is weak and anything greater is strong.
- Sun Jan 20, 2019 9:26 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K=1
- Replies: 2
- Views: 187
Re: K=1
When K=1 this means that when equilibrium is reached, the concentration of products and reactants is the same.
- Fri Dec 07, 2018 9:13 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Function of polydentate ligand
- Replies: 2
- Views: 306
Function of polydentate ligand
What does a polydentate ligand allow us to do? What is its function?
- Fri Dec 07, 2018 8:49 pm
- Forum: Hybridization
- Topic: Hybridization on Test
- Replies: 3
- Views: 418
Hybridization on Test
If we are trying to determine hybridization of an atom and we are given a structure but an atom in that structure does not have a full octet, do we assume that their is/are lone pairs?
- Fri Dec 07, 2018 8:46 pm
- Forum: Bronsted Acids & Bases
- Topic: Oxoacids
- Replies: 2
- Views: 310
Oxoacids
How do we determine that something is an oxoacid?
- Fri Nov 30, 2018 10:07 pm
- Forum: Bronsted Acids & Bases
- Topic: What are conjugate acids and bases??
- Replies: 2
- Views: 343
Re: What are conjugate acids and bases??
A conjugate acid results when a base accepts a proton. A conjugate base results when an acid gives up a proton.
- Fri Nov 30, 2018 8:49 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: 17.31
- Replies: 2
- Views: 253
Re: 17.31
A) K₃[Cr(CN)₆]
B) [Co(SO4)(NH3)5]
C) [Co(NH3)4(H2O)2]Br3
D)Na[Fe(OH2)2(C2O4)2]
B) [Co(SO4)(NH3)5]
C) [Co(NH3)4(H2O)2]Br3
D)Na[Fe(OH2)2(C2O4)2]
- Fri Nov 30, 2018 3:10 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: Sigma and Pi Bonds
- Replies: 12
- Views: 1034
Re: Sigma and Pi Bonds
Yes a triple bond will have 1 sigma bond and 2 pi bonds.
- Fri Nov 23, 2018 4:23 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polarity
- Replies: 7
- Views: 748
Re: Polarity
You can draw an arrow toward the partial negative end and if these partial negatives cancel the molecule will be nonpolar.
- Fri Nov 23, 2018 4:18 pm
- Forum: Hybridization
- Topic: when to use hybridization
- Replies: 4
- Views: 409
when to use hybridization
How do we know when to use hybridization?
- Fri Nov 23, 2018 4:15 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR Models and Resonance Structures
- Replies: 4
- Views: 1008
Re: VSEPR Models and Resonance Structures
When determining lewis structure resonance you should keep resonance in mind but it does not affect VSEPR models. The number of electron densities around the central atom is the same in all the resonance structures and those regions of e- density determine the VSEPR model. So they if the regions of ...
- Fri Nov 16, 2018 10:38 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Repulsion and Stability
- Replies: 3
- Views: 241
Re: Repulsion and Stability
The farther away the electrons are from each other, the less repulsion there is between them. Therefore the shape where electrons are farthest apart will have the lowest amount of repulsion and will be the most stable.
- Fri Nov 16, 2018 10:25 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR- Polar vs Nonpolar
- Replies: 5
- Views: 254
VSEPR- Polar vs Nonpolar
How do we determine whether the VSEPR model will be polar or nonpolar? Is it only based on symmetry?
- Fri Nov 16, 2018 10:20 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Sigma & Pi bonds
- Replies: 2
- Views: 224
Sigma & Pi bonds
How are sigma and pi bonds related to bond strength?
- Fri Nov 09, 2018 9:24 pm
- Forum: Lewis Structures
- Topic: 6th edition ch3 3.123
- Replies: 1
- Views: 130
Re: 6th edition ch3 3.123
This is a radical because it has one unpaired electron on carbon.
- Fri Nov 09, 2018 8:52 pm
- Forum: Dipole Moments
- Topic: Dipole
- Replies: 8
- Views: 768
Re: Dipole
If there is a dipole attraction then there must be a negative and positive part of the molecule. One end of the molecule will be delta negative and the other will be delta positive. I believe you can include the delta negative/positive on the lewis structure and this will help you see how the molecu...
- Fri Nov 09, 2018 8:46 pm
- Forum: Electronegativity
- Topic: Electronegativity Difference from 1.5-2
- Replies: 1
- Views: 485
Re: Electronegativity Difference from 1.5-2
When the electronegativity is between 1.5-2 the bond will exhibit ionic and covalent characteristics. The bond is neither completely covalent nor completely ionic. These bonds are also usually good in polar solvents.
- Fri Nov 02, 2018 9:22 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Ground state and excited state ?
- Replies: 2
- Views: 2275
Re: Ground state and excited state ?
Ground state atoms are going to be atoms where their electrons are at normal energy level. All atoms at ground state have their electrons in the lowest possible energy levels, and they are said be at the zero energy level. An excited atom will have be in a higher energy level. They will be more unst...
- Wed Oct 31, 2018 9:54 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Question 2A.9 7th Edition
- Replies: 1
- Views: 133
Re: Question 2A.9 7th Edition
When an atom has a 3+ charge that means they have lost electrons therefore you must subtract electrons not add them. The question is asking you to identify the element that would have that specific electron configuration after losing 3 electrons. For example a neutral Co has and electron configurati...
- Wed Oct 31, 2018 9:41 pm
- Forum: Lewis Structures
- Topic: Double bonds [ENDORSED]
- Replies: 3
- Views: 332
Re: Double bonds [ENDORSED]
You would usually add a double bond when the central atom does not have a full octet but you have to keep the exceptions in mind. In order to know how many double bonds to put you need to calculate the formal charge for each atom. The formal charges all need to add up to the overall charge of the mo...
- Fri Oct 26, 2018 9:47 pm
- Forum: Ionic & Covalent Bonds
- Topic: Chemical Bonding and Periodic Trends
- Replies: 4
- Views: 364
Re: Chemical Bonding and Periodic Trends
Another example is electronegativity, as it increases it affects how electrons will act in a bond. If atoms are close in electronegativity they will equally share the electron and it will create a nonpolar covalent bond. If their is a big difference in electronegativity there will be an unequal shar...
- Fri Oct 26, 2018 9:36 pm
- Forum: Ionic & Covalent Bonds
- Topic: Focus 2D #3 - HW Problem
- Replies: 4
- Views: 865
Re: Focus 2D #3 - HW Problem
Be and Br have a similar electronegativity therefore they both pull on the electron equally. In order for it to be ionic one would have to have a significantly greater electronegativity so that it could pull the electron from the other atom, but because the electronegativity is similar between these...
- Fri Oct 26, 2018 9:23 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Writing electron configurations [ENDORSED]
- Replies: 5
- Views: 286
Writing electron configurations [ENDORSED]
When writing out the configuration and there is only 1 electron in the orbital does the spin always have to be an up spin? can it be a down spin?
- Fri Oct 19, 2018 9:33 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Electrostatic Attraction
- Replies: 5
- Views: 4893
Re: Electrostatic Attraction
As distance between e- and the nucleus increases the electrostatic attraction between the two will decrease.
- Fri Oct 19, 2018 9:20 pm
- Forum: Properties of Electrons
- Topic: Questions about the energy level [ENDORSED]
- Replies: 3
- Views: 443
Re: Questions about the energy level [ENDORSED]
As n increases the energy of the electron increases as well. As n increases the e- moves farther away from the nucleus which means that the attraction between the nucleus and the e- will be weaker and the e- will be more unstable(as energy increases stability of e- decrease). Therefore the electron ...
- Fri Oct 19, 2018 9:07 pm
- Forum: Properties of Light
- Topic: Atomic Spectrum Module #28
- Replies: 1
- Views: 153
Re: Atomic Spectrum Module #28
First you are going to convert the wave length from nm to meter. 1850nm= 1.85x10^-6 m. In order to find the # of photons first calculate the energy of each photon using E =hc/λ. =(6.626 × 10−34 J · s)(3 × 108 m/s) /1.85 × 10−6 m = 1.07449 × 10−19 J (per photon) Now that you have the energy of one ph...
- Fri Oct 12, 2018 9:46 pm
- Forum: Photoelectric Effect
- Topic: Threshold energy [ENDORSED]
- Replies: 17
- Views: 2122
Threshold energy [ENDORSED]
We went over an example that included threshold energy in the problem but what exactly is threshold energy of an electron and how does that factor into calculating the energy of a photon?
- Fri Oct 12, 2018 9:33 pm
- Forum: DeBroglie Equation
- Topic: Equations
- Replies: 9
- Views: 807
Re: Equations
I'm pretty sure all the equations and constants will be provided for every test/exam.
- Fri Oct 12, 2018 9:32 pm
- Forum: Properties of Light
- Topic: question from class today
- Replies: 3
- Views: 186
Re: question from class today
If you make it into a fraction it will be easier to see
- Sun Oct 07, 2018 9:32 pm
- Forum: Properties of Light
- Topic: Formula for energy of a photon
- Replies: 4
- Views: 229
Re: Formula for energy of a photon
Julia Lindner 1I wrote:Where in the book (7th ed.) can I find the formula for calculating energy of a photon? A question requires you to use it but I can't seem to find it anywhere.
The equation can be found on page 13 it falls under Topic 1B Quantum Theory and in the sub section 1B.1 Radiation, Quanta, and Photons
- Sun Oct 07, 2018 9:27 pm
- Forum: Significant Figures
- Topic: Sig Figs in the Middle of a Problem
- Replies: 9
- Views: 2469
Re: Sig Figs in the Middle of a Problem
My TA also recommended using as many digits as possible during the calculation to avoid any rounding errors and use sig figs for the final answer
- Sun Oct 07, 2018 9:22 pm
- Forum: Significant Figures
- Topic: Calculating process
- Replies: 5
- Views: 852
Re: Calculating process
Rounding while calculating can lead to a different answer so it is best to round until you reach your final step/answer