Search found 60 matches

by Samantha Pacheco 2K
Sat Mar 16, 2019 11:31 pm
Forum: Second Order Reactions
Topic: Half Life
Replies: 5
Views: 441

Half Life

Will the half life equations be given to us or will we have to derive them?
by Samantha Pacheco 2K
Sat Mar 16, 2019 11:28 pm
Forum: General Rate Laws
Topic: pseudo rate laws
Replies: 4
Views: 225

pseudo rate laws

What exactly is a pseudo rate law and when would we use it?
by Samantha Pacheco 2K
Sat Mar 16, 2019 11:23 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: atm to torr
Replies: 3
Views: 201

Re: atm to torr

1 atm= 760 torr
by Samantha Pacheco 2K
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: 3
Views: 180

Nerst Equation

Do we need to know how to derive the Nerst Equation or will it be given to us?
by Samantha Pacheco 2K
Sat Mar 16, 2019 11:02 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: cell potential
Replies: 2
Views: 181

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 ...
by Samantha Pacheco 2K
Sat Mar 16, 2019 10:54 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Activated Complex
Replies: 1
Views: 196

Activated Complex

What exactly is an activated complex model and how does it account for temperature dependence of a reaction?
by Samantha Pacheco 2K
Sat Mar 16, 2019 10:48 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: UNITS
Replies: 2
Views: 217

UNITS

What is the unit used for ∆S
by Samantha Pacheco 2K
Sat Mar 16, 2019 10:39 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: adiabatic systems
Replies: 7
Views: 242

Re: adiabatic systems

Adiabatic means there is no heat flow, no heat is being transferred between the system and the surroundings
by Samantha Pacheco 2K
Sat Mar 16, 2019 10:36 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: n value
Replies: 3
Views: 189

Re: n value

n stands for the number of electrons and it has no units.
by Samantha Pacheco 2K
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: 179

Re: Bond enthalpy

You would use
∆Hrxn=∆H(bonds broken)-∆H(bonds formed)
by Samantha Pacheco 2K
Sat Mar 16, 2019 10:28 pm
Forum: First Order Reactions
Topic: Rate Law
Replies: 2
Views: 185

Re: Rate Law

The outline says we should know how to derive the rate laws so it is possible it may appear.
by Samantha Pacheco 2K
Sat Mar 16, 2019 10:25 pm
Forum: First Order Reactions
Topic: Rate Law
Replies: 2
Views: 166

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.
by Samantha Pacheco 2K
Sat Mar 16, 2019 10:21 pm
Forum: Balancing Redox Reactions
Topic: Acidic conditions
Replies: 3
Views: 207

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
by Samantha Pacheco 2K
Sat Mar 16, 2019 10:08 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Elementary steps
Replies: 3
Views: 194

Re: Elementary steps

For naming molecularity you only consider the reactants taking part in a reaction.
by Samantha Pacheco 2K
Sat Mar 16, 2019 10:05 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: cell potential
Replies: 3
Views: 182

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.
by Samantha Pacheco 2K
Sat Mar 16, 2019 10:00 pm
Forum: Zero Order Reactions
Topic: overall rate
Replies: 4
Views: 204

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
by Samantha Pacheco 2K
Sat Mar 16, 2019 9:34 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cellm Potential
Replies: 1
Views: 49

Cellm Potential

For E° when is the case that we do not flip its sign even if we reversed the reaction?
by Samantha Pacheco 2K
Sat Mar 16, 2019 9:32 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagram
Replies: 4
Views: 62

Cell Diagram

Will we always use platinum as our inert conductor? If not which other conductor would we use?
by Samantha Pacheco 2K
Sun Feb 24, 2019 11:54 pm
Forum: Student Social/Study Group
Topic: Test 2
Replies: 3
Views: 74

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.
by Samantha Pacheco 2K
Sun Feb 24, 2019 11:33 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Wmax=-nFE
Replies: 1
Views: 43

Wmax=-nFE

Does Wmax always equal G or is that only when temperature and pressure are constant?
by Samantha Pacheco 2K
Sun Feb 24, 2019 11:08 pm
Forum: Balancing Redox Reactions
Topic: Test #2
Replies: 9
Views: 183

Re: Test #2

I don't think so, the outline has the information that we need to know.
by Samantha Pacheco 2K
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: 70

Re: Standard Enthalpies of Formation

I'm pretty sure that any standard enthalpy of formation that we will need will be given.
by Samantha Pacheco 2K
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: 72

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?
by Samantha Pacheco 2K
Sun Feb 03, 2019 10:03 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Midterm
Replies: 12
Views: 214

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.
by Samantha Pacheco 2K
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: 44

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
by Samantha Pacheco 2K
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: 44

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.
by Samantha Pacheco 2K
Sun Jan 20, 2019 9:52 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ice table mols/molarity
Replies: 3
Views: 72

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.
by Samantha Pacheco 2K
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: 69

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.
by Samantha Pacheco 2K
Sun Jan 20, 2019 9:26 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K=1
Replies: 2
Views: 56

Re: K=1

When K=1 this means that when equilibrium is reached, the concentration of products and reactants is the same.
by Samantha Pacheco 2K
Fri Dec 07, 2018 9:13 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Function of polydentate ligand
Replies: 2
Views: 71

Function of polydentate ligand

What does a polydentate ligand allow us to do? What is its function?
by Samantha Pacheco 2K
Fri Dec 07, 2018 8:49 pm
Forum: Hybridization
Topic: Hybridization on Test
Replies: 3
Views: 222

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?
by Samantha Pacheco 2K
Fri Dec 07, 2018 8:46 pm
Forum: Bronsted Acids & Bases
Topic: Oxoacids
Replies: 2
Views: 65

Oxoacids

How do we determine that something is an oxoacid?
by Samantha Pacheco 2K
Fri Nov 30, 2018 10:07 pm
Forum: Bronsted Acids & Bases
Topic: What are conjugate acids and bases??
Replies: 2
Views: 78

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.
by Samantha Pacheco 2K
Fri Nov 30, 2018 8:49 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: 17.31
Replies: 2
Views: 65

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]
by Samantha Pacheco 2K
Fri Nov 30, 2018 3:10 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Sigma and Pi Bonds
Replies: 2
Views: 220

Re: Sigma and Pi Bonds

Yes a triple bond will have 1 sigma bond and 2 pi bonds.
by Samantha Pacheco 2K
Fri Nov 23, 2018 4:23 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polarity
Replies: 7
Views: 120

Re: Polarity

You can draw an arrow toward the partial negative end and if these partial negatives cancel the molecule will be nonpolar.
by Samantha Pacheco 2K
Fri Nov 23, 2018 4:18 pm
Forum: Hybridization
Topic: when to use hybridization
Replies: 4
Views: 96

when to use hybridization

How do we know when to use hybridization?
by Samantha Pacheco 2K
Fri Nov 23, 2018 4:15 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR Models and Resonance Structures
Replies: 4
Views: 101

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 ...
by Samantha Pacheco 2K
Fri Nov 16, 2018 10:38 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Repulsion and Stability
Replies: 3
Views: 45

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.
by Samantha Pacheco 2K
Fri Nov 16, 2018 10:25 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR- Polar vs Nonpolar
Replies: 5
Views: 70

VSEPR- Polar vs Nonpolar

How do we determine whether the VSEPR model will be polar or nonpolar? Is it only based on symmetry?
by Samantha Pacheco 2K
Fri Nov 16, 2018 10:20 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Sigma & Pi bonds
Replies: 2
Views: 51

Sigma & Pi bonds

How are sigma and pi bonds related to bond strength?
by Samantha Pacheco 2K
Fri Nov 09, 2018 9:24 pm
Forum: Lewis Structures
Topic: 6th edition ch3 3.123
Replies: 1
Views: 59

Re: 6th edition ch3 3.123

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This is a radical because it has one unpaired electron on carbon.
by Samantha Pacheco 2K
Fri Nov 09, 2018 8:52 pm
Forum: Dipole Moments
Topic: Dipole
Replies: 8
Views: 208

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...
by Samantha Pacheco 2K
Fri Nov 09, 2018 8:46 pm
Forum: Electronegativity
Topic: Electronegativity Difference from 1.5-2
Replies: 1
Views: 80

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.
by Samantha Pacheco 2K
Fri Nov 02, 2018 9:22 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Ground state and excited state ?
Replies: 2
Views: 150

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...
by Samantha Pacheco 2K
Wed Oct 31, 2018 9:54 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Question 2A.9 7th Edition
Replies: 1
Views: 41

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...
by Samantha Pacheco 2K
Wed Oct 31, 2018 9:41 pm
Forum: Lewis Structures
Topic: Double bonds [ENDORSED]
Replies: 3
Views: 103

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...
by Samantha Pacheco 2K
Fri Oct 26, 2018 9:47 pm
Forum: Ionic & Covalent Bonds
Topic: Chemical Bonding and Periodic Trends
Replies: 4
Views: 102

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...
by Samantha Pacheco 2K
Fri Oct 26, 2018 9:36 pm
Forum: Ionic & Covalent Bonds
Topic: Focus 2D #3 - HW Problem
Replies: 3
Views: 213

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...
by Samantha Pacheco 2K
Fri Oct 26, 2018 9:23 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Writing electron configurations [ENDORSED]
Replies: 5
Views: 96

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?
by Samantha Pacheco 2K
Fri Oct 19, 2018 9:33 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electrostatic Attraction
Replies: 5
Views: 83

Re: Electrostatic Attraction

As distance between e- and the nucleus increases the electrostatic attraction between the two will decrease.
by Samantha Pacheco 2K
Fri Oct 19, 2018 9:20 pm
Forum: Properties of Electrons
Topic: Questions about the energy level [ENDORSED]
Replies: 3
Views: 144

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 ...
by Samantha Pacheco 2K
Fri Oct 19, 2018 9:07 pm
Forum: Properties of Light
Topic: Atomic Spectrum Module #28
Replies: 1
Views: 53

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...
by Samantha Pacheco 2K
Fri Oct 12, 2018 9:46 pm
Forum: Photoelectric Effect
Topic: Threshold energy [ENDORSED]
Replies: 17
Views: 443

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?
by Samantha Pacheco 2K
Fri Oct 12, 2018 9:33 pm
Forum: DeBroglie Equation
Topic: Equations
Replies: 9
Views: 154

Re: Equations

I'm pretty sure all the equations and constants will be provided for every test/exam.
by Samantha Pacheco 2K
Fri Oct 12, 2018 9:32 pm
Forum: Properties of Light
Topic: question from class today
Replies: 3
Views: 47

Re: question from class today

If you make it into a fraction it will be easier to see
by Samantha Pacheco 2K
Sun Oct 07, 2018 9:32 pm
Forum: Properties of Light
Topic: Formula for energy of a photon
Replies: 4
Views: 68

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
by Samantha Pacheco 2K
Sun Oct 07, 2018 9:27 pm
Forum: Significant Figures
Topic: Sig Figs in the Middle of a Problem
Replies: 9
Views: 521

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
by Samantha Pacheco 2K
Sun Oct 07, 2018 9:22 pm
Forum: Significant Figures
Topic: Calculating process
Replies: 5
Views: 404

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

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