Search found 48 matches

by Samantha Joseph 1F
Wed Mar 14, 2018 9:08 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Net rate of formation of products
Replies: 2
Views: 132

Re: Net rate of formation of products

In other words, the net rate of formation of a species is its forward rate of formation plus its reverse rate of formation.
by Samantha Joseph 1F
Wed Mar 14, 2018 9:04 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Cell Concentration
Replies: 3
Views: 255

Re: Cell Concentration

I think you just have to understand it conceptually, like how a concentration cell can be treated like a battery that gains voltage by transferring electrons from the lower concentrated cell to the higher concentrated cell. I think it's also supposed to be an example for application of the Nernst eq...
by Samantha Joseph 1F
Tue Mar 13, 2018 12:20 pm
Forum: Phase Changes & Related Calculations
Topic: Test #1 question
Replies: 2
Views: 120

Test #1 question

What is the main reasoning as to why heat is being transferred in this process?

"A balloon filled with gas is expanded to a larger volume and lower pressure while maintaining the same temperature."
by Samantha Joseph 1F
Tue Mar 06, 2018 2:30 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Unstable Compounds
Replies: 1
Views: 127

Re: Unstable Compounds

Thermodynamics shouldn't be on the test so I don't think you need to worry about this!
by Samantha Joseph 1F
Tue Mar 06, 2018 2:27 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Pre Equilibrium Condition
Replies: 1
Views: 73

Re: Pre Equilibrium Condition

Also, is the pre-equilibrium condition/approximation only used when the first step is fast?
by Samantha Joseph 1F
Tue Mar 06, 2018 2:24 pm
Forum: General Rate Laws
Topic: Proper units
Replies: 7
Views: 268

Proper units

Just to clarify, if the problem uses mmol, is it preferred to use mmol or mol in the answer (unless specified)?
by Samantha Joseph 1F
Sat Mar 03, 2018 3:05 pm
Forum: General Rate Laws
Topic: rate law
Replies: 3
Views: 131

Re: rate law

Typically when we're asked this question, they provide us with a couple different experiments and their corresponding initial concentrations of each reactant as well as the initial reaction rate. To find the orders of each reactant, you would compare experiments that differ in only one reactant's in...
by Samantha Joseph 1F
Sat Mar 03, 2018 2:37 pm
Forum: Second Order Reactions
Topic: Non-integer orders [ENDORSED]
Replies: 3
Views: 164

Non-integer orders [ENDORSED]

Will we ever be expected to know/find non-integer (like 1.5) reactant orders?
by Samantha Joseph 1F
Sat Mar 03, 2018 2:31 pm
Forum: General Rate Laws
Topic: Differential and Integrated Rate Laws
Replies: 3
Views: 156

Re: Differential and Integrated Rate Laws

The main difference between differential and integrated rate laws are that differential rate laws are used to describe a reaction rate as a function of the change in concentration over a time period, whereas integrate rate laws show the initial and actual concentration values after a period of time....
by Samantha Joseph 1F
Sat Feb 24, 2018 3:17 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: negative order
Replies: 2
Views: 109

negative order

What does it mean for a concentration's order to be negative?
by Samantha Joseph 1F
Sat Feb 24, 2018 3:06 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 14.13 (b)
Replies: 3
Views: 112

Re: 14.13 (b)

And as long as it is a metal, you can use either a solid or liquid as the conductor.
by Samantha Joseph 1F
Sat Feb 24, 2018 2:59 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Rate constant (k)
Replies: 4
Views: 173

Re: Rate constant (k)

Varying reactions will have varying reaction constants, but within a reaction, k remains constant so that's why they give it the name.
by Samantha Joseph 1F
Sat Feb 17, 2018 1:37 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Periodic Trends
Replies: 1
Views: 87

Periodic Trends

Are there any other periodic trends aside from the leftmost elements' standard potentials being more negative versus the upper rightmost being more positive?
by Samantha Joseph 1F
Sat Feb 17, 2018 1:23 pm
Forum: Balancing Redox Reactions
Topic: Oxidizing/reducing agent given E˚
Replies: 1
Views: 80

Oxidizing/reducing agent given E˚

When given two half reactions and their E˚, is the reducing agent just the one with a more negative E˚?
by Samantha Joseph 1F
Wed Feb 14, 2018 1:06 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Using Kelvin [ENDORSED]
Replies: 3
Views: 161

Using Kelvin [ENDORSED]

Just to clarify, we're allowed to use the rounded conversion of 273 Kelvin on the midterm right? We don't have to do 273.15 K?
by Samantha Joseph 1F
Sat Feb 10, 2018 3:20 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Work
Replies: 6
Views: 460

Re: Work

If it is an irreversible isothermal expansion, then work would equal 0 because external pressure (due to this being a vacuum) equals 0, and the equation w= pex*deltaV makes w=0.
by Samantha Joseph 1F
Sat Feb 10, 2018 2:28 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Deriving equations
Replies: 1
Views: 94

Deriving equations

Will we need to know how to derive any of the equations related to Gibbs free energy on the midterm?
by Samantha Joseph 1F
Sat Feb 10, 2018 2:16 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: negative entropy [ENDORSED]
Replies: 3
Views: 166

negative entropy [ENDORSED]

Can someone explain what it means for there to be "negative" entropy? Does it only apply to open systems?
by Samantha Joseph 1F
Sat Feb 03, 2018 11:20 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Maximum work
Replies: 2
Views: 144

Maximum work

When temperature or pressure aren't constant, what is the relationship between maximum work and change in free energy?
by Samantha Joseph 1F
Sat Feb 03, 2018 11:09 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Entropy and Work
Replies: 2
Views: 149

Re: Entropy and Work

Since the relationship between entropy and work that IS done as heat is S = Q/T, and we know that Q = U - w, where U is the total internal energy and w is work that's not done as heat, then you can substitute that in and say S = (U-w)/T, showing the relationship between S and w.
by Samantha Joseph 1F
Sat Feb 03, 2018 11:03 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Isothermal pressure change
Replies: 3
Views: 110

Isothermal pressure change

Why is it that the equation for finding the entropy of a system with an isothermal pressure change uses P1/P2 when temperature and volume are typically T2/T1 or V2/V1?
by Samantha Joseph 1F
Sat Jan 27, 2018 1:42 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Perfect Crystal
Replies: 9
Views: 317

Re: Perfect Crystal

A perfect crystal is just an ideal substance where there is no thermal or positional disorder (as justified by S->0 and T->0), but the main purpose of defining a "perfect crystal" is to create a scale of measuring entropy for realistic substances.
by Samantha Joseph 1F
Sat Jan 27, 2018 1:31 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Positional disorder
Replies: 1
Views: 88

Positional disorder

Can someone better explain positional disorder? What would be an example of increasing/decreasing positional disorder?
by Samantha Joseph 1F
Sat Jan 27, 2018 1:24 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Adiabatic system
Replies: 6
Views: 219

Adiabatic system

Aside from there being no heat transfer, is there any other important characteristic we should know about adiabatic systems?
by Samantha Joseph 1F
Sat Jan 20, 2018 3:15 pm
Forum: Phase Changes & Related Calculations
Topic: Change in Internal Energy
Replies: 3
Views: 129

Re: Change in Internal Energy

If it helps to remember, it's basically the first law of thermodynamics! If you think about the "compressing a piston" example, the person is clearly doing work by pushing on the piston, or exerting a force over a certain distance. And force x distance = work, which is a form of energy.
by Samantha Joseph 1F
Sat Jan 20, 2018 3:01 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Most Accurate Method [ENDORSED]
Replies: 3
Views: 122

Most Accurate Method [ENDORSED]

Can someone clarify which is the most accurate method of finding a reaction's net enthalpy?
by Samantha Joseph 1F
Sat Jan 20, 2018 2:55 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Perfect System
Replies: 1
Views: 84

Perfect System

Unless otherwise stated in the question, do we assume the system is a "perfect system," where the heat given off by the reaction is equal to the (negative) heat absorbed by the solution?
by Samantha Joseph 1F
Sat Jan 13, 2018 5:09 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Reversible vs irreversible
Replies: 2
Views: 133

Reversible vs irreversible

Can someone fully explain why reversible processes tend to do more work than irreversible processes?
by Samantha Joseph 1F
Sat Jan 13, 2018 5:02 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: work equation
Replies: 2
Views: 131

work equation

Is there any situation where we wouldn't be able to use the equation w=deltaU - q?
by Samantha Joseph 1F
Sat Jan 13, 2018 4:52 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Irreversible vs. Reversible Processes
Replies: 3
Views: 169

Re: Irreversible vs. Reversible Processes

And to find the work for reversible processes, you would use the equation w=-nRT*ln(Vfinal/Vinitial) whereas for irreversible processes, it would be w=-P*deltaV.
by Samantha Joseph 1F
Sun Dec 10, 2017 3:57 pm
Forum: Bronsted Acids & Bases
Topic: Acid/base trends on periodic table [ENDORSED]
Replies: 1
Views: 269

Acid/base trends on periodic table [ENDORSED]

What trends are there on the periodic table that show progression of weak to strong acids/bases? (ie. going down/up a group, across a period, etc.)
by Samantha Joseph 1F
Sun Dec 10, 2017 3:54 pm
Forum: Biological Examples
Topic: Hemoglobin
Replies: 5
Views: 529

Re: Hemoglobin

And what would be the best response for function of hemoglobin?
by Samantha Joseph 1F
Sun Dec 03, 2017 4:21 pm
Forum: Amphoteric Compounds
Topic: d-block elements
Replies: 1
Views: 188

d-block elements

Why is it that certain elements of the d-block can form amphoteric oxides? Are their oxidation states any form of determinants?
by Samantha Joseph 1F
Sun Dec 03, 2017 4:16 pm
Forum: Calculating the pH of Salt Solutions
Topic: Question 12.77
Replies: 1
Views: 227

Question 12.77

Can someone help with this problem?
A 3.38-g sample of the sodium salt of alanine, NaCH3CH(NH2)CO2, is dissolved in water, and then the solution is diluted to 50.0 mL. For alanine, Ka1=4.57x10^-3, Ka2=1.30x10^-10. What is the pH of the resulting solution?
by Samantha Joseph 1F
Sun Nov 26, 2017 6:00 pm
Forum: Naming
Topic: Using Roman Numerals
Replies: 2
Views: 120

Using Roman Numerals

What exactly do the roman numerals represent in compound names, and what are the rules we need to look into when using roman numerals?
by Samantha Joseph 1F
Sun Nov 26, 2017 5:50 pm
Forum: Ideal Gases
Topic: Units of Partial Pressure
Replies: 7
Views: 466

Re: Units of Partial Pressure

My TA said atm is preferred!
by Samantha Joseph 1F
Fri Nov 17, 2017 3:57 pm
Forum: Administrative Questions and Class Announcements
Topic: Homework for Week 8 [ENDORSED]
Replies: 2
Views: 179

Re: Homework for Week 8 [ENDORSED]

You can probably do questions from either chapter 4 or 17!
by Samantha Joseph 1F
Fri Nov 17, 2017 3:48 pm
Forum: Naming
Topic: Transition Metal Oxidation States
Replies: 1
Views: 96

Transition Metal Oxidation States

Why is it that transition metals have variable oxidation states? Is this true for all TMs or only certain ones?
by Samantha Joseph 1F
Fri Nov 10, 2017 2:10 pm
Forum: Octet Exceptions
Topic: Radicals [ENDORSED]
Replies: 1
Views: 140

Radicals [ENDORSED]

When drawing the lewis structure for a radical, how do we know which atom to assign the unpaired electron to?
by Samantha Joseph 1F
Fri Nov 10, 2017 2:04 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Drawing lewis structures
Replies: 5
Views: 272

Drawing lewis structures

If we draw a lewis structure for a molecule with 0 formal charge on each atom but it isn't the conventional structure for that molecule, will we be docked points? How can we know what is the accepted structure if several work?
by Samantha Joseph 1F
Sat Nov 04, 2017 10:13 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Aufbau principle
Replies: 4
Views: 266

Aufbau principle

Just to clarify—is the Aufbau principle inclusive of the Puali exclusion rule and Hund's rule?
by Samantha Joseph 1F
Sat Nov 04, 2017 10:03 pm
Forum: Electronegativity
Topic: Electronegativity related to solubility
Replies: 2
Views: 183

Electronegativity related to solubility

How can we use the electronegativity of a compound to see how soluble it is in water?
by Samantha Joseph 1F
Sat Oct 28, 2017 6:23 pm
Forum: Resonance Structures
Topic: How to find the most stable structure [ENDORSED]
Replies: 3
Views: 318

Re: How to find the most stable structure [ENDORSED]

I think when the compound clearly has more than one possible structure, then yes, you'd likely have to calculate the formal charges for each structure just to be sure. And you won't necessarily find a structure with a formal charge of 0, so just find the smallest charge overall.
by Samantha Joseph 1F
Sat Oct 28, 2017 12:09 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron configuration for Fe^2+ [ENDORSED]
Replies: 2
Views: 186

Electron configuration for Fe^2+ [ENDORSED]

Why is it that the configuration for Fe^2+ is [Ar]3d^6 and not [Ar]3d^5 4s^1 (similar to Cr)?
by Samantha Joseph 1F
Sun Oct 22, 2017 2:04 pm
Forum: Einstein Equation
Topic: Comparing E=pc and E=.5mv^2
Replies: 3
Views: 308

Re: Comparing E=pc and E=.5mv^2

It's best to use E = (1/2)mv^2 because you're given the mass m of an electron and you can just solve for v. Also, it doesn't matter what the electron is being described as since the equations you use depend on the information provided to you.
by Samantha Joseph 1F
Sun Oct 22, 2017 1:55 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Electron density distribution?
Replies: 2
Views: 186

Electron density distribution?

Can someone explain what it means for p- and d- orbitals to have a nodal plane with non-symmetric electron density distribution?
by Samantha Joseph 1F
Sun Oct 15, 2017 3:19 pm
Forum: Properties of Light
Topic: 1.21- understanding how light acts as a wave
Replies: 2
Views: 192

Re: 1.21- understanding how light acts as a wave

To my understanding, intensity is unrelated to wavelength/frequency but it is related to amplitude, as the question's answer explains briefly. Greater amplitude means more photons are emitted, which causes an increase in intensity.
by Samantha Joseph 1F
Wed Oct 11, 2017 3:48 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Bohr Condition/Rydberg Constant
Replies: 2
Views: 230

Bohr Condition/Rydberg Constant

Can someone explain how Rydberg's experiment (and constant) can be tied to the Bohr frequency condition? I'm still a little confused after the reading.

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