Search found 58 matches
- Sun Mar 18, 2018 6:46 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: complex molecules
- Replies: 8
- Views: 1720
Re: complex molecules
The more the molecular complexity, the more the disorder, and thus the more the entropy.
- Sun Mar 18, 2018 6:41 pm
- Forum: Calculating Work of Expansion
- Topic: Final Question W18: Reversible vs. Irreversible External Pressure
- Replies: 4
- Views: 599
Re: Final Question W18: Reversible vs. Irreversible External Pressure
I further defined a reversible
process as one that can be reversed by an infinitely small change in a variable
process as one that can be reversed by an infinitely small change in a variable
- Sun Mar 18, 2018 6:34 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: State Functions
- Replies: 4
- Views: 771
Re: State Functions
I believe that the 4 points for the question indicated 4 answer choices that were correct.
- Sun Mar 18, 2018 6:29 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Adiabatic Process
- Replies: 4
- Views: 658
Re: Adiabatic Process
An adiabatic process indicates that q=0.
- Sun Mar 18, 2018 3:32 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3941418
Re: Post All Chemistry Jokes Here
The name's Bond. Ionic Bond. Taken, not shared.
- Sun Mar 18, 2018 3:31 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3941418
Re: Post All Chemistry Jokes Here
A photon checks into a hotel and is asked if he needs any help with his luggage. He says, "No, I'm traveling light."
- Sun Mar 18, 2018 3:27 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3941418
Re: Post All Chemistry Jokes Here
Making bad chemistry jokes because all the good ones Argon
- Sun Mar 18, 2018 3:26 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3941418
Re: Post All Chemistry Jokes Here
Did you know that you can cool yourself to -273.15˚C and still be 0k?
- Sun Mar 18, 2018 3:25 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3941418
Re: Post All Chemistry Jokes Here
Don't trust atoms, they make up everything.
- Wed Mar 07, 2018 5:10 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: 15.47
- Replies: 1
- Views: 229
Re: 15.47
On the tests they are usually given.
- Wed Mar 07, 2018 5:10 pm
- Forum: Zero Order Reactions
- Topic: Units of K based on the order
- Replies: 3
- Views: 1122
Re: Units of K based on the order
This is a useful equation to figure out the units:
K = M^-n+1 x s^-1
M = mol/liter
n = total reaction order
K = M^-n+1 x s^-1
M = mol/liter
n = total reaction order
- Wed Mar 07, 2018 4:50 pm
- Forum: First Order Reactions
- Topic: First Order Integrated Rate Law
- Replies: 3
- Views: 454
Re: First Order Integrated Rate Law
They seem to be interchangeable, but I'm not sure
- Sun Mar 04, 2018 12:28 am
- Forum: General Rate Laws
- Topic: 15.39a
- Replies: 3
- Views: 476
Re: 15.39a
Perhaps because it is looking at the concentration and not the number of moles.
- Sun Mar 04, 2018 12:25 am
- Forum: First Order Reactions
- Topic: half life
- Replies: 2
- Views: 415
Re: half life
Im assuming that you would treat each element individually in that case.
- Sun Mar 04, 2018 12:23 am
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: 15.55 a
- Replies: 3
- Views: 484
Re: 15.55 a
A large equilibrium constant means that the products are favored.
- Wed Feb 21, 2018 12:37 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: voltage
- Replies: 1
- Views: 250
Re: voltage
The units for voltage is joules per coulomb. The unit for Farraday's constant is coulombs per volt. Multiplying these and the number of moles together leaves joules per mol which is the unit of Gibbs free energy.
- Wed Feb 21, 2018 12:27 pm
- Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
- Topic: Electroplating
- Replies: 2
- Views: 436
Re: Electroplating
The test should not have this on there.
- Wed Feb 21, 2018 12:26 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Calculating K
- Replies: 3
- Views: 432
Re: Calculating K
Of the equations you listed, only the first two equations allow for you to calculate K, the last equation is Q which is the reaction quotient not the equilibrium constant.
- Tue Feb 13, 2018 5:10 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Useful Table of Thermodynamic definitions!!
- Replies: 2
- Views: 653
Re: Useful Table of Thermodynamic definitions!!
This is so helpful!
I think one good thing to add would be that reversible work occurs under ideal conditions and is very rare in real life.
I think one good thing to add would be that reversible work occurs under ideal conditions and is very rare in real life.
- Tue Feb 13, 2018 5:06 pm
- Forum: Van't Hoff Equation
- Topic: Derivation
- Replies: 5
- Views: 867
Derivation
Will we be tested on the derivation of this equation?
- Tue Feb 13, 2018 5:05 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Problem 9.47
- Replies: 1
- Views: 201
Problem 9.47
For part A is it also possible to use the work equation?
As in: q/T = -w/T
How would that work?
As in: q/T = -w/T
How would that work?
- Tue Feb 06, 2018 8:13 pm
- Forum: Balancing Redox Reactions
- Topic: Basic vs. Acidic
- Replies: 6
- Views: 621
Re: Basic vs. Acidic
I would add that if OH- and H+ ions are on the same side, then they are written as water.
- Tue Feb 06, 2018 8:07 pm
- Forum: Balancing Redox Reactions
- Topic: Transition Metals
- Replies: 4
- Views: 506
Transition Metals
Because the transition metals have variable oxidation states, which ones are we expected to memorize or will they be given?
- Tue Feb 06, 2018 8:02 pm
- Forum: Balancing Redox Reactions
- Topic: Water in Redox reaction
- Replies: 1
- Views: 211
Water in Redox reaction
In today's (Wednesday week 5) lecture, Dr. Lavelle put water in the half-reaction for reduction. Is there a reason to do so?
- Tue Jan 30, 2018 5:15 pm
- Forum: Phase Changes & Related Calculations
- Topic: Hw #8.49 standard state
- Replies: 4
- Views: 604
Re: Hw #8.49 standard state
Because it doesn't say otherwise and because all the given information assumes a standard state, it is a safe assumption to make.
- Tue Jan 30, 2018 5:13 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: 9.25
- Replies: 3
- Views: 464
Re: 9.25
I think the simplest approach is to look at the shape of the molecule as well as the number of different elements involved (e.g. switching the positions of two oxygens doesn't count as a different arrangement). Here there are four atoms around the central sulfur atom and they are of two types
- Tue Jan 30, 2018 5:08 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: 9.13
- Replies: 7
- Views: 1014
Re: 9.13
I think using nR allows us to cancel out the moles in the denominator but I am not sure.
- Wed Jan 24, 2018 4:48 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm
- Replies: 2
- Views: 328
Midterm
Will our midterm basically cover chapter 8,9, and 11?
- Wed Jan 24, 2018 4:42 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Week 3 Test Topic is endorsed
- Replies: 37
- Views: 4951
Re: Week 3 Test Topic is endorsed
There are no calculations on heat and internal energy but you do have to understand the concepts.
- Wed Jan 24, 2018 4:39 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3941418
Re: Post All Chemistry Jokes Here
If you're not part of the solution, you're part of the precipitate.
- Wed Jan 24, 2018 4:39 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3941418
Re: Post All Chemistry Jokes Here
Q: Why does hamburger yield lower energy than steak?
A: Because it's in the ground state.
A: Because it's in the ground state.
- Wed Jan 24, 2018 4:37 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3941418
Re: Post All Chemistry Jokes Here
Did you know that you can cool yourself to -273.15˚C and still be 0k?
- Wed Jan 17, 2018 6:42 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Equations for gases using R
- Replies: 4
- Views: 331
Re: Equations for gases using R
I think there are some homework problems that use those equations indirectly in order to derive other values. But I don't think those equations will be tested on directly because they were not touched on in a detailed manner in class.
- Mon Jan 15, 2018 10:14 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Equations and formulas
- Replies: 2
- Views: 232
Equations and formulas
Will the formula and equation sheet be posted on the website like it is for Chem 14A?
- Mon Jan 15, 2018 8:05 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Homework Problem 8.23
- Replies: 1
- Views: 171
Homework Problem 8.23
The solution indicates the use of the equation q=mC delta T. However the mass is not shown in the solution or indicated in the question. How do you solve this question without knowing the mass?
- Mon Jan 08, 2018 7:56 pm
- Forum: Phase Changes & Related Calculations
- Topic: Enthalpy and Volume of a System
- Replies: 2
- Views: 214
Re: Enthalpy and Volume of a System
From the textbook: The state function that allows us to keep track of energy changes at constant pressure is called the enthalpy, H: H = U + PV U, P, and V are the internal energy, pressure, and volume of the system With this being the case, I am assuming that the great the volume, the greater the e...
- Mon Jan 08, 2018 7:51 pm
- Forum: Phase Changes & Related Calculations
- Topic: Topics covered for Test 1 [ENDORSED]
- Replies: 1
- Views: 248
Topics covered for Test 1 [ENDORSED]
Does anyone know what topics will be covered in Test 1? Is it only Chapter 8?
- Mon Jan 08, 2018 5:30 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Strength of Interactions in a Solid
- Replies: 3
- Views: 260
Strength of Interactions in a Solid
In a conceptual paragraph in the textbook, it said that when a solid melts, the molecules can move more freely,
but the interactions between them remain as strong. Does anyone understand why this is true?
but the interactions between them remain as strong. Does anyone understand why this is true?
- Sat Dec 09, 2017 7:30 pm
- Forum: Identifying Acidic & Basic Salts
- Topic: Salts
- Replies: 3
- Views: 927
Re: Salts
Just to make sure, salts will not be covered on the final exam due to the fires.
- Tue Nov 28, 2017 8:32 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: change in temperature
- Replies: 4
- Views: 435
Re: change in temperature
A change in temperature will always favor the exothermic reaction whether it is an increase or decrease.
- Tue Nov 28, 2017 8:26 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: polar or nonpolar
- Replies: 1
- Views: 220
Re: polar or nonpolar
Drawing the Lewis structures definitely helps because you are essentially looking at the symmetry of dipole moments in the molecule. If there is no one direction of electron density it is non-polar and if there is it's polar.
- Sun Nov 26, 2017 8:43 pm
- Forum: Naming
- Topic: Cyano vs Cyanido
- Replies: 1
- Views: 279
Cyano vs Cyanido
The solution manual sometimes uses cyano but the table in the textbook that has the steps for naming uses cyanido. Are they interchangeable?
- Sun Nov 26, 2017 8:40 pm
- Forum: Naming
- Topic: Charge of a Ligand
- Replies: 2
- Views: 361
Charge of a Ligand
Do we just have to memorize ligands and their charges, or is there a manner in which we can find them?
- Tue Nov 14, 2017 5:10 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone Pairs and Bond Angle
- Replies: 3
- Views: 498
Lone Pairs and Bond Angle
Could someone clarify the relationship between lone pairs and bond angles? I understand that the bond angles are "strained" by the lone pairs but am not quite sure how to show that in our answers.
- Tue Nov 14, 2017 5:06 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent vs Angular
- Replies: 7
- Views: 805
Bent vs Angular
Just to clarify, Dr.Lavelle uses the terminology "bent" when describing molecular shape while the textbook seems to use "angular" to mean the same thing. Are those terms interchangeable?
- Sat Nov 11, 2017 9:23 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Resonance
- Replies: 3
- Views: 510
Resonance
Does resonance have an impact on the molecular shape? How do we decide which Lewis structure to base our VSEPR theory on?
- Sat Nov 11, 2017 9:20 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angle Exceptions
- Replies: 3
- Views: 1575
Bond Angle Exceptions
As I was reading the textbook, I noticed that many molecular shapes have bond angles that are different from what is expected of that shape. Is there any way to predict these exceptions or do they have to be memorized?
EX: the HOH bond angle
EX: the HOH bond angle
- Wed Nov 01, 2017 1:13 pm
- Forum: Coordinate Covalent Bonds
- Topic: Coordinate Covalent Bonds - Lewis Acids and Bases [ENDORSED]
- Replies: 1
- Views: 455
Coordinate Covalent Bonds - Lewis Acids and Bases [ENDORSED]
In one of the answers on this forum, the moderator answered that an atom that donates two electrons is a Lewis base. I'm a little confused about the relationship between coordinate covalent bonds and Lewis Acids and Bases. Thank you for the help!
- Wed Nov 01, 2017 1:05 pm
- Forum: Trends in The Periodic Table
- Topic: Noble Gas Electron Affinity
- Replies: 3
- Views: 1814
Re: Noble Gas Electron Affinity
The trend in electron affinity is best applied to elements that do not have a full octet and thus benefit from additional electrons that allow them to be more stable. Thus the halogens have extremely high electron affinity because the only require one more electron to fulfill their octet, but the tr...
- Tue Oct 24, 2017 10:43 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: f-block
- Replies: 3
- Views: 538
f-block
Could someone explain the layout of the f-block on the periodic table?
- Tue Oct 24, 2017 10:42 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Electron Configuration writing
- Replies: 8
- Views: 881
Electron Configuration writing
I just have a pretty simple question about the manner in which we write electron configuration. In lectures in was written in order of the periodic table (putting 3d after 4s) but in my discussion, we were told to order it in terms of principal quantum number. Which way is correct?
- Wed Oct 18, 2017 3:11 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Post Module Question #16
- Replies: 2
- Views: 360
Re: Post Module Question #16
The correct answer is C. The textbook says if one property is known the other cannot be known simultaneously.
- Wed Oct 18, 2017 3:07 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: E-p distribution
- Replies: 2
- Views: 227
E-p distribution
During Wednesday's lectur of Week 3, can someone explain what Dr.Lavelle meant by the term e-p distribution?
- Wed Oct 11, 2017 8:45 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Energy Level Series
- Replies: 2
- Views: 365
Re: Energy Level Series
I would like to add that there is also the Paschen series which has a lower energy level of n=3.
- Wed Oct 11, 2017 8:41 pm
- Forum: Limiting Reactant Calculations
- Topic: Net moles produced (Test question)
- Replies: 3
- Views: 576
Net moles produced (Test question)
In one of the questions on our test, it asked for the net moles of gas produced. However, in the calculation, it added the total number of moles produced on the product side (including that of H2O which I assumed was in liquid form). When questions ask for net moles produced do we just include the m...
- Tue Oct 10, 2017 5:55 pm
- Forum: Limiting Reactant Calculations
- Topic: Net moles produced (Test question) [ENDORSED]
- Replies: 2
- Views: 390
Net moles produced (Test question) [ENDORSED]
In one of the questions on our test, it asked for the net moles of gas produced. However, in the calculation, it added the total number of moles produced on the product side (including that of H2O which I assumed was in liquid form). When questions ask for net moles produced do we just include the m...
- Mon Oct 02, 2017 11:45 pm
- Forum: Balancing Chemical Reactions
- Topic: Prep Quiz 2015 #7
- Replies: 2
- Views: 567
Re: Prep Quiz 2015 #7
All combustion reactions follow the basic setup of hydrocarbon + O2 (g) -> CO2 (g) + H2O (l).
You put the hydrocarbon in this set up and balance the equation as necessary.
You put the hydrocarbon in this set up and balance the equation as necessary.
- Mon Oct 02, 2017 11:38 pm
- Forum: Empirical & Molecular Formulas
- Topic: How to tell if Empirical and Molecular Formula are the same? [ENDORSED]
- Replies: 2
- Views: 517
Re: How to tell if Empirical and Molecular Formula are the same? [ENDORSED]
I guess the quickest way is to estimate the molar mass of the empirical formula in your head without doing any calculation. and compare that to the given mass. If it is not close, you know that the molecular formula is a multiple of the empirical formula.