Search found 55 matches
- Fri Mar 16, 2018 12:07 pm
- Forum: *Electrophiles
- Topic: what is going to be on the final? [ENDORSED]
- Replies: 12
- Views: 2645
Re: what is going to be on the final? [ENDORSED]
There will be some questions on the functional groups which he introduced in class on Monday, so be able to recognize them if they are in line structures.
- Fri Mar 16, 2018 12:05 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Calculating standard cell potentials
- Replies: 2
- Views: 418
Re: Calculating standard cell potentials
You want E to be positive because the reaction has to be spontaneous which only happens in galvanic cells. So, I believe that you have to flip the oxidation side if you are using that method of calculating E.
- Fri Mar 16, 2018 12:01 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Cp or Cv??
- Replies: 1
- Views: 450
Re: Cp or Cv??
If it is a sealed container, the final volume is always constant. It seems like volume is changing because there is a divider, but overall volume is not changing.
- Sun Mar 11, 2018 11:28 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: enthalpy of sublimation
- Replies: 5
- Views: 934
Re: enthalpy of sublimation
I'm pretty sure you need to know all the enthalpies, but they should be on the equations sheet.
- Sun Mar 11, 2018 11:19 am
- Forum: Student Social/Study Group
- Topic: Chem 14BL Exchange
- Replies: 1
- Views: 517
Re: Chem 14BL Exchange
Hi, I have the other professor for a Tuesday lab from 11 am to 1:50 pm. If you would like this, let me know!
- Sun Mar 11, 2018 11:16 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: concept question
- Replies: 2
- Views: 499
Re: concept question
A gas phase has a higher level of entropy because there are more arrangements for the molecules. On the other hand, for liquids, entropy is lower because the liquid cannot have more arrangements.
- Sun Mar 11, 2018 11:13 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Delta G at Boiling Point
- Replies: 3
- Views: 3385
Re: Delta G at Boiling Point
At boiling point, the change in temperature is zero so change in enthalpy is also zero (infer that pressure is constant so W=0). Since change in enthalpy is zero, we also want change in entropy to be zero. This happens when W=0.
- Sun Mar 04, 2018 12:54 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: slow step
- Replies: 3
- Views: 436
Re: slow step
The slow step and the rate law should be the same in terms of reactants. The rate law should match the slow step’s reactants.
- Sun Mar 04, 2018 12:32 pm
- Forum: General Rate Laws
- Topic: drivations
- Replies: 2
- Views: 433
Re: drivations
Also one the equation sheet, it won’t tell you what orde the derivations or integrations are so make sure to know which one is first, second, and zero orders.
- Wed Feb 28, 2018 8:35 pm
- Forum: Zero Order Reactions
- Topic: Zero Order Reactions and Rate of Reaction
- Replies: 5
- Views: 785
Zero Order Reactions and Rate of Reaction
When a product/reactant has a zero order, does that mean it’s concentration is independent of the rate?
- Tue Feb 20, 2018 4:48 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Question 14.25
- Replies: 3
- Views: 439
Re: Question 14.25
In this question, Zinc has a more negative standard potential than Chromium, but the answer key shows that chromium is the stronger reducing agent. Why is that?
- Tue Feb 20, 2018 4:45 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Rule of Thumb for Cell Diagrams
- Replies: 3
- Views: 443
Re: Rule of Thumb for Cell Diagrams
You use a comma when the ions or compounds are in the same state on the same side, and use a single line when they have different states.
- Mon Feb 19, 2018 10:32 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 14.13
- Replies: 5
- Views: 824
Re: 14.13
For 14.13c why is the Cl- put before the Cl2 when they are the ones being reduced. Shouldn't Cl be put in front of the Cl- or does the phase matter?
- Sun Feb 18, 2018 7:22 pm
- Forum: Balancing Redox Reactions
- Topic: Half Reaction
- Replies: 3
- Views: 430
Re: Half Reaction
I don't think it will because the half reactions need to be cancelled out. In the half reactions the H+ should be included and full compounds/ions.
- Sun Feb 18, 2018 7:20 pm
- Forum: Balancing Redox Reactions
- Topic: Basic conditions
- Replies: 3
- Views: 498
Re: Basic conditions
Yes, for basic solutions, you add OH-.
- Sun Feb 18, 2018 6:32 pm
- Forum: Balancing Redox Reactions
- Topic: 14.5A
- Replies: 1
- Views: 354
Re: 14.5A
To see which compounds are reduced or oxidized, you have to look at the oxidation states. Br is going from an oxidation state of 1- to 5+ which shows that it's being oxidized.
- Sun Feb 11, 2018 10:01 am
- Forum: Administrative Questions and Class Announcements
- Topic: Sunday Midterm Review Session Worksheet
- Replies: 2
- Views: 673
Re: Sunday Midterm Review Session Worksheet
It should be under administrative questions, and will be labeled as Winter 2018 Practice Midterm.
- Fri Feb 09, 2018 5:02 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Homework problem 9.47
- Replies: 2
- Views: 439
Homework problem 9.47
In 9.47, the question asks about an isothermal, irreversible, free expansion. How do we know that the change in internal energy is zero from this phrase? Since internal energy is zero, that means q is also zero.
- Sun Feb 04, 2018 11:40 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Constant K and reaction quotient
- Replies: 3
- Views: 469
Re: Constant K and reaction quotient
K is supposed to symbolize when the reaction is at equilibrium. The reactant quotient is when the reaction is not at equilibrium. When Q>K, that means there is too much product which means the reverse reaction is favored. When Q<K, that means there is too much reactant which means the forward reacti...
- Sun Feb 04, 2018 11:37 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Equations
- Replies: 3
- Views: 461
Re: Equations
G is defined as the maximum non-expansion work under constant temperature and pressure. If work done by the system is negative, DeltaG < w, since G = H-TS = U+PV-TS.
Then DeltaG is the maximum work that may be done.
Then DeltaG is the maximum work that may be done.
- Wed Jan 31, 2018 11:40 am
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Why should deltaG=0?
- Replies: 4
- Views: 825
Why should deltaG=0?
For the example shown in class today, why does deltaG have to be zero to find the minimum temperature?
- Sun Jan 28, 2018 12:45 pm
- Forum: Calculating Work of Expansion
- Topic: The integral equation
- Replies: 8
- Views: 697
Re: The integral equation
Will we need to know how to derive the integral for the test/ midterm coming up?
- Sun Jan 28, 2018 12:41 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bondy Enthalpy Accuracy
- Replies: 3
- Views: 631
Re: Bondy Enthalpy Accuracy
in addition to what others said, bond enthalpies for diatomic molecules are the only exact calculations. Every other bond enthalpy is an average.
- Sun Jan 28, 2018 12:39 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: Third Law of Thermodynamics
- Replies: 4
- Views: 569
Re: Third Law of Thermodynamics
The third law of thermodynamics states that for a perfect crystal at absolute zero, the entropy is also zero.
- Wed Jan 24, 2018 8:15 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Reversible Expansion vs Irreversible Expansion
- Replies: 1
- Views: 179
Reversible Expansion vs Irreversible Expansion
Why does a reversible expansion do more work than an irreversible expansion?
- Sun Jan 21, 2018 7:27 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Heat capacity
- Replies: 2
- Views: 211
Re: Heat capacity
Different phases need more energy to convert the substance into another state, so some need more energy which is what the heat capacity states.
- Sun Jan 21, 2018 7:25 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 8.77
- Replies: 2
- Views: 199
Re: 8.77
This problem is just allowing you to see how benzene'S resonance allows it to have a lower molar energy than the different resonance structures that we can draw it of the c-c and c=c bonds. The kekule structure is the ones that we've drawn out with the 3 single and 3 double carbon bonds, while reson...
- Mon Jan 15, 2018 1:10 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Intensive vs extensive property
- Replies: 2
- Views: 348
Intensive vs extensive property
What is the difference between extensive and intensive properties? In the notes, it states that heat capacity is an extensive property while specific heat capacity is an intensive property.
- Sun Jan 14, 2018 11:01 am
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Why isn't heat a state function?
- Replies: 2
- Views: 738
Re: Why isn't heat a state function?
Heat is not an internal property of the system. It depends on the path taken to go from point A to point B which is why it's not a state function.
- Sun Jan 14, 2018 10:55 am
- Forum: Administrative Questions and Class Announcements
- Topic: Test #1
- Replies: 1
- Views: 223
Re: Test #1
It depends on how much material we cover before the Tuesday when the tests start in discussions. Usually it's material up to Friday before the test.
- Thu Jan 11, 2018 9:47 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Differences in the delta Hs
- Replies: 2
- Views: 372
Differences in the delta Hs
What is the difference between a delta H with a subscript of c and a delta H with a subscript of h? The delta h had a subscript of c in the homework problem in 8.57?
- Thu Dec 07, 2017 12:52 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Practice Test Fall 2017 [ENDORSED]
- Replies: 19
- Views: 3378
Re: Practice Test Fall 2017 [ENDORSED]
Hi,
Can you post the answers for the past two review worksheets for Week 7 and Week 9?
Can you post the answers for the past two review worksheets for Week 7 and Week 9?
- Tue Dec 05, 2017 2:25 pm
- Forum: Lewis Acids & Bases
- Topic: 12.15
- Replies: 3
- Views: 563
Re: 12.15
You can also count the number of electrons each compound or ion has. PF5 would have 40 electrons and F- would have 8 electrons. If PF6 didn't have a charge it would only have 47 electrons, but the structure should have the same number of electrons as its reactants, so it would need an extra electron...
- Tue Dec 05, 2017 11:44 am
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: 5% Rule for Weak Acids
- Replies: 2
- Views: 604
5% Rule for Weak Acids
When we calculate the pH for weak acids, and the change in concentration is extremely small because kA is extremely small, do we automatically assume the change in concentration for the initial concentration is negligible like how we did the example in lecture? Do we always have to check using the 5...
- Sun Dec 03, 2017 6:49 pm
- Forum: Lewis Acids & Bases
- Topic: Memorizing Acids and Bases
- Replies: 7
- Views: 857
Memorizing Acids and Bases
Do we have to memorize the list of weak acids and bases, and strong acids and bases for the final?
- Sun Dec 03, 2017 6:46 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Coordination Number
- Replies: 4
- Views: 616
Re: Coordination Number
To find the coordination number, only look at the elements within the brackets and the number of ligands attached to the transition metal. Anything outside the brackets should not be counted.
- Mon Nov 20, 2017 6:46 pm
- Forum: Naming
- Topic: H2O in Coordination compounds
- Replies: 2
- Views: 495
H2O in Coordination compounds
When figuring out the order of coordination compounds, how do you know to put OH2 or H2O as the structure within the compound? It has them both ways in the solutions manual.
- Mon Nov 20, 2017 6:37 pm
- Forum: Naming
- Topic: Homework #17.31
- Replies: 1
- Views: 290
Homework #17.31
When figuring out the elements of a compound, does it matter in which way compounds are ordered in the coordination compound? For example in 17.31b, the compound is pentaamine sulfatocobalt(III) chloride, and the sulfate is mentioned second but is connected to the cobalt in the answer, [Co(SO4)(NH3)...
- Sat Nov 18, 2017 5:51 pm
- Forum: Hybridization
- Topic: Hybridized Orbitals
- Replies: 2
- Views: 386
Hybridized Orbitals
Are we going to have to show how we came up with the hybridized orbital on the test like how he did in class?
- Sat Nov 18, 2017 5:44 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lewis Structures and VSEPR Shape
- Replies: 4
- Views: 586
Re: Lewis Structures and VSEPR Shape
I don't think you need to unless he specifically asks for it. Otherwise, you can just normally do a Lewis structure.
- Wed Nov 08, 2017 11:58 pm
- Forum: Trends in The Periodic Table
- Topic: Noble Gases
- Replies: 3
- Views: 1631
Noble Gases
What type of ionization energy and electron affinity doe noble gases have?
- Wed Nov 08, 2017 11:48 pm
- Forum: Lewis Structures
- Topic: Lewis Structure [ENDORSED]
- Replies: 4
- Views: 548
Re: Lewis Structure [ENDORSED]
Yes, since the lowest energy structure means that the structure is the most stable for the compound or element.
- Sun Nov 05, 2017 11:49 am
- Forum: Lewis Structures
- Topic: Cl as an Expanded Octet
- Replies: 3
- Views: 5720
Re: Cl as an Expanded Octet
Since Chlorine is in the n=3 shell, that means it can gain more electrons to put into a 3d shell, if necessary.
- Sun Nov 05, 2017 11:47 am
- Forum: Resonance Structures
- Topic: Homework problem 3.57
- Replies: 1
- Views: 398
Homework problem 3.57
In all of the Lewis structures, the highest ionization energy atoms are the central atoms, even though we learned that the central atom should have the lowest ionization energy. Why is it like that? Is it only to show the resonance structures?
- Sat Oct 28, 2017 4:48 pm
- Forum: *Shrodinger Equation
- Topic: Node
- Replies: 3
- Views: 617
Re: Node
I think it means when an electron has gone through a full wave cycle that it means that it goes through a node.
- Sat Oct 28, 2017 4:45 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Electron Configuration Exceptions [ENDORSED]
- Replies: 3
- Views: 520
Re: Electron Configuration Exceptions [ENDORSED]
The only exceptions we are required to know are Chromium and Copper.
- Sat Oct 28, 2017 4:42 pm
- Forum: Trends in The Periodic Table
- Topic: Electron Affinity [ENDORSED]
- Replies: 5
- Views: 749
Electron Affinity [ENDORSED]
Do all half-filled subshelled atoms always have a higher electron affinity than the atom right next to them because they are more stable? For example, carbon has a higher electron affinity than nitrogen. Does this also correspond with phosphorus and sulfur?
- Sun Oct 22, 2017 8:27 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: ORBITALS, SHELLS ETC. [ENDORSED]
- Replies: 6
- Views: 898
Re: ORBITALS, SHELLS ETC. [ENDORSED]
I think if you do the homework for chapter 2, the questions will be a little similar to what can be on his test.
- Sun Oct 22, 2017 8:24 am
- Forum: DeBroglie Equation
- Topic: Should velocity always be in m.s. when solving? [ENDORSED]
- Replies: 11
- Views: 1929
Re: Should velocity always be in m.s. when solving? [ENDORSED]
Velocity should be in its SI units unless state otherwise on a test.
- Sun Oct 22, 2017 8:13 am
- Forum: Einstein Equation
- Topic: Comparing E=pc and E=.5mv^2
- Replies: 3
- Views: 608
Comparing E=pc and E=.5mv^2
When finding the velocity of an electron, which formula should you use, E=pc or E=.5mv^2? Does it depend on if the electron is being described as a particle or a wavelength?
- Sun Oct 15, 2017 12:20 am
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: why is Bohr Frequency equation negative
- Replies: 4
- Views: 1822
Re: why is Bohr Frequency equation negative
As the electron returns to a ground state, it's point of reference was at the highest energy level who's energy was zero. Since the electron is returning to a lower energy level, it is emitting energy and would have to be a negative number because of the reference point's energy which is zero.
- Sat Oct 14, 2017 11:53 pm
- Forum: Properties of Electrons
- Topic: Conversions [ENDORSED]
- Replies: 4
- Views: 930
Re: Conversions [ENDORSED]
Will we get this conversion, if needed, on the sheet of paper for the quiz, or do we have to memorize this?
- Sat Oct 14, 2017 11:49 pm
- Forum: Properties of Electrons
- Topic: Energy Levels [ENDORSED]
- Replies: 2
- Views: 458
Re: Energy Levels [ENDORSED]
Since the electron is returning to the ground state, it is emitting energy, which would be a negative number. However, this number is used to find wavelengths, and the calculation can't have a negative energy because then it would result in a negative wavelength, which isn't possible. The energy is ...
- Fri Oct 06, 2017 1:02 am
- Forum: Limiting Reactant Calculations
- Topic: M.9
- Replies: 4
- Views: 727
Re: M.9
Quick question about these net ionic equation thing. Do we need to write the charges for everything or is that just a little extra thing that the solutions manual does? Like Cu2+ (aq) + 2OH-(aq) ... Also in regular reactions/equations when would we need to write the charges if ever? Also in a react...
- Fri Oct 06, 2017 12:54 am
- Forum: Empirical & Molecular Formulas
- Topic: Identifying Empirical and Molecular Formulas [ENDORSED]
- Replies: 13
- Views: 8936
Re: Identifying Empirical and Molecular Formulas [ENDORSED]
When writing an empirical or molecular formula, how do you know in what order to write the elements? For example, how would you know to write Na3AlF6 rather than AlNa3F6 or Na3F6Al? When writing the molecular or empirical formula the order usually is the elements C followed by H, and then it always...