Search found 54 matches
- Sat Mar 17, 2018 8:35 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Elementary Reaction
- Replies: 2
- Views: 453
Re: Elementary Reaction
Most likely for the exam you will be given whether the elementary reaction is fast or slow.
- Sat Mar 17, 2018 8:29 pm
- Forum: *Ketones
- Topic: Ketones vs Aldehydes
- Replies: 2
- Views: 1247
Re: Ketones vs Aldehydes
Aldehydes' C is bonded to either 1 or 2 H. Ketones' C is bonded to 2 C.
- Sat Mar 17, 2018 3:51 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: A?
- Replies: 6
- Views: 1090
Re: A?
If T increases, k increases, and if k increases, A increases. This should mean that as T increases, A should increase.
- Sun Mar 11, 2018 11:46 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Intermediates
- Replies: 3
- Views: 535
Re: Intermediates
A compound is an intermediate if it is produced in one step of the reaction and is consumed as a reactant in a later step, but does not appear in the overall reaction. If it appears as one of the reactants at the beginning and later appears as a product in a subsequent step, the compound is instead ...
- Sun Mar 11, 2018 11:43 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Rate constant
- Replies: 6
- Views: 753
Re: Rate constant
Rate constant is just a constant of proportionality relating how the concentrations of the participants of the reaction relate to the rate of reaction. The rate itself just shows how fast the concentration of one of the participants changes, in units of concentration/pressure per unit time. The rate...
- Sun Mar 11, 2018 11:39 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Intermediates in Rate law
- Replies: 3
- Views: 4192
Re: Intermediates in Rate law
Yes, when writing the overall rate law, you shouldn't include intermediates, only substances that are in the overall reaction.
- Sun Mar 04, 2018 11:26 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: test 2 last Q
- Replies: 3
- Views: 557
Re: test 2 last Q
What was the question? I'm not in 1I, but I might be able to help if I see the question.
- Sun Mar 04, 2018 11:19 pm
- Forum: Balancing Redox Reactions
- Topic: Test 2, Q5
- Replies: 4
- Views: 570
Re: Test 2, Q5
These rankings are not based off the placement of the elements in the periodic table. They are based on the standard reduction potentials of each, given in the table provided on the test. Elements with a stronger reducing power will have a lower reduction potential, therefore; organize them based o...
- Sun Mar 04, 2018 11:15 pm
- Forum: Second Order Reactions
- Topic: Week 9 HW and test promblems
- Replies: 5
- Views: 921
Re: Week 9 HW and test promblems
Supposedly everything on the HW is fair game, but I think for the tests themselves, the questions before the Integrated Exercises are enough (at least that's how it has been). The integrated HW should be done for finals prep, however.
- Sun Feb 25, 2018 11:18 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: how to write a cell diagram [ENDORSED]
- Replies: 7
- Views: 2044
Re: how to write a cell diagram [ENDORSED]
My TA said that the order is not always followed that way. For the purpose of this class, I don't think the order will be stressed upon.
- Sun Feb 25, 2018 11:16 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 14.13c
- Replies: 4
- Views: 468
Re: 14.13c
I don't think that matters, as long as you place the right compounds into the right anode or cathode.
- Fri Feb 23, 2018 1:42 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 14.13(b)
- Replies: 2
- Views: 335
14.13(b)
Does the order in which we write the galvanic cell components matter? More specifically, is there a reason why I2(s) is in the third position in the given answer, which is Pt(s) | I-(aq) | I2(s) || Ce4+(aq), Ce3+(aq) | Pt(s) ?
- Mon Feb 19, 2018 8:26 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Acidic vs. Basic
- Replies: 2
- Views: 329
Re: Acidic vs. Basic
My TA said that the questions on the test won't necessarily be given all in acidic conditions. To find out how many H+, H2O, and OH- to add, you'd have to find the oxidation numbers and charges of both sides of the equation, and then add the necessary ions and water molecules to balance the equation...
- Mon Feb 19, 2018 8:20 am
- Forum: Balancing Redox Reactions
- Topic: 14.15c
- Replies: 2
- Views: 417
Re: 14.15c
The KOH is there as a salt bridge to allow for the flow of ions.
- Mon Feb 19, 2018 8:19 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 14.15.c
- Replies: 2
- Views: 427
Re: 14.15.c
The KOH is there as a salt bridge to allow for flow of ions.
- Sun Feb 11, 2018 11:44 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: troutons rule
- Replies: 3
- Views: 573
Re: troutons rule
Exercise 9.17 (which is on Trouton's Rule) is skipped on the outline, so I don't think so.
- Sun Feb 11, 2018 10:41 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: Reversible/equilibrium
- Replies: 1
- Views: 288
Re: Reversible/equilibrium
No, but they have to be reversible to return to equilibrium.
- Sun Feb 11, 2018 10:29 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Maximum Potential
- Replies: 2
- Views: 785
Re: Maximum Potential
Max potential of a cell is the maximum potential difference between two half cells in an electrochemical cell.
- Sun Feb 04, 2018 11:28 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: 9.19
- Replies: 2
- Views: 293
Re: 9.19
The first step is to heat the reactants to 100 degrees Celsius using the formula delta S = C(P,m)*ln(T2/T1).
- Sun Feb 04, 2018 9:35 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Equations
- Replies: 2
- Views: 455
Re: Equations
I'd say your best bet is to familiarize yourself with the Constants and Equations sheet, since that'll be given to us on the test. As for which equations are used in a given circumstances, practicing questions helps the most.
- Sun Feb 04, 2018 8:06 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: 9.35
- Replies: 2
- Views: 339
Re: 9.35
Container A's change in entropy is higher than that of Container C since Container A's monatomic particles have greater disorder than Container C's diatomic molecules. Complexity of the molecules are important, but in this question's case, we are looking at the rigidity of the structure.
- Sun Jan 28, 2018 10:11 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: Reversible and Irreversible Pathways
- Replies: 4
- Views: 612
Re: Reversible and Irreversible Pathways
I believe in irreversible, the pressure is changed immediately, whereas in reversible, the pressure is changed slowly.
- Fri Jan 26, 2018 12:38 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Exercise 8.45
- Replies: 1
- Views: 247
Exercise 8.45
For part a, the SSM shows that to find change in H, we should multiply 1.25 mol by 358.8 kJ/mol. However, the book gives us that the change in enthalpy is 358.8 kJ. Why are the two units different?
- Thu Jan 25, 2018 10:44 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: 8.31
- Replies: 5
- Views: 657
Re: 8.31
On the same question but regarding units, can molar heat capacity be J/(mol.C)? It thought it had to be J/(mol.K)...
- Sun Jan 21, 2018 9:52 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 8.67 gas to liquid
- Replies: 2
- Views: 271
Re: 8.67 gas to liquid
Endothermic reactions have a positive change in enthalpy, and exothermic reactions have a negative change in enthalpy. Because a gas to liquid change is exothermic, the change in enthalpy is negative.
- Sun Jan 21, 2018 9:42 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 8.67
- Replies: 2
- Views: 256
Re: 8.67
If I'm understanding your question correctly, the value of the standard enthalpy of sublimation of carbon is, it's +717 kJ*mol^(-1), which was written in the question. If I didn't interpret your question correctly, can you clarify the question?
- Sun Jan 21, 2018 9:37 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Homework 8.85
- Replies: 1
- Views: 165
Re: Homework 8.85
I think it will be tested, since Professor Lavelle put that topic on the outline.
- Sun Jan 14, 2018 10:57 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Closed Versus Isolated System
- Replies: 3
- Views: 427
Re: Closed Versus Isolated System
Although both systems' matter do not have contact with the environment an thus cannot exchange matter, a closed system is one in which the matter can exchange energy with the environment, whereas an isolated system is one in which the matter cannot exchange energy with the environment.
- Sun Jan 14, 2018 10:48 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: 8.5
- Replies: 2
- Views: 316
Re: 8.5
In this question's case, yes. In general, the change in internal energy can be found by adding the two energies, while paying attention to the signs on the energy changes.
- Sun Jan 14, 2018 10:45 pm
- Forum: Phase Changes & Related Calculations
- Topic: Good hw questions to practice?
- Replies: 2
- Views: 302
Re: Good hw questions to practice?
Not sure if this will help, but Section 8.8 is where enthalpy questions start, which is what we started going over in class. So I guess 8.29 and on?
- Sat Dec 09, 2017 11:02 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Test 4 #6
- Replies: 1
- Views: 306
Test 4 #6
After configuring the ICE box and then solving for x, I eventually arrive at x = 2.40, 2.6. Why does x have to be 2.4, and why can't it be 2.6?
- Sat Dec 09, 2017 9:34 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Lewis Structures of Compounds with Ligands
- Replies: 1
- Views: 312
Lewis Structures of Compounds with Ligands
When drawing Lewis structures of compounds with ligands, do we need to draw in each ligand's valence electrons?
- Sat Dec 09, 2017 9:31 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Naming of coordination compounds
- Replies: 1
- Views: 346
Re: Naming of coordination compounds
When there is an overall charge that is not zero in the compound.
- Thu Dec 07, 2017 8:25 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: 12.55(a)
- Replies: 1
- Views: 187
12.55(a)
Why does (x^2)/([Molarity of CH3COOH] - x) round to (x^2)/[Molarity of CH3COOH]?
- Wed Dec 06, 2017 4:06 pm
- Forum: Amphoteric Compounds
- Topic: Bi2O5 vs Bi2O3 [ENDORSED]
- Replies: 2
- Views: 2035
Bi2O5 vs Bi2O3 [ENDORSED]
On exercise 12.17 d, Bi2O3 is listed as an amphoteric oxide in the SSM. However, as an oxide, Bi is listed as an acidic oxide on Professor Lavelle's lecture notes (the periodic table of oxide figure). Why do the two differ? Does it have something to do with the number of O bonded to the Bi?
- Thu Nov 30, 2017 12:37 am
- Forum: Sigma & Pi Bonds
- Topic: Sigma and Pi bonds
- Replies: 5
- Views: 836
Re: Sigma and Pi bonds
Sigma bonds occur when two orbitals, each with 1 electron, overlap end to end to form 1 sigma bond. They allow bound atoms to rotate. Pi bonds occur when two orbitals, each with 1 electron, overlap side by side to form 1 pi bond. Unlike sigma bonds, pi bonds do not allow bound atoms to rotate. When ...
- Thu Nov 30, 2017 12:30 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: EDTA and Bonding Sites [ENDORSED]
- Replies: 5
- Views: 1265
Re: EDTA and Bonding Sites [ENDORSED]
Oops, I'm sorry I meant ligand.
- Wed Nov 29, 2017 12:10 am
- Forum: Ideal Gases
- Topic: Pascal vs Atmosphere
- Replies: 3
- Views: 804
Re: Pascal vs Atmosphere
Lavelle uses atm for the purposes of Chem 14A (at least it says so in his course reader).
- Sun Nov 26, 2017 11:34 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: EDTA and Bonding Sites [ENDORSED]
- Replies: 5
- Views: 1265
Re: EDTA and Bonding Sites [ENDORSED]
EDTA is a ligate, so it has 4 binding sites with oxygen and 2 binding sites with nitrogen.
- Sun Nov 26, 2017 11:28 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Determining Molecular Shape
- Replies: 3
- Views: 302
Re: Determining Molecular Shape
They all should have the same number of each atoms, so I'm pretty sure you can use any, unless I'm not understanding your question right?
- Mon Nov 20, 2017 12:21 am
- Forum: Hybridization
- Topic: Sigma Bond
- Replies: 3
- Views: 437
Re: Sigma Bond
There could be more than one sigma bond, but for the purposes of this class, I'm pretty sure we only have to be concerned with the fact that there is usually only one sigma bond (something about how it's hard to draw two orthogonal sigma bonds?).
- Mon Nov 20, 2017 12:06 am
- Forum: Lewis Structures
- Topic: Organic Lewis Structures
- Replies: 2
- Views: 364
Re: Organic Lewis Structures
When I asked my TA, he said that it was intentional that Lavelle labeled the molecule as HOCO as a hint? Generally, it could be written as CHO2.
- Sun Nov 12, 2017 11:41 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Book Questions 4.1&4.2
- Replies: 4
- Views: 476
Re: Book Questions 4.1&4.2
I think it depends on the bond angles? For example, for part a on the first question, the molecule has a bond angle of 120, which should mean a trigonal planar, or basically 3 electron domains around the central atom. The diagram only shows 2 bonded pairs (which would otherwise be bond angle 180) s...
- Sun Nov 12, 2017 11:37 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Drawing VSEPR Models
- Replies: 2
- Views: 2056
Drawing VSEPR Models
Can someone explain to me what the dashed lines and/or solid triangles between two atoms signify, and when to draw them? Thanks in advance.
- Mon Nov 06, 2017 8:43 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Spin Quantum Number Question
- Replies: 2
- Views: 696
Spin Quantum Number Question
The following question was presented: "Copper is an interesting element as it has 10 elections in its 3d subshell and only one in its 4s subshell. What are the quantum numbers (n and l) that are associated with this last 3d^10 electron? Also, write all the possible values that a spin quantum nu...
- Mon Nov 06, 2017 8:37 pm
- Forum: Trends in The Periodic Table
- Topic: Electron Affinity - P, Na, Ar
- Replies: 4
- Views: 1014
Re: Electron Affinity - P, Na, Ar
According to my TA, noble gases have very low electron affinities.
- Sun Oct 29, 2017 5:04 pm
- Forum: Resonance Structures
- Topic: Delocalized
- Replies: 7
- Views: 873
Re: Delocalized
The example of benzene in lecture shows an example of the electrons involved in multiple bonds, as the structure shows a dotted circle within the carbon ring.
- Sun Oct 29, 2017 4:56 pm
- Forum: Lewis Structures
- Topic: Sulfate Ion
- Replies: 4
- Views: 633
Sulfate Ion
When you draw the sulfate ion (SO4)^2-, how can the sulfur share six electrons and have a total of 12? I thought the max was 8... Thanks in advance.
- Sun Oct 22, 2017 11:14 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Paired & Parallel Configurations
- Replies: 2
- Views: 284
Paired & Parallel Configurations
Can someone explain to me what it means when Lavelle says that paired electrons have opposite spins and parallel electrons have the same spins? I'm trying to visualize it but it's hard picture.
- Sun Oct 22, 2017 11:03 pm
- Forum: Properties of Electrons
- Topic: Rydberg Equation [ENDORSED]
- Replies: 6
- Views: 1074
Rydberg Equation [ENDORSED]
In the Rydberg equation, does (n1)^2 always have to be the lower energy level? Or can it be the first given energy level (for example if the problem says it went from energy level n = 4 to n = 2, can n1 be 4)?
- Fri Oct 13, 2017 12:33 am
- Forum: Properties of Light
- Topic: Exercise 1.9 Sig Fig
- Replies: 3
- Views: 525
Exercise 1.9 Sig Fig
Based on the SSM, for the second row in the table, why don't the number of sig figs match? 5.0E14 Hz is 2 sig figs, and 600 nm is 1 sig fig... Thanks in advance.
- Fri Oct 13, 2017 12:18 am
- Forum: Properties of Electrons
- Topic: Energy Levels [ENDORSED]
- Replies: 2
- Views: 473
Energy Levels [ENDORSED]
In discussion we discussed energy levels and changes in energy (delta E), absorption, and emission. We were told that E (photon) = delta E. I understand that absorption of photons results in increased energy levels (n), with delta E being positive. I was curious, in emission, since photons are eject...
- Thu Oct 05, 2017 7:52 pm
- Forum: Empirical & Molecular Formulas
- Topic: Caproic Acid Question
- Replies: 6
- Views: 5115
Caproic Acid Question
Caproic acid is composed of C, H, and O. 0.225 g of this sample is combusted. 0.512 g of CO2 is produced. 0.209 g of H2O is produced. What is the empirical formula? This question was given during discussion section. I found how many moles of each product were produced (both were 0.0116 mol), but I d...
- Mon Oct 02, 2017 9:11 pm
- Forum: Balancing Chemical Reactions
- Topic: States of Matter in Chemical Equations
- Replies: 4
- Views: 780
States of Matter in Chemical Equations
May seem like a silly question, but I noticed during lecture notes that every time the professor displayed a chemical equation, he'd always have each molecule's state of matter in parentheses. Is it incorrect to write a chemical equation without writing the states of matter? Thanks in advance.