Search found 60 matches
- Sat Mar 16, 2019 1:38 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Reverse and Forward
- Replies: 1
- Views: 232
Re: Reverse and Forward
The equilibrium constant is equal to the forward reaction rate constant divided by the reverse reaction rate constant.
- Sat Mar 16, 2019 1:36 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Activation Energy
- Replies: 2
- Views: 264
Activation Energy
How can you tell whether a reaction is exothermic or endothermic based on activation energies for the forward and the reverse reaction, such as the homework problem 15.65 in the sixth edition?
- Thu Mar 14, 2019 8:44 pm
- Forum: General Rate Laws
- Topic: 15.19 6th edition
- Replies: 4
- Views: 397
Re: 15.19 6th edition
I am having the same issue too. Here is my work:
- Sun Mar 10, 2019 4:32 pm
- Forum: General Rate Laws
- Topic: Writing Rate Laws
- Replies: 3
- Views: 433
Re: Writing Rate Laws
Products are not included in the rate law because it looks at the initial concentrations when there are no products formed.
- Sun Mar 10, 2019 4:31 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Activation Energy
- Replies: 3
- Views: 331
Re: Activation Energy
The activation energy is the amount of energy required to go from the reactants to the transition state. So, if activation energy increases that results in more energy required, which causes for a slower reaction. A slower reaction means a higher reaction rate.
- Sun Mar 10, 2019 4:17 pm
- Forum: General Science Questions
- Topic: Discussion Section Test
- Replies: 3
- Views: 610
Re: Discussion Section Test
Yeah, my TA emailed us and said that if you put that photosynthesis is non-spontaneous, he would give us our points back.
- Sun Mar 03, 2019 6:35 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Pt(s)
- Replies: 10
- Views: 1002
Re: Pt(s)
Pt(s) is generally used whenever a solid is not given to write the cell diagram for both the anode and the cathode.
- Sun Mar 03, 2019 6:34 pm
- Forum: Balancing Redox Reactions
- Topic: balancing redox reactions
- Replies: 5
- Views: 513
Re: balancing redox reactions
You use H+ and H20 to balance half reactions in an acidic solution. H20 is used to balance the oxygen atoms while H+ is used to balance the hydrogen ions. It is easier to balance oxygen first, so that you know how many H+ ions you need to balance the equation.
- Sun Mar 03, 2019 6:31 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Test 2 Scores
- Replies: 6
- Views: 584
Re: Test 2 Scores
I believe we get them during discussion this week.
- Sun Feb 24, 2019 6:02 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Quiz 3
- Replies: 3
- Views: 334
Re: Quiz 3
Yeah, I was told the test will include everything from Gibbs Free energy till last Friday's lecture.
- Sun Feb 24, 2019 6:00 pm
- Forum: Student Social/Study Group
- Topic: How are you guys going to study for Test 2?
- Replies: 10
- Views: 930
Re: How are you guys going to study for Test 2?
Yeah, I always do all the homework problems to get prepared for the exams. Also, I try to do some of the worksheets that the UAs post on here.
- Sun Feb 24, 2019 3:59 pm
- Forum: Balancing Redox Reactions
- Topic: TEST
- Replies: 7
- Views: 847
Re: TEST
I don't think it will include concepts for Monday's lecture, but it will definitely include gibbs free energy.
- Sun Feb 17, 2019 3:39 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Midterm Question
- Replies: 8
- Views: 749
Re: Midterm Question
Yeah, I just used the equation for constant pressure of an ideal gas to solve for the heat capacity of nitrogen gas.
- Sun Feb 17, 2019 3:37 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Work done vs work on system
- Replies: 18
- Views: 3788
Re: Work done vs work on system
When work is being done on the system, w is positive, and when work is being done by the system w is negative.
- Sun Feb 17, 2019 3:36 pm
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: constant C
- Replies: 7
- Views: 1005
Re: constant C
There are different types of heat capacities. C refers to heat capacity when there is no constant pressure or volume. Cp refers to the heat capacity when it is an ideal gas at constant pressure while Cv is the heat capacity of an ideal gas at constant volume.
- Sat Feb 09, 2019 1:11 am
- Forum: Administrative Questions and Class Announcements
- Topic: Lyndon's Midterm Review Sheet
- Replies: 2
- Views: 396
Re: Lyndon's Midterm Review Sheet
He hasn't uploaded it on here yet, but he will make it sometime this weekend and will go over it during his review session on Monday 7pm-10pm in Franz 1178.
- Sat Feb 09, 2019 1:07 am
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm
- Replies: 8
- Views: 866
Re: Midterm
The midterm will cover all the topics we talked about in lecture until Friday (2/8/18). It is helpful to go over the objectives on his outlines for concepts on the midterm.
- Sat Feb 09, 2019 12:57 am
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: w=-PdeltaV
- Replies: 6
- Views: 579
Re: w=-PdeltaV
The first one is used when the external pressure is not constant, which is reversible expansion, and the other equation is used when the external pressure is constant, which is irreversible expansion.
- Sun Feb 03, 2019 3:08 pm
- Forum: Calculating Work of Expansion
- Topic: Units for pressure
- Replies: 10
- Views: 723
Re: Units for pressure
To play it safe, I would just convert to atmospheres anytime you are asked for pressure.
- Sun Feb 03, 2019 3:06 pm
- Forum: Calculating Work of Expansion
- Topic: What is Work?
- Replies: 5
- Views: 486
Re: What is Work?
Work is the energy required to complete a certain reaction in terms of chemistry.
- Sun Feb 03, 2019 3:01 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Midterm Review
- Replies: 14
- Views: 1175
Re: Midterm Review
Will the Peer Learning Sessions continue with the week's content, content for Week 5, or will they be backtracking in order to help with Midterm review?
I think it will be content from Week 4 and a little bit of Week 5 depending on which day you go. I feel like most will be review for the midterm.
- Sun Jan 27, 2019 9:32 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Ph and Pka
- Replies: 5
- Views: 395
Re: Ph and Pka
If you are given the pKa, you would have to use the ICE table to find the concentration of [H3O+] at equilibrium and then take the -log of that value to find pH.
- Sun Jan 27, 2019 9:27 pm
- Forum: Ideal Gases
- Topic: SI Units
- Replies: 5
- Views: 647
Re: SI Units
It is atmospheres, which is the same thing as atm.
- Sun Jan 27, 2019 9:26 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Lecture Slides
- Replies: 5
- Views: 462
Re: Lecture Slides
No, he said if you ever miss a lecture, just get the notes from someone.
- Sat Jan 19, 2019 11:09 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Changes in K
- Replies: 4
- Views: 437
Re: Changes in K
The equilibrium constant only changes when temperature changes. Anything else will not cause the ratio of products and reactant to change.
- Sat Jan 19, 2019 11:00 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Concentrations Effect on K
- Replies: 8
- Views: 519
Re: Concentrations Effect on K
K only changes when the ratio of products and reactants change, but when concentrations change, the ratio stays the same. Therefore, K stays the same.
- Sat Jan 19, 2019 2:27 pm
- Forum: Ideal Gases
- Topic: PV=nRT
- Replies: 8
- Views: 1107
Re: PV=nRT
R is always a constant, so it will always be given. I think we may use the ideal gas law to convert from Kc to Kp or to find concentration when given pressure.
- Sun Jan 13, 2019 1:00 pm
- Forum: Ideal Gases
- Topic: A bit of confusion
- Replies: 3
- Views: 251
Re: A bit of confusion
Use the information in Table 11.2 to determine the value of K at 300 K for the reaction 2 BrCl(g) + H2(g) <--> Br2(g) + 2 HCl(g). So for this textbook question, you have to go to table 11.2 where it tells you the equilibrium constants at different temperatures for two separate equations. If you mul...
- Sun Jan 13, 2019 12:51 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Keq
- Replies: 3
- Views: 234
Re: Keq
Keq is used to represent either Kc or Kp, but I don't think you will be marked down if you use Keq all of the time. However, just to be safe I would use Kc when dealing with molarity and Kp when using partial pressure.
- Sat Jan 12, 2019 11:27 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Solving for K
- Replies: 7
- Views: 443
Re: Solving for K
It doesn't really matter if you use parentheses or brackets when solving for K in terms of calculation. But to find K c , you use concentrations, so it is more appropriate to use brackets to represent molarity while when finding K p , you use partial pressure which is represented with parentheses. T...
- Sat Dec 08, 2018 3:07 pm
- Forum: Bronsted Acids & Bases
- Topic: Metal oxides and non-metal oxides
- Replies: 1
- Views: 295
Re: Metal oxides and non-metal oxides
In the sixth edition of the textbook, table J.1 lists the strong acids and bases in water, so it would be helpful to memorize these. Strong acids include HBr, HCl, HI, HNO 3 , HClO 4 , HClO 3 , H 2 SO 4 . Strong bases include group 1 hydroxides, alkaline earth metal hydroxides, such as Ca(OH) 2 , Sr...
- Sat Dec 08, 2018 3:00 pm
- Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
- Topic: Rydberg’s Equation - Hydrogen
- Replies: 2
- Views: 421
Re: Rydberg’s Equation - Hydrogen
Yes, the Rydberg's equation only applies to hydrogen, and we will only be required to know how to calculate energy levels for Hydrogen atoms.
- Sat Dec 08, 2018 12:25 am
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Polydentates
- Replies: 2
- Views: 242
Polydentates
Why is CO32- monodentate and bidentate?
- Sun Dec 02, 2018 2:58 pm
- Forum: Lewis Acids & Bases
- Topic: Strong acids and strong bases
- Replies: 5
- Views: 450
Re: Strong acids and strong bases
Yeah in lecture, he stated that strong acids and bases are completely ionized in water and weak acids and weak bases are not. So, for the scope of this class, you can say 100% dissociated.
- Sun Dec 02, 2018 2:43 pm
- Forum: Naming
- Topic: With Respect to the Final
- Replies: 9
- Views: 923
Re: With Respect to the Final
Yeah, you will need to know how to name compounds because in a lot of the homework problems, the name is given instead of the molecular formula. He usually says that the final will be similar to the homework problems.
- Sun Dec 02, 2018 2:30 pm
- Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
- Topic: Is Hydrogen Bonding a type of Dipole-Dipole Interaction?
- Replies: 5
- Views: 508
Re: Is Hydrogen Bonding a type of Dipole-Dipole Interaction?
If the final asks for the intermolecular forces in a molecule, can we always write that London forces are present or are there cases where they are not? I believe Lavelle said that London Dispersion Forces are always present in between molecules that are close to each regardless of whether they are...
- Sun Nov 25, 2018 7:02 pm
- Forum: Hybridization
- Topic: Hybridization scheme
- Replies: 3
- Views: 330
Re: Hybridization scheme
It also helps to determine the VSEPR formula or the steric number of the molecule and then determine the hybridization from there.
- Sun Nov 25, 2018 6:54 pm
- Forum: Hybridization
- Topic: Hybridized orbitals for Boron
- Replies: 1
- Views: 78
Re: Hybridized orbitals for Boron
So in this molecule, all the borons have a formal charge of -1 and all the nitrogens have a formal charge of +1. Therefore, the molecule would have a net charge of zero.
- Sun Nov 25, 2018 6:48 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Molecular Shape of (CH3)2Be
- Replies: 1
- Views: 199
Re: Molecular Shape of (CH3)2Be
Since it is a polyatomic species, you would look at the individual molecular compounds to determine the shape. For each C, the 3 Hs and the Be are arranged symmetrically, around the C. So, the shape about the carbons would be tetrahedral. However, since the question is asking for the hybridization o...
- Sun Nov 18, 2018 2:52 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Square Planar vs Tetrahedral
- Replies: 8
- Views: 2366
Re: Square Planar vs Tetrahedral
Also, in the example we did in class with XeF 4 , this is a square planar because it has 4 bonding pairs plus 2 lone pairs while a tetrahedral only has 4 bonding pairs, such as CH 4 . XeF4 has 6 regions of electron density while CH4 has 4 regions of electron density, which can also play a role in th...
- Sun Nov 18, 2018 2:39 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: lone pairs
- Replies: 11
- Views: 827
Re: lone pairs
Yes. In the example we did in class with the sulfite ion, the bond angles are expected to be 109.5 degrees because they are arranged tetrahedrally, but the bond angles are actually 106 degrees due to the extra lone pair on the sulfur atom.
- Sun Nov 18, 2018 2:34 pm
- Forum: General Science Questions
- Topic: Audio Visuals
- Replies: 6
- Views: 799
Re: Audio Visuals
MaiaRodriguezChoi3E wrote:Does anyone know of any resources similar to the audio visuals for the other topics this quarter? Do people find Khan academy helpful, or crash course videos?
I find Kahn Academy pretty helpful for understanding the general topics and if I need more specifics I will refer back to the textbook.
- Sun Nov 11, 2018 5:27 pm
- Forum: Ionic & Covalent Bonds
- Topic: Lattice Energy
- Replies: 2
- Views: 267
Re: Lattice Energy
Lattice energy is used in ionic compounds to describe the bond strength. It is the amount of energy required to separate a mole of an ionic solid into the gaseous form of its ions. For example, the lattice energy of NaCl is the energy released when gaseous Na+ and Cl– ions come together to form a la...
- Sun Nov 11, 2018 5:07 pm
- Forum: Lewis Structures
- Topic: Formal Charge
- Replies: 14
- Views: 1223
Re: Formal Charge
I agree that the formal charge should be close to 0 on the central atom and if there are any charges they should be on the outer elements. It is also important to look at electronegativity, but the least electronegative element is more likely to be the central atom, so this follows the pattern that ...
- Sun Nov 11, 2018 5:01 pm
- Forum: Lewis Structures
- Topic: Expanded Octets
- Replies: 9
- Views: 2786
Re: Expanded Octets
Any element on or below period 3 of the periodic table can have an expanded octet because these elements have d orbitals that can hold more electrons.
- Sat Nov 03, 2018 9:11 pm
- Forum: Administrative Questions and Class Announcements
- Topic: What the Midterm Will Cover
- Replies: 5
- Views: 454
Re: What the Midterm Will Cover
I believe that questions about the properties of bonds will not appear on the midterm because professor Lavelle said that midterm material that will appear on the test will be up to what we covered in lecture on Wednesday.
- Sat Nov 03, 2018 9:06 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Test 2 1b
- Replies: 2
- Views: 511
Re: Test 3 Version 2 1b
The change in uncertainty in momentum is inversely proportional to the uncertainty in its wavelength. Yes, you have to use De Broglie because wavelength equals h/momentum, so if momentum decreases, then wavelength increase and vice versa.
- Sat Nov 03, 2018 8:55 pm
- Forum: Lewis Structures
- Topic: HW 6th Edition 3.57
- Replies: 1
- Views: 97
HW 6th Edition 3.57
In the sixth edition, question 57 on chapter 3 asks to draw the lewis structure of hydrogen sulfite ion (HSO3^-). How do you know that hydrogen is not bonded to sulfur and instead it is bonded to oxygen because I found a way that all the formal charges are 0 expect for an oxygen when hydrogen is bon...
- Sun Oct 28, 2018 1:42 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: 4s and 3d [ENDORSED]
- Replies: 2
- Views: 319
Re: 4s and 3d [ENDORSED]
The 4s orbital is filled before the 3d orbitals because the 4s subshell is lower in energy compared to 3d.
- Sun Oct 28, 2018 1:39 pm
- Forum: Photoelectric Effect
- Topic: Work Function
- Replies: 14
- Views: 2169
Re: Work Function
The work function specifically refers to the minimum amount of energy required to eject an electron, and the threshold energy refers to the frequency that light has to reach to eject an electron. However, when calculating using the equation, they are the same thing, which is why Professor Lavelle us...
- Sun Oct 28, 2018 1:33 pm
- Forum: Ionic & Covalent Bonds
- Topic: Determining the number of electrons in a compound [ENDORSED]
- Replies: 2
- Views: 311
Re: Determining the number of electrons in a compound [ENDORSED]
So, to add up the electrons of a compound, you need to first count the number of valence electrons for each atom. In SO4^2-, Sulfur has 6 valence electrons and Oxygen has 6 valence electrons. But there is 4 oxygens, so the total number of electrons of oxygen is 24e-. You add the 24e- of oxygen with ...
- Sun Oct 21, 2018 2:48 am
- Forum: Properties of Light
- Topic: 1.9 6th Edition
- Replies: 1
- Views: 103
Re: 1.9 6th Edition
To fill in the activities section for this question, you had to correspond each event with the type of wave it uses. So, for example, reading is visible light and suntan is UV. Then, you compare the wavelengths you calculated in nanometers and list the events from largest to shortest wavelength. For...
- Sun Oct 21, 2018 2:36 am
- Forum: Properties of Light
- Topic: Test 2
- Replies: 7
- Views: 579
Re: Test 2
My TA said that the main topics covered on this test are photoelectric effect, De Broglie wavelength, Heisenberg uncertainty, Atomic spectra, and quantum numbers.
- Sun Oct 21, 2018 2:28 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Test 2 Material
- Replies: 9
- Views: 627
Re: Test 2 Material
I believe there will be questions on quantum numbers, but I don't think there will be anything on electron configuration since he hasn't gone over that yet. Dr. Lavelle also said on Friday that the Friday lecture will be the last topics covered on test 2.
- Sun Oct 14, 2018 5:14 pm
- Forum: SI Units, Unit Conversions
- Topic: Sig Figs
- Replies: 8
- Views: 930
Re: Sig Figs
I remember that I came across a question that listed no numbers, so I was told to use 4 significant figures. The answer in the book also listed 4 sig figs, so I would use 4 sig figs if no numbers were given.
- Sun Oct 14, 2018 5:09 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Test #2
- Replies: 3
- Views: 342
Re: Test #2
I think it will be only on quantum world, so you should understand everything listed under outline 2.
- Sun Oct 14, 2018 5:05 pm
- Forum: Significant Figures
- Topic: When to round the answers to significant figures
- Replies: 11
- Views: 2574
Re: When to round the answers to significant figures
Personally, I tend to be as accurate as possible on every step to get the closest I can to the correct answer, then I will round to the amount of significant figures. Sometimes,I am still a bit of by about .1 or .2, but most of the time it is pretty accurate.
- Sat Oct 06, 2018 5:42 pm
- Forum: Significant Figures
- Topic: Empirical and Molecular Formula's Video #19
- Replies: 3
- Views: 525
Re: Empirical and Molecular Formula's Video #19
The number of significant figures that the answer should have is determined by what is given in the question and not what has been calculated. Therefore, since the molar mass of 84 is the only number that is given, then the answer should have 2 significant figures because 84 has 2 sig figs. If there...
- Sat Oct 06, 2018 5:35 pm
- Forum: Empirical & Molecular Formulas
- Topic: Chem Mod Empirical and Molecular Formulas Problem 22
- Replies: 1
- Views: 113
Re: Chem Mod Empirical and Molecular Formulas Problem 22
So, I got the same ratio as you did, but instead of multiplying by 3, I multiplied by 5 to get 5:5:12. By multiplying by 3, the H would be 7.14 and you need whole numbers. Therefore, the answer is C5H12O5.
- Sat Oct 06, 2018 5:12 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Naming Compounds
- Replies: 3
- Views: 220
Naming Compounds
On the homework for E.9 on the sixth edition, there was a compound called magnesium sulfate heptahydrate, which is MgSO4, but they didn't provide the actual formula. For the first test, do we have to know how to name compounds? If so, how do we do that?