Search found 59 matches
- Fri Mar 15, 2019 10:02 pm
- Forum: General Rate Laws
- Topic: Rate laws
- Replies: 2
- Views: 352
Rate laws
On the lecture slide, it said "rate written as a function of concentration often referred to as rate law". Does that mean that a rate law is the same as a differential rate law?
- Fri Mar 15, 2019 9:00 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Activated structure [ENDORSED]
- Replies: 2
- Views: 294
Activated structure [ENDORSED]
I know Dr. Lavelle went over these briefly in class, but what are they, and do we need to know how to draw them?
- Fri Mar 15, 2019 8:07 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Pre-equilibrium approach
- Replies: 2
- Views: 342
Pre-equilibrium approach
When do you leave the equilibrium constants and when do you substitute k/k'? For example, in the one Dr. Lavelle did in lecture, he got rate=2k2*K*[NO]^2*[O2]. He then replaced K with k1/k1' to get rate=2k2*k1/k1'*[NO]^2*[O2]. Do you always replace K or are there times where you have to leave it in?
- Sun Mar 10, 2019 4:57 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Microscopic reversibility
- Replies: 3
- Views: 385
Microscopic reversibility
Can we always assume that microscopic reversibility is being applied?
- Sun Mar 10, 2019 4:52 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Reactions with Multiple Reactants
- Replies: 3
- Views: 370
Reactions with Multiple Reactants
In lecture, Dr. Lavelle went over how to find the rate constant for reactions with multiple reactants. At the end, he said that k[A]^N*[B]0^M*[C]0^L=k'[A]. Could you do this with B and C as well? ex. k[A]0^N*[B]^M*[C]0^L=k'[B]
- Sun Mar 10, 2019 4:46 pm
- Forum: First Order Reactions
- Topic: Graphs
- Replies: 2
- Views: 366
Graphs
Will we need to be able to set up graphs to find the order of a reaction on the final? If so, how do you do it?
- Sun Mar 03, 2019 12:04 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: 14.55 6th edition
- Replies: 1
- Views: 226
14.55 6th edition
Given NiSO4(aq), how do you know that the SO4^2- ion will not oxidize?
- Sun Mar 03, 2019 10:51 am
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: 14.47 6th Edition
- Replies: 1
- Views: 222
14.47 6th Edition
For part a, I keep getting 2649868 for Q, but the answer in the manual is 10^6. Is the reaction quotient always going to be rounded to a multiple of 10?
- Sun Mar 03, 2019 8:24 am
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: 14.37
- Replies: 1
- Views: 245
14.37
In part a, to find Q, the book multiplies the reactant concentration of H+(0.075 M) by the reactant partial pressure of H2 (1 bar) divided by the product of the product concentration of H+ (1 M) multiplied by the product partial pressure of H2 (1 bar). Why are we allowed to multiply concentration by...
- Sat Feb 23, 2019 9:34 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Platinum
- Replies: 3
- Views: 392
Platinum
When do you include platinum in the cell diagram?
- Sat Feb 23, 2019 7:28 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: 14.13 6th Edition
- Replies: 1
- Views: 261
14.13 6th Edition
I understand cell diagrams go anode||cathode, but what about the order of the anode ions and cathode ions? I've heard to write it reactants|products and to put it in order depending on the phase with the solids on the outside. However, in 14.13 part b, the cell diagram is Pt(s)|I^-(aq)|I2(s)||Ce^4+(...
- Sat Feb 23, 2019 3:26 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: 14.9 6th Edition
- Replies: 2
- Views: 277
14.9 6th Edition
The question asks you to calculate the standard reaction Gibbs free energy for a. 2Ce^4+(aq)+3I^-(aq)—>2Ce^3+(aq)+I3^-(aq). How do you find the moles of electrons transferred? Also, I understand that Ce^4+ is getting reduced, but how is 3I^- getting oxidized? It's oxidation number doesn't change.
- Sun Feb 17, 2019 1:35 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: S=qrev/ T
- Replies: 3
- Views: 3371
Re: S=qrev/ T
I think if it is a constant temperature you can assume that it is a reversible reaction because irreversible reactions have changing temperatures.
- Sun Feb 17, 2019 1:25 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: reversible and irreversible processes
- Replies: 9
- Views: 1474
Re: reversible and irreversible processes
Reversible is expansion/compression against constant pressure, while irreversible is infinitesimal steps of expansion/compression against a changing pressure. Therefore, irreversible does more work, but does not actually happen in real life.
- Sun Feb 17, 2019 1:24 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Midterm Question
- Replies: 8
- Views: 747
Re: Midterm Question
I think if you used the Cp value 5/2*R you would get a value around 20.785. The value they gave us during the exam was 20.81, so I think if you used either you would get around the same answer.
- Sat Feb 09, 2019 9:19 am
- Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
- Topic: 9.37 6th Edition
- Replies: 1
- Views: 253
9.37 6th Edition
Why are all the units J.K^-1.mol^-1? For example, in part d, I did [(3 mol)*(151.0 J.K^-1.mol^-1)+(1mol)*(82.59 J.K^-1.mol^-1)]-[(4 mol)*(143.1 J.K^-1.mol^-1)] which equals -36.81 J.K^-1.mol^-1. However, since you're multiplying mol by J.K^-1.mol^-1, shouldn't the units just be J.K^-1?
- Fri Feb 08, 2019 9:53 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: 9.13 6th Edition
- Replies: 1
- Views: 193
9.13 6th Edition
The answer key uses delta S=nR(ln(T2/T1)). When can you use this instead of delta S=cln(T2/T1)?
- Fri Feb 08, 2019 9:38 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Ideal Behavior
- Replies: 3
- Views: 390
Ideal Behavior
For 9.13 in the 6th edition, it says "During the test of an internal combustion engine, 3.00 L of nitrogen gas at 18.5 degrees C was compressed suddenly and irreversibly to 0.5 L by driving in a piston. In the process, the temperature of the gas increased to 28.1 degrees C. Assume ideal behavio...
- Sun Feb 03, 2019 2:30 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Calibrating the Calorimeter
- Replies: 1
- Views: 615
Calibrating the Calorimeter
What does it mean when it says that the calorimeter is calibrated (for example 8.23 and 8.25 in 6th edition)?
- Sun Feb 03, 2019 10:11 am
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: kJ vs J
- Replies: 9
- Views: 781
kJ vs J
The textbook switches between giving the answer in kJ and J. Does it matter which one I use?
- Tue Jan 29, 2019 6:40 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Standard Enthalpy of Combustion
- Replies: 1
- Views: 245
Standard Enthalpy of Combustion
For 8.57 in the 6th edition, it gives us the standard enthalpies of combustion. In the solution manual, it writes balanced combustion equations for the given reaction and then adds the reactions together to find the final enthalpy. Do we need to do this? I literally added the given enthalpies of com...
- Sun Jan 27, 2019 6:01 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Standard Reaction Enthalpy
- Replies: 1
- Views: 204
Re: Standard Reaction Enthalpy
I think it is the enthalpy when all reactants and products are in their standard state at 1 atm. The standard state for a gas is 1 atm, the standard state for a solution is 1 M, and the standard state for a pure liquid or solid is the pure liquid or solid.
- Sun Jan 27, 2019 5:57 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Exothermic vs. Endothermic
- Replies: 10
- Views: 3137
Re: Exothermic vs. Endothermic
Exothermic reactions favor the formation of products and give off heat. Endothermic reactions favor the formation of reactants and require heat.
- Sun Jan 27, 2019 5:55 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Catalysts in Kc
- Replies: 6
- Views: 674
Re: Catalysts in Kc
Catalysts don't affect Kc because they only make reactions faster. They don't change the concentrations of the reactants or products.
- Sun Jan 20, 2019 6:22 pm
- Forum: Ideal Gases
- Topic: Ideal Gas as Approximation
- Replies: 2
- Views: 215
Ideal Gas as Approximation
On Outline 1, it says we have to be able to identify reactions where the ideal gas law can be used as an approximation. What does this mean?
- Sun Jan 20, 2019 5:40 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Biological Examples
- Replies: 1
- Views: 134
Biological Examples
On outline 1 it mentions biological examples, such as ATP hydrolysis and osmotic pressure. What should we know about these?
- Wed Jan 16, 2019 9:02 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 12.45 6th edition
- Replies: 1
- Views: 214
12.45 6th edition
Can someone explain arylamines, alkylamines, methyl-, and ethyl-? Also, do we have to know these?
- Sun Jan 13, 2019 1:36 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 11.49 6th Edition
- Replies: 2
- Views: 257
11.49 6th Edition
Why are solids not included in the ICE table?
- Sat Jan 12, 2019 1:27 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 11.45 6th Edition
- Replies: 1
- Views: 198
11.45 6th Edition
What does it mean when it asks if Cl2 or F2 is thermodynamically more stable relative to its atoms? How do you know?
- Sat Jan 12, 2019 12:56 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: ICE Table
- Replies: 6
- Views: 594
ICE Table
If given the initial concentration/pressure of the reactant(s), are the initial concentrations/pressures of the products always going to be 0 in the ICE table?
- Sat Dec 08, 2018 1:25 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Periodic trend of acid strength
- Replies: 2
- Views: 600
Re: Periodic trend of acid strength
You can use bond length when referring to an A-H bond like HBr and HCl. However, HBrO2 and HClO2 have the same A-H bond being broken (O-H). Therefore, you have to use electronegativity to determine their strengths instead.
- Sat Dec 08, 2018 1:20 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polarity
- Replies: 7
- Views: 675
Re: Polarity
It means that there is a difference in electronegativity between the two atoms the bond is connecting.
- Sat Dec 08, 2018 1:08 pm
- Forum: Naming
- Topic: Latin Names
- Replies: 2
- Views: 345
Re: Latin Names
My TA's notes have Iron (Ferrate), Copper (Cuprate), Lead (Plumbate), Silver (Argentate), Gold (Aurate), and Tin (Stannate). I would know those, just to be safe.
- Sat Dec 01, 2018 10:34 pm
- Forum: Lewis Acids & Bases
- Topic: Strength of Acids
- Replies: 3
- Views: 353
Strength of Acids
Given lewis structures, how can you tell if one acid is stronger than another?
- Sat Dec 01, 2018 10:22 pm
- Forum: Amphoteric Compounds
- Topic: acidic, basic, and amphoteric oxides
- Replies: 2
- Views: 362
Re: acidic, basic, and amphoteric oxides
I think amphoteric oxides have both basic and acidic character. For example, H20 can be both an acid and a base, meaning it can donate or accept electrons. They are found diagonally on the periodic table between the metals and the nonmetals near the metalloids.
- Sat Dec 01, 2018 5:11 pm
- Forum: Naming
- Topic: kE in textbook
- Replies: 1
- Views: 192
kE in textbook
Hi in the 6th edition of the textbook, toolbox 17.1 says "If there is an ambiguity in which atom is linked to the metal atom, then kE is added to the name in parentheses, where E denotes the connecting atoms (and k is kappa):[Fe(NCS)(OH2)5]2+ thiocyanato(kN)pentaaqua(III) iron [Fe(NCS)(OH2)5]2+...
- Sun Nov 25, 2018 10:13 am
- Forum: Sigma & Pi Bonds
- Topic: HW 4.43
- Replies: 1
- Views: 110
HW 4.43
The homework question says: Noting that the bond angle of an sp3 hybridized atom is 109.5 degrees and that of an sp2 hybridized atom is 120 degrees, do you expect the bond angle between two hybrid orbitals to increase or decrease as the s-character of the hybrids is increased? Can someone explain wh...
- Sun Nov 25, 2018 10:10 am
- Forum: Sigma & Pi Bonds
- Topic: Location of Sigma and Pi Bonds
- Replies: 5
- Views: 390
Location of Sigma and Pi Bonds
How do you determine where each sigma and pi bond goes?
- Sun Nov 18, 2018 8:56 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Dipole-Dipole forces
- Replies: 4
- Views: 473
Dipole-Dipole forces
Does everything have dipole-dipole forces unless atoms of the same element are arranged symmetrically around the central atom?
- Sun Nov 18, 2018 8:41 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Polar or nonpolar [ENDORSED]
- Replies: 1
- Views: 692
Polar or nonpolar [ENDORSED]
For molecules, such as CH2Cl2, that can be drawn in multiple ways, how do you know which one is correct? For example, you could put the two hydrogens and two chlorines next to each other around the central carbon or you could alternate them. This would affect whether the molecule is polar or not, so...
- Sun Nov 18, 2018 8:37 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Drawing structures
- Replies: 8
- Views: 756
Drawing structures
How do you represent double bonds using the VSEPR method with wedges?
- Sat Nov 10, 2018 7:25 pm
- Forum: SI Units, Unit Conversions
- Topic: Angstrom and SI Units
- Replies: 2
- Views: 771
Re: Angstrom and SI Units
No, I believe Dr. Lavelle said this is the only non SI unit we should know.
- Sat Nov 10, 2018 6:58 pm
- Forum: Bond Lengths & Energies
- Topic: Potential Energy Equation
- Replies: 4
- Views: 327
Potential Energy Equation
Hi, in class Dr. Lavelle brought up the equation Ep is proportional to alpha1*alpha2/r^6. What does this mean?
- Sat Nov 10, 2018 6:39 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: E- configuration
- Replies: 3
- Views: 409
Re: E- configuration
When you get to period 3, even though the periodic table makes it look like 4s should go before 3d, it goes afterwards because the 3d orbital has less energy than 4s after 4s is filled. However, when doing the diagram using Aufbau's rule, 4s goes before 3d.
- Sun Nov 04, 2018 10:40 am
- Forum: Quantum Numbers and The H-Atom
- Topic: Drawing orbitals
- Replies: 4
- Views: 1643
Drawing orbitals
Hi my TA mentioned that we might have to know how to draw the different orbitals like 3px, 3py, and 3pz. Can someone explain how to do this?
- Sun Nov 04, 2018 10:38 am
- Forum: Quantum Numbers and The H-Atom
- Topic: Probability of finding an electron at a certain location
- Replies: 1
- Views: 238
Re: Probability of finding an electron at a certain location
Is this the heisenberg uncertainty principle?
- Sat Nov 03, 2018 11:04 am
- Forum: Trends in The Periodic Table
- Topic: Metals, metalloids, and nonmetals
- Replies: 3
- Views: 489
Metals, metalloids, and nonmetals
Hi can someone explain how you know if an element is a metal, metalloid, and nonmetals? Also, do we have to know this?
- Sat Oct 27, 2018 4:57 pm
- Forum: Trends in The Periodic Table
- Topic: Homework 2.67b
- Replies: 2
- Views: 236
Homework 2.67b
Can anyone explain why carbon has a higher electron affinity than nitrogen?
- Sat Oct 27, 2018 4:39 pm
- Forum: Trends in The Periodic Table
- Topic: Homework 2.59
- Replies: 3
- Views: 279
Homework 2.59
The problem asks you to place the ions in order of increasing ionic radius: S^2-, Cl^-, P^3-. I understand that ionic radii decrease from left to right across a period, but I don't get what the exponents do. How do they affect the size of the radius?
- Sat Oct 27, 2018 4:14 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Homework 2.45d
- Replies: 1
- Views: 157
Homework 2.45d
It asks which element is predicted to have the following ground-state electron configuration: [Rn]7s^2 6d^2. First, why is the 7s before 6d? Also, the answer is Thorium, which I thought was in the f-block? How does that work?
- Sat Oct 20, 2018 11:46 am
- Forum: Trends in The Periodic Table
- Topic: Textbook Reading
- Replies: 4
- Views: 373
Textbook Reading
For Chapter 2, are there sections I can skip? For example, Atomic Radius, Ionic Radius, Ionization Energy, Electron Affinity, Inert-Pair Effect, Diagonal Relationships, General Properties of the Elements, etc.
- Sat Oct 20, 2018 11:27 am
- Forum: *Shrodinger Equation
- Topic: Using the Schrodinger Equation
- Replies: 3
- Views: 652
Re: Using the Schrodinger Equation
I believe Professor Lavelle said that we just need to understand what it is, and problems where you would have to solve a Schrodinger Equation are too complicated for this course.
- Sat Oct 20, 2018 11:06 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: 2.43 Electron Configurations
- Replies: 1
- Views: 185
2.43 Electron Configurations
The question asks what is the ground-state electron configuration expected for each of the following elements: (a) silver; (b) beryllium; (c) antimony; (d) gallium; (e) tungsten; (f) iodine? I feel like we didn't go over this in class, and I was wondering if we would have to know this for test two.
- Sat Oct 13, 2018 6:55 pm
- Forum: Properties of Light
- Topic: E=hv
- Replies: 13
- Views: 1026
E=hv
In the equation E=hv, I know E stands for energy, but specifically what energy? Like threshold energy or energy of the photons?
- Sat Oct 13, 2018 6:46 pm
- Forum: Properties of Light
- Topic: Photoelectric Effect Module #34b
- Replies: 1
- Views: 126
Photoelectric Effect Module #34b
How do you solve this? Molybdenum metal must absorb radiation with a minimum frequency of 1.09 x 10^15 s-1 before it can emit an electron from its surface. b. If molybdenum is irradiated with 194 nm light, what is the maximum possible KE of the emitted electrons?
- Sat Oct 13, 2018 6:44 pm
- Forum: Properties of Light
- Topic: Photoelectric Effect Module #28
- Replies: 1
- Views: 153
Photoelectric Effect Module #28
How do you solve this? Light hits a sodium metal surface and the velocity of the ejected electron is 6.61x10^5 m.s-1. The work function for sodium is 150.6 KJ.mol-1. a. What is the KE of the ejected electron? b. How much energy is required to remove an electron from one sodium atom? c. What is the f...
- Sat Oct 06, 2018 10:52 am
- Forum: Empirical & Molecular Formulas
- Topic: HW F11
- Replies: 4
- Views: 446
HW F11
For part c, I got NH6PO4, which is correct. However, the answer says NH6PO4 or [NH4][H2PO4]. How do you convert NH6PO4 into [NH4][H2PO4] and do we have to know this?
- Sat Oct 06, 2018 10:40 am
- Forum: Molarity, Solutions, Dilutions
- Topic: Changing Units
- Replies: 10
- Views: 787
Re: Changing Units
I think in class, he said you could use either. However, sometimes it makes more sense to use one instead of the other. For example, when you're doing an experiment, you would normally measure 16.2 mL rather than 0.0162 L. Both answers would be correct though.
- Sat Oct 06, 2018 10:33 am
- Forum: SI Units, Unit Conversions
- Topic: Chemistry Community Points
- Replies: 3
- Views: 207
Re: Chemistry Community Points
I think the TAs said you have until Sunday to complete your posts, so you still have time to get your 3 points. Otherwise, yes, I believe it counts as 0 points for week 1 if you don't do them.