Search found 59 matches
- Tue Mar 12, 2019 7:41 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: Nernst
- Replies: 14
- Views: 1229
Re: Nernst
Yes, n is the number of moles of of e- transferred in the redox reaction.
- Tue Mar 12, 2019 7:39 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Frequency Factor
- Replies: 1
- Views: 269
Re: Frequency Factor
I believe that each reaction has a unique frequency factor, but it should be given specifically if required for calculations.
- Tue Mar 12, 2019 7:38 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: correct statement? concerning rate laws
- Replies: 1
- Views: 225
Re: correct statement? concerning rate laws
This is correct; the rate law deriving solely from elementary steps information relies on the coefficients in the steps, since no experimental data is given.
- Wed Mar 06, 2019 5:37 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: zero and first
- Replies: 5
- Views: 591
Re: zero and first
The rate of reaction in a zero order reaction is not dependent on the concentration of the reactant, whereas the rate of reaction in a first order reaction is directly proportional to the concentration of reactant.
- Wed Mar 06, 2019 5:35 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: 6th edition 14.35
- Replies: 3
- Views: 415
Re: 6th edition 14.35
This might have been an error on the solution manual's part; however, would this reduction be a result of combining two different reduction phrases together? I believe I saw one question that had that similar issue.
- Wed Mar 06, 2019 5:34 pm
- Forum: General Rate Laws
- Topic: Question 15.5, Sixth Edition
- Replies: 1
- Views: 299
Re: Question 15.5, Sixth Edition
It is true that the rate of oxygen should be negative since it is a reactant, but the negative sign in the formula for unique rate makes sure that no rates are given as negative values.
- Sat Mar 02, 2019 5:06 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Order of Cell Diagrams
- Replies: 13
- Views: 1589
Re: Order of Cell Diagrams
order should be anode - liquids/gases - aqueous species // aqueous species - liquids/gases - cathode.
- Sat Mar 02, 2019 5:04 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: 6h Edition; 14.23
- Replies: 2
- Views: 341
Re: 6h Edition; 14.23
To calculate the cell potential of the reaction, there are two methods in doing so; one is not switching any signs on any of the standard reduction potentials and simply subtracting them in this manner (cathode - anode) or the other method is flipping the anode potential's sign and then adding the t...
- Sat Mar 02, 2019 5:01 pm
- Forum: Balancing Redox Reactions
- Topic: Problem 6N.7 Part A (7th Edition)
- Replies: 1
- Views: 239
Re: Problem 6N.7 Part A (7th Edition)
I believe that it is written this way due to it being written as the standard reduction potential, in which all of the half-reactions are written as reductions rather than oxidations.
- Wed Feb 20, 2019 10:52 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Standard Reduction Potential
- Replies: 1
- Views: 241
Standard Reduction Potential
Is the cell potential the same as the potential of the redox reaction?
- Wed Feb 20, 2019 10:51 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Porous disc explanation?
- Replies: 6
- Views: 638
Re: Porous disc explanation?
The main difference is that the use of porous disk implies that the solutions are not in separate beakers and allows electron flow; overall the function of the porous bridge is same as that of the salt bridge: prevent charge buildup on one electrode.
- Wed Feb 20, 2019 10:49 pm
- Forum: Ideal Gases
- Topic: units
- Replies: 15
- Views: 1393
Re: units
K should not have any units since it is a ratio of concentrations/partial pressures.
- Wed Feb 13, 2019 11:01 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: DeltaS total
- Replies: 2
- Views: 210
Re: DeltaS total
Delta S total is equal to zero when the system is under equilibrium or undergoes a reversible process.
- Wed Feb 13, 2019 11:00 am
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Internal Energy and Enthalpy
- Replies: 3
- Views: 403
Re: Internal Energy and Enthalpy
Enthalpy is the amount of heat absorbed or released by a system under constant pressure, which essentially is the heat at constant pressure, qp. Since the change in internal energy is equal to the sum of heat and work, enthalpy can be related to change in internal energy if the system is at constant...
- Wed Feb 13, 2019 10:57 am
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: delta S
- Replies: 7
- Views: 767
Re: delta S
Delta S (surroundings) is zero under free expansion; delta S (universe) is zero under reversible conditions and equilibrium; delta S (system) should be zero when there is no transfer of heat from and to the system and when the temperature and volume are constant in the system.
- Tue Feb 05, 2019 9:32 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: 7th Edition 4A.3
- Replies: 2
- Views: 320
Re: 7th Edition 4A.3
Did the problem specifically indicate that the process was adiabatic for there to be no heat transfer?
- Tue Feb 05, 2019 9:30 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: 4.D.11 (7th ed)
- Replies: 2
- Views: 329
Re: 4.D.11 (7th ed)
What is the context of this problem's system? Is this process occurring isothermally or reversibly?
- Tue Feb 05, 2019 9:28 pm
- Forum: Calculating Work of Expansion
- Topic: Units
- Replies: 5
- Views: 726
Re: Units
Standard units should be used, so for pressure use atmospheres and for volume use liters; just as long as the units are in accordance with the constants in the equations provided.
- Mon Jan 28, 2019 9:05 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Breaking Bonds
- Replies: 4
- Views: 379
Re: Breaking Bonds
You need to visualize the lewis structures of the individual molecules and deduce which bonds have been added to the original central atom of the molecule.
- Mon Jan 28, 2019 9:04 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Cp and Cv
- Replies: 3
- Views: 369
Re: Cp and Cv
I believe you would have to use the ideal gas constant version that cancels out whatever unit is present in the problem.
- Mon Jan 28, 2019 9:02 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: qp
- Replies: 3
- Views: 553
Re: qp
When referring to qp, it is the heat quantity that is derived from using the specific heat capacity at constant pressure; professor Lavelle indicated that qp is also equal to enthalpy change.
- Fri Jan 25, 2019 12:01 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Units When Calculating Equilibrium Constant
- Replies: 4
- Views: 480
Re: Units When Calculating Equilibrium Constant
K is a constant and units are not regarded in terms of equilibrium constants.
- Fri Jan 25, 2019 12:00 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 12.81b (6th edition)
- Replies: 1
- Views: 208
Re: 12.81b (6th edition)
You would only have to carry out an ICE table for Ka2 if you are focusing on the second deprotonation of that acid; we work on the first and second deprotonations separately.
- Thu Jan 24, 2019 11:59 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 6D.3 7th
- Replies: 1
- Views: 220
Re: 6D.3 7th
When using the equilibrium constant expression, we look at the equilibrium reaction in terms of reactants or products decreasing to increase reactants or products; subtract what will dissociate and add what will be formed. Whether or not the concentrations of H+ or OH- is subtracted depends on the c...
- Sat Jan 19, 2019 9:35 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: "Shifting"
- Replies: 15
- Views: 1772
Re: "Shifting"
He avoided using the word "shift" because some students confuse the reaction favoring foward or reverse directions of reaction as actually changing the K constant; sitting just refers to the reaction no longer being at equilibrium and that the reaction will proceed in that specific directi...
- Sat Jan 19, 2019 9:32 pm
- Forum: Acidity & Basicity Constants and The Conjugate Seesaw
- Topic: Direction of an Acid/Base Reaction
- Replies: 2
- Views: 572
Re: Direction of an Acid/Base Reaction
We use the equilibrium constant K to compare it with the current state of the reaction (reaction quotient Q); the reaction will favor the forward direction if Q<K and it will favor the reverse direction if Q>K. Acids do not specifically only favor the forward and bases do not specifically favor the ...
- Sat Jan 19, 2019 9:29 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Concentrations Effect on K
- Replies: 8
- Views: 550
Re: Concentrations Effect on K
K does not change when concentration changes, so the ratio remains the same regardless of change in product or reactant concentration occurs.
- Sun Jan 13, 2019 3:58 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: equations
- Replies: 10
- Views: 748
Re: equations
The reactant side should have the arrow pointing towards the product side; in terms of equilibrium, regarding the double arrows, the left side is the reactant side and the right side is the product side.
- Sun Jan 13, 2019 3:56 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: concentration vs partial pressure
- Replies: 2
- Views: 200
Re: concentration vs partial pressure
You are able to use concentration when you are referring to gases as well.
- Sun Jan 13, 2019 3:55 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kp Units
- Replies: 6
- Views: 557
Kp Units
Which units do we use when evaluating the equilibrium constant with partial pressure? Is atmosphere used or bar used?
- Wed Dec 05, 2018 6:28 pm
- Forum: Identifying Acidic & Basic Salts
- Topic: zinc nitrite
- Replies: 1
- Views: 571
Re: zinc nitrite
It is based on the chemical formula that you are given; if you are given Zn(NO2)2 and you know that the charge of the nitrite ion is -1, and the compound's overall charge is neutral, then you can derive that the charge on zinc is +2.
- Wed Dec 05, 2018 6:25 pm
- Forum: Identifying Acidic & Basic Salts
- Topic: Identifying the difference
- Replies: 3
- Views: 235
Re: Identifying the difference
We tell whether a salt is acidic or basic based on whether the pH is changed by the addition of H+ or OH-; a salt is acidic if it forms H30+ when reacting with water in solution and it is basic if it forms OH- when reacting with water in solution.
- Wed Dec 05, 2018 6:23 pm
- Forum: Naming
- Topic: OH2 vs H2O
- Replies: 5
- Views: 535
Re: OH2 vs H2O
In some answers, H2O is written as OH2 because we want to emphasize that the oxygen atom in the water molecule is the partially negative part of the ligand that binds to the metal central atom in the coordination compound.
- Wed Nov 28, 2018 5:47 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: Polarizability and Bond Strength
- Replies: 2
- Views: 1146
Re: Polarizability and Bond Strength
If an anion has greater polarizability, then it will more likely be "sharing" its electrons with the cation that is exerting a force on its electrons; hence, molecules with anions having a greater polarizability are not necessarily stronger in bond strength; rather, it is simply more coval...
- Wed Nov 28, 2018 5:45 pm
- Forum: Naming
- Topic: Naming Coordination Compounds
- Replies: 9
- Views: 1095
Re: Naming Coordination Compounds
It will most likely be that we will have to familiarize ourselves with the common ligands and recognize them in the molecules; naming the coordination compounds will also require us to have knowledge of the naming rules taught in lecture.
- Wed Nov 28, 2018 5:43 pm
- Forum: Hybridization
- Topic: atomic orbitals
- Replies: 2
- Views: 283
Re: atomic orbitals
An atomic orbital is a region where the electron will most likely be in around the atom it belongs to. The specific electron lone pair that you are referring to is considered a region of high electron concentration, or density when writing out the shape of the molecule.
- Tue Nov 20, 2018 2:18 pm
- Forum: Hybridization
- Topic: d Orbital
- Replies: 6
- Views: 590
Re: d Orbital
We do work with d orbitals, but I believe that we do not have to know how to draw out complex d orbitals for this class!
- Tue Nov 20, 2018 2:17 pm
- Forum: Electronegativity
- Topic: Electronegativity and Polarity
- Replies: 3
- Views: 463
Re: Electronegativity and Polarity
Polarizability is the degree to which a particle's electron clouds can be distorted. Electronegativity is the degree to which a particle wants to pull in electrons. The bigger the polarizability a particle has, the less electronegativity it has; for example, larger atoms have bigger electron clouds ...
- Tue Nov 20, 2018 2:14 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angles
- Replies: 2
- Views: 177
Bond Angles
When looking at the shape of molecule being analyzed, if there are different angles between different bonds, how do we know which angles within the shape of the molecule are the bigger angles or smaller angles based on the shape of the molecule?
- Mon Nov 19, 2018 12:46 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VESPR Theory
- Replies: 3
- Views: 917
Re: VESPR Theory
The VSEPR model bases off the shape of the molecule by the idea of electron repulsion around the central atom of the molecule; the more lone pairs the central atom has, the more asymmetrical its bounded atoms are, which determines the shape of the molecule itself.
- Mon Nov 19, 2018 12:44 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Electron geometry vs molecular shape
- Replies: 4
- Views: 401
Re: Electron geometry vs molecular shape
The difference between electron geometry and molecular shape is whether the lone pairs are taken into account or not; electron geometry demonstrates the complete positions of all shared or lone pair electrons around the central atom, while the molecular shape depicts the physical appearance of the a...
- Mon Nov 19, 2018 12:42 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Pi bonds and sigma bonds
- Replies: 5
- Views: 498
Re: Pi bonds and sigma bonds
Each bond determines the properties of the molecule, like whether or not the atoms bonded can rotate freely (sigma bonds) or not (pi bonds).
- Sat Nov 10, 2018 5:58 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone Pairs
- Replies: 4
- Views: 372
Re: Lone Pairs
Although the repulsion of the bond pairs is greater than that of the repulsion of the lone pairs with one another, lone pairs still repel one another in the atom and hence affect the angle of the bond, possibly increasing the bond that it is near.
- Sat Nov 10, 2018 5:53 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Shapes
- Replies: 5
- Views: 1544
Re: Shapes
The bonding pairs are what determine the naming of the shape of the molecule; hence, a molecule with four bonding pairs of electrons will always be tetrahedral. If a molecule has two bonding pairs and two lone pairs of electrons (which adds up to four regions of electron density), it is not a tetrah...
- Sat Nov 10, 2018 5:46 pm
- Forum: Dipole Moments
- Topic: Dipole Induced Dipole
- Replies: 2
- Views: 234
Re: Dipole Induced Dipole
The electron cloud of the atom is not evenly distributed at all times around the atom and may sometimes aggregate instantaneously and temporarily on one side of the atom, therefore leading to a dipole in the atom in which one side of the atom is partially negative and the other side is partially pos...
- Sat Nov 03, 2018 8:53 pm
- Forum: Lewis Structures
- Topic: Expanded Valence Shells
- Replies: 2
- Views: 233
Expanded Valence Shells
When writing out Lewis structures for molecules, I know that we can expand the valence shells of the central atoms of the molecule that belong to period 3 and beyond; is there a limit as to how many extra electrons we can expand on the valence shell of the central atom?
- Sat Nov 03, 2018 8:49 pm
- Forum: General Science Questions
- Topic: How do we determine number of unpaired electrons?
- Replies: 1
- Views: 585
Re: How do we determine number of unpaired electrons?
You should write out the electron configurations of those ions and elements, and from there, you would identify what subshell is not filled completely; apply Pauli exclusion rule and Hund's rule to determine how many unpaired electrons are present in the ions and elements.
- Sat Nov 03, 2018 8:45 pm
- Forum: Lewis Structures
- Topic: Radicals?
- Replies: 4
- Views: 364
Re: Radicals?
Since we did go over exceptions to the octet rule which may include radicals, it would be best to know and familiarize yourself with radicals!
- Sat Oct 27, 2018 3:32 pm
- Forum: Lewis Structures
- Topic: Drawing lewis structures with molecules
- Replies: 1
- Views: 203
Re: Drawing lewis structures with molecules
The polyatomic ions that you listed have separate lewis structures drawn enclosed by the symbolic representation of its overall charge; to connect the polyatomic ions, you simply list the separate strutures next to one another, as shown in class.
- Sat Oct 27, 2018 3:28 pm
- Forum: Properties of Electrons
- Topic: Degeneracy
- Replies: 11
- Views: 1252
Re: Degeneracy
Degeneracy simply means same energy; it is indicating that the orbitals within that shell have the same energy.
- Sat Oct 27, 2018 3:22 pm
- Forum: Ionic & Covalent Bonds
- Topic: Replacement for Modules
- Replies: 7
- Views: 672
Re: Replacement for Modules
I find that Khan Academy is a great tool for practicing chem principles and applications!
Obviously, practice problems from the textbook supplemented by office hours and peer learning sessions is helpful as well.
Obviously, practice problems from the textbook supplemented by office hours and peer learning sessions is helpful as well.
- Fri Oct 19, 2018 10:42 am
- Forum: DeBroglie Equation
- Topic: De Broglie equation
- Replies: 3
- Views: 656
Re: De Broglie equation
To derive the de Broglie equation, we rely on these equations: c (speed of light) = (lambda, wavelength)(nu, frequency) E (energy) = (momentum)(velocity) Note that for a photon, E = (momentum)(speed of light, c) because the velocity of a photon is the speed of light and E = (h, planck's constant)(nu...
- Fri Oct 19, 2018 10:29 am
- Forum: *Shrodinger Equation
- Topic: Orbitals, Lobes, e- density
- Replies: 3
- Views: 636
Re: Orbitals, Lobes, e- density
I believe that the main gist of wavefunctions is that it is a mathematical representing of the wavelike properties of electrons; an orbital is like a valid wavefunction and it is a region where the electron will most likely be found around the nucleus of the atom.
- Fri Oct 19, 2018 10:27 am
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Nodal Planes
- Replies: 3
- Views: 493
Re: Nodal Planes
I thought that nodal planes were regions where the electron density is zero. The cone is a nodal plane, meaning that the probability density of the atom is zero there?
- Fri Oct 12, 2018 10:59 am
- Forum: Einstein Equation
- Topic: Symbol for frequency
- Replies: 12
- Views: 2293
Re: Symbol for frequency
We should stick to v (nu) for the symbol representing frequency.
- Fri Oct 12, 2018 10:53 am
- Forum: Einstein Equation
- Topic: calculating kinetic energy
- Replies: 5
- Views: 356
Re: calculating kinetic energy
The unit is supposed to be in kg, as that is the standard SI unit.
- Fri Oct 12, 2018 10:52 am
- Forum: Administrative Questions and Class Announcements
- Topic: Audio-Visual Assignments
- Replies: 4
- Views: 277
Re: Audio-Visual Assignments
These audio-visual modules are essentially a resource for students to clarify on lecture topics and review old concepts; I believe they do not count towards our grades but it is strongly advised to be used!
- Tue Oct 02, 2018 8:20 am
- Forum: Empirical & Molecular Formulas
- Topic: Question F11 from 6th edition
- Replies: 3
- Views: 1804
Re: Question F11 from 6th edition
I did the math and I got about 2.957 for the Na subscript and about 5.910 for the F subscript; I think you would be able to round off to the nearest whole number so that Na has a subscript of 3 and F has a subscript of 6? Does anyone agree with this? Unless you multiply everything by 1000 so that th...
- Mon Oct 01, 2018 8:44 pm
- Forum: Balancing Chemical Reactions
- Topic: Post Module Assessment
- Replies: 3
- Views: 897
Re: Post Module Assessment
You would first balance out the original chemical equation C4H10(g) + O2(g) → CO2(g) + H2O(g) Since the problem calls for 4 moles of C4H10 (g), we add the coefficient to that molecule: 4C4H10(g) + O2(g) → CO2(g) + H2O(g) After that we simply balance out the rest of the chemical equation following th...