Search found 69 matches
- Sat Mar 16, 2019 10:13 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Inert Conductor
- Replies: 3
- Views: 346
Re: Inert Conductor
To be on the safe side, you should always use Pt(s) when you are unsure, unless Hg is present in the first place.
- Sat Mar 16, 2019 10:11 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Arrhenius Equation
- Replies: 3
- Views: 637
Re: Arrhenius Equation
If you need to find frequency factor of collisions (A) and you are given activation energy (Ea) you would use the Arrhenius equation.
- Sat Mar 16, 2019 10:05 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Galvanic Cells
- Replies: 4
- Views: 439
Re: Galvanic Cells
The anode is the one being oxidized, and the cathode is the one being reduced (an ox, red cat).
- Sat Mar 16, 2019 10:03 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Platinum
- Replies: 5
- Views: 482
Re: Platinum
Since platinum is inert, it will not interfere with the overall redox reaction. Therefore it can be used in the place of a solid metal, transferring electrons from an aqueous solution to the cathode.
- Sat Mar 16, 2019 10:01 pm
- Forum: Administrative Questions and Class Announcements
- Topic: LYNDON'S PORK RAMEN REVIEW
- Replies: 37
- Views: 7390
Re: LYNDON'S PORK RAMEN REVIEW
Thank you Lyndon!!
- Sat Mar 16, 2019 10:00 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K and Kc
- Replies: 6
- Views: 915
Re: K and Kc
K and Kc can be the same thing, but Kc refers specifically to concentration while Kp refers to partial pressures.
- Sat Mar 16, 2019 9:56 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Deadline to post
- Replies: 7
- Views: 781
Re: Deadline to post
You should probably get your posts in before the final.
- Sat Mar 16, 2019 9:54 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Final
- Replies: 18
- Views: 1962
Re: Final
I think Lavelle always has at least one question per larger section on his syllabus.
- Sat Mar 16, 2019 9:53 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: [H2O] omitted??
- Replies: 2
- Views: 609
Re: [H2O] omitted??
Yes, because water is present in all aqueous solutions is it implied that it is already present.
- Sat Mar 16, 2019 9:51 pm
- Forum: First Order Reactions
- Topic: Half-Lives
- Replies: 4
- Views: 803
Re: Half-Lives
Yes, you should definitely know how to use all the half-life equations because they are different for every order and can sometimes be useful in finding k.
- Thu Mar 07, 2019 2:50 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Pt
- Replies: 14
- Views: 1249
Re: Pt
You would add Pt(s) if there are no solids present on either the anode or cathode side.
- Thu Mar 07, 2019 2:49 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Study Advice
- Replies: 73
- Views: 6784
Re: Study Advice
I definitely recommend attending step-up sessions if you are completely lost and don't know where to start and need some momentum. Workshops are really good if you already have a basic handle on everything.
- Thu Mar 07, 2019 2:45 pm
- Forum: First Order Reactions
- Topic: First order graph
- Replies: 7
- Views: 847
Re: First order graph
The x axis is time, usually in seconds but it can also be in minutes, days, etc.
- Thu Feb 28, 2019 1:16 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: H2O in Cell Diagrams
- Replies: 4
- Views: 403
Re: H2O in Cell Diagrams
Correct, because if there are aqueous solutions already present it implies that water is present as well.
- Thu Feb 28, 2019 1:15 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: speed of reaction based on activation energy
- Replies: 6
- Views: 631
Re: speed of reaction based on activation energy
Yes, because more energy is necessary in order for the reaction to move forward.
- Thu Feb 28, 2019 1:13 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell Diagrams
- Replies: 3
- Views: 414
Re: Cell Diagrams
If you are referring to Pt(s) or C(graphite), those elements are added to the cell diagram if there is no solid present in the original equation. This is because if you refer to the visual representation of the cell diagram, the anode and cathode require a solid metal to transfer electrons from one ...
- Tue Feb 26, 2019 2:17 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: test 2
- Replies: 6
- Views: 482
Re: test 2
Yes, I am pretty sure he will provide a redox table if necessaary.
- Tue Feb 26, 2019 2:16 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: E˚ vs E
- Replies: 13
- Views: 15236
Re: E˚ vs E
I believe E˚refers to standard conditions and E refers to nonstandard conditions.
- Tue Feb 26, 2019 2:13 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Topics for Test2
- Replies: 1
- Views: 296
Re: Topics for Test2
I believe the test covers Gibbs Free Energy and Electrochemistry up until and not including the Nernst equation.
- Sun Feb 17, 2019 5:37 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Work done vs work on system
- Replies: 18
- Views: 3797
Re: Work done vs work on system
When work is done on a system, or by the environment, energy is added to the system and is thus positive. when work is being done by the system, energy is being used by the system and is thus negative.
- Sun Feb 17, 2019 5:36 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: DeltaS= nCln(T2/T1)
- Replies: 4
- Views: 1249
Re: DeltaS= nCln(T2/T1)
the question should always tell you if the system is at constant volume or constant pressure, in which you would use Cv and Cp, respectively.
- Sun Feb 17, 2019 5:28 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Temperature
- Replies: 2
- Views: 255
Re: Temperature
If a reaction is endothermic, increasing temperature will favor the products while decreasing will favor the reactants. Conversely, if a reaction is exothermic, an increase in temperature will favor the reactants and a decrease in temperature will favor the products.
- Thu Feb 07, 2019 1:37 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: when to solve for specific vs. molar heat capacity
- Replies: 2
- Views: 289
Re: when to solve for specific vs. molar heat capacity
Specific heat capacity is the heat requires to raise 1 gram of a substance by 1 degree Celsius/Kelvin, whereas molar heat capacity is the heat required to raise 1 mole of substance by 1 degree Celsius/Kelvin. Look and see if the problem gives you grams or moles, and go from there.
- Thu Feb 07, 2019 1:32 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Bomb calorimeters vs polystyrene cup calorimeters
- Replies: 3
- Views: 583
Re: Bomb calorimeters vs polystyrene cup calorimeters
A bomb calorimeter measures heat flow at a constant volume, as you can imagine a bomb as a rigid chamber that cannot increase in volume. A polystyrene cup calorimeter on the other hand measured changes in temperature at a constant pressure.
- Thu Feb 07, 2019 1:24 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Work
- Replies: 4
- Views: 485
Re: Work
When the work of the system on the atmosphere is positive, that means work is done by the system, and so the equation would look like delta U = Q - W. When the work of the atmosphere or environment on the system is positive, it means work is being done on the system, which would correlate with the e...
- Fri Feb 01, 2019 10:53 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Heat vs. Temp
- Replies: 9
- Views: 886
Re: Heat vs. Temp
Heat refers to the transfer of energy between molecules which is why heat is measured in Joules, whereas temperature merely refers to the random motion of molecules.
- Fri Feb 01, 2019 10:50 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Surroundings
- Replies: 11
- Views: 899
Re: Surroundings
The surroundings consists of everything outside of the system.
- Fri Feb 01, 2019 10:47 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Closed System
- Replies: 6
- Views: 633
Re: Closed System
When dealing with closed systems, you are able to assume that the number of moles remains constant. This will in most cases allow for certain equations to be utilized (such as PV= nRT and certain calorimetry problrems) in order to solve for other components of the equations. Additionally, it is much...
- Thu Jan 24, 2019 4:27 pm
- Forum: Student Social/Study Group
- Topic: ICE Table
- Replies: 6
- Views: 453
Re: ICE Table
You would only need to use an ICE table if you are specifically asked to get from initial concentrations to equilibrium concentrations or vise versa. Usually you can go through a problem and if you think you need ICE table then you can try it out but if you don't have enough information for it or it...
- Thu Jan 24, 2019 4:22 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: 5% Rule and % Deprotonation
- Replies: 3
- Views: 380
Re: 5% Rule and % Deprotonation
Yes, they both use change in concentration over initial concentration times 100%
- Thu Jan 24, 2019 4:20 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Tricks for identifying Strong/Weak Acids & Bases
- Replies: 6
- Views: 559
Re: Tricks for identifying Strong/Weak Acids & Bases
These are some general strong acids/bases I memorized:
Strong Acids - HCl, HBr, HI, HNO3, HClO3, HClO4, H2SO4
Strong Bases - LiOH, NaOH, KOH, RbOH, CsOH, Ca(OH)2, Ba(OH)2, Sr(OH)2
Strong Acids - HCl, HBr, HI, HNO3, HClO3, HClO4, H2SO4
Strong Bases - LiOH, NaOH, KOH, RbOH, CsOH, Ca(OH)2, Ba(OH)2, Sr(OH)2
- Tue Jan 15, 2019 4:41 pm
- Forum: Ideal Gases
- Topic: Homework for week 2 [ENDORSED]
- Replies: 10
- Views: 2952
Re: Homework for week 2 [ENDORSED]
I think as long as you turn in work from either section you will be fine, such we are still going over both in lecture.
- Tue Jan 15, 2019 3:52 pm
- Forum: Ideal Gases
- Topic: Water
- Replies: 13
- Views: 1030
Re: Water
No, water cannot be aqueous since an aqueous solution is dissolved in water. That is why it is referred to as liquid.
- Tue Jan 15, 2019 3:49 pm
- Forum: Ideal Gases
- Topic: pressure [ENDORSED]
- Replies: 13
- Views: 1032
Re: pressure [ENDORSED]
If you look at the equation pV = nRT changing either temperature or inert gas (if volume remains constant) will change pressure.
- Thu Jan 10, 2019 3:20 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Giving Qc or Qp when asked for Q
- Replies: 5
- Views: 597
Re: Giving Qc or Qp when asked for Q
If the problem has to do with concentration (Mol/L) Qc will be used. If the problem has to do with pressure or gas-state molecules, Qp will be used.
- Thu Jan 10, 2019 3:17 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: how to write the formula for K
- Replies: 6
- Views: 419
Re: how to write the formula for K
You only use subscript for P when you are representing partial pressure, which will only be used in chemical equilibrium problems with gas state molecules.
- Thu Jan 10, 2019 3:14 pm
- Forum: Ideal Gases
- Topic: Q and K [ENDORSED]
- Replies: 35
- Views: 3024
Re: Q and K [ENDORSED]
There is no difference in the way we calculate Q and K, the difference is that Q is associated with initial values and K is associated with equilibrium values.
- Thu Jan 10, 2019 3:11 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K, Kc and Kp
- Replies: 8
- Views: 537
K, Kc and Kp
What are the differences in using K, Kc and Kp? Are K and Kc interchangeable?
- Thu Dec 06, 2018 8:36 pm
- Forum: Conjugate Acids & Bases
- Topic: Conjugate Bases
- Replies: 7
- Views: 2544
Re: Conjugate Bases
If you have an acid, its conjugate base would be the result of losing a H+, and if you have a base, its conjugate acid would be the result of gaining an H+.
- Thu Dec 06, 2018 8:33 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Focus 9C.3 Part d
- Replies: 3
- Views: 417
Re: Focus 9C.3 Part d
I think the parenthesis are just to separate the two ligands.
- Thu Dec 06, 2018 8:31 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Coordination number
- Replies: 1
- Views: 285
Re: Coordination number
The coordination number would be 6 because a single edta compound forms 6 bonds to the Fe atom, as it is hexadentate, and the number of bonds that are formed to the central atom make up the coordination number. Similarly, the bidentate compound en can form two bonds with a central atom.
- Tue Nov 27, 2018 8:34 pm
- Forum: Dipole Moments
- Topic: 4.29
- Replies: 3
- Views: 185
Re: 4.29
1 has the largest dipole moment because since the chlorines are positioned close to one side of the molecule, that side of the molecule will have a polarized charge in comparison to the other side with no chlorines. 3 has the smallest dipole moment because since the molecule is symmetrical, any char...
- Tue Nov 27, 2018 8:29 pm
- Forum: Dipole Moments
- Topic: LDF
- Replies: 5
- Views: 552
Re: LDF
All molecules have LDFs because an LDF is just a weak, short-range electrostatic force between uncharged molecules, arising from the interaction of transient electric dipole moments. Any molecule, for example a nonpolar covalent molecule with normally no charge, can have its electrons positioned in ...
- Tue Nov 27, 2018 8:22 pm
- Forum: Dipole Moments
- Topic: Dipole-Dipole
- Replies: 3
- Views: 310
Re: Dipole-Dipole
Usually, if a molecule is asymmetrical or has lone pairs of electrons then it will be polar. If two polar molecules come together, they can form a dipole-dipole interaction from the partially positive side of the molecule attracting a partially negative side of another polar molecule.
- Tue Nov 20, 2018 12:50 am
- Forum: Bond Lengths & Energies
- Topic: VSEPR
- Replies: 6
- Views: 1992
Re: VSEPR
When first learning VSEPR shapes I would recommend googling "VSEPR Geometry" in images and going off of that table until you memorize the shapes because it it very easy to follow. Steric number refers to how many bonds (single, double, or triple) AND electron pairs surround the shape.
- Tue Nov 20, 2018 12:45 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Molecular shape on test
- Replies: 5
- Views: 386
Re: Molecular shape on test
My TA specified that only one-dimensional Lewis structure diagrams will be necessary for 14A, and shape should be known but does not need to be drawn out.
- Tue Nov 20, 2018 12:43 am
- Forum: Administrative Questions and Class Announcements
- Topic: Discussion
- Replies: 6
- Views: 695
Re: Discussion
I don't think any discussions are cancelled except for those on the official days off (thursday and friday)
- Tue Nov 20, 2018 12:33 am
- Forum: SI Units, Unit Conversions
- Topic: Significant 0’s [ENDORSED]
- Replies: 8
- Views: 1320
Re: Significant 0’s [ENDORSED]
You can tell significant 0's by whether or not they contribute to the number's specificity. For example, 0.0850 is more specific than 0.085 because the latter is rounded, but 0.0085 is not a more specific version of 0.0850, it is just an entirely different number.
- Wed Nov 14, 2018 4:19 pm
- Forum: Octet Exceptions
- Topic: Resonance Structures
- Replies: 7
- Views: 802
Re: Resonance Structures
When asked to draw resonance, you should always draw all possible structures and then a combination of all those structures as the hybridization of those structures.
- Wed Nov 14, 2018 4:14 pm
- Forum: Properties of Electrons
- Topic: Polar vs Non polar
- Replies: 15
- Views: 4572
Re: Polar vs Non polar
The molecule will most likely be polar if there are different atoms around the central atom. A molecule will most likely be nonpolar if the molecule is symmetrical and has the same atoms around the central atom.
- Wed Nov 14, 2018 4:11 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Grades
- Replies: 5
- Views: 465
Re: Grades
If he does curve it, it will only help your grade. I don't think this class will be curved by much though.
- Tue Nov 06, 2018 12:20 am
- Forum: Octet Exceptions
- Topic: Octet rule vs. Formal charge
- Replies: 7
- Views: 1014
Octet rule vs. Formal charge
What is more important when drawing a Lewis Diagram of the lowest energy - the octet rule or formal charge?
- Tue Nov 06, 2018 12:19 am
- Forum: Octet Exceptions
- Topic: Octet Exceptions
- Replies: 4
- Views: 372
Octet Exceptions
How do you know if an element is an exception to the octet rule?
- Tue Nov 06, 2018 12:09 am
- Forum: Resonance Structures
- Topic: Radicals
- Replies: 11
- Views: 1375
Re: Radicals
An easy way to tell if a neutral molecule is a radical is to count up the number of valence electrons in each atom and add them together - if your number is odd then it is most likely a radical.
- Tue Nov 06, 2018 12:06 am
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Lewis Structures
- Replies: 1
- Views: 199
Re: Lewis Structures
P in the center and 3 Ks branching out connected by single bonds, with a lone pair of electrons also attached to P. Every element is "happy" because K only has 1 valence electron and P has 5 valence electrons.
- Tue Nov 06, 2018 12:01 am
- Forum: Lewis Structures
- Topic: Lewis Structure for N2O
- Replies: 7
- Views: 1210
Re: Lewis Structure for N2O
Oxygen is more electronegative than nitrogen, thus nitrogen is the LEAST electronegative of the two and should be in the center.
- Mon Nov 05, 2018 11:52 pm
- Forum: Lewis Structures
- Topic: BH4-
- Replies: 2
- Views: 487
Re: BH4-
You can definitely place the negative charge on the central atom, just make sure to change the charge of the entire molecule as a whole as well.
- Mon Nov 05, 2018 11:50 pm
- Forum: Trends in The Periodic Table
- Topic: Electronegativity vs. Electron Affinity?
- Replies: 11
- Views: 1620
Re: Electronegativity vs. Electron Affinity?
Electronegativity is how well an atom can attract electrons towards itself while electron affinity is the amount of energy released when an electron is added to an atom.
- Sun Oct 28, 2018 2:33 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Ionization of elements
- Replies: 3
- Views: 320
Ionization of elements
Why do certain elements tend to have certain ions like Cu ---> Cu+ and Cu2+? but not Cu3+?
- Sun Oct 28, 2018 2:24 pm
- Forum: Trends in The Periodic Table
- Topic: Smallest ionic radius [ENDORSED]
- Replies: 6
- Views: 780
Re: Smallest ionic radius [ENDORSED]
Atomis radius increases down and to the left, and since they are all in the same Period you would check for which is closest the the right hand side to find the smallest.
- Sun Oct 28, 2018 2:20 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Quantum Numbers n, l, and m
- Replies: 5
- Views: 344
Re: Quantum Numbers n, l, and m
Spin up is +1/2 and spin down is -1/2.
- Sun Oct 28, 2018 2:16 pm
- Forum: Lewis Structures
- Topic: Electron configuration
- Replies: 1
- Views: 306
Re: Electron configuration
Electrons are always removed from the outermost shell because those are the electrons with the highest energy and are therefore the most unstable. 5s has more energy than 4d and therefore when Ru is ionized electrons are taken from the 5s orbital first.
- Sun Oct 21, 2018 1:13 am
- Forum: Einstein Equation
- Topic: Joules per photon?
- Replies: 5
- Views: 661
Re: Joules per photon?
I'm pretty sure leaving it as Joules would be considered correct units.
- Sun Oct 21, 2018 1:11 am
- Forum: Properties of Electrons
- Topic: Balmer vs Lyman Series [ENDORSED]
- Replies: 5
- Views: 539
Re: Balmer vs Lyman Series [ENDORSED]
Wavelengths in the ultraviolet band are always in the Lyman series and wavelengths in either the visible light spectrum or the solar spectrum are in the Balmer series.
- Sun Oct 21, 2018 12:54 am
- Forum: Properties of Light
- Topic: De Broglie's equation [ENDORSED]
- Replies: 7
- Views: 1148
Re: De Broglie's equation [ENDORSED]
Since light always travels at the speed of constant c, light is never at rest and therefore has zero rest mass. This is why photons have no rest mass and De Broglie's equation cannot be used.
- Tue Oct 16, 2018 12:17 am
- Forum: *Black Body Radiation
- Topic: Black Bodies and Temperature
- Replies: 2
- Views: 606
Black Bodies and Temperature
Why is it that as the temperature of a black body increases, the wavelength at which the max intensity is found decreases?
- Sun Oct 07, 2018 3:54 pm
- Forum: Limiting Reactant Calculations
- Topic: Textbook question M3 [ENDORSED]
- Replies: 1
- Views: 412
Textbook question M3 [ENDORSED]
When limestone, which is principally CaCO3, is heated, carbon dioxide and quicklime, CaO, are produced by the reaction CaCO3(s) --> CaO(s) + CO2(g). If 17.5g of CO2 is produced from the thermal decomposition of 42.73g of CaCO3, what is the percentage yield of the reaction? How would you go about fin...
- Sun Oct 07, 2018 3:36 pm
- Forum: Significant Figures
- Topic: Rounding molar mass on the periodic table
- Replies: 3
- Views: 1761
Rounding molar mass on the periodic table
Should you ever round molar mass from the periodic table based on sig figs or should you always use the given number without rounding?
- Sun Oct 07, 2018 3:33 pm
- Forum: Significant Figures
- Topic: Sig Figs & Molar Mass
- Replies: 4
- Views: 577
Sig Figs & Molar Mass
When figuring out sig figs do you include the sig figs of the molar mass of an atom?